Oh dear, now we have three peer reviewed papers (Lindzen and Choi, Spencer and Braswell, and now Richard P. Allan) based on observations that show a net negative feedback for clouds, and a strong one at that. What will Trenberth and Dessler do next? Maybe the editor of Meteorological Applications can be persuaded to commit professional suicide and resign? The key paragraph from the new paper:
…the cloud radiative cooling effect through reflection of short wave radiation is found to dominate over the long wave heating effect, resulting in a net cooling of the climate system of −21 Wm−2.
After all the wailing and gnashing of teeth over the Spencer and Braswell paper in Remote Sensing, and the stunt pulled by its former editor who resigned saying the peer review process failed, another paper was published last week in the journal Meteorological Applications that agrees well with Spencer and Braswell.
This new paper by Richard P. Allan of the University of Reading discovers via a combination of satellite observations and models that the cooling effect of clouds far outweighs the long-wave or “greenhouse” warming effect. While Dessler and Trenberth (among others) claim clouds have an overall positive feedback warming effect upon climate due to the long-wave back-radiation, this new paper shows that clouds have a large net cooling effect by blocking incoming solar radiation and increasing radiative cooling outside the tropics. This is key, because since clouds offer a negative feedback as shown by this paper and Spencer and Braswell plus Lindzen and Choi, it throws a huge monkey wrench in climate model machinery that predict catastrophic levels of positive feedback enhanced global warming due to increased CO2.
The cooling effect is found to be -21 Watts per meter squared, more than 17 times the posited warming effect from a doubling of CO2 concentrations which is calculated to be ~ 1.2 Watts per meter squared. This -21 w/m2 figure from Richard P. Allan is in good agreement with Spencer and Braswell.
[While the -21wm2 and ~1.2 W/m2 values are correct, the comparison is wrong, and it is my mistake. The values are Top of Atmosphere and Surface, which aren’t the same. This prompts a new rule for me, I shall not publish any posts after midnight again (other than something scheduled previously during the day), because clearly I was too tired to recognize this mistake. I’ll add that I have emailed Dr. Allan regarding the question of feedback on hisfigure 7, and have not received a response. – Anthony]
Here’s the paper abstract, links to the full paper (which I located on the author’s website) follow.
Combining satellite data and models to estimate cloud radiative effect at the surface and in the atmosphere
Richard P. Allan
Abstract: Satellite measurements and numerical forecast model reanalysis data are used to compute an updated estimate of the cloud radiative effect on the global multi-annual mean radiative energy budget of the atmosphere and surface. The cloud radiative cooling effect through reflection of short wave radiation dominates over the long wave heating effect, resulting in a net cooling of the climate system of -21 Wm-2. The short wave radiative effect of cloud is primarily manifest as a reduction in the solar radiation absorbed at the surface of -53 Wm-2. Clouds impact long wave radiation by heating the moist tropical atmosphere (up to around 40 Wm-2 for global annual means) while enhancing the radiative cooling of the atmosphere over other regions, in particular higher latitudes and sub-tropical marine stratocumulus regimes. While clouds act to cool the climate system during the daytime, the cloud greenhouse effect heats the climate system at night. The influence of cloud radiative effect on determining cloud feedbacks and changes in the water cycle are discussed.
1. Introduction
Earth’s radiative energy balance (solar radiative energy absorbed and terrestrial radiation emitted to space) determines current patterns of weather and climate, the complexity of which is illuminated by satellite observations of the evolving distribution and diversity of cloud structures. Representing clouds and the physical processes responsible
for their formation and dissipation is vital in numerical weather and climate prediction, yet many approximations must be made in these detailed models of our atmosphere (e.g. Bony et al., 2006; Allan et al., 2007). Observations of cloud characteristics from satellite instruments and in situ or ground-based measurements are crucial for improving understanding of cloud processes and their impact on Earth’s radiative energy balance (Sohn, 1999; Jensen et al., 2008; Su et al., 2010). The energy exchanges associated with cloud formation and precipitation are also a key component of the global water cycle, of importance for climate change (Trenberth, 2011). In this paper, initially presented at a joint meeting of the Royal Meteorological Society and Institute of Physics on Clouds and Earth’s Radiation Balance (Barber, 2011), the utility of combining weather forecast model output with satellite data in estimating the radiative effect of cloud is highlighted. Using a combination of models and satellite data a simple question is addressed: how do clouds influence the radiative energy balance of the atmosphere and the surface.
As an example of the radiative impact of cloud, Figure 1 displays thermal infra-red and visible channel narrow-band images of the European region from the Spinning Enhanced Visible and Infra-Red Imager (SEVIRI) on board the Meteosat-9 satellite (Schmetz et al., 2002).
In both images clouds appear bright: this denotes relatively low infra-red emission to space and relatively high reflection of visible sunlight to space. The hot, generally clear regions of northern Africa are also noticeable in both images since they are associated with substantial thermal emission to space (dark regions in the infra-red image) and high surface reflection from the desert surface (bright in the visible image). The brightest clouds in the thermal image correspond with (1) a trailing cold front extending from the coast of Norway, across Scotland and to the west of Ireland, (2) a developing low pressure system to the west of Iceland, and, (3) a low pressure system in the Mediterranean centred on Sardinia.
These are regions of ascending air with relatively high altitude, low temperature cloud tops which depress the thermal emission to space compared with surrounding regions. These features are also present in the visible image. However, many more cloud structures are also present. There is a prevalence of low altitude cloud over the oceans: this cloud contains large amounts of water droplets which are highly reflective (e.g. Stephens et al., 1978). The imagery captures the complex cellular structure of this cloud (e.g. Jensen et al., 2008) over the region surrounding the Canary Islands. These cloud types are thought to contribute strongly toward uncertainty in climate projections (Bony et al., 2006). While these clouds also strongly attenuate infra-red radiation, their impact on the thermal radiation escaping to space is modest since cloud-top temperatures are not dissimilar to the surface at night and so they do not contribute significantly to the strong natural greenhouse effect of the clear-sky atmosphere.
The altitude and optical thickness of cloud determines the overall radiative impact of cloud, a combination of the warming greenhouse effect and the surface-cooling solar
shading effect. Yet, probably an even stronger influence does not relate to the cloud itself. The time of day and time of year dictate the incident solar radiation and, therefore,
modulates the strength of the short wave reflection: clearly at night the solar influence of cloud is absent.
…
7. Conclusions
Exploiting satellite measurements and combining them with NWP models initialized through assimilation of available observations enables the effect of clouds on the Earth’s radiative energy balance at the surface and within the atmosphere to be quantified for the present day climate. Consistent with previous results (Ramanathan et al., 1989; Su et al., 2010), the cloud radiative cooling effect through reflection of short wave radiation is found
to dominate over the long wave heating effect, resulting in a net cooling of the climate system of −21 Wm−2.
The short wave radiative effect of cloud is primarily manifest as a reduction in the solar radiation absorbed at the surface of −53 Wm−2 for the global multi-annual mean. The magnitude of this effect is strongly modulated by the incoming solar radiation and the dominance of cloud short wave cooling over long wave greenhouse trapping is maximum around local noon (Nowicki and Merchant, 2004) while the cloud long wave heating effect dominates at night.
The long wave greenhouse effect of cloud measured at the top of the atmosphere is manifest primarily as a heating of the atmosphere in the moist tropics, consistent with calculations by Sohn (1999).
Over the marine stratocumulus regions and across higher latitudes the cloud-base emission to the surface becomes substantial and dominates over the reduced outgoing long wave radiation to space resulting in enhanced radiative cooling of the atmosphere and heating of the surface. The cloud radiative influence on the exchange of radiative fluxes between the atmosphere and the surface are intimately linked with the water cycle through radiativeconvective balance. While tropical, high-altitude clouds act to stabilize the atmospheric profile radiatively, clouds over polar regions tend to cool the atmosphere while heating the surface through enhanced atmospheric longwave radiative emission to the surface. In future work it would be informative to categorize these effects by cloud type further (e.g. Futyan et al., 2005) and compare with climate model simulations. These analyses are vital in constraining cloud feedback processes further and in linking to future changes in the water cycle (Stephens, 2005; Bony et al., 2006; John et al., 2009).
A particular challenge is the accurate quantification of surface radiative fluxes due to the sparse ground-based observing network (Roesch et al., 2011) and also monitoring current changes in cloud radiative effect in satellite data, reanalyses and models (Wielicki et al., 2002); combining meteorological reanalyses with satellite data and surface observations provide a vital methodology for meeting these challenges.
Abstract is here: http://onlinelibrary.wiley.com/doi/10.1002/met.285/abstract
Full paper is here: http://www.met.reading.ac.uk/~sgs02rpa/PAPERS/Allan11MA.pdf
UPDATE: Some people in comments including Dr. Roy Spencer, (and as I was writing this, Dr. Richard Allan) suggest that the paper isn’t about feedback (at least in the eyes of IPCC interpretations, but Spencer adds “it could be”). Thus I’ve removed the word from the headline to satisfy such complaints. My view is that clouds are both a feedback and a forcing. Others disagree. That’s an issue that will occupy us all for sometime I’m sure.
Regarding cloud feedbacks, here’s what I noted in the paper in section 6, near the end. Allan is referring to figure 7 which shows (a) net radiation and (b) net cloud radiative forcing:
Substantial negative anomalies in net radiative flux from ERA Interim are apparent in 1998 and 2010, both El Niño years, suggesting that the substantial re-organization of atmospheric and oceanic circulation systems act to remove energy from Earth during these periods.
You can clearly see the famous double peak in the 1998 El Niño, but it is inverted. To me that looks like a thermostat action, and not one with stuck electrical contacts, i.e. a negative feedback. I’ve also updated the text related to the incorrect comparison I made. – Anthony
Nonsense.
If this were true then when the clouds covered the sun you would feel colder…oh, hang on a minute…
but I thought the science was settled………………………………….
Having stood under the odd cloud, tropical and extra-tropical, in my 60 years, I’m shocked that it has taken people this long to work out 🙂
Funnily enough – it’s often cooler!
Wait for it, the author will be denounced at any moment as a meat eating anti-science rabid believer in Creationism, whose work cannot be trusted because he has a happy home life, is married and cares for his children … or something of the sort.
Given that this work seems to support the recent discoveries at CERN and the theories developed by an Australian scientist described as a Meteorologist and Physicist in 1939, I expect we will now see a frantic attempt to rubbish this work and bury it in an avalanche of vague accusations and nit-picking. I sincerely hope that both the editor of this journal and his peer reviewers have the courage to fight back.
Another arrow in the elephant. It’s starting to look like a pincushion now.
Oh noes! Not another Allan from Reading. We have Allen (Perce) and Allen (JRL) already.
So if clouds are such a strong negative feedback, how come we aren’t in a permanent ice age?
So science agreeing with observation that a cloudy day is cooler than a sunny one.
Wonderful.
Science and research often seem silly. There are often popular science news items that report things that everyone knows already, and lots of things that beggars belief that anyone is paid to research such things. This cloud thing, for all its controversy, seems a bit like this.
When I stand on the beach and the sun shines I feel hot, and when it is too hot I like it when the clouds come over for a while. All that energy that was burning me has got to go somewhere else and the only thing that changed was the cloud coming between the Sun and me. Isn’t it obvious that the more cloud we have the less the Earth will heat up?
For all it’s ability to reflect a narrow band of radiation, CO2 cannot generate any heat, only reflect a bit of it and keep things from cooling down as fast as they otherwise would.
Isn’t this obvious?
oops
Well, well, dig a little deeper and we find the Spencer-Braswell paper isn’t so far off after all. This should be an interesting day. Dessler will be pulling his hair out, among others, in frustration. Wonder what kind of emails the editor at Met Apps is going to get?
So they found the missing heat! It’s not missing just going back into space.
Trenbeth is going to have to play whack-a-mole
We may be approaching a tipping point. Or at least a wobbling point.
Comparing the Spencer and Allan papers is like comparing Apples and Oranges.
[you may wish to expand on your statement so as to help others understand the point you are making . . ]
Perhaps that is why solar panels do not work well on cloudy nights.
Surely this paper is not acceptable as the empirical findings disagree with the models? Does not this indicate a singular failure of peer review and gross professional misconduct on the part of the editor? Obviously a job for the CAGW Inquisition. /sark off
PS. Anyone running a book on the speed with which a peer-reviewed rebuttal will appear?
How about starting a sweepstake on how quickly Dessler or Trenberth can get out a new critical paper? By the way, here in UK today it is cloudy and it definitely doesn’t feel like the clouds are helping to warm things up.
The Team will never accept this! The Team will be frothing at the mouth by the time this is over–and I predict as more and better observations are made, their relevance will decline and The Team will finally slip away into obscurity–which is about time!
Gosh, I wonder if the $Billions they’ve wasted on their nefarious scheme will constitute an epic example of moral terpitude*?
I certainly think so! As evidence, I submit the following:
*Synonyms: abjection, corruptness, debasement, debauchery, decadence, decadency, degeneracy, degenerateness, degeneration, degradation, demoralization, depravity, dissipatedness, dissipation, dissoluteness, libertinage, libertinism, perversion, pervertedness, rakishness, corruption http://www.merriam-webster.com/dictionary/turpitude
Three peer reviewed papers that agree, we have consensus, so the science is settled then 😉
Oh, WOW!
What a killer punch, a perfect one-two with Spencer-Braswell. And just in time for inclusion in IPPC5. These two papers are going to seriously rattle a few cages in the Warmista camp, where the wagons are no doubt being circled right now. To mix in another metaphor, I doubt that all this evidence is going to cause any Team member to come out with their hands up just yet; but I’ll bet that one or two of them are starting to think about it.
I just looked at Richard Allen’s CV. He is A List Climate Science.
Methinks the Team would prefer to be having root canal treatment without anaesthetic about now.
Me also thinks that the term “denier” is heading back where it belongs
The trickle becomes a rivulet.
Keep the science coming and let it talk.
Anthony,
Could you please point out where in this paper it is mentioned that “clouds have large negative-*feedback* cooling effect on Earth’s radiation budget”?
I may be wrong, but I think you’re confusing two issues:
– the net effect of clouds on climate
– the net feedback of clouds on a change in climate
The paper, as I read it with a first quick overview, addresses the first, whereas you interpret it as if it addresses the second.
They are two distinctly different issues. The second (clouds as feedback) is about how cloud cover and properties might change in response to a warming or cooling of the climate: Will the net cloud radiative effect become more or less negative.
The net radiative effect of clouds on climate has long been known to be negative (i.e. cooling). See e.g this quote from the paper: “The overall global net cloud radiative effect is one
of cooling as documented previously (Ramanathan et al., 1989).” That can be verified in any textbook on the subject and most introductions of papers on this topic.
See also http://ourchangingclimate.wordpress.com/2009/04/16/aerosols-clouds-and-climate/
REPLY: Thanks, I can see where you’re coming from, but I saw things differently. See the update I posted at the end of the article. – Anthony
I set the over/under on the publication of a rebuttal at 12 hours…
You are confusing forcing with feedbacks.
Oh dear indeed.
“If this were true then when the clouds covered the sun you would feel colder…oh, hang on a minute…”
And cloudy nights would feel colder than clear nights …. oh!
An interesting site – always nice to have additional view-points and information and an ability to partake in open discourse.
Thanks, cheers…
The link at the end of the “[t]his -21 w/m2 figure from Richard P. Allan is in good agreement with Spencer and Braswell” sentence goes to an article about Dessler instead. — John M Reynolds
James said, ‘And cloudy nights would feel colder than clear nights….oh!’
But there is no sun at night so no heat source for the clouds to block.
I think you’ve jumped the gun on this. The -21 W/m^2 is not feedback — which would typically be in the units of W/m^2/K — but the overall effect of clouds. In a quick scan of the paper, it appears that they didn’t find much of a trend in radiative forcing due to clouds over the period studies — but a back-of-the-envelope estimate of the size of any expected trend over that period (due to feedback) would be small and probably not discernible within the noisiness of their charts.
They do say this: “Substantial negative anomalies in net radiative flux from ERA Interim are apparent in 1998 and 2010, both El Ni˜no years, suggesting that the substantial re-organization of atmospheric and oceanic circulation systems act to remove energy from Earth during these periods.”
James says:
September 20, 2011 at 4:03 am
Did you forget that the sun doesn’t shine at night?
Duh!
Re: Apples and Pears: Spencer (and Dessler as well) are interested in the feedbacks between clouds and temperatures. Allan (so far) doesn’t care too much for temperature or feedbacks. He just updates some (two) of the numbers in Trenberth’s “global annual mean Earth’s energy budget”. For example, his net cooling effect is 8 W/m² larger than the one in table 3.1 of the IPCC-FAR in 1990.
John Marshall says:
“So science agreeing with observation that a cloudy day is cooler than a sunny one”
and a cloudy night is warmer then a clear sky night.
.
Ah clouds, too nebulous and foggy for the absolutists to comprehend…
This paper does not appear to say what is claimed by Mr. Watts. That is, the -21 W/m2 is a mean net forcing “for the present day climate” (as the paper says.) By contrast, the cloud feedback effect under discussion by Dessler and Spencer (among others) has to do with changing radiative forcings and how cloud would respond. “Feedback diagnosis” (to use Spencer’s term) is challenging because–as this paper notes–the most direct ways of figuring out how clouds affect must immediately confront the diversity of cloud types, locations, and even times, all of which affect the clouds’ net effect.
Note that the paper says that its results are “Consistent with previous results (Ramanathan et al., 1989; Su et al., 2010).” Don’t know about Su et al., but Ramanathan is AGW mainstream as you can get. And I note, too, that one of the most iconic images in climate science (the Kiehl-Trenberth-Fasullo energy budget diagram) gives the shortwave forcing of clouds as -79 W/m2–so (amazing, isn’t it?) climate science has not hitherto neglected the cooling effect of daytime cloud–contrary to what some commenters above have allowed themselves to believe.
Bart is correct. This paper is not about cloud feedback…it is about the average effect of clouds on the climate system, which the IPCC, Trenberth, Dessler, et al. will all agree is a cooling effect. It is an update of the early estimates from ERBE many years ago.
Feedback is instead how clouds will change in response to a temperature *change* from the average climate state.
Now, it might well be that since the average effect of clouds on the climate system in response to radiative heating by the sun is to cool the Earth, then a small increment in radiative heating (e.g. from more CO2) will ALSO result in clouds having a further increment in cooling. That’s basically what Monckton has been claiming, and he might well be correct. Lindzen pointed this out also in his 1990 BAMS paper.
I just wanted to point out that the IPCC view is that this paper is not about cloud feedback….even though it might be about cloud feedback. 😉
REPLY: Thanks Roy for the clarification. The question of whether clouds act as feedback, forcing, or both is one that will occupy us as a while. My interpretation is as both, they act as a forcing (albedo) and as a feedback via the water vapor cycle, see Willis: Further Evidence for my Thunderstorm Thermostat Hypothesis
See the update I’ve posted.
– Anthony
James:
In the full paper, Allan states that clouds will warm nights, although it will cool days.
If the calculations are verified, it’s good news for climate. But I don’t see that it challenges any prevailing understanding: The fact that clouds reflect sunlight although they hold in infrared is well known, and is why the magnitude and even the sign of the cloud feedback has been allocated a high degree of uncertainty. It will be interesting to see the reaction in the literature: Whether it enables the models to home in on a more restricted range of parameters.
Just to clarify a point on the cause/effect issue.
My view is that latitudinal air mass shifting (and thus cloudiuness and albedo changes on a global scale) will occur from either or both of:
i) A top down change in solar activity altering the vertical temperature profile of the upper atmosphere above the tropopause.
ii) A bottom up change in the rate at which oceans release energy to the air altering the temperature differential between surface and tropopause.
In practice both effects are competing with one another all the time with the latitudinal shift constantly adjusting to maintain the overall energy budget by changing the speed of the water cycle. That shifting is always a negative system response.
In consequence it will be very hard to separate cause and effect as regards cloudiness and albedo changes.
Solar influences will disguise oceanic effects and vice versa.
However I would suggest that overall the cloudiness changes are a result of latitudinal shifts and those shifts arise from the combined net effect on the energy budget from the solar and oceanic forces.
Poleward shifts cause decreasing cloudiness overall by widening the equatorial high pressure cells either side of the ITCZ and thereby increasing the speed of the water cycle globally.
Equatorward shifts cause increasing cloudiness overall so that the equatorial high pressure cells shrink thereby decreasing the speed of the water cycle globally.
That is clearly the opposite of initial expectations because one would normally anticipate that a faster water cycle would involve more clouds but that appears not to be the case due to the latitudinal shifting.
I think the best way to explain it is to point out that when the jets are more poleward they become more zonal with a greater temperature contrast between polar and equatorial air masses and more vigour in the zonal flow. That increased vigour increases the speed of the water cycle by more than the reduced cloudiness decreases it. In effect the faster water cycle is concentrated into smaller areas.
In contrast when the jets are more equatorward they become more meridional with a reduced temperature contrast between polar and equatorial air masses for less vigour in the zonal flow. Thus one then sees a slower water cycle but more clouds overall for the opposite effect.
That results in a faster water cycle offsetting warming from whatever cause and a slower water cycle trying to reduce energy loss offsetting cooling from any cause (but only temporarily because energy reflected never gets into the system in the first place).
Phil Clarke says “Oh dear indeed” … in regard to confusing forcing and feedbacks. That one of the best under-statements one could possibly respond with!
Set that against the original post’s language which starts with “Oh dear …” and then goes on to say:
“… can be persuaded to commit professional suicide and resign?”
“… all the wailing and gnashing of teeth …”
“… the stunt pulled …”
“… machinery that predict catastrophic levels of positive feedback …”
The gentle contrast with error illumination is splendid.
REPLY: What I think is splendid is figure 7, which shows an elegant relationship, have a look. Show me where there’s positive feedback demonstrated there and the next time I’m in the UK I’ll look you up and buy you a beer. – Anthony
@James,
I didn’t know anyone was proposing that the Earth got warmed by the Sun at night.
