Home/BlogWhat follows is a mini-debate by e-mail during the last 3 weeks between myself and Andy Dessler over the question of whether cloud feedbacks in the climate system are positive or negative.
Last night, Andy Revkin suggested that I post it. I believe this e-mail exchange is rather unusual during a time when scientists arguing over global warming more often spar with sound bites in the popular press rather than personally between themselves.
This was partly the result of my somewhat scathing post on December 9, 2010 regarding Science recently publishing Andy’s paper claiming positive cloud feedback. (I was not asked to peer review Andy’s paper even though I have published the most recent and directly comparable paper on the subject.)
The e-mail debate, which is still in progress, has been cc’d to a variety of people, the more recognizable addresses being: mann@meteo.psu.edu; gschmidt@giss.nasa.gov; trenbert@ucar.edu; jgillis@nytimes.com; rkerr@aaas.org; santer1@llnl.gov; revkin@optonline.net; rlindzen@mit.edu; olivermorton@economist.com; ekintisch@aaas.org; p.campbell@nature.com; john.christy@nsstc.uah.edu; mlemonick@climatecentral.org; eric.berger@chron.com; jhalpern@howard.edu.
The exchange of e-mails is listed in chronological order, following an initial e-mail alert from Scott Mandia of the Climate Science Rapid Response Team of my blog post on Andy’s paper. I am not posting Scott’s e-mail in respect of his privacy.
I entered the e-mail discussion after Scott criticized my my blog post implying that Andy’s paper being published by Science on the last day of the Cancun climate conference was motivated by more than just science. I have italicized where one of us quotes from an earlier e-mail.
SPENCER (11 December, 2010, #1 of 2):
In retrospect, my questioning of the timing has distracted from the central science issues, and was a bad move on my part. My apologies to Andy.
-Roy
SPENCER (11 December, 2010, #2 of 2):
…but I stand by my assertion that Andy’s paper is a step backwards for science. I would debate him or anyone else on this issue in a public or professional forum at any time.
I would be happy to submit a response to Science if I thought it had “a snowball’s chance”, but many of us have learned over the years that the editorial process there is quite biased on the subject of anthropogenic global warming.
BTW, I have stopped corresponding with Andy after he made public our e-mail exchange without asking me.
-Roy Spencer
DESSLER (11 December, 2010):
Roy-
I certainly accept your apology.
…but I stand by my assertion that Andy’s paper is a step backwards for science. I would debate him or anyone else on this issue in a public or professional forum at any time.
I ACCEPT! Let’s start immediately. Since you’re willing to do this essentially anywhere and anytime, I say we do this via e-mail. And since you want this to be public, I pledge to post the entirety of all of our e-mail correspondence on a blog that everyone can read (and since you also have copies of our correspondence, you’ll also be free to post it).
If you accept (and I don’t see how you can refuse given your statement above), then you can begin by answering this e-mail I sent to you yesterday:
Hi Roy-
I wanted to follow up on our interesting discussion. My main question involves your theory of cause-and-effect for an ENSO. During our first e-mails it seemed you were saying it was caused by clouds, but then things seemed to change. Could you send me a short summary of what’s driving the temperature changes during those cycles?
Thanks!
I look forward to a renewed and energetic discussion of these issues. After all, this is how science is supposed to operate.
And to the reporters on this e-mail, I hope you all see that the mainstream science community is pushing to engage the skeptics. I hope Roy shows that skeptics are similarly willing to engage.
Regards,
Andy Dessler
SPENCER (13 December, 2010):
Andy:
Sorry about the late reply…I wanted to get to the office to look at some IPCC model output that might help shed light on this.
So, since you want to talk about ENSO, let’s do that.
Of all the IPCC AR4 climate models, the one that has the best match to observed sea surface temperatures (SST) related to ENSO is CNRM-CM3 (see Fig. 8.13 from the IPCC AR4 Report).
