A paper published Friday in the Journal of Geophysical Research (GRL) finds that a known and natural atmospheric oscillation, the Southern Annular Mode or SAM, is correlated with observed increases in cloud cover resulting in regional cooling of approximately -2.5C. See for example this comparison from the paper with MODIS satellite data:
From UCAR:
The Southern Annular Mode (SAM), which is defined by changes in the westerly winds that are driven by temperature contrasts between the tropics and southern polar areas. The annular modes generally take a circular pattern (‘annular’ means ring-shaped) and see-saw between positive and negative phases for weeks or months. In the SAM’s positive mode, the ring is stronger and further south, inhibiting Antarctic air outbreaks. In the negative mode, a weaker, more variable vortex allows Antarctic air to spill north more easily.
The Southern Annular Mode has steadily trended positive in recent decades. Computer models indicate this trend is related to ozone depletion above Antarctica and increases in greenhouse gases. (Image courtesy Jianping Li, China Institute for Atmospheric Physics.)
As presently programmed, climate models assume clouds result in net positive feedback and increased temperatures, however this new paper and several others that have recently been published show that clouds instead result in net negative feedback and cooling.
Key Points of the paper:
- Sudden regional increases in cloud cover are detected over S. America
- Changes linked to the Southern Annular Mode
- The cloud changes are associated with regional temperature reductions
The paper and abstract:
Understanding sudden changes in cloud amount: The Southern Annular Mode and South American weather fluctuations
JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 117, D13103, 7 PP., 2012
doi:10.1029/2012JD017626
Benjamin A. Laken Instituto de Astrofísica de Canarias, La Laguna, Spain, Department of Astrophysics, Faculty of Physics, Universidad de La Laguna, La Laguna, Spain
Enric Pallé Instituto de Astrofísica de Canarias, La Laguna, Spain, Department of Astrophysics, Faculty of Physics, Universidad de La Laguna, La Laguna, Spain
This work investigates the cause and effects of extreme changes in synoptic-scale cloud cover operating at daily timescales using a variety of satellite-based and reanalysis data sets. It is found that the largest sudden increases detected in globally averaged cloud cover over the last ten years of satellite-based observations occur following positively correlated shifts in the phase of the Southern Annular Mode (SAM) index. The associated pressure anomalies are found to generate frontal cloud formation over large areas of the South American continent, increasing regional cloud cover by up to 20%; these changes are correlated to statistically significant reductions in local temperatures of approximately −2.5°C with a +1 day time lag, indicating the SAM index is associated with large scale weather fluctuations over South America.
Joel Shore:”My point is simply that the complexity of the issues defies attempts to reach very simple conclusions about how clouds will behave in a warming climate. Your intuition that cloudiness will increase contradicts Lindzen’s intuition that at least some types of clouds (high clouds in the tropics) will decrease. That ought to give you pause if you think that you can come to a conclusion on the basis of any extremely simple ideas.”
Well, it seems to me that simple conclusions are reached one way or another here. You can either assume that cloud feedback is 0, negative or positive. My point, however, is that by using *the very same logic* that assumes the RH will be more or less constant, you will also be led to the conclusion that a warmer atmosphere will condense more than a cooler one.
See here:
http://hyperphysics.phy-astr.gsu.edu/hbase/kinetic/relhum.html#c4
I don’t recall the precise details of the Iris hypothesis but doesn’t it go something like this? Drier conditions decrease precipitation efficiency which allows moisture to “survive” in the atmosphere for a longer period before raining out. Low precipitation efficiency is directly related to the formation of cirrus clouds which act to raise surface temps. As such, I don’t necessarily see any contradiction between what I am saying and the Lindzen hypothesis.
Cheers,:)
joeldshore says:
“This does not make sense. Convection can’t do an “end run” around the greenhouse effect because ultimately the energy has to escape the Earth system via radiation.”
