I’ve Looked at Clouds from Both Sides Now -and Before
by Roy W. Spencer, Ph. D.
…sometimes, the most powerful evidence is right in front of your face…..
I never dreamed that anyone would dispute the claim that cloud changes can cause “cloud radiative forcing” of the climate system, in addition to their role as responding to surface temperature changes (“cloud radiative feedback”). (NOTE: “Cloud radiative forcing” traditionally has multiple meanings. Caveat emptor.)
But that’s exactly what has happened. Andy Dessler’s 2010 and 2011 papers have claimed, both implicitly and explicitly, that in the context of climate, with very few exceptions, cloud changes must be the result of temperature change only.
Shortly after we became aware of Andy’s latest paper, which finally appeared in GRL on October 1, I realized the most obvious and most powerful evidence of the existence of cloud radiative forcing was staring us in the face. We had actually alluded to this in our previous papers, but there are so many ways to approach the issue that it’s easy to get sidetracked by details, and forget about the Big Picture.
Well, the following graph is the Big Picture. It shows the 3-month variations in CERES-measured global radiative energy balance (which Dessler agrees is made up of forcing and feedback), and it also shows an estimate of the radiative feedback alone using HadCRUT3 global temperature anomalies, assuming a feedback parameter (λ) of 2 Watts per sq. meter per deg (click for full-size version):
What this graph shows is very simple, but also very powerful: The radiative variations CERES measures look nothing like what the radiative feedback should look like. You can put in any feedback parameter you want (the IPCC models range from 0.91 to 1.87…I think it could be more like 3 to 6 in the real climate system), and you will come to the same conclusion.
And if CERES is measuring something very different from radiative feedback, it must — by definition — be radiative forcing (for the detail-oriented folks, forcing = Net + feedback…where Net is very close to the negative of [LW+SW]).
The above chart makes it clear that radiative feedback is only a small portion of what CERES measures. There is no way around this conclusion.
Now, our 3 previous papers on this subject have dealt with trying to understand the extent to which this large radiative forcing signal (or whatever you want to call it) corrupts the diagnosis of feedback. That such radiative forcing exists seemed to me to be beyond dispute. Apparently, it wasn’t. Dessler (2011) tries to make the case that the radiative variations measured by CERES are not enough energy to change the temperature of the ocean mixed layer…but that is a separate issue; the issue addressed by our previous 3 papers is the extent to which radiative forcing masks radiative feedback. [For those interested, over the same period of record (April 2000 through June 2010) the standard deviation of the Levitus-observed 3-month changes in temperature with time of the upper 200 meters of the global oceans corresponds to 2.5 Watts per sq. meter]
I just wanted to put this evidence out there for people to see and understand in advance. It will be indeed part of our response to Dessler 2011, but Danny Braswell and I have so many things to say about that paper, it’s going to take time to address all of the ways in which (we think) Dessler is wrong, misused our model, and misrepresented our position.
“R. Gates says:
October 9, 2011 at 11:16 am
ENSO changes (specifically heat transport by the ocean) drives changes in surface temperatures which drive cloud formation. In short, during the short time frame involved, clouds are reacting to heat transport by the oceans,”
Conjecture? Has a statistically significant lag been observed that shows that ENSO drive clouds? Didn’t Bart recently show that clouds feedback is negative with a 4.88 year ocean lag?
richard verney says:
October 9, 2011 at 8:12 am
My point is this. Merely because a low temperature object radiates energy, it does not follow that that energy can pass the threshold and get absorbed by a warmer object which is radiating energy at a higher state.
Temperature doesn’t give a treshold for receiving photons by any object. The only point is that the object must be a real blackbody. If the object is a 100% blackbody every foton received is absorbed (if not, part of the photons are reflected, that only reduces the energy exchange speed), no matter the temperature of the sending object. A photon is only a package of energy, which intrinsic amount of energy depends of its wavelength, which depends of the temperature of the sending object, that means that a hotter object will emit more energetic photons (and more photons), but that doesn’t mean that it can’t receive lower energetic photons of another radiating object.