When the clouds are gone at night I also notice that the CO2 doesn’t seem very effective at keeping the warmth in. I know, it is just obvious, but to conclude the obvious, In the daytime clouds keep more heat out and at night they keep more heat in – can I have a Ph.D now?
Phil and James,
So it seems CO2 can tell the time as well now, only producing clouds at night and not during the day?
Did I get that right?
Well, I guess we all knew cloudy days are cooler and cloudy nights are warmer, but now that has been quantified. An important step in determining whether these values change in response to some stimuli like cosmic rays or temperature.
If you look at figures 3 and 4 in the paper you’ll see the equator very pronouncedly negative, I wonder if this is Willis’ thermostat in action.
Those saying that this paper is not addressing the feedback issue may be missing the point. For the strongly positive water vapour feedback demanded by the IPCCs doom scenarios to work, the increased evaporation would need to be prevented from causing more clouds. This is not plausible in an atmosphere with a vertical pressure gradient.
Bart Verheggen says:
September 20, 2011 at 3:59 am
As the overall climate warms, cloud cover will increase (the earth has a surface disproportionately covered in water, which rate of evaporation is proportional to the temperature). As the overall climate cools, cloud cover will decrease (the oceans provide less moisture to the air, hence less source for clouds).
Are you saying the earth will have more clouds with less atmospheric moisture? That’s an illogical conclusion. More clouds–more radiative effect; less clouds–less radiative effect (daytime radiative impact far exceeds that at night). It’s a self modulating system that can easily dissipate any additional heat man’s activities may generate.
lol, out with the forcing/feedback meme. Predictable, is suppose. One step at a time I suppose.
Ladies, we’re told CO2 provides extra warming, causing climate change. You can call it a forcing if you desire, but its really a feedback in the truest sense in a few different perspectives. Now, we’re learning clouds have a cooling effect. You can call it a feedback if you wish. The point is, I no of no model that properly accounts for the cooling the clouds provide. But, that’s not the interesting point. What will be interesting is to watch the warmista contort themselves trying to explain how warming won’t increase cloud cover. Then tell us how that wont cool the planet. Then explain again what a forcing is. Symantics, I love that part of the debate. phhtt.
Anthony, your link that states, “…..in good agreement with Spencer and Braswell. Here’s….” provides a link to some Dessler ramblings, here. http://www.sciencedaily.com/releases/2010/12/101209141231.htm I could be wrong, but I don’t believe that’s what you wanted to show when one would click on the link.
Bart Verheggen says: (September 20, 2011 at 3:59 am)
“Anthony,
Could you please point out where in this paper it is mentioned that “clouds have large negative-*feedback* cooling effect on Earth’s radiation budget”?
I may be wrong, but I think you’re confusing two issues:
– the net effect of clouds on climate
– the net feedback of clouds on a change in climate
The paper, as I read it with a first quick overview, addresses the first, whereas you interpret it as if it addresses the second. ”
From the abstract: “The influence of cloud radiative effect on determining cloud feedbacks and changes in the water cycle are discussed.”
Perhaps I read that incorrectly.
Oh dear, I think this is really going to cloud the issue…
Sorry could.. not… resist….
Bart Verheggen says:
September 20, 2011 at 3:59 am
I may be wrong, but I think you’re confusing two issues:
– the net effect of clouds on climate
– the net feedback of clouds on a change in climate
The paper, as I read it with a first quick overview, addresses the first, whereas you interpret it as if it addresses the second.
They are two distinctly different issues. The second (clouds as feedback) is about how cloud cover and properties might change in response to a warming or cooling of the climate: Will the net cloud radiative effect become more or less negative.
Bart, put down that goalpost and do some thinking.
http://tallbloke.wordpress.com/2011/09/17/cloud-albedo-what-does-it-respond-to
Verheggen: “Will the net cloud radiative effect become more or less negative”
Thought you and your compadres knew?
“While clouds act to cool the climate system during the daytime, the cloud greenhouse effect heats the climate system at night.”
As I’ve been saying for years… higher nightime lows without higher daytime highs is a great boon to agriculture especially when the effect is primarily in higher latitudes. This greatly lessens the chance of unexpectedly late killer frosts in the spring and unexpectedly early killer frosts in the fall. It can spell the difference between one and two crop cycles per growing season and for more extreme places like Greenland the difference between being able to grow and harvest silage for livestock and not being able to raise livestock.
Add to this the well known benefits of CO2 enrichment in accelerating plant growth rates and making them more efficient in water use.
Then one last benefit to living things of a warmer earth is having a larger safety margin against the day when things like earth-cooling volcanic eruptions conspire with a grand solar minimum to end the current interglacial period.
At the end of the day there’s little not to love about rising atmospheric CO2. It makes for a greener earth and a greener earth is what we all want, right?
James says:
September 20, 2011 at 4:03 am
“If this were true then when the clouds covered the sun you would feel colder…oh, hang on a minute…”
And cloudy nights would feel colder than clear nights …. oh!
In the day the sun is the heat source at it it’s the earth!
Typo Correction
James says:
September 20, 2011 at 4:03 am
“If this were true then when the clouds covered the sun you would feel colder…oh, hang on a minute…”
And cloudy nights would feel colder than clear nights …. oh!
In the day the sun is the heat source at night it’s the earth!
This was actually already known, it just wasn’t widely known or promoted by the pro-AGW scientists for obvious reasons.
The climate models project that this -21 W/m2 (might be as high as -30 W/m2) and project that it will turn into -20 W/m2 in a doubling scenario. So it is projected as a net +1.0 W/m2 feedback, about half of the feedbacks shown by the IPCC in its most recent report.
This is an illogical result in that more clouds (also predicted) should be even more negative rather than less negative. Having this feedback be +2 W/m2 or -2 W/m2 will be a make or break feature in the global warming debate and, hence, the spirited response to Spencer and Braswell from Trenberth, Dessler and the Team.
I’m confused as to some of the details in this paper. Clearly there is not a -21 W/m^2 forcing on the climate that is unaccounted for. That level of negative forcing would bring on a severe ice age (which come from negative forcing from changes in albedo on the order of 4 W/m^2, if I’m remembering it correctly).
How is that -21 W/m^2 number reconciled with the net cloud forcing (NCF) in figure 7? If I just fit the anomalies by eye, I seem to get 0 W/m^2, except for the Pinatubo eruption and the last few years of data
Concerning the last few years, it seems to me that from the data shown in Figure 7 that the net forcing is on the order of -1 W/m^2. This would seem to be enough to counteract the equivalent forcing from greenhouse gas emission. I would imagine that this is related to the leveling off of temperature rise in that same period and also related to the increase of water in the atmosphere, as indicated by the floods and snowfall experienced globally.
Anyone who lives in a normally hot dry climate knows clouds can make a huge difference in temperatures.
When clouds occur in summer in interior Western Australia, daytime high temperatures drop from the usual 40C to 20C or less.
BTW, they are assuming clouds operate as a feedback. Clouds could equally well be a primary driver of climate (ref GCR). Although of course operating as a feedback as well.
Bart Verheggen says:
September 20, 2011 at 3:59 am
“The net radiative effect of clouds on climate has long been known to be negative (i.e. cooling). See e.g this quote from the paper: “The overall global net cloud radiative effect is one
of cooling as documented previously (Ramanathan et al., 1989).” That can be verified in any textbook on the subject and most introductions of papers on this topic.”
I’ve long suspected that the GCM authors didn’t have any basic textbook knowledge of how clouds effect the climate, or the subtleties of the water cycle in general otherwise they couldn’t have proposed their ballyhooed water vapor amplification with a straight face. Thanks you for confirming their ignorance. Spread the word.
Anthony, you’ve misunderstood the term ‘feedback’. I think you would have been better off with the notes that Richard Allan gives out for his ‘climate change’ course before jumping in at the deep end!
James says:
September 20, 2011 at 4:03 am
“If this were true then when the clouds covered the sun you would feel colder…oh, hang on a minute…”
And cloudy nights would feel colder than clear nights …. oh!
I think you meant to say that cloudy nights would feel warmer than clear nights.
Criminogenic, were not in a permanent ice age for 2 reasons:
1. if CERN is correct, then the cloud cover varies by intensity of the sun’s activity
2. cooler = less evaporation = less available water vapor for creating clouds.
Thus, in clouds, we have a self-regulating system with the absolute setting determined by the input of the sun, the relative setting determined by water vapor availability.
Bart, I see it this way.
If the net effect of a square kilometre of cloud is negative, then in a warmer world with more moisture and therefore more cloud, the feedback also has to be negative.
Put it another way. If the current cloud cover is say 20% (and is nett cooling) and a warming world will increase this to 22% then the feedback from this will be increased cooling.
While science frequently makes discoveries contrary to common sense
‘Knowledge’, here is a case where common sense was in the vanguard.
Everyone under the sun KNEW clouds have a cooling effect.
A victory for common sense and empiric data, ( I feel therefore I am.)
Yay!
A nicely modulated system!
During colder cycles:
cooler atmosphere => less ocean evaporation => less cloud cover = gradual warming
During warmer cycles:
warmer atmosphere => more ocean evaporation => more cloud cover = gradual cooling
Who’d a thunk it.
Hmm – more surface heat = warmer = more evaporation = more clouds = less heat = cooler. Limits imposed by the thermodynamics of water on Earth and what hits us from the sun. Kind of what you’d expect, unless you get reductionist science running unchecked with a healthy dose of political agenda.
Time to consign ‘climate’ to the geography books folks…about time too. How much wasted money and how much of a tarnish for Science and peer-review?
I found this statement in the abstract curious:
While clouds act to cool the climate system during the daytime, the cloud greenhouse effect heats the climate system at night. The influence of cloud radiative effect on determining cloud feedbacks and changes in the water cycle are discussed.
(It’s near the end of the abstract.)
I thought clouds prevented heat loss i.e. performed as insulation or a reflector of IR if you will. I did not think that they were a source of energy — i.e. could “heat” the earth.
An interesting paper in light of the recent controversy. Looking forward to the obits…
criminogenic says:
September 20, 2011 at 3:05 am
“So if clouds are such a strong negative feedback, how come we aren’t in a permanent ice age?”
Indeed. At current CO2 level the earth, for the past several million years, has been cycling between 100,000 years of glacial advance and 10,000 years of glacial retreat. 280ppm CO2 clearly isn’t enough to keep the earth out of an ice age. The average temperature of the global ocean is 3.9C which is a reflection of the average surface temperature over the course of a full glacial/interglacial cycle.
Affirming these basic facts about the earth’s climate during the past several millions leads any reasonable, informed person to not ask “Is there too much anthropogenic CO2 in the atmosphere” but rather ask “Is there enough anthropogenic CO2 in the atmosphere?”. My feeling on the matter is that if burning fossil fuels wasn’t adding some badly needed warmth to this planet we’d have to invent some other way to do it lest the last 10,000 years of advance in human civilization be destroyed by massive glaciation over most of the northern hemisphere.
Like duh. It isn’t global warming we should be worried about – global cooling is the real destroyer of life and unless something has changed history is going to repeat itself right on time as interglacial periods haven’t lasted very long anytime in the past several million years. The current interglacial is long in tooth already and the Milankovich cycle is still advancing on the sweet spot favoring glacial advance and won’t reach it for a few thousand years yet. In the meantime the first unpredicatable perfect storm of earth-cooling volcanic eruptions during a solar grand minimum is going to be the straw that breaks the modern interglacial’s back. The modern solar maximum appears to have ended and solar physicists are now predicting a solar minumum is on the way but just how minumum is something they don’t know. If the GCR hypothesis is correct this is not good. We might want to think about sacrificing some virgins to the volcano gods just in case. I’ve got some nerdy climate boffins in mind for the role of sacrifical virgins.
David Wright@3.52
I also suspect they won’t come out with their hands up but they may well have a labyrinth of tunnels and sympathisers with spider holes. Where do you reckon we go searching first? The polar regions or the Maldives?
@Dave Springer
“While clouds act to cool the climate system during the daytime, the cloud greenhouse effect heats the climate system at night.”
How can this be true? There is no energy or energy source to heat the earth at night? only to retain more of what was there in the day time.
The Royal Meteorological Society published this paper. That will make the task of character assassination a bit more difficult for the team.
Erik Ramberg says:
September 20, 2011 at 5:44 am
“I’m confused as to some of the details in this paper. Clearly there is not a -21 W/m^2 forcing on the climate that is unaccounted for. That level of negative forcing would bring on a severe ice age (which come from negative forcing from changes in albedo on the order of 4 W/m^2, if I’m remembering it correctly).”
What you’re confused about is the behavior of systems with negative feedbacks. More clouds lowers average daily surface temperature. The lower surface temperature decreases cloud formation. Decreased cloud formation allows more daytime heating. More daytime heating produces more clouds. An equilibrium point is thereby established. The water cycle makes surface temperature self-regulating. The only “tipping point” we’re near is tipping away from the interglacial period. Snow and ice are not self-regulating. Once permanent snow cover starts advancing down northern hemisphere continents it becomes a vicious cycle where more southerly snow reflects more surface-warming sunlight and this breeds even more snow. The end result, which has happened a great many times with alarming regularity over the past several million years is the liberal northeastern United States being buried under a mile of ice – which just goes to prove that every cloud has a silver lining…
Erik Ramberg: that’s because Figure 7 is ‘anomalies’, which are changes from the average. i.e. the average (21 W m-2) has been taken away from each of those values!
This is the mistake Watts has made in this article, which should be rewritten or retracted immediately. A forcing is a change in heating – there hasn’t been a 21 W m-2 change in clouds recently, it’s just all the clouds we have today contribute 21 W m-2. If you took them away and kept everything else magically constant then you would get 21 W m-2 of warming.
If Watts wants clarification he can email Dr Allan.
The paper does NOT say that cloud FEEDBACK is negative.
Clouds are, and always have been, a negative FORCING (specifically, the negative effect on SW exceeds the positive effect on LW, with the net effect being negative). This paper attempts to quantify the net forcing effect and analyze it by time of day and location.
The question of cloud feedback is the first derivative of this net forcing with respect to changes in temperature. This raises a whole host of important questions:
– Does a change in temperature lead to more clouds or fewer?
– During the day or at night? At high or low altitudes? At high or low latitudes?
– Do individual clouds have larger water droplets or smaller?
– Is there an impact on cloud convection, evaporation or condensation?
– What is the net effect of all these (and other) possible changes?
Once those questions can be addressed, we might have a sense of whether cloud feedback is positive or negative. Until then, I’m in the “I don’t know” camp (though my uneducated guess would be that cloud feedback is probably negative).
Dave Springer:
“Like duh. It isn’t global warming we should be worried about – global cooling is the real destroyer of life ”
That’s like saying “it’s not overeating we should be worried about, but undereating?”, “it’s not underdosing we should be worried about, but overdosing?”
Philip Bradley says:
September 20, 2011 at 5:45 am
Yes, Eschenbach’s thunderstorm model accurately describes what happens daily from May through September in central Florida. Between 3 and 5 PM, the temperature can drop from 100 to 80 degrees Fahrenheit. Cloud cover alone can lower the temperature by 10 degrees. Most people do not understand this. If you haven’t lived in Florida (or the equivalent), you do not know sunshine.
I think Barghumer is correct. During the day, clouds have a net cooling effect. At night, even if clouds were a perfect insulating blanket, they could only retain what had not been reflected. So, from basic physics (conservation of energy), there doesn’t seem to be any way that clouds can increase the temperature of the earth – their net contribution must be negative. What have I missed?
WillR:
Clouds don’t provide the heat, but they change the heat balance, leading to a net increase in heat at the surface. The heat is all ultimately provided by the Sun (plus piddly bits from geothermal, cosmic rays & tidal).
In common science parlance something which causes a net heating can be just said to be heating it.
BargHumer says:
September 20, 2011 at 6:08 am
Don’t get all pedantic on me. It’s clumsy to say, in an informal blog environment, that nightly lows become higher than they would be otherwise. I understand that CO2 doesn’t produce energy. It works as one way insulation through the properties of being transparent to visible light from the sun and opaque to infrared light leaving the earth’s surface.
Wow, that’s pretty much èverything skeptics have suspected, but here we have real datapoints to back up our hunches.
The paper took five minutes to download, so people must be hammering the Reading server hard.
Isn’t this directly counter to what Dessler was saying?
Willis should be very interested in Section 5.
Roy W. Spencer says: “Bart is correct. This paper is not about cloud feedback…it is about the average effect of clouds on the climate system, which the IPCC, Trenberth, Dessler, et al. will all agree is a cooling effect….”
Thanks, Roy, for confirming what I thought I had read. And thanks for the further expansion/explanation.
I know. The ice cap over Holland is already a mile thick.
@WillR and Dave Springer,
Apologies for being pedantic (it’s in my nature).
I know all things are relative, but less cooling, less loss of heat, may be said to be “net” heating but it is misleading and contributes to the confusion in the debate. There is no heating (other than the piddly bits). Losing less money means I have more to spend but I don’t gain money, I just lose less.
Lets seee…
Rebuttal in GRL by Trenberth and Dessler on the article… accepted the 20th of September..reciewed the 21.. peer review… in blanco the the 22nd
“Siliggy says:
September 20, 2011 at 3:35 am
Perhaps that is why solar panels do not work well on cloudy nights.”
WRONG. Solar panels work very well at night because the taxpayer subsidies allow owners to run diesel powered generators to run lights to power the solar panels and still make a profit by selling electricity at five times normal rates back to the national grid.
I see a number of comments along the lines that: It gets cool when the sun is blocked by a cloud. This is true, but in and of itself, not sufficient to prove negative feedback. It also cools slower on a cloudy evening. The radiating area of the planet is 4 times the absorbing. This research shows that the net of these is negative. I don’t see any discussion in the paper of the impact of cloud absorbance of incoming radiative energy, only reflectance, hence I think an effect is being missed.
Bert Verheggan would seem to have a point. The net effect of clouds is to cool. Will the net effect of a 0.67% increase in temperature (i.e. 2 celsius degrees) result in more clouds (negative feedback) or fewer clouds (positive feedback) or same clouds (no feedback). I don’t see anything in the paper that addresses this.
I suggest that further radiative measurements may not be necessary. We now have daily sattelite images from the entire planet. We could, with relative ease, measure cloud cover for a statistically significant number of unit areas for a statistically significant period of time and see if there are more clouds when it is warmer (negative feedback) or fewer clouds when it is warmer (positive feedback) or no correlation between clouds and temperature (no feedback). I’m thinking that this would be relatively easy to automate.
JE
This is exactly what I found when analyzing Australian temperature records at http://gustofhotair.blogspot.com/
In that clouds have a negative effect on temperature, mores during the middle of the day, and increase temp at night.
Interestingly the amount of cloud cover in Australia has decreased which accounts for 70% of all warming in the past 50 years.
More here: http://gustofhotair.blogspot.com/
Can we add something in the references pages here at WUWT that defines feedbacks and forcings and how they are different?
I believe we have a semantics problem here. When a person refers to “cloud feedback” it can be read that as “feedbacks caused by changes in clouds due to a forcing” where the effects of the clouds are the feedback. It appears others can read that as “change in clouds due to a forcing” where the cloud changes are the feedback.
The point is, warming has been projected to increase or to decrease clouds? Everyone knows clouds are net coolers, the point is whether warmer = less clouds (warming effect) or more clouds (cooling effect).
Even I can imagine for warmers it works both ways – more humidity and more clouds, so warmer nights, we always told it will be warmer – or less clouds and more sunlight, so see the positive loop, we always told it will be warmer.
criminogenic says:
September 20, 2011 at 3:05 am
So if clouds are such a strong negative feedback, how come we aren’t in a permanent ice age?
****************
You obviously don’t understand negative feedback do you ?
Negative feedback drives the temperature back to it’s “set point”.
Warming causes cooling and cooling causes warming.
Positive feedback works the opposite.
Warming causes more warming and cooling causes more cooling.
Sounds unstable and it is. This would be more likely to result in ice-ball earth.if some cooling started to happen.
So in answer to your naive question it is possible to move the set point but negative feedback resists this change.
RockyRoad, JohnB,
To first approximation, relative humidity stays the same in a warming world (i.e. specific humidity goes up, but just about enough to conserve RH). Since cloud formation depends (a.o.) on relative humidity and not on specific humidity, your argument doesn’t hold.
Tom in Florida,
That sentence (“The influence of cloud radiative effect on determining cloud feedbacks and changes in the water cycle are discussed.”) and the discussion it refers to is there to show how interesting and relevant this piece of research supposedly is. I searched the paper for a quantification of this feedback and couldn’t find it. If you do, please let us know.
TallBloke,
This post is clearly confusing two very different things; how is that changing goalposts?
Bob Tisdale says:
September 20, 2011 at 6:35 am
Roy W. Spencer says: “Bart is correct. This paper is not about cloud feedback…it is about the average effect of clouds on the climate system, which the IPCC, Trenberth, Dessler, et al. will all agree is a cooling effect….”
Thanks, Roy, for confirming what I thought I had read. And thanks for the further expansion/explanation.
==========================================
I’d like to thank Dr. Spencer, also. But, Bob, you stopped in your quote too early.
Bob, just to be clear, I’m not directing this at you. But, it seems to me, some people read a paper and stop there and wait for another paper to try and understand the significance of the papers that they’ve read. I, for one, like the information provided, but I’ll infer and extrapolate from the knowledge and not wait for some other scientist to tell me the significance of the information.
As Russ R. (September 20, 2011 at 6:21 am) points out, this leads us to more questions. As any scientific paper should. While Russ is correct, in my mind, the questions now become, how much more cloud cover can we expect per warming? At what point will the effects of the clouds cause no more increase in cloud cover? Are the effects logarithmic or closer to linear?
The point is, this is opening up a field and perspective of climatology that has been neglected for far too long. So the paper isn’t this or it isn’t that, but boy! It sure could be.
James Sexton
Let me do the spin:
“Catastrophic night-time warming caused by anthropogenic clouds!”
followed by:
Obama’s new scheme to tax clouds.
While it seems that Bart Verheggen is clutching at straws here, he does have a point – the paper if calculating the instantaneous effect of clouds on the radiation budget, not the delayed/longer term feedbacks (the point of Spencer & Bracewell). What the paper does do, however, is provide some nice backup of the method of using satellite data instead of hand-waving – which is where Spencer & Bracewell, Dressler, Lindzen & Choi, come in. We are now getting some data on which to calculate cloud effects instead of just assuming them to be what would like them to be.