Your comment defies common sense. Of course heat can rocket upwards via convection and get above 95% of the radiation blocking CO2. That is what I would call an end run. The only question is, why are climate scientists not including this real effect into their models? I LOL when I watched thos professors lecture at U of Chicago on radiative physics. It was a static model! I cannot imagine any student being so dumb as not to see through that charade!
joeldshore says:
My point is simply that the complexity of the issues defies attempts to reach very simple conclusions about how clouds will behave in a warming climate. Your intuition that cloudiness will increase contradicts Lindzen’s intuition that at least some types of clouds (high clouds in the tropics) will decrease.
Reduction in high cloudiness has occurred,
And that also has a cooling effect!!!!
A consistent reduction in cloud height would allow Earth to cool to space more efficiently, reducing the surface temperature of the planet and potentially slowing the effects of global warming. This may represent a “negative feedback” mechanism — a change caused by global warming that works to counteract it.
http://www.auckland.ac.nz/uoa/home/news/template/news_item.jsp?cid=466683
Carl B can have some of my tax money. I don’t want Joel S to have a cent–he should go find a productive job.
[Moderator’s Note: Ken, that was not really called for. Joel does have a productive job and is easily located on the internet. Maybe we can stick to substantive arguments? -REP]
Dear Moderator. I disagree. Joel is an academic and gets a paycheck that is partially funded by tax dollars. In my opinion, he does a lot of damage supporting wrong-headed ideas about human-caused global warming. As long as he sticks to his OLEDS, I have no problem, but he’s a vocal supporter of AGW. What is he saying in the classroom? Does he present both sides of our ongoing argument? I doubt it. I pay a lot in Federal Income taxes and I object to any of it going in his direction. That’s fair enough, isn’t it?
[REPLY: Ken, RIT is a private institution. I am not aware of any private institution that does not take government dollars in one form or another. Do you really want the government deciding what can or cannot be taught because they fund some of the programs? Asking for a level playing field means that Joel gets to teach the subject as he understands it, just as I, in another life, get to teach my subject as I understand it. Criticism is the name of the game. Joel does real work, and if you disagree with his perspective, as I do, engage it substantively or expose the errors. My university accepts Federal dollars and we would all be upset if someone objected to my society and environment lecture and demanded I go out and get a real job. -REP]
I do get your point and if you want to edit my comment as follows, I understand. Your house, your rules.
Carl B can have some of my tax money. I don’t want Joel S to have a cent–[Snip].
In the last three decades there has been on average a 22% increase in cloud condensation nuclei between 50 and 65 deg South due to increasing wind speed.
“These fractional increases are similar in magnitude to the decreases over many northern hemisphere land areas due to changes in air pollution over the same period.”
http://www.agu.org/pubs/crossref/2010/2009GL041320.shtml
Changing aerosol concentrations appear to be the factor which dictates the amount of cloud cover. Salt aerosols make effective water attracting, cloud forming c.c.n. whereas dark silt aerosols might be more heat absorbing and less likely to act as c.c.n. and there is a plethora of different forms of aerosol in between.
Regional and seasonal variations in aerosol concentrations must play an important role in dictating how climate changes. They may have short lifetimes but there is a constant supply, they can be wet (in clouds) or dry, either way they are shifting energy about.
Is my view of their major climatic influence misguided?
Re positive/negative feedback
I also have been bemused by the question of clouds and negative v. positive feedback.
I have posed a thought experiment for myself –
1. Assume a steady temperature, evaporation rate etc etc.
2. Now suppose that there is a rise in temperature from some cause
3. That causes an increase in water vapour in the atmosphere
4. That in turn causes an increase in temperature
5. And so forth and so on (and not a sign of CO2…after all it’s only a thought experiment).
What is wrong with this picture?
I compare this with the theory that CO2 causes some warming, which is ‘amplified’ by water vapour, which increases warming….
And so I wonder: “Why has the planet not overheated long ago?”
