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
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!
🙂