What I take from this (I’ve tried to read the paper, but my maths isn’t up to really understanding it) is that changes in cloud effects (around the -21 Wm*2) are going to swamp CO2 effects (calculated to be around 1.3 in total – but isn’t that based on blaming CO2 for all of the recent warming?). A 5% difference in cloud cover would equal the entire CO2 effect.
Furthermore, since doubling of CO2 produces less and less of an effect as the relevant part of the spectrum becomes saturated, clouds will have a n even greater impact as their effect covers a greater part of the whole spectrum.
Clouds are certainly going to have their day in the future and paper like this one making sense of the new data from satellites are the way to bring them in from the cold.
I appreciate that Richard Allan has produced some real science using public funding, but I feel that Anthony has made a horrendous blunder in his interpretation. I suggest he actually asks Allan what the results mean instead of making faulty self assessments.
People are missing the fact that during the late 20th century warming spell total global cloudiness DECLINED and now that warming has ceased cloudiness has INCREASED.
The only way to account for that is as I suggested upthread but I will summarise it here.
The effect on cloudiness of shifting the air circulation latitudinally is GREATER than the effect on cloudiness of temperature changes alone.
If the Earth could become warmer with no latitudinal shifting the climate zones would stay in place but they do not. Nor did global cloudiness increase whilst the globe was warming.
I think one sees more vigorous mid latitude jets and ITCZ when the globe is warming but the area covered is not large. The thing is that at the same time the low cloud quantities in the tropics and subtropics decline due to enhanced descending air from the stronger convection elsewhere which widens the equatorial air masses relative to the polar air masses.
Thus a warming world gives more deep convective clouds where all the action goes on as a result of a faster water cycle (the jets and ICTZ) but in other larger areas where solar insolation to the oceans is potentially strongest the amount of low level cloud shielding those oceans actually declines. In terms of global albedo reflectivity is greater from the latter than from the former.
As the paper says:
“There is a prevalence of low altitude cloud over the oceans: this cloud contains large amounts of water droplets which are highly reflective (e.g. Stephens et al., 1978).”
So in general, cloudiness changes (less clouds in a warmer world, more clouds in a cooler world) are actually a positive feedback to whatever forcing caused the system to warm (or cool) in the first place but a negative feedback then arises namely the increase in speed of the water cycle as manifested in the poleward shift of the surface pressure distribution.
More CO2 might have a miniscule effect on the surface air pressure distribution but as compared to what sun and oceans achieve as a matter of routine we would never be able to tell.
I’ve done some calculations breaking-down the greenhouse effect into its components.
CO2 : +44.2 W/m2
Other GHGs : +11.9 W/m2
Water Vapour as a GHG: +113.9 W/m2
Cloud SW Reflectance : – 53 W/m2
Cloud as a GHG : +32 W/m2
Total : +150 W/m2
There are a few other smaller components like aerosols, SW interception by atmospheric molecules but they net out to a small number.
Based on many of the articles we read here: The sun sleeps, therefore more clouds due to GCR, therefore cooler, therefore more snow pack, therefore even more reflection, therefore even more cold, therefore more ice, therefore less total ocean area to heat the atmosphere..etc.
P.S. I do my own peer review. 🙂
Interesting tie to Svenmark / CLOUD experiment – by concluding cloud feedback is a larger negative feedback & if the Svenmark / cosmic ray hypothesis is correct, it explain why solar effects dominate : “hot” sun = less clouds = warmer temps; “cool” sun = more clouds = cooler temps.
Trenberth not happy …
http://www.humorsharing.com/public/files/posts/images/1264/simpsons-headlines-002_1.jpg
Regarding the forcing or feedback issue, the paper is addressing the forcing issue. Fine. But explain to me again how clouds which have a cooling effect as a forcing can have a warming effect as a feedback… I still don’t get that part.
As Ursus noted earlier, Richard P. Allan is well connected in Climate circles. His CV suggests that he is active with the IPCC and has been doing this work for some time. He did his undergraduate work at the Univeristy of East Anglia. Perhaps Paul Dennis can comment. I suspect he does not see his research as supportive of Spencer & Braswell and Lindzen and Choi – hence all the red in the diagrams.
Bart Verheggen has a point which I think was overlooked. As he stated, the paper didn’t address feedbacks.
1. If a doubling of CO2 would increase temperatures 1 C, and you get additional clouds increasing earth’s albedo and reducing temperatures to an increase of only 0.5 C, you’d have a negative feedback from clouds- total warming is less than the 1 C solely from CO2.
2. If a doubling of CO2 would increase temperatures 1C, and you get additional water vapor increasing temperatures a additional 1C, and additionl clouds reducing temperatures 0.6 C,
you get a warming of 1C from CO2, 1C from water vapor, and minus 0.6 C from clouds, for a net increase of 1.4 C- an increase of 0.4 C over the 1C CO2 doubling with NO feedbacks. Verheggen should have added the qualifier- net feedback from water vapor and clouds- rather than just clouds, but he’s correct that the paper didn’t specify whether situation 1 or situation 2 holds.
My money is on situation 1.
Isn’t this actually the 4th new paper which says that clouds have negative feedback, and that increasing water vapor in the atmosphere produces cooling, not warming?
The Carnegie Institute sponsored a very recent paper which finds that trees produce net cooling because they release water vapor, and this water vapor creates more clouds, which reflect more light back to space.
Go to Carnegie’s website, look around, and you will come to this (Wed. Sept. 14 release):
————–
Water evaporated from trees cools global climate (headline)
Washington, DC — Scientists have long debated about the impact on global climate of water evaporated from vegetation. New research from Carnegie’s Global Ecology department concludes that evaporated water helps cool the earth as a whole, not just the local area of evaporation, demonstrating that evaporation of water from trees and lakes could have a cooling effect on the entire atmosphere. These findings, published September 14 in Environmental Research Letters, have major implications for land-use decision making.
…The researchers even thought it was possible that evaporation could have a warming effect on global climate, because water vapor acts as a greenhouse gas in the atmosphere. Also, the energy taken up in evaporating water is released back into the environment when the water vapor condenses and returns to earth, mostly as rain. Globally, this cycle of evaporation and condensation moves energy around, but cannot create or destroy energy. So, evaporation cannot directly affect the global balance of energy on our planet.
…Using a climate model, they found that increased evaporation actually had an overall cooling effect on the global climate.
Increased evaporation tends to cause clouds to form low in the atmosphere, which act to reflect the sun’s warming rays back out into space. This has a cooling influence.
————–
Isn’t it time to have a climate scientist or statistician with an open mind write a review article, including all these new articles, comparing them with the Trenberth attempt to put a finger in the breaking dike? Is Steve McIntyre or Ross McKittrick available?
Now, how do we get so that these things can be understood by Joe Sixpack. Oh, wait…..
Jeff L
“if the Svenmark / cosmic ray hypothesis is correct, it explain why solar effects dominate : “hot” sun = less clouds = warmer temps; “cool” sun = more clouds = cooler temps.”
Good point but the Svensmark hypothesis doesn’t explain how cosmic rays can alter the vertical temperature profile of the atmosphere and cause a redistribution of the surface air pressure of the type observed.
I prefer the idea that cloudiness and albedo changes are a result of latitudinal shifting of the cloud areas rather than simply the presence of more condensation nuclei.
The fact that GCRs increase whilst the sun is less active could well just be a fortuitous correlation with little (but maybe some) climate effect.
It’s official: this is the wettest summer since 1906
Wednesday 31 August 2011
This summer has been the wettest since 1906, with 10cm more rain than in average years, the KNMI weather bureau said on Wednesday.
In total, 35 cm of rain fell in June, July and August, with July particularly wet, the KNMI said.
This contrasts with the dry spring – the driest of the past century with just 4.9 cm of rain, compared with 17.2 cm in a normal year.
http://www.dutchnews.nl/news/archives/2011/08/its_official_this_is_the_wette.php
Dry spring = less clouds = higher temperatures
Wet summer = more clouds = lower temperatures
http://www.knmi.nl/klimatologie/grafieken/jaar/index.cgi?station=260&graphtype=anomalie&element=tg
http://www.knmi.nl/klimatologie/grafieken/jaar/index.cgi?station=260&graphtype=lopend&element=tg
The sun was there, just behind the clouds.
Solar panels provide more energy on sunny days or cloudy days?
I thought the consensus say that clouds are a positive feedback because higher temperatures lead to more clouds which lead to more heat retained because the clouds absorb LW radiation emitted by the earth. If this paper is correct and clouds offer net cooling (SW reflection outweighs radiative effects by day) then surely clouds must actually be a negative feedback to increased temperatures not a positive one? In any case, if the net cooling effect is greater than previously thought then isn’t the energy budget now incorrect?
I’ve looked at clouds from both sides now. Time to send in the clowns.
Reading the blog comments, the IPCC stuff, and this paper, it appears that clouds do not add to the radiation budget.
The IPCC ,Trenberth, Dessler team appear to believe that if AGW is happening, then clouds might increase and increase the effect of AGW, or clouds might decrease and increase the effect of AGW.
Have I got this right?
(not really bothered by the way)
“Konrad says:
September 20, 2011 at 5:05 am
Those saying that this paper is not addressing the feedback issue may be missing the point. For the strongly positive water vapour feedback demanded by the IPCCs doom scenarios to work, the increased evaporation would need to be prevented from causing more clouds. This is not plausible in an atmosphere with a vertical pressure gradient.”
And yet, while temperatures have been increasing, cloudiness has been decreasing. Contrary to what the models and the IPCC predict. Could it be that temperature is not the primary factor forcing cloudiness? Could it be that some other mechanism is at work? Is it just possible that someone got it backwards, that cloudiness is forcing temperature?
Bill Illis says:
September 20, 2011 at 5:43 am
“The climate models project that this -21 W/m2 (might be as high as -30 W/m2) and project that it will turn into -20 W/m2 in a doubling scenario. So it is projected as a net +1.0 W/m2 feedback, about half of the feedbacks shown by the IPCC in its most recent report. ”
I note that you don’t specifically say that it is *cloud* cooling that the models project will fall by 1.0 W/m^2 in response to CO2-concentration doubling–for all that is apparent from what you say, the 1.0 W/m^2 could instead be the net of (1) *increased* cooling by clouds and (2) increased heating due to a greater optical-depth contribution by water vapor (as opposed to droplets).
Is there a primary source relatively understandable to us laymen that tells whether the models project (1) increased cloud cover and/or (2) decreased cooling by *clouds* and/or (3) increased greenhouse effect from water *vapor* in response to increased CO2 concentration?
In other words, I keep reading on the blogs what the models are doing, but I don’t as a layman have any good way to develop confidence in those descriptions, and it would be helpful to many of us more-casual observers to find something that explains the models but is not so opaque and jargon-prone as to require a prohibitive amount of time for a layman to decode. Does anyone know of such a source?
I think you guys arguing forcing / feedbacks is sort of ridiculous and off point. True, it should read forcing, Anthony should change it, but on a complex climate system forgings lead to feedbacks, both known and unknown.
The point is -21 W/M2 is a very large number. So a very small change has a large impact on the global radiation budget. It is foolish to think that cloud cover does not vary and is constant in a dynamic atmosphere.
Just to reiterate, this paper does not say what Anthony thought it said.
Clouds are a negative forcing, as was well known all along. Allen has just produced a slightly different number for that forcing.
No rebuttal required.
Over the last few years this issue has become the Achilles heal of the AGW belief. I was expecting something more close to neutral myself but -21? Holy hole in the theory Batman. Good to see real science being done. I am predicting a “ignore it and hope it goes away” attitude from the media.
Here is a video showing Ken Caldiera, one of the authors of the new study showing that increasing water vapor in the atmosphere causes net cooling by causing increasing cloud formation:
Let me chime in with the people who pointed out that this isn’t feedback. Negative feedback is when the clouds respond to temperature, not to another stimulus, such as ionizing radiation. Furthermore, it’s mathematically impossible for negative feedback to have an effect greater than the original effect. It’s impossible to create a feedback system that cools in net in response to warming.
To RobB (7:59 AM):
Yes, you are correct about negative, not positive feedback. See Caldiera video just above.
John says:
September 20, 2011 at 7:43 am
Isn’t it time to have a climate scientist or statistician with an open mind write a review article, including all these new articles, comparing them with the Trenberth attempt to put a finger in the breaking dike?
That was what most people thought the UN IPCC was going to do. However, as history has shown, the process itself is flawed. It is very unlikely that a lead author is going to point out work that contradicts their own, at least not in a favorable light. This leads to resignations from the IPCC of folks with more central and/or skeptical positions, which skews the results over time.
Thus, the IPCC concludes with great certainty that warming is caused by CO2, while downplaying the almost complete lack of understanding of the effects of clouds. Expect the next IPCC report to say we understand the clouds, they have a positive feedback effect, and we are very certain of this, because anyone that says otherwise is rubbish.
BargHumer says:
September 20, 2011 at 6:08 am
@Dave Springer
“While clouds act to cool the climate system during the daytime, the cloud greenhouse effect heats the climate system at night.”
How can this be true? There is no energy or energy source to heat the earth at night? only to retain more of what was there in the day time.
This is now getting confusing. Note that in the top two lines the phrase “climate system at night” is used and in the second 2 lines the phrase “heat the earth at night” is used.
Are these two phrases meant to describe the same thing or not? Maybe, but I can’t tell. Not being able to tell, clouds the meaning (pun intended). The discussion, so far, has many such problems and, thus, has collapsed like a glob of warmed Jell-O.
Anthony, I am afraid that those who are saying you have misinterpreted the results of this paper are correct. The main result is about the effect of all the clouds on the radiation coming in to the earth, not feedback.
However, there is in fact a suggestion of negative feedback where this is discussed in sec 6.
“Substantial negative anomalies in net radiative flux from ERA Interim are apparent in 1998 and 2010, both El Ni˜no years, suggesting that the substantial re-organization of atmospheric and
oceanic circulation systems act to remove energy from Earth during these periods.”
You can also see this in fig 7. There are dips in the cloud forcing in the hot El Nino years of 1998 and 2010, showing that when the earth is hotter it loses more heat, ie negative feedback.
So in the end I think you are right – the paper does show negative cloud feedback!
I see that the CAGW rent-a-mob have been instructed to jump on this thread. At least it stops them bullying scientists, I suppose.
In this thread the opacity of the atmosphere to LW has been mentioned, and the role of clouds at trapping nighttime heat has been offered. This has to mean that the altitude of the cloud base comes in to play and so I can ask this question: Because of the atmospheric opacity, at what altitude must a cloud be to stop trapping night time heat? This would be the altitude at which the cloud is invisible to surface LW radiation, and obviously, the reverse would be true – the cloud generated LW radiation is invisible to the surface.
If the answer is the altitude does not matter then one has to ask if the atmosphere is actually opaque to LW radiation.
I’ve not seen any mention of vertical distribution in any of this.
ChE. It isn’t mathematically impossible to have -ve feedback >1, but it would result in an oscillating system. Agree that what is quoted in the main post does not focus on feedback numbers.
PaulM says:
September 20, 2011 at 8:13 am
Anthony, I am afraid that those who are saying you have misinterpreted the results of this paper are correct.
If you watch the video above, you will see that the study says the effect of increased evaporation is both local cooling AND global cooling.
AGW and the GCM all are based on the assumption that increased evaporation will cause local cooling BUT global warming.
The difference between the points of view is AND in the first, and BUT in the second. If the AND is true, AGW is not possible and the theory collapses, if the cooling effect is of any size.
The reason is that CO2 itself has very little warming effect. AGW and the GCM’s attribute most of the warming to increased evaporation and the net GHG effect of increased water vapor in the atmosphere.
However, if the effect of increased evaporation is a net cooling, as the study shows, then AGW is wrong and CO2 does not explain the warming post 1980. Something other than CO2 must have caused the warming and climate science will have to go back to the drawing board and figure it out.
I don’t understand how there can be any question about this. Some fairly simple observations (I know, observation of physical reality has to take second place to computer models…) should give enough clue:
From underneath the clouds, at ground level, as a cloud covers the sun, you feel cold. This really is telling you that the radiation from the sun is no longer reaching ground level. This can be confirmed by looking at the output of a solar panel, it drops drastically when a cloud obscures the sun. Again a strong indication that radiation is no longer reaching ground level.
So where is all that radiation/energy going? Well its possible that it is being absorbed by the cloud itself, except that as you observer the cloud from above, it is pretty evident that it is reflecting an awful lot of energy. It’s very bright, and its white, which s telling you that it is reflecting all the energy equally (at least in the visible spectrum). I suppose that you might think that ou its outwards journey it is being absorbed by the atmosphere, but having not been absorbed and re-radiated at a different wavelength we have to assume that the atmosphere remains as transparent on the way out, as it was on the way in. Besides, from space the cloud still appears white and bright.
Anyone arguing that cloud in itself does anything other than cool the earth is a crackpot.
The only remaining question is does increasing temperature cause more clouds?
Well, the models, and observation (that pesky physical reality stuff again!) tell us that increasing temperature increases the level of water vapor in the atmosphere.
So does more water vapor lead to more clouds?
I want to see the grant submission to ask for a few million to investigate that idea! 🙂
Well of course clouds cause cooling! What was the 1815 ‘summer that never was’ and other post volcanic winters if not a perfectly good example that the cloud forming aerosols ejected by volcanoes affect temperature a lot.
This paper, in association with the recent CERN research, its very powerful and strongly suggests Svensmark (and Herschel centuries ago) got it right.
I think there was a famous leprechaun that said:
GK
If you are going to do modeling at all, it will be important to properly model cloud dynamics. Any pilot will tell you there are strong updrafts under big cumulus clouds. The updraft very likely continues to the top of the cloud where the upward velocity drops to zero, cooling occurs, and the velocity of the droplets subsequently becomes negative. If the droplets get big enough, you get rain falling out of the center. Cumulonimbus clouds can have a shape like a stovepipe top hat with rain falling from the center and hot moist air flowing up the walls of the stovepipe. The idea is some clouds can act more like a heat conveyor, and other clouds can act more like a blanket. It is important to distinguish between the two and accurately handle the heat flow. I think that was an important point this paper was making, if not explicitly. Using optical density alone will be insufficient for some cloud types.
Mann, Hansen, Jones et al. Back to the drawing board. Run along. Shoo
I wish someone who knew what they were talking about would draw a picture. A nice block diagram with the the blocks and energy flows properly labelled would really help.
“So does more water vapor lead to more clouds?”
Yes, but primarily where there is sufficient uplift or in regions of air mass mixing. Primarily (but not exclusively) at the ITCZ and along the various jet stream tracks.
The consequent additional uplift along the more vigorous ITCZ and jet stream tracks causes a growth in the amount of descending air elsewhere and that suppresses low cloud development especially over water in the tropics with a widening of the sub tropical high pressure cells for a general growth of the equatorial air masses at the expense of polar air masses which pushes ALL the components of the surface air pressure distribution poleward.
Perversely that then leads to MORE solar energy into the oceans in a POSITIVE feedback.
However the more vigorous ITCZ and jetstreams represent a faster water cycle which provides the negative feedback sufficient to cancel out BOTH the initial forcing from whatever cause AND the positive feedback from reduced low cloud cover in the tropics.
It all goes into reverse when there is a cooling globe.
Forgive the shaudenfreude, but its a classic case of comfirmation bias.
The heading and many of the posts clearly read this research as supporting Spencer and Lindzen in their speculations about the magnitude, and sign, of cloud FEEDBACKS in AGW.
While this is just a refinement of the total/net effect of clouds in the average climate with no climate change.
With the overall effect just -21W/m2, it would require a 10% change in cloud cover – a massive and obvious alteration – to equal the effect of rising CO2.
izen says:
September 20, 2011 at 8:49 am
With the overall effect just -21W/m2, it would require a 10% change in cloud cover – a massive and obvious alteration – to equal the effect of rising CO2.
You mean the “claimed” effect of rising CO2, don’t you?
izen,
I’d like to see where you get the figures from to the effect that it would need a 10% change in cloud cover to equal the effect of rising CO2.
Well,
I really don’t see the issue. They’re talking about the radiative contribution, not the feedback. And they reach the conclusion that clouds tend to heat the surface (please read the conclusions’ section!). So, all in all, he just confirms the IPCC report, but with a different value for the radiative contribution (and a more subtle study of spatial dependence).
It’s a bit sad that this posting is being buried beneath new ones without appropriate corrections or an update addition to correct the feedback/forcing misunderstanding and the originals inferences.
Looks like the clouds captured a La Nina in cloud radiation. It was a long time span so I wonder if it was a net La Nina. It would be interesting to run the data during different time spans and see.
BTW, everyone knows it’s a cooling during the day. I believe the issue is night vs. day and long vs. short. This appears to show that the net Night + Day is dominated by daytime cooling. The net is very far from the variation though. He had some numbers in the +100, -400 range which seem staggering. That would seem to indicate that not only is it currently dominated by cooling but it will be massively responsive to cloud cover changes. Massive negative feedback if -400 is correct.
Will peer reviewed papers like these make it to the congress and will they understand it. Probable no.
Bart Verheggen
The Allan study has suggested a somewhat higher net negative climate forcing from clouds than earlier studies (Ramanathan + Inamdar 1989, for example) , i.e. -21 Wm-2 versus -18 Wm-2.
This is good information.
Incidentally, this difference in cloud forcing of 3 Wm-2 is twice the total anthropogenic radiative forcing estimate of IPCC from 1750 to 2005 (1.6 Wm-2), so the Allan finding is significant.
The cloud feedback versus cloud forcing issue is still open, as you say, as Spencer + Braswell 2011) seem also to have concluded.
My conclusion based on the data I’ve seen would be that clouds exert a slight negative feedback with surface warming but that forcing from natural changes in cloud cover play a greater role (Palle 2005). More work is needed to identify the mechanism for these observed natural changes in cloud cover. Maybe the CLOUD experiment at CERN will give us some new data.