The main point is that even in a vacuum, the hotter object will cool down and the cooler will heat up from a distance. If no heat is lost to the surroundings, at steady state both will have the same temperature, depending of the differences in masses and specific heat, as if they were in direct contact with each other and the energy exchange was only by conduction.
i know it was never about science – but wondering why people still pretend it is – and that statistics IS science.
Do you think you can get over this bee in your bonnet and move into the century the rest of us are in? Please?
Statistics are scientific. They generate knowledge that literally could not be found any other way, because direct experiment is not always possible. (Or in many quantum cases, literally never possible.)
How do you prove smoking increases the risk of lung cancer when it is fairly easy to find 100 year olds who smoke without lung cancer? Do we say : an experiment has been performed, and the theory falsified? So people can smoke and won’t die young?
Statistical data needs to be properly examined by experts in statistics, for sure. But to throw all the modern advances out just because you don’t understand/like them is just idiotic.
R. Gates says:
October 9, 2011 at 11:16 am
Taken directly from Dessler’s paper:
“And since most of the climate variations over this
period were due to ENSO, this suggests that the ability to
reproduce ENSO is what’s being tested here, not anything
directly related to equilibrium climate sensitivity.”
—–
Question: Do you or do you not agree with this? Why or why not?>>>
Two questions to you R. Gates:
1. If you agree with the above, then do you also agree that since 19 of the 23 models cited by the IPCC clearly do a very poor job of modeling ENSO, they are wrong and hence useless until that matter is corrected? Or is ENSO not significant?
2. What has that matter got to do with the issue raised above by Dr. Spencer?
Sensible:
M.A.Vukcevic (October 9, 2011 at 1:05 am) wrote:
“Temperature, humidity, clouds, atmospheric pressure,… etc. are the internal inter-dependent components of the climate system, with all feedbacks automatically factored in by nature, the laws of physics and the strong modulation by the annual insolation cycle.
Only the external factors can be the long term causes of the climate oscillations.”
Thanks for sharing.
Matt G says:
October 9, 2011 at 11:21 am
*******
IPCC AR4 concluded that clouds have a negative radiative forcing component (cooling effect) – although they do note that “cloud feedbacks remain the largest source of uncertainty”. See page 4 of this: http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-spm.pdf
Matthew says:
October 9, 2011 at 1:41 pm
That is well known thanks, the ignorance appears with the relationship between changing global temperatures and clouds. Plus with warmer temperatures, there should be more clouds. How are more low level clouds suppose to cause a positive feedback? It is not possible when solar radiation is by far the major component and we have not seen an increase in global cloud levels with increasing global temperatures. Therefore the change in global cloud levels had nothing to do with caused by warming. Hence, there is no feedback detected observed by changing global clouds levels from warming, since the 1980’s until this century.
Eternal Optimist…
Thanks for updating the Devil’s Dictionary. It needed to be done, and provided me a lot of good laughs. 🙂
Although I, too, would love to be kept in the loop as Spencer is addressing Dessler issues, I don’t think it’s a good idea. If Spencer “spills the beans” on a Blog before submitting a paper, some journals will refuse to publish it because the idea is no longer novel, or because they want to publish what has not already been published. Even when, in the case of the first reason, the idea is actually contradictory (blogs don’t count, you know), the reason has actually been used before.
It’s better to give journals as little excuse as possible, so that when they do reject, the rejection looks silly.
Eric Barnes says:
Eric, Roy says Dessler said “cloud changes must be the result of temperature change only”
I don’t believe he did. And I can’t find anything like that in your quote.
Matt G says:
October 9, 2011 at 2:37 pm
********
Wait, so are there more clouds because of rising temperatures or not? I ask because in the same paragraph you said, first, that “with warmer temperatures, there should be more clouds,” but then said that ” the change in global cloud levels had nothing to do with caused by [sic] warming.” Care to clarify?