As an engineer, I am constantly seeking and applying forces and materials and effects that are useful…that do work. It troubles me when academics put such faith in their models and constructs. Literally, they invent things out of thin air. Don’t you know how useful if would be to heat something by an average of 33C (GHE)? Or, how useful it would be to heat something by an average of 66C (by doubling the GHE)? Or, how useful it would be to cool something by an average of 33C (by blocking or defusing the GHE)? However, the activists say, you can’t make this powerful force of nature work on command in your living room–you must have thin layers of cold, rarefied gases to make this powerful heating engine work.
It would be easy to shut me up. Just tell me how long the GHG delay is for energy leaving our system. What is the median delay? What is the distribution of this delay? Is the delay uniform from the tropics to the poles? How does a small delay in OLWR change an average temperature in a diurnal system? How long must the delay be to contribute positive feedback: 9 hours or so? 12? Is that how long it takes for photonic energy to leave our system? The incoming delay is something like 2 hours for materials (land and water) with greater thermal mass and a longer thermal time constant than air. The outgoing delay is longer than that? Prove it.
There is nothing wrong with the picture except that you seem to have failed to understand the fact that an infinite series does not necessarily diverge. For example, if 1 C of warming due to CO2 causes 0.5 C of warming via the water vapor feedback, then the feedback on that amount will cause an additional 0.25 C of warming, and the feedback on that will cause an additional 0.125 C of warming. The geometric series 1 + (1/2) + (1/4) + (1/8) + … does not get larger and larger without bound; rather, it approaches 2 as you approach an infinite number of terms.
Ed_B says:
The climate models incorporate both radiative and convective effects as understood by the laws of physics. So, that means your “rocketing effect” is either included…or it is not included because there is no known law of physics that includes. It is easy to talk in words of magical effects when one is unconstrained by having to actually create physical models constrained by the known laws of physics. People like Stephen Wilde over at tallbloke’s blog have made this into a high art form. As art, its impressive; as science, not so much.
Ken Coffman:
Ken: I think history has proven that nothing can shut you up, as you have had the greenhouse effect explained to you many times by AGW skeptics and those who agree with the scientific consensus alike and it has completely failed to register. We have told you that the issue is not one of delay. It is an issue of the rate in and rate out. You have energy coming in at a certain rate and you have to have energy going out at the same rate. If you do something that decreases the rate at which energy leaves the system, like increasing greenhouse gas concentrations, then the rate at which energy leaves the system will be lower than the rate at which it enters. The system responds by increasing its temperature until the rate out again matches the rate in (which occurs because the rate at which energy escapes is an increasing function of temperature).
This ought not be something that a reasonably competent engineer should have a problem understanding unless they are so ruled by their ideology that they cannot understand anything that challenges it.
Can anyone tell me if what seems obvious to me is actually true? Do sunshine hours recorded act as a proxy for cloud cover in general? This obviously only has daytime relevance but are sunshine hours a good enough indicator of cloud trends overall?
I have the monthly and annual weather means for my area (Palmerston North, New Zealand) going back to 1928. The sunniest years and decades were the 1930’s & 1940’s, although the Noughties came in third overall. The worst period was from 1979 to 1993, with 1980, 1983 and 1992 being the worst individual years.1983 suffered from the effects of El Chichon and Mayon, while 1992 was obviously affected by Mt Pinatubo, so I would surmise from the graph supplied by Jiangping Li that the 1980 low figure was as a result of a positive SAM at the time. The period 1952 to 1968 was also a time of average or below average annual sunshine figures with a few exceptions courtesy of strong La Nina events, in my part of New Zealand strong La Ninas have a positive affect in sunshine hours.
The last three years have seen a return to average and below average sunshine. This last southern summer saw the North Island covered in cloud for long periods while the lower South Island was bathed in sunshine.
As an example of natural oscillation, the first three months of the year here were the 3rd worst for that period while the last three months were the 3rd best on record for sunshine!