Max
I was surprised that this paper was mis-interpreted as suggesting negative cloud feedback. This is a basic error by the author of the post that has been highlighted by many contributors including Roy Spencer.
REPLY: Dr. Allan, thank you for visiting and for your correction. Please note that I’ve made an update to the post, removing the word negative from the headline and including why I interpreted the paper to demonstrate a negative feedback for clouds. I welcome your thoughts. It seems to me that if clouds had a positive feedback, the dips in 1998 and 2010 in your figure 7 would be peaks rather than deep valleys.
Thanks for your consideration.
– Anthony
Hector Pascal says:
September 20, 2011 at 3:03 am
Oh noes! Not another Allan from Reading. We have Allen (Perce) and Allen (JRL) already.
The latter of whom is a geologist/archaeologist of monumental standing. It’d be interesting to know what he thinks of the undebate.
I see this paper as trying to nail down the number. We can measure how much shortwave is reaching the top of the atmosphere in Wm^-2, now we need a good estimate of how much of that actually reaches the surface (and once it reaches the surface, how much is thermalized and reemited in long wave versus how much is reflected). The authors have measured the total cloud reflectance as -21W/m^2. Now we can take that number and plug it in everywhere the calculations say subtract shortwave reflected by clouds. It seems more related to answering a “what is the total albedo of the sunlight side of the Earth?” kind of question.
I don’t think the science is at all settled numerically of how the cloud cycle impacts the energy budget. That’s a very important number to have, and once someone can show that number definitively and verifiably, a major hurdle to understanding how the climate works will be overcome. Right now we are all just hand-waving. (though personally I love “hand-wavy” proofs, takes away all that rigor and mathy stuff)
EJT, you just hit on what is so confusing about talking about feedback on a blog: there are two related parameters, the open-loop gain, and the closed-loop gain. They’re related by the geometric series, so that as the negative open loop gain approaches (negative) infinity, the closed loop gain approaches zero. With time lags, the loops will oscillate at higher open-loop gain, but op amps operate quite stably with 10^5 open loop gain, because their high frequency response allows it.
What I was saying is that the closed loop gain for a negative open loop gain system can never be less than zero (you can’t get more than 1 degree of cooling in response to one degree of warming). Positive feedback is a whole nuther matter, and can run away. But that’s a another discussion entirely in the climate context.
suyts says: “I’d like to thank Dr. Spencer, also. But, Bob, you stopped in your quote too early.”
That’s why I ended with the elipse and thanked Roy for the further explanation.
As many commenters have noted, the fact that clouds have negative feedback is well known, it isn’t new information.
The issue is, does an increase in GHGs cause an increase in water vapor, which then causes either positive or negative feedback? If clouds don’t change, and if there is added water vapor in the atmosphere, the odds favor a positive feedback because water vapor is an important GHG.
But if increased water vapor then means more clouds, we may get net negative feedback because the clouds may reflect back a greater increment of energy than the increased water vapor will keep in the earth’s system.
That is why the new Carnegie paper, in conjunction with the new paper by Allen reaffirming that clouds have negative feedback, is so important. The Carnegie paper links increased evaporation with net negative feedback due to increases in reflective clouds.
We do need to keep in mind that just because this study fits with our priors — the earth has been warming at a rate well below those predicted by GC models, which incidentally have net positive feedback from more water vapor in the air — doesn’t mean that this new science is the end of the argument. We do need confirmation from more studies. That is the scientific process, or at least WAS the process before Trenberth and Mann and Jones and Briffa and Bradley etc. hijacked it.
Richard Allan says:
September 20, 2011 at 9:27 am (Edit)
I was surprised that this paper was mis-interpreted as suggesting negative cloud feedback. This is a basic error by the author of the post that has been highlighted by many contributors including Roy Spencer.
########
it is also fascinating because of what we dont see. usually you will see a whole crew of commeters pounce on the word “model”. This time they didnt.
They didnt because they thought the paper supported spencer. But it was on an entirely different topic. That misunderstanding kinda silenced the usual “models are bad” crew.
BTW I was glad to see Roy and Bart come here to correct the misunderstanding. And thank you for coming here as well.
REPLY: Thanks Mosh, I’ve responded to Dr. Allan also, and provided an update. I ask viewers to note how WUWT handles criticism from a science professional, versus say, some award winning Australian websites. -Anthony
So, how are people like this still able to publish? Are they giving their papers amusingly obscure titles to sneak them past peer review, or is this thing we call science genuinely working at last?
Correction to my last post: In this sentence, substitute the word “forcing” for the word “feedback:”
As many commenters have noted, the fact that clouds have negative feedback [no, FORCING] is well known, it isn’t new information.
I do not think it is current to say Allan’s paper is just about the forcing. Allan mentions feedbacks nine times.
I asked how clouds, which everyone seems to agree causes significant cooling as a forcing, can also cause net warming as a feedback. It seems to me the feedback is necessarily less powerful than the forcing. Unless I am reading Allan wrong, this is exactly what he is saying.
The abstract ends with this line: “The influence of cloud radiative effect on determining cloud feedbacks and changes in the water cycle are discussed.”
He concludes: “Consistent with previous results (Ramanathan et al., 1989; Su et al., 2010), the cloud radiative cooling effect through reflection of short wave radiation is found to dominate over the long wave heating effect (the mechanism by which a positive feedback would occur), resulting in a net cooling of the climate system of −21 Wm−2. The short wave radiative effect of cloud is primarily manifest as a reduction in the solar radiation absorbed at the surface of −53 Wm−2 for the global multi-annual mean. The magnitude of this effect is strongly modulated by the incoming solar radiation and the dominance of cloud short wave cooling over long wave greenhouse trapping is maximum around local noon (Nowicki and Merchant, 2004) while the cloud long wave heating effect dominates at night.”
So what I am missing? Is he not saying clouds cause a change in radiative forcing resulting in significant cooling which completely swamps the warming feedback at night? Is this not in opposition to the IPCC reports which claim a net positive (warming) feedback?
Well, I thought that adding CO2 to the atmosphere would increase temperature, result in increase in water vapor and clouds, that would have a positive feedback effect, increasing temperature further.
Call it “forcing” or ‘feedback” (who cares), this paper indicates that clouds have a significant net cooling effect. If it is true that CO2 added to the atmosphere will increase cloud cover, how do the new clouds know that they are supposed to have a net warming effect, rather than the net cooling effect of the non-CO2 generated clouds?
dp says:
September 20, 2011 at 8:21 am
“In this thread the opacity of the atmosphere to LW has been mentioned, and the role of clouds at trapping nighttime heat has been offered. This has to mean that the altitude of the cloud base comes in to play and so I can ask this question: Because of the atmospheric opacity, at what altitude must a cloud be to stop trapping night time heat? This would be the altitude at which the cloud is invisible to surface LW radiation, and obviously, the reverse would be true – the cloud generated LW radiation is invisible to the surface. If the answer is the altitude does not matter then one has to ask if the atmosphere is actually opaque to LW radiation.”
Extinction altitude for primary CO2 absorption band is about 2000 meters AGL. That’s what I calculated from IR spectrograph looking downward from 20 kilometers above the arctic ocean. In the IR window you see the temperature of the arctic ocean and in the CO2 absorption band you see a temperature that is 20C colder. Using dry adiabatic lapse rate of 1C per 100 meters that works out to a 2000 meter column of air beginning at sea level.
I’ve not seen any mention of vertical distribution in any of this.
Rich says:
September 20, 2011 at 8:48 am
I wish someone who knew what they were talking about would draw a picture. A nice block diagram with the the blocks and energy flows properly labelled would really help.
AMEN!
However, I believe one of the problems that “someone” will encounter is that in most “flow diagrams” the inputs and outputs are the same–i.e., have the same units, such as voltage, or current, or in the case of digital signal processing flow diagrams, numbers. When you try to make a flow diagram whose inputs are in some cases power density (watts per square meter) and in other cases temperature and CO2 levels, the “flow diagram” will likely be complex. In any event, I too would like to see someone attempt to generate a flow diagram of the physical process of energy flow/temperature/CO2 in the earth’s atmosphere.
Reading this thread, two additional comments did, however, come to mind. First, given that “the science is settled”, there seems to be a whole lot of settling still going on. Second, as many other readers have commented, I too am confused by the terms “forcing”, “feedback–both positive and negative”, etc. However, one thing is becoming increasingly clear by the minute: the CERN experiments, the Spencer paper, and now the Allan paper are likely to constitute a “negative feedback” to the CAGW alarmist “feedbag”.
Can someone let me know I have got this right?
1. The IPCC climate models all work on the hypothesis that increased Co2 causes warming which causes more clouds. The IPCC reports conclude that the net effect of a cloud is that they capture the Earth’s heat and warm up the earth. (a bit like a blanket). So in the models the calculated Co2 warming is magnified by a factor of about 4.
2. The Spenser and Braswell paper, and now this new paper by Richard Allen, calculate that more clouds cause more cooling than warming. So when the C02 in the air rises, and the atmosphere warms there will be more clouds formed, but these clouds will start to cool the atmosphere back down again. So the calculated Co2 heating effect is partly cancelled out by some cooling caused by the extra clouds.
The reason I need this confirmation is that I will spread word of this work in the comment sections of blogs. I want my form of words to be accurate. Thanks
The word ‘feedback’ is multiply ambiguous. That is because there are many kinds of feedback systems that work on different principles. I am talking about physical feedback systems, not mathematical representations of feedback systems. There is a way to clarify these matters and it is the way of traditional science.
Instead of talking about feedbacks, present the physical hypotheses which describe the phenomena in question. In the context of the present discussion, the simplest possible hypothesis is that “Increased GHGs cause increased temperatures (warming) and increased temperatures cause increased cloud cover and increased cloud cover causes increased reflection of sunlight and increased reflection of sunlight causes a lowering of Earth’s temperature.” Then we calculate the net change in Earth’s temperature, find that it is a decrease, and make the simple minded assertion that increased GHGs lower Earth’s temperature. We can choose the unpack the latter claim as the generalization.
Notice that the word ‘feedback’ is neither used nor needed.
“NetDr says:
September 20, 2011 at 6:54 am
Negative feedback drives the temperature back to it’s “set point”.
Warming causes cooling and cooling causes warming.”
Since Earth is relatively stable temperature wise, would you say Le Chatelier’s principle applies on a global scale so that whatever changes are made by nature or man, Earth’s climate system will make adjustments to counteract these changes?
All this talk of feedbacks recalls an interesting post by Willis about his idea of a “homeostatic” mechanism in climate regulation. As I read it, Willis is proposing a “governor” mechanism rather than a simple feed back mechanism in climate regulation. In order to function properly, a governor’s response must exceed the perturbation: which differentiates it from a simple feedback mechanism.
http://wattsupwiththat.com/2011/08/14/its-not-about-feedback/
Dire Wolf says(September 20, 2011 at 5:49 am):
You almost nailed it. I imagine that if you replace your “the relative setting determined by weater vapor availability” with Willis Escenbach’s thermometer theory (i.e. tropical cumulus acting as a governor for temperature) you would be pretty close to where things will settle out after the real scientists take over from the ‘true believers’ and ‘want-a-be’ scientists that currently control government funded climate research.
Let’s call it the Svenmark-Eschenbach Theory for a habitable Earth.
All this minutiae and yet the ice continues to melt. Oh and by the way there are quite a few major corporations out there, taking advantage of the situation – Koreans building ships for the NW passage, Exxon Mobile signing arctic ocean drilling pacts with Russia.
This can only happen because there is less ice and what there is, is thinner. Of course I am not sure that’s all bad it’s just that reality is taking over and your blog is pretty much passé. Also, the sooner we all jump on the band wagon the better – imagine beach front property on the Labrador coast!
Roger Pielke Sr. also has a post on the Carnegie paper, very worth reading:
http://pielkeclimatesci.wordpress.com/2011/09/16/new-paper-climate-forcing-and-response-to-idealized-changes-in-surface-by-ban-weiss-et-al-2011/
Its interesting / amusing(?) that the title of this post has now been amended to drop the word “feedback” without any explicit acknowledgment of the error. However the text of the post is (in my opinion) still erroneous and unnecessarily provocative.
REPLY: Read the update, as well as my reply to Spencer and Allan in comments. The issue remains for discussion because (in my opinion) Dr. Allan clearly demonstrates negative cloud feedback in figure 7 in 1998 and 2010 -Anthony
“There is a prevalence of low altitude cloud over the oceans: this cloud contains large amounts of water droplets which are highly reflective (e.g. Stephens et al., 1978). The imagery captures the complex cellular structure of this cloud (e.g. Jensen et al., 2008) over the region surrounding the Canary Islands. These cloud types are thought to contribute strongly toward uncertainty in climate projections (Bony et al., 2006)”
This would be an ideal location to look for a cloud/CR correlation.
In addition to problems with the word ‘feedback’, there is another dispute that has to be uncovered through the fog of talk about feedback. Warmista, especially Trenberth and friends, strive to handle the phenomena of climate science on a “radiation only” model. They are interested in radiation that arrives from the sun, radiation that leaves Earth, and the radiation that is returned to Earth by CO2 in the atmosphere. I do not think that Trenberth can work with a statement such as “Increased cloud cover causes less sunlight to reach Earth and less sunlight reaching Earth causes a lowering of Earth’s temperature.” He will translate it in some fashion that I have not yet decoded. The big point is that if you are conversing with Trenberthians about the claim that increased cloud cover can reduce Earth’s temperature, then be aware that what they understand by that claim is not what you understand.
Bart Verheggen says:
September 20, 2011 at 6:56 am
RockyRoad, JohnB,
“To first approximation, relative humidity stays the same in a warming world (i.e. specific humidity goes up, but just about enough to conserve RH). Since cloud formation depends (a.o.) on relative humidity and not on specific humidity, your argument doesn’t hold.”
Bart,
True, but perhaps a gross oversimplification of atmospheric processes. With warming, convective processes carry air containing more quantities of water vapour to altitudes at which condensation occurs. Perhaps the condensation occurs at a somewhat higher altitude due to the altered lapse rate but I can’t see your reasoning as precluding enhanced cloud formation as a response to atmospheric warming.
Bart Verheggen says:
September 20, 2011 at 6:56 am
TallBloke,
This post is clearly confusing two very different things; how is that changing goalposts?
Bart, the warmists have claimed for years that cloud feedback is positive. They offer no proof which has any credibilty (R^2=0.02 anyone?).
Now you say:
(clouds as feedback) is about how cloud cover and properties might change in response to a warming or cooling of the climate: Will the net cloud radiative effect become more or less negative.
I reply that if it becomes slightly less negative, it’s still very negative, and overwhelms the effect of changes in co2. I invite you to consider why it is that cloud amount reduced according to ISCCP data in the 80s and 90’s. I think it was due to ongoing above average solar activity.
Got any better ideas? Can’t be temperature according to your statement.
http://tallbloke.wordpress.com/2011/09/17/cloud-albedo-what-does-it-respond-to/
Ron Cram says:
September 20, 2011 at 9:48 am
“So what I am missing? Is he not saying clouds cause a change in radiative forcing resulting in significant cooling which completely swamps the warming feedback at night? Is this not in opposition to the IPCC reports which claim a net positive (warming) feedback?”
What’s missing is the difference between land and water. Downwelling longwave has little effect over the ocean. The primary means of heating and cooling over land is radiative – absorption of shortwave by day and emission of longwave day and night. The ocean is different. First of all ocean absorbs nearly 100% of shortwave that hits it and it is absorbed to a depth of 50-100 meters (the mixed layer). Land absorbs about 20% less shortwave because it is higher albedo and it only heats it down to a few centimeters in a single day. Land gives up this heat very quickly at night. There is very little diurnal temperature variation over the ocean because the shortwave radiation is absorbed to great depth and can’t readily escape radiatively because water is essentially a brick wall to longwave infrared. The ocean cools primarily (70%) through evaporation. Because downwelling longwave cannot penetrate water beyond a depth of a few micrometers the primary effect of downwelling longwave radiation from low clouds or CO2 is increased evaporation rate. Clouds and GHGs don’t insulate deep bodies of water like they insulate land surfaces. This IMO is answer Trenberth’s Travesty (the missing heat). He expected to find it in the ocean but it just isn’t there. It’s being rejected by the skin layer of the ocean in latent heat of vaporization and it remains insensible until it rises far enough for adiabatic lapse rate to cool it below the dewpoint. This effectively functions like an express elevator carrying heat from the ocean upward thousands of feet where it is released upon condensation. The atmosphere between the cloud deck and ocean surface now insulates the surface against the downwelling IR from the cloud and makes the path of least resistance for radiation to travel upwards into space.
Every actual observation supports this scenario. Longwave IR just plain cannot heat a body of water because it’s completely absorbed in a skin layer literally just a few microns deep and between warmer water not being able to sink into colder water and viscosity being the dominant force in the skin layer it isn’t mixed downward by mechanical forces (waves) either.
So for 70% of the earth’s surface there is very little effect from greenhouse gases of any sort. Radiative cooling in the oceanic heat budget is a paltry 20% of the total, 10% is conductive, and the lion’s share of 70% is evaporative. Where longwave radiative cooling is a small fraction of cooling it MUST follow that longwave radiative heating is of similarly small influence.
I though that Roy Spencer came up with the thermostat hypothesis…right?
izen said
September 20, 2011 at 8:49 am
“…While this is just a refinement of the total/net effect of clouds in the average climate with no climate change.With the overall effect just -21W/m2, it would require a 10% change in cloud cover – a massive and obvious alteration – to equal the effect of rising CO2.”
This from the Met Office relating to the UK.
“There is quite a strong positive correlation between maximum temperature and sunshine, especially in the spring and autumn, with values of r up to 0.85. Minimum temperature is negatively correlated with sunshine in the winter, and positively correlated in spring and autumn, but with lower values of r than for maximum temperature. There is a strong positive relationship between sunshine and diurnal temperature range.”
There is an interesting composite chart of temp/sun/rain etc immediately above this comment-sorry no table number
http://www.metoffice.gov.uk/climate/uk/about/UK_climate_trends.pdf
The sunshine records are since 1929 so don’t capture the dramatic decrease in sun due to smog/low cloud and the subsequent increase through various clean air acts. One of the London smog’s is caught here in this;picture of Waterloo Bridge London in 1900 by Monet showing chimneys and smog.
http://www.artnet.com/Magazine/features/nkarlins/karlins7-7-04.asp
Artists came here especially to paint these sort of scenes. A French version from the mid 1880’s can be seen here in this famous painting ‘The bathers’ by Georges Seurat-note the chimney factories in the background
http://www.nationalgallery.org.uk/artists/georges-seurat
Generally the oldest instrumental temp data sets were in industrial cities which for at least 100 years had their temperature records skewed by the effects of atmospheric pollution/lack of sunshine.
tonyb
Steven Mosher says:
September 20, 2011 at 9:40 am
“it is also fascinating because of what we dont see. usually you will see a whole crew of commeters pounce on the word “model”. This time they didnt.
They didnt because they thought the paper supported spencer. But it was on an entirely different topic. That misunderstanding kinda silenced the usual “models are bad” crew.”
No, wrong. We refrained from pouncing on the word ‘model’ because what we are seeing is a conflict among modelers. We celebrate the emergence of a tiny bit of a critical voice in Warmista Land. We (OK, I) see this paper as giving rise to a dispute in Warmista Land. If the Veil of Ignorance which forbids criticism of models can be lifted in Warmista Land then that can only be a good thing for genuine science. I want to see models going head-to-head daily until Warmista realize the futility of modeling as a substitute for creating physical theory.
For those arguing “feedback” versus “forcing” I have a simple question:
If cloud FORCING is highly negative, how is it that cloud FEEDBACK is positive?
Can one point to an example where higher temperatures = fewer clouds?
Richard Allan says:
September 20, 2011 at 9:27 am
I was surprised that this paper was mis-interpreted as suggesting negative cloud feedback. This is a basic error by the author of the post that has been highlighted by many contributors including Roy Spencer.
———————–
That is the author of the paper specifically stating, in this thread, that the paper hes been misinterpreted by Anthony and many commenters.
Anthony, maybe you should consider clearing this up as an update to the original post.
REPLY: I did make an update in the post, two hours ago please see it at the end – Anthony
The paper is strongly indicative that clouds have a huge effect on the temperature. Whatever influences cloud formation/deformation is probably the main controller of temperature (climate). If increases in CO2 causes slight warming and the warming leads to fewer clouds then it COULD have a strongly positive feedback (aka CAGW). However, if that is the case then you shouldn’t need any further increase in CO2 to have runaway global warming because as soon as you drove up the temperature just a little with CO2 you have essentially lit the catastrophic climate fuse. The initial warming would have led to fewer clouds which lead to more warming which leads to still fewer clouds which… well you get the picture. Thus I would have to think then that the feedback MUST be negative (which one would expect anyway in a stable system) with temperature so that you don’t get runaway warming. Therefore since temperature does not appear to have a strong influence on cloud formation (witness the low correlation in the Dessler and Spencer papers) that leaves other effects that influence cloud formation. CERN perhaps?? Ocean cycles??
Looking at Fig. 7, provided above by Anthony, you can see what certainly looks like negative feedback in the El Nino years of 1998 and 2010. But 2010 was a far smaller El Nino than in 1998, as I recall, with a strong La Nina right after it, and yet the drop starting in 2009 and continuing through 2011 is larger than in 1998. This is at least, “consistent” with the cosmic ray hypothesis. But not proof by any means. Merely suggestive.
climatereason says:
September 20, 2011 at 10:35 am
…………..
Hi T
One of more accurate rain records, 160 year long, is held by Oxford University; it shows that rainfall pattern repeats about every 40+ years.
http://www.vukcevic.talktalk.net/ORR.htm
“”””” While clouds act to cool the climate system during the daytime, the cloud greenhouse effect heats the climate system at night. “””””
How often do you have to say that it DOES NOT heat up at night; except when the sun shines at night; which only happens if your planet orbits two stars. That doesn’t apply to earth, so Earth COOLS DOWN at night; it does not heat up by the Greenhouse effect or by any other mechanism; it COOLS DOWN at night.