Also, I’m pretty sure you agree that clouds have a negative net forcing capacity. But despite having more clouds now than the past (due to warming, which, again, I’m only kind of sure you agree has happened), temperatures continue to rise. Shouldn’t that tell us that there is another culprit whose net forcing capacity is not only positive, but bigger than the absolute value of the forcing capacity of clouds?
It seems like there should be some distinction between clouds over the ocean and clouds over land as far as feedback goes.
Land gives up daytime heating primarily through radiation. So a warm cloud can really slow down that process. The ocean gives up daytime heating primarily through evaporation. A warm cloud that blocks radiative heat loss will only serve to accelerate evaporative heat loss.
In the meantime, over both land and water, the cloud will of course throttle how much sunlight makes it to the surface to warm it in the first place. The reason teasing the noisy data apart looking for a feedback signal only turns up a poorly correlated pattern with several months of delay is because you’re seeing the sunlight throttling effect. It’s pretty well known in ocean heat budget that a lot of tropical summer solar energy is stored and released in the winter when the air is cooler, dryer, and evaporation proceeds at a faster rate. That’s where your several months of delay comes from.
This is being made WAY more complicated than it is. It almost seems like making it over-complicated is a means for making sure researchers in the field have paid projects to keep them busy.
Matthew says:
October 9, 2011 at 3:29 pm
Sure, global cloud levels have declined by ~5 percent since 1983 until 2001, when they have stabilised since. During this period with a warming planet global cloud levels, should have been expected to increase if the warming caused the global cloud levels to change. Therefore during a warmer planet now they are still less clouds globally than nearly 30 years ago. The reason why global temperatures at least partly warmed up, due to increasing solar radiation reaching the surface. So your last paragraph is what should have been expected to happen, but didn’t. While the global cloud levels are close to 5 percent less than nearly 30 years ago, it is expected to be warmer now compared to then. The planet should return to similar levels 30 years ago, when cloud levels increase another 5 percent in future.
John Marshall says:
“i wait with baited breath.”
“Sally, having swallowed cheese,
Directs down holes the scented breeze,
Enticing thus with baited breath
Nice mice to an untimely death.”
Geoffrey Taylor
Where does the red dashed line of “Natural Radiative Forcing” come from?
I assume the CERES NET is the measured difference (black line).
The blue line is modeled feedback?
“But that’s exactly what has happened. Andy Dessler’s 2010 and 2011 papers have claimed, both implicitly and explicitly, that in the context of climate, with very few exceptions, cloud changes must be the result of temperature change only.”
Incredible. Classic.
Does Herr Doktor Dressler specify which is the chicken and which is the egg?
richard verney says:
October 9, 2011 at 8:12 am
Re: DocMartyn says:
October 9, 2011 at 6:09 am
//////////////////////////////////////////
It is not really appropriate to get into this debate since it is O/T to the Spencer article.
I envisage that everyone accepts the statement that “…you know that matter radiates photons as a function of its temperature and emissivity. Cold objects radiate less energy than hot objects, if they have the same emissivity….”
The problem is with your further statement “Take two equally sized nearby objects with the emissivity, one at 100K and one at 400K, They will both emit photons and both absorb photons, the cold object will receive photons from the hot object and the hot one will receive photons from the cold one.” That statement may be correct but then again, it may not be. I have never seen an experiment proving the correctness of that assertion and I consider that it is mere supposition albeit it I can understand the reason why someone may conclude that it is correct. However, I consider that we know and understand and have insufficent understanding of photons to be certain that you are correct.
This statement is the fundamental underpinning of radiation heat transfer, it’s used by engineers all over the world every day, read any undergraduate text on the subject.
Mooloo says:
October 9, 2011 at 12:38 pm
i know it was never about science – but wondering why people still pretend it is – and that statistics IS science.