Looking at the data for Relative Humidity which I have up until 2000, this has been increasing through the 80’s & 90’s. I must track down the data since 2000 to see how it is running.
The article focusses on what happened in South America last winter but a significant snow event occurred over New Zealand last winter as well. Snow in many places right to the top of the North Island which was last seen in 1939, and to levels and thicknesses not seen in a lifetime. For Palmerston North snow of this nature hadn’t been seen since the winter solstice of 1912, and another big event in August 1904, although there have been other significant events in the valleys to the north which are at a higher elevation.
From what I can tell the oscillating positive/negative phases of SAM are the route cause of the bad weather/good weather patterns that dominate the short term weather patterns. When a negative SAM combines with a strong La Nina we have hot, sunny & dry summers. When a positive sam combines with a strong El Nino phase we have the opposite result.
Cheers
Coops
joeldshore says:
July 7, 2012 at 12:45 pm
“This does not make sense. ”
I’m not surprised; convection is unknown to the IPCC.
joeldshore says:
There is nothing wrong with the picture except that you seem to have failed to understand the fact that an infinite series does not necessarily diverge.
Let us agree immediately that not all infinite series diverge. That is trivial.
But that doesn’t answer the point of the thought experiment.
a) If you look to that part of my comment which follows the thought experiment you will note that my musings are intended to explore the notion that CO2 is responsible for current warming due to the ‘amplifying’ effect of water vapour. (Warming by CO2 alone simply doesn’t account for the extent of warming which some people report that they ‘see’).
It seems to me that what you have argued in relation to warming by water vapour must also apply to warming due to CO2?
b) Where do you get the idea that warming due to water vapour (or CO2 or anything else) is (i) incremental and (ii) most conveniently occurs in just such increments as to form a converging series?
Doug proctor says:
It always seems to come back to clouds. Svensmark clouds, that is.
And aerosol seeded clouds, which have decreased in recent decades over much of the Earth’s land surface, including the UK.
Philip Bradley says:
“And aerosol seeded clouds, which have decreased in recent decades over much of the Earth’s land surface, including the UK.”.
All cloud formations are the result of water vapour condensation on aerosol of some description. Salt and dust being the most prolific. If wind speeds are increasing in the Southern Hemisphere you would expect more salt spray and so more clouds.
I suspect more dust aerosol formation in the NH due to there being more land surface and that this could be playing a role in suppressing cloud formation due to there being more dark, heat absorbing silt aerosol and less light scattering clay aerosol than currently estimated.
http://sitemaker.umich.edu/jasperkok/files/kok2011_pnas_scalingtheorydustpsd.pdf
I think seasonal and regional variations in aerosol concentrations play a part in shaping weather systems.
Many people here are making a major mistake.
One cannot compare regional cloudcover increase with a global trend. The global trend is not a sudden 20% increase in cloudcover. Besides the paper never speaks of a relation between CO2 increase and cloudcover effects, but about an effect caused by the SAM which was probably also there before humans existed on the planet. A natural process.
It is generally known and accepted throughout the scientific community that more clouds will cause cooling, but it remains a mystery so far if cloudcover increase will negate AGW.
However it is funny though that a paper like this is easily projected onto global climate by a lot of posters here (Eyal Porat, Kohl, son of mulder, etc.) and the text of this piece also would like to suggest that cloud cover increase is a big negative feedback (in the >20% range yes, but this increase will never happen globally in the nearby future), while other papers are scrutinezed here to the minute detail for doing exactly the same:
http://wattsupwiththat.com/2011/06/23/reduce-your-co2-footprint-by-recycling-past-errors/
Another funny detail perhaps: If you need a >20% increase in cloudcover to cause a net reduction in temperatures of approximately 2.5°C. What do you think a cloud cover increase of just 1 or 2% will cause for a cooling? That’s the range we are talking about globally. The net effect would still be a good deal of warming.
pochas says:
That is a complete and utter falsehood…but I am sure you had fun saying it.