As for the clouds (increase) causing massive cooling by blocking solar spectrum radiation; I’d like just one dollar for every time I have written that here at WUWT. It’s 8th grade high school Science; or maybe 4H Club Science. It doesn’t require any satellites or terraflop computers to see that clouds block sunlight, as well as reflect more of it back into space. That means it doesn’t get to the top 700 metres of the ocean surface to show up on Bob Tisdale’s graphs.
And maybe none of these three peer reviewed papers authors will say it; but I don’t mind saying it. As a consequence of the NEGATIVE cloud feedback, the result of CO2 based greenhouse effects (which I acknowledge), is for all practical purposes, effectively negated.
K Denison
For those arguing “feedback” versus “forcing” I have a simple question:
If cloud FORCING is highly negative, how is it that cloud FEEDBACK is positive?
Can one point to an example where higher temperatures = fewer clouds?
Yes. Eastman 2011, Variations in cloud cover and cloud types over the ocean from surface observations, 1954–2008, http://journals.ametsoc.org/doi/abs/10.1175/2011JCLI3972.1
Sorry, in my previous comment I posted too soon. From Eastman 2011:
“…the decrease (of marine stratus and stratocumulus clouds, MSC) combined with observed increases in SST and the negative correlation between marine stratus and sea surface temperature suggests a positive cloud feedback to the warming sea surface. The observed decrease of MSC has been partly but not completely offset by increasing cumuliform clouds in these regions; a similar decrease in stratiform and increase in cumuliform clouds had previously been seen over land.” (emphasis added)
“Dave Springer says:
The ocean cools primarily (70%) through evaporation. Because downwelling longwave cannot penetrate water beyond a depth of a few micrometers the primary effect of downwelling longwave radiation from low clouds or CO2 is increased evaporation rate. Clouds and GHGs don’t insulate deep bodies of water like they insulate land surfaces. This IMO is answer Trenberth’s Travesty (the missing heat). ”
I would venture that the ‘missing heat’ has a name and that name is work.
Generating fresh water from brine and transporting it vertically and horizontally counts as work where I come from.
Alcheson says:
September 20, 2011 at 10:53 am
“The initial warming would have led to fewer clouds which lead to more warming which leads to still fewer clouds which… well you get the picture. ”
Let’s do a thought experiment. Suppose a CO2 increase sufficient to raise temperature 1 degree reduces clouds enough to raise temperature another half degree. That half degree reduces clouds enough to raise temperature another quarter degree . . . so that after an infinite number of such responses the temperature has been raised a total of two degrees.
So you haven’t necessarily “lit the catastrophic climate fuse” as soon as you’ve added a little CO2.
Steven Mosher says:
September 20, 2011 at 9:40 am
“it is also fascinating because of what we dont see. usually you will see a whole crew of commeters pounce on the word “model”. This time they didnt.”
It is one thing to use a model for physical parameters where you feed in real world data; and an entirely different thing to let a model run iteratively for a hundred simulated years, and pretend that the result of that run means something.
The first use is justifiable, the second is crackpottery and mostly politically motivated; see e.g. “Limits To Growth”.
@- Theo Goodwin says:
September 20, 2011 at 9:59 am
“Instead of talking about feedbacks, present the physical hypotheses which describe the phenomena in question. In the context of the present discussion, the simplest possible hypothesis is that “Increased GHGs cause increased temperatures (warming) and increased temperatures cause increased cloud cover and increased cloud cover causes increased reflection of sunlight and increased reflection of sunlight causes a lowering of Earth’s temperature.” Then we calculate the net change in Earth’s temperature, find that it is a decrease, and make the simple minded assertion that increased GHGs lower Earth’s temperature.”
Very simple minded; you have ended up with a logical contradiction.
That a rise in temperature causes the temperature to be lower than it was before the rise….
Better to analyze it as a contingent chain with the strength of each effect determined.
1)- Increased GHGs cause an increase in temperature.
2)- Warming increases the water vapor content of the atmosphere.
3)- Increased water vapor as a GHG increases the amount of warming.
4)- Increased water vapor increases cloud cover decreasing the amount of warming.
The first three effects are established by direct measurement. The change in cloud cover is much less well determined. Its effect must be LESS than the total warming effect because without that warming there would be no extra wayer vapor = +cloud to reduce the degree of warming. Past temperature changes indicate just how tightly, or not, the cloud negative feedback may constrain a rise in temperature.
Knowing the total magnitude of cloud effects in a ‘stable’ state gives some indication of how MUCH effect cloud variation may have. We know clouds neither vanish totally or double in low altitude coverage from observations so the total influence they can have in response to temperature change will have some (undoubtedly non-linear) proportionality to the percentage change in cloud cover.
I know of no source of good data that shows variation in cloud coverage at the time/scale required, perhaps you have suggestions ?
As has been discussed before that cloud cover variation will only be a RESPONSE to a temperature change unless you hypothesize a process independent of the climate that can alter cloud coverage. The radical change in atmospheric sulfur chemistry from fossil fuel combustion is one candidate. While GCR flux has been another, as Leif has indicated there is little correlation between GCR flux and climate variations. The recent CERN/CLOUD results further reduce the probability of a significant effect and the recent improvements in understanding the galactic structure have refuted any paleoclimate-GCR link.
Hi Vuk
I think we are both believers in natural cycles whether it is rain/clouds/snow or any other weather condition. There is very little new under the sun if you can go back far enough. Unfortunately the IPCC seem to be unaware of these things.
Tonyb
“”””” EJT says:
September 20, 2011 at 8:23 am
ChE. It isn’t mathematically impossible to have -ve feedback >1, but it would result in an oscillating system. Agree that what is quoted in the main post does not focus on feedback numbers. “””””
Sorry EJT, but negative feedback NEVER leads to an oscillating system; no matter how large that feedback is.
Only positve feedback (aka “regeneration”) can result in an oscillating system.
Certainly some systems that were intended to be negative feedback have resulted in oscillation; but only because the feedback switched to positive under those conditions. Propagation delays in either the forward (izzat forcing ?) gain channel or the feedback network, can result in the feedback unintentionally being positive; but negative feedbacks never oscillate.
So next as opposed to tilting at CO2 government will be tilting at clouds. Currently they are trying to figure out how to tax clouds with criminal penalty for non compliance.
This is why windmills MUST BE STOPPED. We need the wind to evaporate water. Slowing down the wind and making it slower will decrease cloud cover.
Now all I need is a few hundred million dollars to discover this phenomenon and create some models that prove my theory.
Also, I might point out wind power could be used as weaponry. If Canada were to stop cold air blowing into the US from the arctic, it could cook the US.
Jeff Wilson wrote: “During colder cycles:
cooler atmosphere => less ocean evaporation => less cloud cover = gradual warming
During warmer cycles:
warmer atmosphere => more ocean evaporation => more cloud cover = gradual cooling ”
Add in some CO2, and you get increased heat retention in colder and warmer cycles. It would be nice to rule this out, and the Allen analysis does not do so.
It may be possible to show that warmer mornings => more cloud cover during mid-day => more heat loss during mid-day => cooler evenings. That is Willis Eschenbach is working toward.
Or, it would be nice to show that some solar effect influences clouds about on the order to alter warming/cooling using the magnitude of the gross cloud effect estimated here. Maybe something will be forthcoming from the CERN CLOUD studies and analyses of the Forbish events.
K Denison
For those arguing “feedback” versus “forcing” I have a simple question:
If cloud FORCING is highly negative, how is it that cloud FEEDBACK is positive?
Can one point to an example where higher temperatures = fewer clouds?
————————
Don’t need to!
1. Higher temperatures -> more water vapour in the atmosphere
2. Some of that water vapour becomes cloud, which produces cooling (i.e. negative feedback)
3. BUT, some of it remains as vapour, which acts as a GHG (i.e. positive feedback)
The net feedback is positive if 3 outweighs 2. Most research suggests that is the case.
KR wrote: “Yes. Eastman 2011, Variations in cloud cover and cloud types over the ocean from surface observations, 1954–2008, http://journals.ametsoc.org/doi/abs/10.1175/2011JCLI3972.1”
Thanks for the link
Am just in and doing my daily WUWT read – an interesting paper, with some interesting comments.
Yes, its been long known that clouds cause a cooling effect to the surface as adequately described by some comments, and the warmist/concensus view seems to be that this is counteracted by ‘blanketing’ outward radiation/heat, as noted by other comments.
I suppose the realistic way to consider clouds is based on whether the radiation on ‘either’ surface is at a higher level than that on the ‘other’ side. So, in truth clouds act as both positive and negative feedbacks.
However, IMO, the net overall effect on the energy budget is easy to assess, at least in a mental capacity – i.e. when clouds are acting as ‘blankets’ – it is usually at nighttime – and when they are acting as ‘shields’, it is usually during daytime. On the reasonable assumption that the actual radiation energy/fluxes kicking about during the day are much larger than those kicking around at night – the net overall effects of clouds must be negative! I don’t see how anyone can refute this from an overall perspective.
As for Mosh’s comment regarding no-one jumping on to a ‘model’ attack – the fundemental difference is that this model seems to come up with ‘understandable’ and somewhat more realistic or should I say believable results! But as I hate all models – to me they are the anti-science when used as standalone ‘proof’ or demonstrations – I do accept the basic point. Personally, I don’t see any models as being pro or anti AGW. They just seem to be a necessary evil in climate science, which is a shame , as in my opinion, (good) data and observations should overrule them any day!
John B says:
September 20, 2011 at 11:40 am
That is a valid observation of course – however, it should be remembered that in THAT case, any warming (global or otherwise) is NOT as a result of anthropogenic CO2 but in fact is a NATURAL part of the climate! I don’t think mixing the water vapour GHG effect in with cloud formation is a valid point within the AGW supposed CO2 major problem context!
Eastman et al 2011 – Variations in cloud cover and cloud types over the ocean from surface observations, 1954–2008: a publicly accessible pre-print is available at:
http://www.atmos.washington.edu/~sgw/PAPERS/2011_OceanClouds_JClim_submitted.pdf
Their data indicates large regions where a positive cloud feedback has been observed, significance >99%, based on 54 million (!) ship-based cloud observations over 55 years.
No models were harmed in the writing of this paper – just observations.
izen says:
September 20, 2011 at 11:20 am
I think you caught the spirit of the thing. My example was intended to be very simple because all I wanted to illustrate is that we can do without the word ‘feedback’ and the confusion that inevitably follows in its train. As for the physical hypotheses that you suggest, scientists have to make up their minds to do the empirical research and create them. At this time, none of them exist as rigorously formulated physical hypotheses that have become reasonably well confirmed.
You write:
“Very simple minded; you have ended up with a logical contradiction.
That a rise in temperature causes the temperature to be lower than it was before the rise….”
Your principle here is “a priori.” Whether a rise in temperature can create a larger decrease in temperature depends entirely on the physical system under discussion. You must be thinking about some sort of internally regulated system that is at equilibrium. The Earth is not an internally regulated system because it is radiated constantly by the sun and history shows that it does not have an equilibrium state that is conducive to human life. For example, volcanic eruptions could lower the temperature indefinitely.
I take it that your rather abstract statement refers to the fact that “If rising atmospheric temperatures created more clouds and more clouds lowered Earth’s temperature then clouds would decrease and temperature would fall back to where it was but not lower.” Well, sure, but this assumes that the behavior of clouds is fully understood and it is not. In any case, I am glad to see that you agree in principle that clouds could cancel all warming from GHGs.
forcings are sources of radiation – the sun, ocean heat, whilst feedbacks are the things that are affected by forcings, whether positive, or negative, surely?
Dave Worley says:
September 20, 2011 at 10:33 am
“I though that Roy Spencer came up with the thermostat hypothesis…right?”
Well, maybe, in some context. But Willis Eschenbach applied the thermostat concept to the tropics and he did a wonderful job of explicating what it involves. You want to find his post to wuwt.
Kev-in-Uk says:
September 20, 2011 at 11:46 am
John B says:
September 20, 2011 at 11:40 am
That is a valid observation of course – however, it should be remembered that in THAT case, any warming (global or otherwise) is NOT as a result of anthropogenic CO2 but in fact is a NATURAL part of the climate! I don’t think mixing the water vapour GHG effect in with cloud formation is a valid point within the AGW supposed CO2 major problem context!
—————–
Not so. The water vapour and clouds are feedbacks. Something has to provide the forcing to cause the climate to shift for the feedbacks to come into play. In the geological past, the forcing was largely from Milankovich cycles, taking thousands of years. In modern times the forcing is primarily from CO2, taking decades. That, in a nutshell, is the AGW argument.
What a relief that you misunderstood the meaning of the article. Climate alarmists can’t afford to lose Meteorological Applications. At least the leak at Remote Sensing has been plugged.
George Smith,
Good observation. In electromechanical systems I’ve worked with, ANY positive feedback leads to catastrophe pretty quickly. This is why I doubt most of the assertions of CAGW. If we had such positive feedbacks in the system, climate would have run away (hot or cold) long ago. A modern aircraft flight control system with a large phase shift in the feedback line (making it a positive feedback) will lead to an ejection and fireball every time. Luckily we don’t see that often, and is the main reason for redundant circuits – these new birds are unflyable without the computer because the basic layout is hypercritical – at the edge of positive feedback mechanically.
In the lab I once created a PID circuit for a automatic centering mechanism, but got the sign wrong on the proportional term. I turned the magnetic centering mechanism into a magnetic accelerator and shot the mass across the room. Positive feedbacks induced in the circuit led to catastrophe (luckily not too big – it just missed me and harmlessly struck a wall). Of course then my sensor failed and melted my coil on the next run, so much for that experiment. (I love playing with things in the lab – the smell of burnt plastic in the morning is something to live for.)
John B says:
September 20, 2011 at 12:01 pm
The water vapour and clouds are feedbacks.
So if co2 made it warmer, and that made more water vapour, how come the cloud amount reduced between 1980 and 1998?
John B said:
“Not so. The water vapour and clouds are feedbacks. Something has to provide the forcing to cause the climate to shift for the feedbacks to come into play. In the geological past, the forcing was largely from Milankovich cycles, taking thousands of years. In modern times the forcing is primarily from CO2, taking decades. That, in a nutshell, is the AGW argument.”
Um John, Did you happen to notice the past decade or so with increased XCO2 but flatline global temperatures, declining ocean temperatures, brutal winters with (“warm” we are told) snow?
“Show me where there’s positive feedback demonstrated there and the next time I’m in the UK I’ll look you up and buy you a beer. – Anthony”
Spectacular missing of the point there! The Allan paper simply is NOT ABOUT feedbacks, positive or negative. The entire comparison with the numbers from Dessler and Spencer is bogus, they don’t even have the same units, for Pete’s sake!
@RobW:
Flatline global temperatures – only if you cherry pick – 2000’s were warmer than 1990’s
Declining ocean temps – ditto
Brutal winters – merely local, there have also been heatwaves (equally local)
According to AGW, temperature rises will resume. The shame is that we will have to wait until they do (10 years should do it) before the “skeptics” will finally accept reality
tallbloke says:
September 20, 2011 at 12:17 pm
John B says:
September 20, 2011 at 12:01 pm
The water vapour and clouds are feedbacks.
So if co2 made it warmer, and that made more water vapour, how come the cloud amount reduced between 1980 and 1998?
—————
Don’t know, but it looks like more of a problem for Spencer than for mainstream climate science (i.e. there was little or no negative feedback from clouds, plenty of positive feedback from water vapour)
IMHO
John B says:
September 20, 2011 at 12:01 pm
Not so to you too, Sir!
Sorry – but that is the whole illogical basis of the CO2 based AGW theory IMO. It is essentially that a small change in CO2 (a small GHG contributor) causes knock on and supposedly massive changes in other GHG’s water vapour and clouds, etc – but this is simply illogical based on geological past CO2 levels.
I’m relatively happy to accept CO2 is a positive effect, albeit extremely small in terms of the energy kicking around. But the +ve and -ve effects of all the other factors far outweigh any CO2 effect.
In my opinion clouds are the primary regulator/thermostat and THEY are based on water vapour – of which, as a wet planet – we have bucketloads – figuratively speaking! When you consider that H2O is responsible for 80+% of any GH effect (I know the figures vary according to source) – something that contributes peanuts to GHG effect (CO2) is just not on the scale!
Joe Born says… ” Let’s do a thought experiment. Suppose a CO2 increase sufficient to raise temperature 1 degree reduces clouds enough to raise temperature another half degree. That half degree reduces clouds enough to raise temperature another quarter degree . . . so that after an infinite number of such responses the temperature has been raised a total of two degrees.”
For your experiment to be true…. an increase in temperature MUST NOT have much of an effect on cloud cover because the paper in question shows that there is expected to be a huge effect on temperature with only a relatively small change in could cover. Once again, the effect of temperature on clouds is consistent with Dessler and Spencer papers.Therefor one can conclude that factors other than temperature increases that effect cloud cover (cosmic rays, ocean cycles or something else) will have a relatively large effect on temperature. Best evidence indicates a slightly negative feedback between temperature and clouds excluding ALL other factors that influence cloud formation, ie higher temps due to CO2 increase clouds cover slightly which lessens the net warming due to CO2 .
On the other hand the current paper suggests that significant cloud cover changes not due to temperature changes can lead to large swings in climate and temperature. Thus cosmic rays and ocean cycles and possibly other factors could be considerably more important that CO2.
Tallbloke,
You wrote: “if it becomes slightly less negative, it’s still very negative, and overwhelms the effect of changes in co2. ”
No. If cloud forcing becomes less negative in response to warming, it be definition acts as a positive feedback. You’re confused by the reference point. The forcing this paper is discussing is in reference to a cloud free planet: How do clouds affact the radiation balance. You (and Anthony) compare that number to the (surface) forcing by a doubling in CO2. That doesn’t make any sense.
Kev-in-Uk says:
September 20, 2011 at 12:44 pm
John B says:
September 20, 2011 at 12:01 pm
Not so to you too, Sir!
Sorry – but that is the whole illogical basis of the CO2 based AGW theory IMO. It is essentially that a small change in CO2 (a small GHG contributor) causes knock on and supposedly massive changes in other GHG’s water vapour and clouds, etc – but this is simply illogical based on geological past CO2 levels.
————
You are right up until the last part about geological levels. The difference is, in the geological past, CO2 was only a feedback (hence the famous 800 year lag), then humans started burning fossil fuels and CO2 became a forcing. That was the game changer. But don’t take my word for it, get out there and read some science, I think you will find it fascinating.
John B. Why do we have to wait 10 years for Global Warming? Why is it not warming now? Could it be the Sun?? Solar Cycle 24 is in full fail mode.
Please explain why temps are flatlined now and how the IPCC could anticipate that. None of the models anticipated it.
John B says:
September 20, 2011 at 12:52 pm
Haha – I guess I’d best resit all my science exams and give back both my first and masters degrees then?
You are making the classic finger pointing mistake, as per the general warmist argument. You ‘see’ only one metric (CO2) and draw a phenomenal conclusion – conveniently ignoring ALL the other effects. Serious AGW has virtually been disproved based on the lack of continued warming, and of course, alongside all the other revelations….
And I respectfully suggest you need to do some reading and understanding of the relevance of the 800 yr time lag. Temp leads CO2 – this means that logically the (non Anthropogenic) past CO2 increase is an EFFECT – not a cause. No amount of squirming can eliminate that as reasonably well proven fact. As a simple (but slightly silly) counter argument – perhaps we are seeing CO2 rises as a result of warmer temps 800 years ago? How do you KNOW this is not the case?
Dire Wolf says:
September 20, 2011 at 12:55 pm
John B. Why do we have to wait 10 years for Global Warming? Why is it not warming now? Could it be the Sun?? Solar Cycle 24 is in full fail mode.
Please explain why temps are flatlined now and how the IPCC could anticipate that. None of the models anticipated it.
—————-
Yes, it is partly the Sun, partly ENSO, partly who knows what. But the point is, none of those things have a trend. That is why climate scientists are confident warming will resume. Nobody ever predicted a monotonic, year-on-year rise. And the models can’t predict things like La Nina and a quiet Sun, but that is not considered fatal because, as I said, those things don’t show a trend.
Why do we have to wait 10 years? We don’t, but some choose to. The science says warming will resume. You can accept that now or wait until it is blindingly obvious to everyone. I am fast coming to the realisation that the latter is more likely.
As anyone who lives on the wet coast of the Northwest of the USA or wet coast of Canada knows when the clouds come in it gets significantly colder. How any scientist could ever imagine that clouds warm up the atmosphere is beyond the personal experience of most people. Sure the heat is trapped at night as is obvious from clear nights being colder but it’s the blocking of the sun that matters the most. At least that is what is obvious from personal experiences that the vast majority of people living on Earth could tell you. Why haven’t climate scientists gotten this till now? The obvious is non-obvious to agenda driven political climate science? [;)]
Also, is there a comprehensive cloud cover database now that satellite images have been taken for a few decades? It would be interesting to review the statistics of each location where there is a ground thermometer to see what the could cover was over the years. Has anyone done such a study?
Oh, each temperature station should also have a camera pointed skyward to monitor the cloud cover at that specific location, and maybe a camera that could do the same during the day and at night. Also maybe a direct sunlight detector instrument to see if the sun is hitting the temperature station box directly; a light level meter. In addition to all the other sensors.
Also can the heat for all the history of the weather stations be calculated in joules? Have the weather stations across the world kept enough information to compute the heat in joules?
John B
C02 doesn’t suddenly change its physical properties to become a forcing. Perhaps if the atmosphere were dense and 70%+ of it were c02 there may be an argument, but only as a result of air pressure and density as commensurate with the laws of gases.
John B
“You are right up until the last part about geological levels. The difference is, in the geological past, CO2 was only a feedback (hence the famous 800 year lag), then humans started burning fossil fuels and CO2 became a forcing. That was the game changer. But don’t take my word for it, get out there and read some science, I think you will find it fascinating.”
I found it fascinating, until I found that the warmist scientists were lying, hiding data, manipulating the peer review process, and denigrating people instead of doing honest science.(see climategate emails for definative proof)
Then I knew for sure that the warming due to CO2 was going to be a non issue, indeed, beneficial!