The first attached plot shows 20 years (1980-2000) of monthly anomalies in global radiative flux and surface temperature from that model’s 20th Century runs:
[PLOT OF CNRM-CM3 TIME SERIES}
A scatter plot of the data is next:
[CNRM-CM3 SCATTER PLOT]
See the spirals? Thats due to radiative forcing of SSTs. How do we know? Because there are only two possibilities: radiative changes (directly or indirectly) causing temperature changes, or temperature changes (directly or indirectly) causing radiative changes (by definition, feedback). The reason the spirals appear is that the radiative forcing is proportional to the CHANGE of temperature with time…not the temperature directly. Feedback is essentially instantaneous with the current radiative state of the armosphere and surface.
This is shown in the following lag correlation plot for the entire 20th Century:
[LAG CORRELATION PLOT]
That atmsopheric circulation changes alone can cause ENSO-typ behavior was also demonstrated by this paper in GRL, The Slab Ocean El Nino.
AGAIN I want to emphasize…the evidence for the direction of causation is whether a lag exists or not.
The NEXT question is to what extent this de-correlated behavior affects the regression slope…this was a subject of our 2010 JGR paper. All I know so far is that, on average, it biases the regression slope toward zero (which could be misinterpreted as a borderline unstable climate system).
-Roy
DESSLER (14 December 2010):
Roy-
Thanks for your message … I knew you couldn’t stay mad at me 
Before I get into the details of the correlation, I’d like to get one thing straight: you’re arguing that the warming during an El Nino is caused by radiative heating by clouds. Right?
Once you confirm that, we can move on with the discussion. If you’re not saying that, then I’m confused by your message — in that case, I’d appreciate it if you could please explain the role of clouds in driving surface temperatures variations during ENSO.
Thanks!
SPENCER (15 December 2010):
Andy:
Feedbacks and forcings involve *temperature* changes, not abstract concepts like “El Nino”. Thus, your question is a bit of a red herring.
What I *AM* saying is that the time-evolving nature of the temperature and radiative flux anomalies is consistent with a significant, non-feedback cloud-induced temperature change. That is what the phase space analysis reveals.
Now, what all of this might mean for how El Nino & La Nina evolve over time is an interesting question, I agree,…I’m just trying to make sure we don’t lose sight of the quantitative evidence. Whether the evidence I am talking about necessarily implies a non-feedback role for clouds in how El Nino and La Nina evolve over time, that is a separate question.
-Roy
DESSLER (18 December 2010):
Roy-
Thanks for your response. I would have gotten back sooner, but I was at the AGU meeting.
What I *AM* saying is that the time-evolving nature of the temperature and radiative flux anomalies is consistent with a significant, non-feedback cloud-induced temperature change. That is what the phase space analysis reveals.
The problem here is that correlation is not causality: if I beat a drum during an eclipse, the Sun will return 100% of the time. You could claim that the time-evolving nature of the drum beating and return of the sun is consistent with a causal mechanism, and you’d be right. It is indeed consistent. But it’s also wrong — we both know that the drum does not make the Sun return.
The existence of a correlation does not mean that there is a causal link — so we cannot conclude that the correlation you’ve identified tells us anything about the role of clouds in generating ENSO surface temperature changes.
Rather, we have to look at the energy budget of an ENSO event. Those data contradict the idea that clouds are important in ENSO: analyses of the heat budget of ENSO (e.g., Trenberth et al., 2010: Relationships between tropical sea surface temperatures and top-of-atmosphere radiation. Geophys. Res. Lett., 37, L03702, doi:10.1029/2009GL042314 and references therein) don’t show a role for clouds.
In fact, the original Cane and Zebiak model of ENSO does not really even have clouds in it
So my question to you is whether there exists any physical evidence (beyond just the correlation) that clouds play any role at all in generating ENSO temperature variations?
Thanks!
SPENCER (20 December 2010):
Andy:
OK, I think now you are raising the possibility that what I am calling a “non-feedback radiative forcing” was at some previous time itself a feedback upon temperature. If that were the case, then there would be a lagged correlation, and you would then need to do your feedback parameter diagnosis at some time lag between the radiative flux and temperature data…not simultaneously. This is what Lindzen has been trying to get published, and is another way of getting a feedback estimate.
But it is not what you did in your Science paper. When I do it with the same 10-year CERES dataset you used, I get a very different result…outside the range of most if not all climate models.