Kohl says:
I don’t understand the first part of your question…If the warming is not incremental, what is it? The point of this picture is to understand how an incremental view of things (which you adopted in your original post) yields a finite result. It is not necessary to think in this incremental way. One could simply say that the total effect of the entire water vapor feedback is to double the original effect. Or, one can look incrementally and see how that naturally arises for a feedback of the strength where the temperature rise due to the direct first-order feedback effect on a certain temperature increment is to add half again as much of an additional increase in temperature.
The converging series has to do with the strength of the water vapor feedback. The point is that the feedback is not strong enough to produce a divergence. If the first-order effect of water vapor on the original temperature increment were larger than the increment itself, you would get a diverging series. Because it is smaller than the original temperature increment itself, you get a converging series.
pochas: Just to bring you up to speed in regards to the actual science regarding convection and the greenhouse effect – The reason convection does not negate the greenhouse effect is that convection proceeds only as far as driving the temperature distribution with altitude (“the lapse rate”) down to the (appropriate, dry or moist) adiabatic lapse rate. If it were able to drive the temperature distribution all the way to an isothermal distribution with altitude (zero lapse rate) then it would indeed negate the entire greenhouse effect (as was well-known already and most recently re-discovered by Nikolov and Zeller who mistakenly put convection into a simple model in exactly this incorrect way).
Because of this limitation, convection does not cancel out the greenhouse effect, although it does reduce the natural greenhouse effect on Earth by a significant amount from what it would be with no convection. (As I recall, calculations show it would be about a factor of two larger in the absence of convection but all else equal.)
Kohl says:
July 7, 2012 at 3:49 pm
Re positive/negative feedback
I also have been bemused by the question of clouds and negative v. positive feedback.
I have posed a thought experiment for myself –
1. Assume a steady temperature, evaporation rate etc etc.
2. Now suppose that there is a rise in temperature from some cause
3. That causes an increase in water vapour in the atmosphere
4. That in turn causes an increase in temperature
5. And so forth and so on (and not a sign of CO2…after all it’s only a thought experiment).
What is wrong with this picture?
I compare this with the theory that CO2 causes some warming, which is ‘amplified’ by water vapour, which increases warming….
And so I wonder: “Why has the planet not overheated long ago?”
You have only included part of the system (as has Joeldshore).
Step 3 is incomplete. There may be a rise in evaporation from the surface which:
a. Cools the surface due to latent heat of evaporation
b. Takes that latent heat upward by convection – humid air is actually less dense than dry air at the same temperature and pressure – and eventually as the air cools with the lapse rate it reaches 100% humidity and water condenses out releasing latent heat which warms the volume of air which continues convecting upward this time with small water droplets – eventually these water droplets freeze releasing latent heat which warms the volume of air which continues convecting upward this time with small ice crystals the volume cools due to the pressure drop (number of molecules per unit volume). At the same time as this is happening the clouds of droplets and/or ice crystals are reflecting the incoming sun’s radiation reducing the input warming.
4. Might not be the case at all…. the only increase in temperature possible is before clouds form… you _have noticed it gets cooler when a cloud goes between you and the sun haven’t you? and once the clouds get dense enough to rain then the atmospheric temperature can really drop. Any returning long wave radiation will not heat water but may excite surface molecules enough to increase evaporation COOLING the surface.
Your thought experiment did not extend to clouds and rain only to mathematically simple radiation. The majority of heat transport to the Tropopause is convective – once there yes it radiates but the atmospheric density is so much lower that the effect of the increased presence of CO2 is probably more to radiate heat rather than trap it.
5. We don’t get to 5 as 4 was not totally true.
This convective cooling is seen everywhere as part of the water cycle it is why the Earth is largely homeostatic. Initially, the feedback is positive then as the water content of the atmosphere increases its enthalpy increases requiring more heat to raise the atmospheric temperature at the same time the humid less dense air will start rising taking heat upwards in the atmosphere and cooling and the feedback is almost zero – then as clouds form and eventually precipitate the albedo increase and the cold precipitation result in negative feedback to the heating. You can watch this as a daily cycle in the sub-tropics and tropics all the time.