“REPLY: Thanks Roy for the clarification. The question of whether clouds act as feedback, forcing, or both is one that will occupy us as a while.”
Clouds are not a forcing. The forcing is radiant energy from the sun. Everything else which responds to that forcing with its own effects is a feedback.
The clouds act as a standard lag-lead compensator to stabilize temperatures.
“Temp leads CO2 – this means that logically the (non Anthropogenic) past CO2 increase is an EFFECT – not a cause.”
YES! In the “non-anthropogenic” past, CO2 increase was an effect. In the past 200 years or so (a) CO2 has gone up far too much to have been an effect from either recent or MWP warming, (b) we are burning fossil fuels and (c) isotope studies show where the added CO2 comes from. Now it is a cause.
But like I said, don’t take my word for it, go and read some mainstream climate science. I may well have got some of the details wrong, so read the experts directly.
Just a quick comment for those who think this the result is obvious.
Ever notice in the winter time, it tends to be warmer on cloudy days and those bright sunny days are the ones where you’ll freeze your butt off? Or that clouds during the night time keep the temperatures from falling as much?
Sometimes what we think is obvious isn’t. That’s why its important to actually do the science. I’m glad these guys did.
P Wilson says:
September 20, 2011 at 1:16 pm
John B
C02 doesn’t suddenly change its physical properties to become a forcing.
—————–
No, it doesn’t. What changed is that for the first time in the history of the planet, masses of the stuff is being released into the atmosphere by the burning of fossil fuels. THAT is why it is now a forcing. Previously, CO2 was added to the atmosphere as a result of some other clamatic event (feedback), now it is a direct result of fossil fuel burning (forcing). But others make the point better than me. Google (or bing) is your friend.
Ed_B says:
September 20, 2011 at 1:17 pm
I found it fascinating, until I found that the warmist scientists were lying, hiding data, manipulating the peer review process, and denigrating people instead of doing honest science.(see climategate emails for definative proof)
—————
What, all of them? Even Tyndall and Arrhenius in the 19th century? And how about the author of this paper? I guess that depends on whether you like what you think he is saying.
James says:
September 20, 2011 at 4:03 am
…..
‘And cloudy nights would feel colder than clear nights …. oh!’
So are you suggesting that water vapour in clouds retain heat more efficiently on a cloudy night than CO2 does on a clear night ? If so, where does this heat go to?
John B says:
September 20, 2011 at 1:27 pm
This is like taking candy from a baby…..
Look – it’s really simple…if something causes something else to occur – it is a forcing. if the response of the effect is to increase the forcing, then its classed as a positive feedback.. do we agree?
so – if we have had higher temps (which we have) – which we accept subsequently led to higher CO2 (most likely) – and which subsequently were later followed with LOWER temps – what is the likely NET effect of the actual increased CO2?
Even if you do not accept that as a basic analysis – it still demonstrates that CO2 cannot be THE major player (at such low concentrations) because CO2 values were many times higher than today and temps STILL came back down…..
and don’t come back with the rising temps bulldust either – we are still recovering from the last ice age – so obviously temps will be rising (with a superimposed natural cyclical variation)…
I don’t dispute that there may be some effect from the increase in CO2 – but it is so minor as to be insignificant compared to ALL the other effects. You’d be a far better environmental protection advocate to be protesting against deforestation and 3rd world wood burning than coal burning power stations…..
Cloud feedback negative. CLOUD at CERN finds pre-cloud seeds greatly increased by GCRs.
The “Barbarians” (actual scientists using observed data rather than unproven models) are at the gate. Where to run to now?
Dire Wolf says:
Your statement about the models is not really correct. The models do not even attempt to predict all of the jiggles up and down in the global temperature (due to El Nino and La Nina for example). That is because these jiggles are very sensitive to the initial conditions…and hence vary from one run of a model to another. (There has been some recent attempts to try to predict these shorter-term variations, but it is actually a more difficult problem than predicting a long-term trend due to a forcing. This should be of no particular surprise to anyone who thinks much about it: Here in Rochester, nobody would doubt the prediction that the temperature is going to be colder on average this January than it is in July. This is based on the significant change in forcing due to the seasonal cycle. However, a prediction that, say, the temperature trend for the week from October 1-7 will be down or up is considerably more difficult to make, even if we know that ON AVERAGE over several years, we would expect a downward trend because of the seasonal cycle. Likewise, predicting whether this January would be colder or warmer than the average January is also more difficult.)
However, one can look at the statistics of what the models predict and compare it to what we see. For example, how often would the models predict that there would be, say, a 10 year period of no warming when forced with steadily-increasing greenhouse gas forcing? That was investigated in this paper: http://www.leif.org/EOS/2009GL037810.pdf And, the basic answer is that it is not all that unusual to find such periods due to the nature of data that has a slowly increasing trend plus a fair bit of noise.
There may be other contributors to the lower temperature trend over the past decade or so, such as the unusually prolonged sunspot minimum … but there is really as of yet no evidence that it is anything more than the statistical fluctuations that one sees in trends of systems with linear trends + noise over periods of time short enough that the noise is still quite dominant.
coaldust says:
September 20, 2011 at 1:59 pm
Cloud feedback negative. CLOUD at CERN finds pre-cloud seeds greatly increased by GCRs.
————–
Except that there has been no trend in GCRs, so even if GCRs did cause clouds to form, which is still merely conjecture, it would be irrelevant.
No need to run.
> “REPLY: Dr. Allan, thank you for visiting and for your correction. Please note that I’ve made an update to the post, removing the word negative from the headline and including why I interpreted the paper to demonstrate a negative feedback for clouds. I welcome your thoughts. It seems to me that if clouds had a positive feedback, the dips in 1998 and 2010 in your figure 7 would be peaks rather than deep valleys.”
——————————————–
El Nino and La Nina are associated with a substantial reorganisation of atmospheric and oceanic circulation and oceanic heat in the top few hundred metres. It would be surprising if clouds did not respond to the rapidly evolving sea surface temperature patterns, yet extracting the cloud feedback processes relevant for global climate change are not so simple.
For example, global temperature anomalies became increasingly positive during 1997 along with positive anomalies in net radation which by your reasoning would be a positive feedback. In fact you can pull out any answer you want if you cherry pick short periods of time and do not consider what is responding to what.
Understanding the physical processes operating during these fluctuations and tracking energy through the climate system, using physical principles, observations and sophisticated models of the atmosphere and oceans, remains an active area of research.
Alcheson says:
September 20, 2011 at 12:48 pm
“For your experiment to be true…. an increase in temperature MUST NOT have much of an effect on cloud cover because the paper in question shows that there is expected to be a huge effect on temperature with only a relatively small change in could cover.”
True dat. But the AGW proponents’ argument does not require the effect to be “much” by your measure. All they require is that the reduction in cloud cover be enough to multiply what would otherwise be the modest temperature response to a CO2 increase–and, as I demonstrated above, even what is apparently not much of an effect by your standards can provide such a multiplication.
The paper does indeed say that clouds have what I view as a large negative effect on surface temperature. But this establishes nothing about how strong the reverse response is: it says nothing about how strongly surface temperature affects clouds.
Now, I personally think that clouds do respond in a negative-feedback way to temperature. (Actually, I find the Eschenbach thermostat theory somewhat compelling, and there’s some controversy about whether that is properly termed a feedback effect.) I also agree that significant components of their variation are essentially independent of surface temperature. I just don’t think this paper sheds much light on those issues.
In any event, my comment above was merely a response to your argument that “[I]f increases in CO2 causes slight warming and the warming leads to fewer clouds . . . then you shouldn’t need any further increase in CO2 to have runaway global warming.” Since this discipline has adopted what to me is a confusing meaning for “positive feedback” (I actually think of it as more a reduction in negative feedback), I doubt that you are the only one who would make that argument. So I provided the thought experiment above to demonstrate that particular argument’s invalidity. I hope it was helpful.
Kev-in-Uk says:
September 20, 2011 at 1:53 pm
John B says:
September 20, 2011 at 1:27 pm
This is like taking candy from a baby…..
Look – it’s really simple…if something causes something else to occur – it is a forcing. if the response of the effect is to increase the forcing, then its classed as a positive feedback.. do we agree?
—————–
Yes, we agree on that, but the rest of your argument doesn’t follow. And the main point is that CO2 can be both a feedback (as it was in the geological past) and a forcing (as it is now). Not because its physical properties changed but because we are now burning fossil fuels whereas we weren’t before. As to whether the effects of anthropogenic CO2 are minor – you have to run the numbers, neither you nor I can conclude anything by handwaving. Go and see what those who have run the numbers conclude.
coaldust says:
September 20, 2011 at 1:59 pm
“CLOUD at CERN finds pre-cloud seeds greatly increased by GCRs.”
Pace my previous comment, one could think of clouds as forcings in this context. But, not really. The GCRs are the forcing here.
While that statement is true, I am pretty sure that Hansen, Ruedy, Sato and Lo did predict a monotonic decade on decade rise:
http://www.columbia.edu/~jeh1/mailings/2010/20100601_TemperaturePaper.pdf
Correct me if I’m mistaken. GK
John B,
You are getting totally desperate. Not surprising, since the planet isn’t doing what you want it to. In fact, it is doing what the rest of us want it to. Rarely has the planet’s temperature been so steady and unchanging for so long.
Forget the grant chasing charlatans who “run the numbers” in their computer models. If CO2 had a significant effect, then temperature would closely follow CO2. But it doesn’t. The insignificant [and entirely beneficial] warming from added CO2 is very likely around 1°Cx2CO2 ± 0.5°. That’s nothing to be worried about.
Joe Born. Also in order for your hypothesis to be true… then the amount of additional warming caused by changes in cloud cover MUST be less than the original amount of warming caused by CO2. Thus by your own admission, the net climate sensitivity factor for warming due to CO2 must be less than 2x the CO2 alone. Thus we have a maximum upper bounds of ~1.4C increase for a doubling of CO2. And if clouds are a net negative (most likely case)…. then it is even less than 1.4C.
@JohnB
I respectfully suggest you look at the numbers for yourself – particularly at things like the radiative absorption spectra of all the different GHG’s etc, etc – CO2 is far less than H2O for example….
I don’t wish to be belligerent – but I was the same as you a few years ago. I’d read the media reports and ‘accepted’ the promoted concensus (stupidly believing that the media were probably unbiased!). It was only by chance, really, that I started to look into it deeper (a long story – but I was curious as to the energy budget values). As soon as I saw conclusion after conclusion being unsubstantiated or based on this guess and that guess, this model and that model, etc, I realised it was not ‘settled’ and to be honest, that’s when I became angry. MY area of science, geology and earth sciences, had been ‘contaminated’ with bad unprofessional work (IMO) and the political promotion (and funding grabbing!) was obvious….when you tie that to the likely economic outcomes from the potential AGW ‘protectionist’ policies – I get doubly angry. Then you get the likes of Climategate and the Hockey Stick – and hey, I’m my own little Vesuvius! I hate being misled, and I am now a confirmed skeptic – because the current science has made me that way. If it was so obviously settled, hey, I’d be with you – but I have my professional opinion, and it is not alongside those of the warmists. If the promoted AGW was so clear cut and beyond reasonable doubt, we would not even be here……because the case would be so obvious…. why is it not so?
G. Karst says:
September 20, 2011 at 2:30 pm
John B says:
September 20, 2011 at 1:07 pm
…That is why climate scientists are confident warming will resume. Nobody ever predicted a monotonic, year-on-year rise…
While that statement is true, I am pretty sure that Hansen, Ruedy, Sato and Lo did predict a monotonic decade on decade rise:
http://www.columbia.edu/~jeh1/mailings/2010/20100601_TemperaturePaper.pdf
‘(6) global warming on decadal time scales is continuing without letup. Figure 8, showing decadal mean temperature anomalies, effectively illustrates the monotonic and substantial warming that is occurring on decadal time scales. But because it is important to draw attention to change as soon as possible, we need ways to make the data trends clear without waiting for additional decades to pass.’2010
Correct me if I’m mistaken. GK
———————-
You are not mistaken. And on “decadal timescales” it is still true. the 2000’s were warmer than the 1990’s and the 2010’s will likely be warmer than the 2000’s You can even see that in the chart Smokey linked, if you look at it honestly.
And Smokey: desperation no, frustration maybe.
Not true. Forcing can be any external influence on the system. If cosmic radiation can lever heat from the sun, cosmic radiation is a forcing to that system. It’s not the energy source, but it’s the forcing in that particular system. Forcing and energy source aren’t the same thing. This is why CO2 can be a forcing without furnishing any energy. It levers energy.
Kev-in-Uk says:
September 20, 2011 at 2:41 pm
@JohnB
…
If the promoted AGW was so clear cut and beyond reasonable doubt, we would not even be here……because the case would be so obvious…. why is it not so?
————————
Not sure if you really want an anwser to that, but here is my opinion. The science is sound. Not settled, as science never is, but sound. Why do some people not accept it? Well, some are simply misled by plausible sounding arguments from incredulity (e.g. “how can a trace gas possibly make a difference?”) while for many others I think it is ideological. Primarily, what this group hate is the thought of big government intevention, or whatever it is they wrongly perceive as the ideological basis of climate science. They see AGW as a liberal/socialist-led scam and then are forced to find ways of denigrating the science so as to avoid cognitive dissonance. And still others are just in it to make money – e.g. the ones who write books on the subject.
And of course, AGW is not the only mainstream-accepted idea that attracts contrarians. There are plenty of people who don’t accept evolution, the moon landings, Obama’s nationality, you name it.
John B says:
September 20, 2011 at 2:47 pm
decadal timescales? for millenial changes? You clearly miss the fundemental point that if we have a temp of X deg 10000 yrs ago (Ice Age) – and an increased temp Y of today (not in an ice age) – on the millenial scale, temps MUST have increased decade upon decade, century upon century! Granted, there will have been some cyclical variation due to Milankovitch, etc, etc – but the average temps will ALWAYS be increasing – at least until we start the next ice age period, in which case they will ALWAYS be decreasing…..Hence, the temp rising argument is NOT definitive proof of an anthropogenic influence IMO. Period. It may be an indicator, but even that has been thrown in the ‘doubt’ pile after the fact that despite further increased CO2 over the last decade+ – there has been no significant warming……Period. I won’t even bother with the ‘global temp is a futile metric /fallacy’ point – because that should be relatively obvious to anyone with half a brain – and if we then discussed the measuring methods.. well, you wouldn’t have a leg to stand on! The uncertainty levels go through the roof.
I’ll leave it there – apologies to all other readers if I have had to state the bleedin obvious – and yes, I know, I should not have taken the bait! Sorry.
Kev says: “but the average temps will ALWAYS be increasing”
So, how did we get from the MWP to the LIA?
Joe Zeise says:
and a cloudy night is warmer then a clear sky night.
Only if the preceding day was warm.
Try the situation where you get a clear, cold night, followed by cloud cover the next day.
The following night is going to be cold regardless of whether or not there is cloud cover and it is not going to warm up till you get some direct sun during the day.
ChE says:
September 20, 2011 at 2:51 pm
“If cosmic radiation can lever heat from the sun, cosmic radiation is a forcing to that system.”
Already covered that.
Dave Springer says:
September 20, 2011 at 10:33 am
Dave,
Thanks for responding to my questions. Your explanation regarding long wave radiation makes sense. However, I was really asking about the meaning of the paper. I quoted from the paper (both the abstract and the conclusion) where Allan, the author of the paper, is talking about feedback. It is surprising to me that Spencer and Allan would come here to say the paper is not about feedback when Allan mentions “feedback” nine times in the article. The article certainly says something about feedback. But I still think I am missing something.
Here, I may be mistaken, BUT wouldn’t 1998 – 2008 or also be on “decadal timescales” or ANY sequential 10 yr period, for that matter. Why would you bias to the calender arbitrary decade demarcation? GK
John B – stop being deliberately obtuse. MWP and LIA were shorter term variations in what has been a relentless long term upwards trend – and you know that is the case. To suggest that the past thirty years are significant, when for nearly ten of those tenos have been almost static, is ludicrous.
tenos = temps
John B. wrote: The science is sound. Not settled, as science never is, but sound. Why do some people not accept it?
First, the science is incomplete: one example that is not well understood is illustrated by today’s publication; the role of CO2 in modulating (if it does) the clouds is not well known. Would an increase in CO2 increase the rate at which clouds formed on sunny days and those clouds cooled the evenings — causing a net reduction in mean temperature? Would it have no effect whatsoever? Answers to these questions have not been demonstrated to be true.
Second, most of the projections of the future, if not all of them, are based on models that, one way or another, are simplifications of the actual relationships. If the inaccuracy of such necessary simplifications is negligibly small, such has not been demonstrated to date. Instead, the available models have over-predicted temperature rise over the last decades, and kludges have been added to the models to “account for the missing heat”, an example of which is presented on another thread at WUWT today.
Alcheson says:
September 20, 2011 at 2:39 pm
“Also in order for your hypothesis to be true …the amount of additional warming caused by changes in cloud cover MUST be less than the original amount of warming caused by CO2.”
Well, yes and no. Pay careful attention here, because the point is perhaps subtler than I had imagined.
Yes, if instability is to be avoided, the warming caused by cloud-cover change in response to *only* the temperature change the CO2 caused does indeed have to be less than the temperature change the CO2 alone caused. But this does not include the follow-on increase that occurs when the clouds additionally respond to the temperature changes they caused themselves. When that is included, then the cloud effects can, in theory, be greater than the CO2 effect alone yet avoid runaway. This tail-chasing behavior means that if r is the fraction the initial response–one-half in the thought experiment above–then the ultimate change is 1/(1-r), i.e., two in the thought experiment above.
Again, I’m not saying that’s what happens in real life. I’m just saying that your argument is not exactly bullet-proof.
Werner Brozek says:
September 20, 2011 at 10:04 am
“NetDr says:
September 20, 2011 at 6:54 am
Negative feedback drives the temperature back to it’s “set point”.
Warming causes cooling and cooling causes warming.”
Since Earth is relatively stable temperature wise, would you say Le Chatelier’s principle applies on a global scale so that whatever changes
******************
The short answer is yes !
The feeble early sun paradox says that the sun was 25 % dimmer in the distant past but the temperature was about the same. [No there was no huge amount of CO2 to compensate]
A strongly negative feedback system is highly resistant to change up or down.
Which is why I’m a hard-core Denier, and sneer at lukewarmists, and all who say CO2 will produce at least a little warming. The negative cloud effect is more than enough to easily “overshoot” and overwhelm any warming “impulse” from CO2.
There is NO CO2 GHE.
. Karst says:
September 20, 2011 at 3:50 pm
John B says:
September 20, 2011 at 2:47 pm
You are not mistaken. And on “decadal timescales” it is still true. the 2000′s were warmer than the 1990′s and the 2010′s will likely be warmer than the 2000′s
Here, I may be mistaken, BUT wouldn’t 1998 – 2008 or also be on “decadal timescales” or ANY sequential 10 yr period, for that matter. Why would you bias to the calender arbitrary decade demarcation? GK
——————————-
Yes, of course the calendar decades shouldn’t matter. But that is not to say that “1998 was warmer than 2008” means anything either. We should look at 10 year running averages, like this:
http://www.thenrgroup.net/news/images/Average-Global-Temperature.gif
Jason says:
September 20, 2011 at 3:59 pm
John B – stop being deliberately obtuse. MWP and LIA were shorter term variations in what has been a relentless long term upwards trend – and you know that is the case. To suggest that the past thirty years are significant, when for nearly ten of those tenos have been almost static, is ludicrous.
——————–
Jason, I was responding to Kev-in-UK, who said “temps MUST have increased decade upon decade”
Clearly not so.
so:
“John B says:
September 20, 2011 at 3:14 pm
Kev says: “but the average temps will ALWAYS be increasing”
So, how did we get from the MWP to the LIA?”
How did we get from the MWP, to the LIA? And how did we get out of the LIA? Wasn’t the level of CO2 monotonous, during that period?
Suggested answer: There was no MWP, or LIA. (Am I close?)
“Large negative cooling effect”. Hmmm … Negative cooling means warming, this look like an unnecessary double negative. Maybe Anthony should revise the title again 🙂 e.g. lose the “negative”.
Or did logic die with Aristotle?
Multi-institutional study group finds strong negative-feedback cooling effect from clouds
http://hockeyschtick.blogspot.com/2011/09/multi-institutional-study-group-finds.html
The Newsletter of the multi-institution Climate Process Team on Low-Latitude Cloud Feedbacks on Climate Sensitivity outlines their significant findings to date:
1. Clouds have a strong negative-feedback cooling effect on climate in both the tropics and extra-tropics
2. A warmer climate enhances [increases] boundary layer clouds resulting in increasing negative-feedback
3. Due to this strong negative-feedback, global climate sensitivity is only 0.41 K/(W m-2) – FAR less than the 3.7 W/m2 + assumed by the IPCC
Introduction:
The Climate Process Team on Low-Latitude Cloud Feedbacks on Climate Sensitivity (cloud CPT) includes three climate modeling centers, NCAR, GFDL, and NASA’s Global Modeling and Assimilation Office (GMAO), together with 8 funded external core PIs led by Chris Bretherton of the University of Washington (UW). Its goal has been to reduce uncertainties about the feedback of low-latitude clouds on climate change as simulated in atmospheric general circulation models (GCMs). To coordinate this multi-institution effort, we have hired liaison scientists at NCAR and GFDL, had regular teleconferences and annual meetings, and developed special model output datasets for group analysis. The cloud CPT web site http://www.atmos.washington.edu/~breth/CPT-clouds.html provides links to all its publications and activities. The cloud CPT has had many interesting subplots; here we focus on two of interesting recent results and its future plans. The results showcase a key CPT strategy – gaining insight from the use of several complementary modeling perspectives on the cloud feedbacks problem.
Two recent findings of the cloud CPT:
(1) The world’s first superparameterization climate sensitivity results show strong negative cloud feedbacks driven by enhancement of boundary layer clouds in a warmer climate.