Do you think you can get over this bee in your bonnet and move into the century the rest of us are in? Please?
Statistics are scientific. They generate knowledge that literally could not be found any other way, because direct experiment is not always possible. (Or in many quantum cases, literally never possible.)
How do you prove smoking increases the risk of lung cancer when it is fairly easy to find 100 year olds who smoke without lung cancer? Do we say : an experiment has been performed, and the theory falsified? So people can smoke and won’t die young?
Even finding one 100 year old smoker without lung cancer disproves (falsifies) that smoking causes lung cancer.
I do recall health stats globally which looked at this and recall several countries with higher levels of smokers had lower levels of lung cancer.
So yes, let’s see the experiments..
The great problems with such generalised ‘statistics’ of the ‘contributing to’ is that anything can appear or be made to appear, and mean nothing at all because imput of any variables have no grounding, they might as well be random if you don’t know what causes lung cancer..
Dr Roy…..give ’em hell!
Chris
Norfolk, VA, USA
Are there any factors other than the temperature and humidity that alter cloud cover? Does the cloud albedo change in response to anything independent of the climate variations?
We have a well established physical mechanism that is adding energy to the surface for reasons independent of any inherent climate process.
Contingent responses of clouds to warming as a negative feedback require the warming to occur for the feedback to happen.
Unless you have a system with precognition that somehow manages to respond to a potential 1degC rise with a negative feedback that COMPLETELY negates it….
izen;
Contingent responses of clouds to warming as a negative feedback require the warming to occur for the feedback to happen.
Unless you have a system with precognition that somehow manages to respond to a potential 1degC rise with a negative feedback that COMPLETELY negates it….>>>
Of course, but that isn’t the point. The point is that the direct effects of CO2 increasing are in and of themselves inconsequential. They are simply too small to be of concern, UNLESS they trigger massive positive feedback that amplifies their effect. That is the basis of the alarmism regarding CO2 increases, and it is the basis of the science quoted by the IPCC and other sources.
The mere fact that the largest positive feedback claimed is being shown by observational research to be negative rather than positive in and of itself negates the alarmist position. Feedbacks need not negate entirely the effects of CO2, and I don’t recall Dr Spencer or anyone else trying to claim they did. The simple fact that they are likely negative at all rather than positive defeats the CAGW meme.
davidmhoffer… I don’t see R. Gates answering your two questions, and he’s certainly had time to do so. Would you agree that he’s negligent in his pursuit of honest science?
I would too.
Scott Brim says:
October 9, 2011 at 10:21 am
I’m afraid that sub-chapter is excluded from every book the climate modelers read (and they avoid Clouds for Dummies entirely). To them, it would only confuse their approach and negate their results. Can’t have a chapter like that…
“Contingent responses of clouds to warming as a negative feedback require the warming to occur for the feedback to happen.”
Of course, but the only molecules affected then evaporate earlier than they otherwise would have done and take away ALL the added energy with them due to the net cooling effect of the evaporative process.
Thus nothing left to add to system temperature because it gets converted to latent heat sooner, is transported upward sooner and is radiated away to space sooner.
So what we have is an ACCELERATION of energy transport upward which is conceivably capable of offsetting the DECELERATION of energy transport from more GHGs in the air.
“We have a well established physical mechanism that is adding energy to the surface for reasons independent of any inherent climate process.”
We also have a well established physical mechanism that is removing energy from the surface for reasons independent of any inherent climate process.
Does anyone have any evidence that there is any energy left over after the negative evaporative process has done its work ?
The so called ocean skin effect which proposes a reduction in energy flow from ocean to air doesn’t work because the faster rate of evaporation is capable of offsetting the otherwise applicable effect of Fourier’s Law as I have explained elsewhere.
The oft used illustration of a warming water surface when a cloud passes over doesn’t work either because a cloud overhead reduces evaporation whereas DLR from a clear sky increases evaporation.