Stefan-Boltzmann does not apply inside layers of convecting fluids with energy dependent state changes in the gaseous fluid with sensible heating from below. You have to be outside the hohlraum.
“Robbie says:
July 8, 2012 at 5:27 am
……… It is generally known and accepted throughout the scientific community that more clouds will cause cooling, but it remains a mystery so far if cloudcover increase will negate AGW.”
I’m glad you recognize that more clouds cause cooling but no one is suggesting that cloud cover increase will negate AGW simply that it will reduce the impact of CO2 increase ie it is a negative feedback and the debate is about CAGW (C=Catastrophic) not about the AGW component derived from anthropogenic CO2 which is approx 1.2 deg C (fairly uncontroversially) without positive or negative feedbacks for a doubling of atmospheric CO2.
Joeldshore says (inter alia)
“The converging series has to do with the strength of the water vapor feedback. The point is that the feedback is not strong enough to produce a divergence. ”
Well yes…. that’s a good part of the point I am making.
IF the ‘greenhouse’ effect was as advertised, then the earth would already be ‘too hot’ (whatever that might mean)
Exactly the same criticism you level at my thought experiment considering water vapour MUST apply to warming caused by CO2. Theoretical considerations would seem to show that this is only a problem if you think that direct warming caused by CO2 is ‘amplified’ by the effect of water vapour.
And again, Joel, you have not answered this part of my original post
As for my answer b) – I suppose it is unfair to berate you for ‘incrementalising’ warming after I set it up that way in my thought experiment. So… I will concede your criticism of that part of my answer to you. However, the rest stands – why should the warming be of just such a value that it supports your convergence example. Might it not be of such a value that you get a diverging series? But that’s not what I am proposing. In fact I agree that the facts show that the figure, whatever it is, is not diverging.
The point is that the earth has not, in 5 billion years, progressed to the ‘hot’ endpoint envisaged by those who are worried about the effect of CO2. My thought experiment underlines that fact – it invites a conclusion per contra. The heating supposed to have occurred has not happened. Therefore there is something wrong with the premise(s) of the experiment. I think the error is in supposing that the heating can be viewed as a diverging series (as you have pointed out). I think that whatever heating is going on now or in the recent past has effects that regulate the extent of the warming. I think that this has been going on in one way or another for eons and that there is nothing special in what we now observe.
Ian W says:
“Step 3 is incomplete. There may be a rise in evaporation from the surface which:
a. Cools the surface due to latent heat of evaporation
b. Takes that latent heat upward by convection”
Well of course! But the thought experiment is, after all, rather artificial.
Nevertheless, it raises a problem with the view that CO2 warms the atmosphere and this degree of heating is amplified by the effects of water vapour and in the not too distant future temperatures will get very uncomfortable indeed. And the punch line? All because mankind has been and continues to emit great clouds of CO2.
Now it seems to me that if that were true, then the atmosphere should long ago have reached some much higher temperature due simply to the effect of water vapour alone. The fact that it hasn’t points to other factors some of which may be the ones to which you draw attention.
It all boils down to the net magnitude and sign of the feedbacks. Because of the complexity, you can’t compute it empiracally. It’s knobs in the models that get tweaked to make the models align with past climate.
That’s where Hansen comes in with his series (and, the manipulation, therof). That’s where the paleoclimate folks come in with their debunked hockey sticks (“we have to make the MWP disappear”). Thats where climate-gate and Team tactics come in. That’s where Yamil and “hide the decline” come in. It’s all about justifying that the feedback is anywhere near high enough to justify even the weakest IPCC projections. Well, they failed to make the MWP disappear. Or, rather, they made it disappear; but, it came back.
The result of their failure to keep the MWP disappeared is that all model predictions have and will diverge from realtiy.