Superparameterization is a recently developed form of global modeling in which the parameterized moist physics in each grid column of an AGCM is replaced by a small cloud-resolving model (CRM). It holds the promise of much more realistic simulations of cloud fields associated with moist convection and turbulence. Superparameterization is computationally expensive, but multiyear simulations are now feasible. The Colorado State University and UW cloud CPT groups collaborated on the first climate sensitivity analysis of a superparameterized AGCM (Wyant et al. 2006b). The Khairoutdinov-Randall (2001, 2005) superparameterized CAM3, hereafter CAM-SP, was used. Each CRM in CAM-SP has the same vertical levels as CAM3, 4 km horizontal resolution, and one horizontal dimension with 32 horizontal gridpoints.
Following Cess et al. (1989), climate sensitivity was assessed by examining the TOA radiative response to a uniform SST increase of 2K, based on the difference between control and +2K 3.5 year CAMSP simulations. Fig. 2 compares the results to standard versions of the NCAR CAM3, GFDL AM2 and GMAO AGCMs. All these models have similar clear-sky responses, so we just plot the +2K changes in longwave (greenhouse) and shortwave (albedo) cloud radiative forcings (ΔLWCF and ΔSWCF). Since ΔSWCF tends to be larger than ΔLWCF. boundary-layer cloud changes (which have little greenhouse effect compared to their albedo enhancement) appear to be particularly important. The CAM-SP shows strongly negative net cloud feedback in both the tropics and in the extratropics, resulting in a global climate sensitivity of only 0.41 K/(W m-2), at the low end of traditional AGCMs (e.g. Cess et al. 1996), but in accord with an analysis of 30- day SST/SST+2K climatologies from a global aquaplanet CRM run on the Earth Simulator (Miura et al. 2005). The conventional AGCMs differ greatly from each other but all have less negative net cloud forcings and correspondingly larger climate sensitivities than the
superparameterization. The coarse horizontal and vertical resolution of CAM3-SP means that it highly under-resolves the turbulent circulations that produce boundary layer clouds. Thus, one should interpret its predictions with caution. With this caveat, cloud feedbacks are arguably more naturally simulated by superparameterization than in conventional AGCMs [conventional climate models], suggesting a compelling need to better understand the differences between the results from these two approaches.
John B says:
September 20, 2011 at 2:06 pm
Except that there has been no trend in GCRs, so even if GCRs did cause clouds to form, which is still merely conjecture, it would be irrelevant.
There is no trend in GCRs? They change with every sunspot cycle. You are assuming the average is the controlling factor, but why would it be? The are the extremes and the rate of change. These are more likely controlling. Physical phenomenon operate on local and immediate conditions, not trends or averages.
The science is incomplete on cloud formation, which means the science is not settled. If cloud feedback is negative, the models must be tweaked. The results will not please those that believe CO2 if the major factor in earth’s temperatures.
Does cloud cover increase when temperatures increase?
The IPCC and the climate models in general estimate that the negative -21.0 W/m2 net cloud impact reduces to -20.0 W/m2 when temperatures increase by 1.0C. This is really the equivalent of a 5.0% reduction in cloud opacity/cover.
They also predict water vapour will increase by about 7.0% per 1.0C increase in temperatures.
So water vapour goes up by 7.0% per 1.0C but cloudiness goes down by 5.0% per 1.0C.
In practise, the climate models have a complex reaction where the height of cloud increases and the cloud fraction drops by about 1.0% resulting in the net change but I imagine this comes out of Hansen’s imagination only. It started with him.
If Hansen’s cloud numbers were correct, then his published Ice Age forcing numbers are way, way off because the 5.0C drop in temperatures in the ice ages should have resulted in a 25% increase in the cloud fraction and a decline in forcing of 5.0 W/m2 from this affect alone. Instead, he has a verty large drop in cloud cover (not exactly specified but that is how the numbers work out).
The Classius Clapeyron relation says water vapour increases by 7.0% per 1.0C increase in temperatures and clouds should increase by 2.0% to 7.0% (not decline by 5.0%). (The empirical data says water vapour increases by 4.5% per 1.0C increase and clouds are about Zero.)
Rewrite the climate models based on reality not on what you want the numbers to show.
I see that John B has posted another NASA chart that misrepresents reality by using a flat baseline. Charts like that are tantamount to lying. They deceive the eye by falsely making it appear that temperatures are rising at an accelerating rate [another hokey stick chart].
The truth is that global temperatures have been rising along a trend line going back to the LIA. Once that simple fact is understood, it logically follows that CO2 has at most an insignificant effect.
Temperatures are not accelerating. They have been rising along the same trend line since the LIA. CO2 has been ≤ 300 ppmv until very recently, thus falsifying the claim that CO2 has any more than a negligible effect, which for all practical purposes can be completely disregarded.
For normal folks, that clarification is all that is necessary to debunk the “carbon” scare.
Let’s consider this: It took a while, not a long while, but a while, to figure out this article. Who here can give an estimate of how long it would have taken arm chair warmers, main stream media, and politicians to figure out this research before they shoot from the hip? It is entirely likely that they have learned to stop here first before responding. This is what makes this blog worth reading. And I mean to say not only the post, but every comment made after the post. At WUWT, research sits down to chew it out with the public.
John B says:
September 20, 2011 at 4:53 pm
We should look at 10 year running averages, like this:
=============================================================
Truthfully, we should step back at look at the big picture…..
What moron put that “normal/zero” line way up at the very top?
….and who’s stupid enough to believe it?
http://www.daviesand.com/Choices/Precautionary_Planning/New_Data/IceCores1.gif
John B says:
September 20, 2011 at 3:02 pm
“The science is sound. Not settled, as science never is, but sound.”
No, the science of AGW is not sound, not even close. That CO2 can backscatter out going LWIR is about as close as it gets to sound, and that’s not close enough. The desire of climate scientists to view the climate purely in radiative terms has blinded them to the reality of a climate governed by the phase change of H2O.
The effect of backscattered LWIR on the cooling rate of the oceans appears to have been miscalculated. Water that is free to evaporatively cool does not respond to LWIR in the same way as rock or soil. The “Missing heat” never got trapped in the oceans.
Even ignoring this error, projected increases in CO2 do not have the ability to cause catastrophic warming on their own. Not even if we used all known fossil fuel reserves. Hence the need to invent strongly positive water vapour feedback and erase the MWP. The discussion on this thread alone should be enough to indicate that the empirical evidence for strongly positive water vapour feedback is lacking.
The CAGW hypothesis depends on strongly positive water vapour feedback. The evidence for strongly positive water vapour feed back is lacking. The science is therefore not sound.
Dave Springer said at September 20, 2011 at 9:54 am
“Extinction altitude for primary CO2 absorption band is about 2000 meters AGL. That’s what I calculated from IR spectrograph looking downward from 20 kilometers above the arctic ocean. In the IR window you see the temperature of the arctic ocean and in the CO2 absorption band you see a temperature that is 20C colder. Using dry adiabatic lapse rate of 1C per 100 meters that works out to a 2000 meter column of air beginning at sea level.”
This was in response to my question asking how high a cloud base must be to be beyond the reach of surface LWR. What this tells me then is that clouds at or above 2000 meters have no direct influence on surface temperature at night, and so the higher they are, the less heat is retained at the surface. The air column below 2000 meters that is heated by surface LWR can reach the cloud with upwelling radiation and also the reach surface with downwelling radiation, but the effect is hindered by the opacity of the atmosphere and this: There are asymmetries in the radiated heat – CO2 does not radiate at the same frequency that excites it, so heat radiated from CO2 is less effective at heating adjacent CO2. But on analysis we can say that high clouds do not retain surface heat effectively. The heat they effectively retain is above the surface by some distance that is a function of the cloud base altitude and the opacity of the lower atmosphere.
Seems simple enough, but now the sun rises and the cloud is still there, very high overhead, and it is reflecting as much light back to space as does its lower altitude neighbors except the atmosphere above it is far less opaque, and because of the altitude advantage it begins reflecting light sooner, and casting a longer shadow, prevents the sun from heating a disproportionately larger area than it will at mid day. We conclude then this: There is nothing remotely symmetrical about the heat impact of very high clouds.
So now I want to know if this study of cloud influence considers cloud base altitude as well as cloud top altitude.
whether or not the gist of this paper is about feedback or net effect, it must be obvious that the impact that clouds have on radiation balance is large compared to changes in CO2 forcing, and that this large effect is calculated as the difference of two numbers that are larger still, and have substantial uncertainties. So, the difference has uncertainties in it that are yet larger yet, and may, in fact, be the sum of two substantial uncertainties.
Lamb, many years ago, thought he had indirect evidence for long period variations in cloudiness–if so is this a driver or feedback?
Anthony says
You can clearly see the famous double peak in the 1998 El Niño, but it is inverted. To me that looks like a thermostat action, and not one with stuck electrical contacts, i.e. a negative feedback. – Anthony
———–
I find this interesting because it says, I think, that Anthony, agrees the planet is warming and that the strong 98 el niño was in response to that warming and that the el niño then acted to counteract that warming. Otherwise the use of the term “feedback” does nor make sense.
Sounds plausible and if it is true then the predicted consequence would be that the el ninos will get stronger or more frequent as the global temperature rises.
REPLY: Nope, and not interested in having you put words in my mouth based on your anonymous opinion. -Anthony
Question about positive and negative forcings – the scientists say clouds may provide positive and negative forcings but I am wondering about agricultural dust. (Maybe another AGW funding issue for some university professor) Here in Alberta, every fall I see about 1000 km of north south dust, and about 1500 km of dust east of the Rocky Mountains from the harvesting activities of farmers. This lasts for three to four weeks every year. I have observed this both driving and flying over the Canadian and US grain belts and with all the discussion of dust and clouds, I wonder what impact the annual harvest has on temperature, if any, and in what direction. In reality, I don’t think it matters but in the context of all those people concerned about the environment and “Big Oil”, I see a lot more impact from food production on the prairies than from oil development. Just asking.
Konrad says:
September 20, 2011 at 5:05 am
Those saying that this paper is not addressing the feedback issue may be missing the point. For the strongly positive water vapour feedback demanded by the IPCCs doom scenarios to work, the increased evaporation would need to be prevented from causing more clouds. This is not plausible in an atmosphere with a vertical pressure gradient.
———–
If this was an easy question to answer it would have been answered already.
It’s not easy to answer since the increase in temperature has two effects:
1. it produces an increase in evaporation therefore increasing the absolute humidity
2. It produces a reduced tendency of water vapour to condense to form rain.
Then throw in the fact that rain happens when cold air streams collide with warm air steams, causing vertical air motions.
Then add in land versus sea and latitude and spinning earth’s and the whole effect becomes impossible to decide on the back of an envelope.
So sorry, common sense is not good enough outside your personal experience.
NetDr says
A strongly negative feedback system is highly resistant to change up or down.
———
Which means you have a serious problem explaining what the set point actually is.
We know there have been hotter periods in the deep past and most recently ice ages are the norm. So it looks like this is proof that negative strong feedbacks cannot exist.
A post that contains an erroneous interpretation of a paper (which the the author of the paper points out in the comment thread, as do other climate scientists) should place the update at the top of the post, not the bottom.
LT says:
“We know there have been hotter periods in the deep past and most recently ice ages are the norm. So it looks like this is proof that negative strong feedbacks cannot exist.”
Ridiculous.
The climate alarmist positive feedback argument is always resurrected to support runaway global warming, not ice ages. And there is no ” ‘proof’ that negative strong feedbacks cannot exist.” Another ridiculous argument. Negative feedbacks are the norm. It is positive feedbacks that are highly unusual.
Really, LT, you shouldn’t pollute this excellent site with your pseudo-science. Go back to tamino where you belong, junior.
I don’t know if this is accurate, when the sky is cloudy in the winter time, it is warmer, when it is cloudy in the summer it is cooler.
What I think I am missing is what is happening on a global basis.
tall bloke
“I invite you to consider why it is that cloud amount reduced according to ISCCP data in the 80s and 90′s. I think it was due to ongoing above average solar activity”
you refer to ISCCP cloud data.
Do you accept the physical models that are used to create the cloud data. Yes, create.
That physics is RTE. And we know from that that doubling c02 gives us 3.7 additional watts for forcing..
Now, you may believe that this forcing is counter balanced by other factors. you may believe that. But every time, every single time you cite data taken from a platform in space, you tacitly accept the physical models that used to turn sensor inputs into data products.
when a sensor in space gives you a picture of a cloud, when it measures SST, when it sees ice, when it provides any data whatsoever that data goes through a physics based algorithm. That algorithm has at it heart the physics which tells us… doubling C02 gives us 3.7W of additional forcing. Again, you can argue that this forcing is balanced or offset by other mechanisms. But when you talk about satellite data you invoke the physics required to produce it. You dont get to cite that data without owning the physics that creates its.
coaldust says:
September 20, 2011 at 5:20 pm
John B says:
September 20, 2011 at 2:06 pm
Except that there has been no trend in GCRs, so even if GCRs did cause clouds to form, which is still merely conjecture, it would be irrelevant.
There is no trend in GCRs? They change with every sunspot cycle. You are assuming the average is the controlling factor, but why would it be? The are the extremes and the rate of change. These are more likely controlling. Physical phenomenon operate on local and immediate conditions, not trends or averages.
———————
Yes, they go up and down – i.e. no trend, only variations. GCRs go up and down, as do other things, so those things can’t explain the trend. So, what has shown a trend over the last couple of hundred years that might explain temperature rises?
One point and one question:
1) Negative feedback normally reduces oscillations, positive feedback increases instability and makes oscillations more likely.
2) Clouds are white at the top and dark at the bottom (own shadow). Does this mean the cloud itself is hotter at the top than at the bottom compared to the air at the same heights? Do we know? Can a cloud really store energy?
Steven Mosher says:
September 20, 2011 at 10:51 pm
Morning (here) Steve – Not sure I follow your point. Yes, in order to define what a sensor measures, we would define the measurement based on the physics. But even if the physics is correct – that does not actually make the definition or measurement totally correct. Take something with a wide range of values e.g. radiation energy from nanometers to longwave – or TSI for example – no single sensor will measure the whole range (as far as I know?) because it will lose sensitivity in some ranges/areas. Hence, a range of sensors must be added together to give the end (summary) result. I for one don’t necessarily trust all the satellite data, and has been adequately demonstrated, neither do the scientists who interpret them based on the various corrections, etc, they seem to ‘need’ to apply.
The point that accurate measurement is fundemental to observations, does seem to get lost in the science publications – with uncertainties and error bars often guessed, or left out altogether – and certainly not highlighted within conclusions!
I find it quite ridiculous that cimate science talks about 1.4w/m of forcing here and there – within a total TSI of 1000 times as much – then say that TSI only varies by a tiny amount (0.1%), which, to all intent and purpose is equivalent to the tiny anthropogenic signal they are trying to measure. How often is this highlighted within the publications? I am not saying it isn’t possible to detect such AGW signals, but it is clear (especially after the last decade) that so called natural variation could easily ‘mask’ any such signal, and in real terms, likely outweighs the effects of any anthropogenic origin. I am not suggesting all the scientists deliberately evade the uncertainty questions – but the IPCC and political proponents certainly do!
“Roy W. Spencer says:
September 20, 2011 at 4:46 am
Now, it might well be that since the average effect of clouds on the climate system in response to radiative heating by the sun is to cool the Earth, then a small increment in radiative heating (e.g. from more CO2) will ALSO result in clouds having a further increment in cooling.”
If the above statement is not true then there would be some point and mechanism between snowball earth and now when the average effect of clouds reached a maximum level of cooling.
What is that point and mechanism? I don’t think there is any theory or evidence for such.
Anthony compared in his post the -21 W/m2 net radiative effects of clouds at the top of the atmosphere (TOA; see table 1 in the paper) to 1.3 W/m2 of surface forcing due to doubled CO2. This comparison has been echoed by several commenters (e.g. TallBloke, Rob Potter).
It is apples and oranges.
The 21 W/m2 of net cloud radiative effect is in reference to having no clouds at all: What is the net effect of clouds (TOA) on the radiation balance in the current climate? It doesn’t say anything directly about the contribution of clouds to current and future changes in climate.
The 1.3 W/m2 otoh refers to the surface forcing due to a hypothetical doubling of CO2. Something entirely different. The units are the same, but that doesn’t mean that can be usefully compared, let alone be interpreted to mean what some want it to mean.
The total (natural) greenhouse effect on Earth (due to water vapor, clouds, CO2 a.o.) is about 150 W/m2. If anything, that would perhaps be a relevant number to compare the 21 W/m2 to.
I posted my reaction also on my blog http://ourchangingclimate.wordpress.com/2011/09/20/net-cloud-effect-cloud-feedback-wuwt-confused/
Bart Verheggen says:
September 20, 2011 at 12:50 pm
Tallbloke,
You wrote: “if it becomes slightly less negative, it’s still very negative, and overwhelms the effect of changes in co2. ”
No. If cloud forcing becomes less negative in response to warming, it be definition acts as a positive feedback. You’re confused by the reference point.
The IPCC scientists claim that warming due to increased co2 will cause a positive water vapour feedback. This would cause more cloud and so cooling.
But cloud cover reduced while the planet warmed 1980-1998, so the supposed water vapour feedback to increased co2 is clearly overwhelmed by some other effect QED.
If it is a solar effect (GCR’s or upper troposphere specific humidity) then these natural variations overwhelm the alleged enhanced greenhouse effect.
Your theory is crumbling Bart V.
George,
Build an electronic circuit and try it. Assuming some lagg. It’ll be underdamped. Overshoot on the way down. Overshoot even more on the way up, etc. Untill the oscillation amplitude is reaches a saturation.
Hockey Schtick says:
September 20, 2011 at 5:20 pm
Multi-institutional study group finds strong negative-feedback cooling effect from clouds
http://hockeyschtick.blogspot.com/2011/09/multi-institutional-study-group-finds.html
Dear Mr. Schtick,
It appears the Climate Process Team did not like the results they were getting and decided to stop their efforts. Alternatively, funding sources saw their results and cut funding. It appears that no work has been done on this since about 2006. Still, it is an interesting find. Thank you for the link.
@EJT
You don’t seem to understand the principles here. George is absolutely right. Negative feedback is what damps the oscillations. Positive feedback is what amplifies them. As an electronics engineer I can say it is basic stuff!
I am a little surprised Allan says the paper is not about cloud feedbacks when it mentions cloud feedbacks four times in the article, including in the abstract and the conclusion.
The abstract reads: “The influence of cloud radiative effect on determining cloud feedbacks and changes in the water cycle are discussed. ”
So is Allan now saying he did not do what the abstract says he did?
From the body of the paper:
“Thus, the radiative effect of changes in cloud cover or properties is highly sensitive not only to cloud type (height, optical thickness, extent) but also to the time of year and time of day at which the changes in cloud properties take place. This is of importance in assessing cloud climate feedbacks which contribute substantially to uncertainty in climate prediction (Bony et al., 2006).”
So is he now saying he is wrong? Is he now saying the radiative effect of cloud changes does not play a role in assessing cloud climate feedbacks?
From the conclusion: “These analyses are vital in constraining cloud feedback processes further and in linking to future changes in the water cycle (Stephens, 2005; Bony et al., 2006; John et al., 2009).”
So is Allan now saying his analysis does not “constrain cloud feedback processes?”
It is fine to say the Allan paper focuses on the radiative effects. It is wrong to say the paper does not say anything about feedbacks. It clearly does.
Perhaps this paper is just a pre-print and Allan will make corrections to it prior to publication like Dessler is doing?
Normally, yes. But the issue raised was with a gain > 1.
John B says:
September 21, 2011 at 12:15 am
coaldust says:
September 20, 2011 at 5:20 pm
John B says:
September 20, 2011 at 2:06 pm
Yes, they go up and down – i.e. no trend, only variations. GCRs go up and down, as do other things, so those things can’t explain the trend.
You haven’t addressed my points.
The frequency spectrum of the inputs to a highly nonlinear coupled system is not insignificant. Thus, the rate of change may matter. The rate of change can vary without any trend. The non-linearity of the system means the extremes may matter. Our current understanding of the climate system is not mature enough to know if they matter.
So, what has shown a trend over the last couple of hundred years that might explain temperature rises?
Not CO2.
tallbloke
“The IPCC scientists claim that warming due to increased co2 will cause a positive water vapour feedback. This would cause more cloud and so cooling.
But cloud cover reduced while the planet warmed 1980-1998, so the supposed water vapour feedback to increased co2 is clearly overwhelmed by some other effect QED.”
“Some other effect”? Perhaps the fact that although absolute humidity has gone up over the last 40 years (an extra Lake Erie since 1970, I believe), the relative humidity amount changes with temperature, and the rise in absolute humidity has not kept up with temperature? So the relative humidity is, if anything, dropping along with the cloud cover (which means a positive feedback to temperature from clouds)? (http://en.wikipedia.org/wiki/Absolute_humidity)
It’s worth noting that the absolute humidity (total amount of water vapor in the air) drives the greenhouse effect from H2O, not the relative humidity – so that greenhouse effect is still going up.
This is pretty basic stuff, tallbloke. I sincerely hope that was a simple error on your part, not being disingenuous.
——————
KK,
It is a pleasure to see you participate here in an open, un-manipulated and enlightened venue. (thanks to Anthony for that)
I believe you are very very late to the party about updated observations on the paper’s interpretation in the original WUWT post. Indeed, the author, skeptics and non-skeptics had a civil discourse that quickly picked it up and discussed it.
Don’t you think this the best place for the free spirit of science? Got to love it.
John
sarc on/
PS – KK, on a personal note, I noticed your post is near the bottom of comments. Why did you do that? I think your comment should have been at the top . . . . shame on you. KK, take care of that, would you please? Really, near the bottom violates your integrity by the mere implication of hiding your comment, n’est ce pas? You are ‘entertainment’.
Sarc off/
[snip not interested in your snark “prufrocks” or whoever you are, note the blog policy on changing handles – Anthony]
I was totally serious. No snark. And I hear that RealClimate is the hypersensitive, deleter. Anyway, your post did nothing to diminish your credibility, and I like that fact that you and Steve Goddard are on top of things. Venus is hot because of high surface pressures according to PV=nRT; that totally convinced me. And I never would have known about Steve Goddard were it not for you. I’m a big fan of both of you guys.
Tony: “Oh dear, now we have three peer reviewed papers (Lindzen and Choi, Spencer and Braswell, and now Richard P. Allan) based on observations that show a net negative feedback for clouds, and a strong one at that. What will Trenberth and Dessler do next? Maybe the editor of Meteorological Applications can be persuaded to commit professional suicide and resign?”
What were you saying about snark, Tony? I’m very aware this is the only example from you on your entire blog that even approaches snark, but I’d hate to see it become the beginning of a trend.
son of mulder says:
September 21, 2011 at 3:07 am
“Roy W. Spencer says:
September 20, 2011 at 4:46 am
Now, it might well be that since the average effect of clouds on the climate system in response to radiative heating by the sun is to cool the Earth, then a small increment in radiative heating (e.g. from more CO2) will ALSO result in clouds having a further increment in cooling.”
If the above statement is not true then there would be some point and mechanism between snowball earth and now when the average effect of clouds reached a maximum level of cooling.
What is that point and mechanism? I don’t think there is any theory or evidence for such.
Indeed, what is more important than clouds per se are the mechanisms and dynamics of cloud formation and dissipation and the (Lyapunov) stability of cloud systems.
That cloud albedo causes cooling is not exactly Nobel prize territory.
Ron Cram,
The paper studies cloud forcings–ie., what the net effect of clouds at a particular time is/was.
It does so, in part, to provide information to help constrain feedbacks–ie., how clouds (and thus their forcings) evolve over time in response to other variables–presumably warming, primarily.
The second point is what is discussed in the bits you highlighted. It’s customary for papers to say why it’s worth studying whatever they study–in this case, it’s worth studying cloud forcings so that we may understand cloud feedbacks better in the future.
Steve McIntyre just posted a new article questioning Dessler’s methodology: click
Regarding the strikken out text, comparing -21 W/m2 net TOA radiative effect of clouds and the 1.2 W/m2 surface forcing of a doubling of CO2:
There is a another, and more important reason why these numbers can’t be compared.
Watts correctly conceeds that -21 W/m2 is the (most commonly used) TOA forcing, and the CO2 number is the surface forcing indeed (more commonly for CO2 doubling the TOA forcing of 3.7 or 4 W/m2 is given),
The more important reason why this comparison fails, however, is that the -21 refers to the total effect of all clouds, whereas the 1.2 (or 3.7) does not refer to the total effect of all CO2, but rather to a doubling. Different beasts.
REPLY: Yep, that was a late night blunder. I’m rewriting the entire post while wide awake. I’m still hoping to hear from Dr. Allan reading Figure 7 – Anthony
Much respect to Anthony for correcting the original post!!!
In light of this update, shouldn’t more than just the title be changed? Take the first sentence for example. From what I understand of the comments, shouldn’t this sentence, and several others be changed?
>> “Oh dear, now we have three peer reviewed papers (Lindzen and Choi, Spencer and Braswell, and now Richard P. Allan) based on observations that show a net negative feedback for clouds, and a strong one at that.”
…..and that was bad for Solar panels too….
Oops, sorry. Didn’t see a comment where a re-write is in the works.
Anthony,
Unless the climate boffins have redefined the word “feedback”, which is a fundamental concept in analog electronics, then clouds provide negative feedback without a shadow of a doubt. Solar energy evaporates water from the surface of the ocean, it rises and forms a cloud, the cloud then reduces the amount of solar energy available to evaporate more water. This is the very definition of a negative feedback, no ifs ands or buts about it.
Now this “forcing” thing they just made up. Except for a few paltry milliwatts that leaks up through the crust from the earth’s hot mantle (which, contrary to Gorian legend isn’t millions of degress but it’s still hot enough to melt iron) there IS NO FORCING except sunlight. In electronics we don’t call it forcing but we do call it electro-motive force or more commonly “voltage”. GHGs don’t force anything. They act like a resister and diode in parallel. The diode allows energy to flow in one direction (a “current” in electronics parlance) from the sun to the ocean with essentially zero resistance. When the solar current is shut off (night) current cannot flow backward through the diode but can pass through the resister. Not as easily as passes the other way through the diode however. Absent any GHGs energy would pass through the atmosphere as easily in both directions. Alas, the klimate kiddes have bastardized the language of engineering and called the resistive property of GHGs a “forcing”. What’s really dumb is they still label the energy flow in Watts which is very common measure of electrical flow.
Anyhoo, if you accept their bastardized definition of (forcing) then there’s no doubt that clouds are a forcing agent 24 hours a day. We just need to be clear that anything which resists the current (or causes drop in force across the barrier) is what they call a forcing. In that case clouds have both a negative feedback and a positive forcing. The net of feedback and forcing however is a negative number – less energy gets to the surface with a cloud than without a cloud on a global average basis taking into account all types of clouds. According to the paper in the OP the net negative is some 21 Watts per square meter.
Kevin, thank you for the response.
Kevin McKinney says:
September 21, 2011 at 12:48 pm
Ron Cram,
The paper studies cloud forcings–ie., what the net effect of clouds at a particular time is/was.
The language regarding forcing and feedback are unclear. It is my understanding that a forcing is something which directly acts on the radiative budget such as solar, CO2 and clouds. In this paper, Allen shows clouds during the day increase albedo reducing radiation into the lower atmosphere and surface which causes cooling at the surface. Feedbacks are a response to changes in the climate system from rising temps. Feedbacks can be either positive (causing more warming) or negative (causing cooling). The computer models generally treat clouds as a positive feedback because the models predict an increase in clouds and clouds hold warmth in at night. However, Allan’s paper indicates that the cooling effect of clouds during the day (the forcing) completely dominates the warming caused by clouds at night (the mechanism by which clouds are thought to be a feedback). So then as temps rise and more clouds are formed, cooling from the clouds during the day will completely swamp any extra warming at night (the feedback mechanism).
I understand Allan is not attempting to quantify the cloud feedback, but it seems clear to me that his paper states the cloud forcing is linked to feedback. How could it not be? If the clouds are reflecting solar rays to outer space, then there is less heat for clouds to hold in at night. And if clouds increase due to warmer temps, then increased clouds look to be a negative feedback.
Dave Springer:
September 21, 2011 at 7:00 pm
I do like the electronic resistor/diode analog! It seems to reduce the complexity to it’s simplest form. How far down the various electrical mathematical formula can you carry it? Curious is all as to what relational perspectives may pop. GK
Sorry my above comment should have been addressed to:
Dave Springer:
September 21, 2011 at 7:00 pm
Kev-in-Uk.
My point is very simple.
In order to turn a sensor reading into a data product there are a series of algorithms applying.
I’ll give you a simple example. SST. person X see a data product from a satillite. That product is SST, the sea surface temperature. They like that data product. They use that data product to make arguments. I am saying that they must also accept the algorithms used to make that data product. You cannot accept the data product and reject the algorithms used to produce it. so you will find people who use satillite data ( clouds, SST, you name it ) without realizing that those data products are actually the output of a model. raw sensor output is run through algorithms to create data products. So, you wantt o use the data product in an argument? you “own” the physical models used to create it. You use your cell phone? then you tacitly accept the physical laws used to design it. whether you acknowledge that or not in some way you rely on that physics being true.
That physics happens to be RTE.
“”””” EJT says:
September 21, 2011 at 4:15 am
George,
Build an electronic circuit and try it. Assuming some lagg. It’ll be underdamped. Overshoot on the way down. Overshoot even more on the way up, etc. Untill the oscillation amplitude is reaches a saturation. “””””
Well EJT, as they say, if you have been building feedback (negative) amplifiers , off and on, for longer than the last 55 years; then you probably know more about it than I do. Of course, back in those days we did it with valves and such; but when I do it today, it is most often done with some Analog CMOS process or other, often starting right down to the “bare metal” as they put it when you need to design your own diffusion layers (or ion implants.)
I’ve even built a few positive feedback amplifiers; with extremely accurate gains of +1. And yes the do oscillate, and at a very precise frequency, since they used highly stable mechanical resonators to derive the feedback signal.
But I’m quite happy to accept your confession, that your negative feedback amplifiers oscillate. A different line of work, might suit your skills better.
Steven Mosher says:
September 21, 2011 at 9:21 pm
I guessed that was your point – you were trying to say that models are good, again?
I think you are stretching it a bit far though. The physics model used for everyday objects, and simple measurements is usually straightforward. RTE’s are well described and used, of course – and it is based on a ‘model’. The trouble is that this model is ‘simple’ – certainly when compared to GCM’s, for example – and (and this is the most important point) – as a simple model, can be easily the radiative transfers can be readily ‘observed’ to confirm the model is correct/working!
I’d suggest that applying RTE’s to the climate, and in particular radiative transfer of CO2 molecules, etc is massively more complex and difficult to match to standard EM energy for example. (My physics is old and rusty, so outside my knowledge to be fair – so I defer to others to demonstrate this either way).
I do accept your point that models are useful – but I do not accept that the climate system is a readily ‘modelable’ system – and certainly not based on our current knowledge/understanding.
@george and EJT and anyone following the electronics analogy.
Feedback is called feedback because it feeds back from an output to an input, and usually it is the same input that is giving rise to the output to add to it (+ve) or subtract from it (-ve). The gain of any amplifying system is not relevant to the feedback fraction unless that gain is unstable or non-linear. If the feedback fraction is zero then the amplifier behaves as an open loop system. The more negative the feedback fraction, the more it damps the amplifier response. The more positive, the more it will tend to oscillate. With very slight negative feedback, oscillation is possible is response to small transients (from wherever) but the ringing response dies out with time, depending on the feedback fraction.
What could be interesting in the discussion is how the feedback fraction can be frequency dependent so that at one frequency the damping is heavy and at another there is oscillation and even a resonance, however, in these cases the effect is still positive feedback, not negative.
The simple model of the Earth heat transfer system as a diode and a resitor is a good starting point, but the analogy needs a large charging capacitor to represet the sea. The Resistor could be better represented as three resistors in series where one represents CO2 at night, one represents clouds at night, and one represents the night time atmosphere when free of either clouds or CO2. Which resistor would be the largest?
Anyone good at modelling?
🙂
Dave Springer says:
September 21, 2011 at 7:00 pm
I totally agree with your comment. They seem to have deliberately coined the term forcing to reflect some kind of ‘new’ energy introduction to the system – which of course, is absolute tosh. In reality, any chopping and changing of the energy ‘whizzing’ about still relies on the net incoming vs the net outgoing radiation. A temporal delay in outgoing radiation (commonly called the GHG effect) is not via the introduction of new energy! (and I have heard the man made energy argument too – but it’s still peanuts compared to the constant incoming solar!).
As for clouds – of course they must be net negative feedback items – or ‘reflector/shields’ if you prefer – it is common sense. The warmist arguments that they keep us warm at night (whilst true) are not presented properly in order to hide the fact that during the day their albedo has a much more pronounced effect – so whilst clouds do ‘both’ – the negative/cooling effect is significantly larger than the positive/warming effect. I really do think the IPCC cronies have deliberately misdiagnosed the cloud issue to keep the falsification of serious AGW going.
Stephen Mosher,
I’ve noticed that you are defending the use of models in climate ‘science’ through examples of models being used to create real world data, which is fine.
However,is there not a difference with a model using real world observation to create real world data and a model used to create future world data where the model is filled with assumptions?
My problem with climate models as science is that they require the assumption that climate science is sufficiently competent to input all variable within the climate system. It is this assumption that defeats climate models as science.
To use an accounting analogy. A balance sheet might fail to balance by a small sum. This small imbalance could be the result of many large/small assets and many large/small liabilities being omitted from the balance sheet (climate system). You could further complicate matters when you understand that the value of the missing assets/liabilities (forcings/feedbacks) change over time.
Climate models as projections of future climate is not science because it presumes we have more knowledge than we actually do.
Paul
.
The large negative effect implies a negative feedback as water vapor increases so must clouds. It is still plausible that the feedback is positive due to the location of the clouds, speed of the water cycle etc. are consider. But only in the sense that anything is possible and nothing is certain. What is all but certain is that there is no positive feedback.
“They seem to have deliberately coined the term forcing to reflect some kind of ‘new’ energy introduction to the system – which of course, is absolute tosh.”
I’ve been saying that for years…”forcing” is a slight of hand techniqe created by certain climatologists. The issue is “energy balance” which does not exist except on paper. Earth is not a closed system so there is no balance.
Well you obviously don’t understand feedback.
More clouds, blocks more solar energy, which cools the surface. If it gets too cold, the normal atmospheric lapse rate makes the atmosphere colder too, so it rains and snows more which removes some clouds, which allows it to warm up again, and verse vicea.
The earth’s oceans are in complete control of the Temperature range, for any given TSI level. Of course significant change in TSI from orbital changes, will shift the set point about which the oceans control the Temperature range.
Konrad says:
Actually, the evidence is not lacking. See, for example,
http://www.see.ed.ac.uk/~shs/Climate%20change/Data%20sources/1020HumidityVaporWarming.pdf
http://www.dca.iag.usp.br/www/material/akemi/radiacao-I/Soden_2005_Science.pdf
For those that say that more water vapor implies more clouds: It is more complicated than that because, as the atmosphere warms, both the amount of water vapor in it and the amount it can hold (i.e., the amount of water vapor at saturation) increase. In fact, the models generally predict that this occurs in such a way that, in the global average, the relative humidity (the ratio of the amount of water vapor to the amount at saturation) remains roughly constant or even decreases a little.
The devil, however, is in the details as to exactly where (both in terms of position on the globe and altitude) clouds are expected to increase and where they are expected to decrease.
Joel Shore is quoting the debunked Dessler??: “The distribution of humidity in this region is well reproduced by ‘large-scale control’ models… Although the water vapor feedback is strong in all global climate models… differences among the models in the amount of upper tropospheric warming… The spread among models in the water vapor feedback…” &etc.
And FYI, the troposphere models have been debunked by observation. When models are falsified so robustly, their premise is simply wrong. But some people just have to believe plainly wrong models over reality. Go figure.
And of course the AAAS, to which I subscribed for almost 30 years before I canceled in disgust for their lunatic runaway global warming alarmism, has totally lost its credibility no matter what any of the Kool Aid drinkers believe. Post some credible sources, like Willis Eschenbach articles, instead of the thoroughly corrupt Science propaganda, which is truly not worth the paper it’s printed on, nor even the screen pixels downloaded. Science is grant-promoting propaganda when it comes to climate issues, and only blinkered fools refuse to see that.
“Joel Shore says:
September 23, 2011 at 7:49 am
Konrad says:
The CAGW hypothesis depends on strongly positive water vapour feedback. The evidence for strongly positive water vapour feed back is lacking.
Actually, the evidence is not lacking.”
You cite a paper from 2005. It is now 2011 and the 1998 record from Hadcrut3 still has not been beaten and to the end of July, 2011, is the 12th warmest year.
http://www.cru.uea.ac.uk/cru/data/temperature/hadcrut3gl.txt
The evidence I want is that the global average temperatures actually increase at least once every ten years.
“”””” Joel Shore says:
September 23, 2011 at 7:54 am
For those that say that more water vapor implies more clouds: It is more complicated than that because, as the atmosphere warms, both the amount of water vapor in it and the amount it can hold (i.e., the amount of water vapor at saturation) increase. In fact, the models generally predict that this occurs in such a way that, in the global average, the relative humidity (the ratio of the amount of water vapor to the amount at saturation) remains roughly constant or even decreases a little.
The devil, however, is in the details as to exactly where (both in terms of position on the globe and altitude) clouds are expected to increase and where they are expected to decrease. “””””
Well Joel has fallen into a trap that it seems is very popular with the climatism “science” crowd, in fact all those who view the climate as a feedback loop.
Actually feedback loops (any kind) are rather simple in concept; but perhaps difficult to depict in words, rather than pictures or diagrams. but it looks something like this:-
“effect”
[Input signal (aka cause “forcing”)] > [System Transfer Function (aka “gain”)] > [Output Signal (aka effect “response”)]> [output terminal] >[“Feedack” network] >[ “feedback” signal] > [ sum with [input signal “forcing”] {add for positive “feedback”; subtract for negative “feedback”}.
That pretty much describes ANY feedback system. The gain block and the feedback network each have a “Transfer Function” that relates the in to the out, and those transfer functions can be unrestrained in complexity; do anything you want.
There is one thing you cannot do, and that is sum apples and oranges.
You can’t sum a feedback current with an input signal Voltage; the feedback network transfer function must supply a feedback signal of the same type as the original input signal.
Now the only input signal to the climate system that is of ANY consequence, is the input solar spectrum electromagnetic radiation energy, that is the driver (forcing) for the earth’s climate; aka TSI
You cannot sum at the input to earth’s climate forward transfer function, a non compatible signal such as the long wave infra-red radiation emitted from trace atmospheric gases like CO2 et al.
In the end, any feedback must be represented as an increase or decrease, in the value of the solar spectrum energy at the input terminals of the climate sytem it drives.
And here is where Joel missed the boat. It is not simply clouds alone that comprise the climate feedback transfer function by changing the albedo.
Water vapor increase in the atmosphere, which Joel freely admits accompanies warming of oceans and atmosphere also directly changes the value of the input solar spectrum energy by absorbing (attenuation) part of that signal in the 700 to near IR (say 4 micron) spectral range.
Any elementary perusal of the solar input terminals to the climate system would demonstrate that the addition of a different signal in the form of atmospheric CO2 LWIR re-emission, cannot be fed back into the same input terminals as the solar signal. They are not both processed by the same forward transfer function, since solar signals go deep into the ocean waters, and escape to the rest of the planet, only after a long propagation delay; whereas the LWIR “signal” is absorbed at the very surface layer of the ocean which is a completely different forward propagation transfer function. It is like trying to make a feedback amplifier, and connecting the feedback signal wire to the power supply terminal or even to the ground terminal.
The feedback loop that IS in the climate system via H2O, is the total effect of H2O molecules in any phase or form; wherever they may be in the climate system, on the ultimate value of the “forcing” aka solar spectrum energy, that drives the earth’s systems.
If a “Climate feedback” is NOT changing the value of input solar energy, either up or down, that is injected into the earth’s sytems (oceans etc); it IS NOT a feedback. It might be a “leakage path” that alters the output, but it isn’t a feedback since it doesn’t change the solar spectrum energy acceptance.
CO2 may act weakly as a feedback, since CO2 also absorbs some portion of the input solar energy spectrum, generally in the weaker 2-4 micron range, and of course the CO2 is much less than the average H2O content. Moreover, CO2 as a feedback alteration of the solar spectrum signal is ALWAYS a negative feedback, since like H2O, more CO2 absorbs more solar energy, reducing the driving signal “aka forcing”.
So no cigar Joel. Water in the atmosphere is always a negative feedback, whether cloud or vapor.
@george E. Smith
Well explained.
Werner Brozek says:
We are discussing the water vapor feedback, not global temperature trends. Hence your whole comment is irrelevant.
However, I will just add that you don’t get to decide by your own arbitrary methods that the global average temperature must set a record every decade in order to be increasing. The record set in 1998 was head-and-shoulder above any previous global temperature…smashing the old record by something like 0.15 C. Hence, it is not surprising that it takes a while before this record gets exceeded again. The 1998 super-El Nino was quite an anomaly.
George E. Smith:
Your whole comment is based on arguing with a strawman. The feedback loop picture is a simplified picture of how the actual atmospheric energy balance plays out. If you don’t like it because you are bothered by the different solar spectra, you don’t have to use it. The climate models do not.
And, the influence of CO2 and H2O in absorbing the incoming solar radiation is much smaller than their absorption of the outgoing infrared radiation, besides which, at the end of the day, what matters is the energy balance at the top-of-the-atmosphere because that, along with the lapse rate is what determines the surface temperature (i.e., it is not the surface radiative balance because of the large non-radiative heat transfers in the troposphere).
You can’t just come up with a lame excuse to ignore the “elephant in the room” (the absorption of outgoing longwave radiation by greenhouse gases) and thus promote the much smaller absorptions of incoming solar radiation to being more important.
Frankly, your entire post wreaks of the sort of pseudo-scientific arguments people come up with when they allow their ideology to trump their scientific reason. I think you are better than that, George.
I am not convinced that Anthropogenic Fossil Fuel consumption is the main cause for atmospheric temperature rise. From other sources I’ve been told that that source is 2/3 the total, while deforestation is the other 1/3. I am an Engineer and tend to follow these discussion to the end, where I say “so, what do we do about it?” I am also very practical. Humanity needs to use energy to support their life styles. Here we are talking about the role of clouds. This subject is sooo complicated that I do not believe mankind has a handle on the complexity and, therefore, is in no position to assert a remedy.
So, I say, let’s continue to study the climate system, use energy in the most efficient way (to maintain our life style) and when we know enough to state what needs to be done — do it.
Dear Mr. Watts,
I haven’t read the article, just the headline. I must say that this “negative cooling effect” caught my eye. In my opinion you should shed the word “negative”, since cooling is enough. “Negative cooling” sounds like the opposite of cooling, i.e. “warming”.
And please don’t get me wrong: I’m a physicist with a doctorate in Physical Chemistry and I’m surely no warmist. Websites like yours got me thinking about all that global warming business and without people like you the rational views wouldn’t get a chance to fight the help-help-we-are-all-doomed view concerning our climate.
I take pride in being a skeptic.
So please keep up the good work.
Best regards,
Georg Huber
I realize this is a gross simplification of Earth’s solar energy budget, but if IPCC models show a net positive feedback cloud effect and Allan’s research shows a net negative cloud effect of -21watts/M2, since the total annual Earth solar energy budget is approximately 8 million Quads, and the average solar energy hitting the Earth is 342 watts/M2, does this mean that IPCC models miscalculate roughly 491,228 Quads worth solar energy that shouldn’t be in their models?: (-21watts/M2)/342 watts/M2) x 8 million Quads= 491,228 Quads.
If this rough calculation is even close to reality, no wonder AGW acolytes have a problem with “missing heat”….
Thank you.
Yep, but a wee comma would fix it: “a negative, cooling effect”, making them parallel and mutually reinforcing!
🙂