-Roy
DESSLER (21 December 2010):
Roy-
Let me be clear: I am not “raising any possibilities” here. What I am trying to do is get you to articulate YOUR THEORY of ENSO causality. I’ve been trying to do this since our initial e-mail and trying to get a straight answer is beginning to feel like eating jello with chopsticks.
So let’s get back to the issue at hand: Do you have any physical evidence that clouds are playing a significant role in causing temperature variations during ENSO (besides the correlation, which (I think) we agree does not prove causality)? If so, what is it? If not, do you concede that I have the correct direction of causality in my paper?
After we resolve this, we can start talking about lags, etc.
Thanks again for your willingness to engage in discussions on this issue!
SPENCER (22 December 2010):
Andy:
How can you insist I answer a question, the answer to which would not refute (or prove) what we demonstrated in Spencer & Braswell (2010 JGR) anyway?
You can ask me, “Do you still beat your wife?”, and I’m not going to answer yes or no to that one either.
Remember, it is not me, but YOU who is claiming our results necessarily imply that clouds are part of the forcing of ENSO-related temperature changes…and you might well be right. If so, congratulations on your finding.
And I would say this interpretation IS entirely reasonable: that a change in the trade winds associated with the initiation of El Nino causes a change in cloud cover, which then is part of the forcing of El Nino-related temperature changes. THAT sounds entirely reasonable to me, and is consistent with the evidence we presented.
But that does NOT mean “clouds cause El Nino”.
Don’t confuse qualitative statements like these with what we showed QUANTITATIVELY in Spencer & Braswell, which was a simple statement of the CONSERVATION OF ENERGY:
The satellite data show radiative imbalances causing temperature changes with time.
That’s just a statement of the 1st Law of Thermodynamics. Are you claiming the 1st Law didn’t apply during 2000-2010?
Maybe YOU should answer THAT question before we continue the discussion.
But if you continue to insist on me answering “yes or no” to a question that is not relevant to what we are debating, I suggest we end this now.
-Roy
DESSLER (26 December 2010):
For those not following closely, let me recap the argument that Roy and I are having. In my research paper, I showed that the energy trapped by clouds increases as the surface temperature increases, and concluded that there is a positive cloud feedback acting. Roy objected to this saying that clouds are actually causing the surface temperature change, so I have cause and effect backwards. My response to this is that the temperature variations over the last 10 years are primarily driven by ENSO, and we know that ENSO is not caused by clouds.
This is the crux of our disagreement. In his last e-mail to me, Roy said, “The satellite data show radiative imbalances causing temperature changes with time” and “Our analysis shows that non-feedback cloud variations do cause large amounts of temperature variability during the satellite data period in question.”
But neither of Roy’s claims seem correct to me. I do not think he’s actually demonstrated that clouds are causing temperature changes.
To resolve this, I pose the following question to Roy: can you summarize for everyone on this list the evidence that clouds are affecting surface temperature over the last ten years. And can we quantify how much are clouds affecting the surface temperature? Are they responsible for 1% of the variance, or 99% of the variance, etc.?
And to show you that I am willing to answer your questions, I will answer the question you posed to me in your last e-mail: “Are you claiming the 1st Law didn’t apply during 2000-2010? Maybe YOU should answer THAT question before we continue the discussion.” The answer is that I do not dispute that the first law applies. I agree that energy is always conserved.
Happy holidays.
Thanks!
SPENCER (30 December 2010):
OK, let me see if I can briefly summarize my side of this…
The evidence that clouds cause a substantial portion of the temperature changes during the ten-year period in question is twofold:
(1) the temperature changes tend to lag the radiative flux changes, something that is revealed by “connecting the dots” in the scatterplots of radiative flux-vs-temperature, and
(2) this lagged behavior strongly decorrelates the temperature-versus-radiative flux variations (as is seen in Andy’s, and virtually all previously published, scatter plots of this type).
This poorly-correlated behavior is consistent with the short-term behavior of most if not all of the AR4 climate models, and was mimicked by our simple forcing-feedback model, both of which we published in JGR earlier this year.
In contrast, feedback (temperature causing cloud changes, which is what Andy believes is going on) is much closer to simultaneous, which would lead to strongly correlated data (which is seldom observed…except on month-to-month time scales).
Our JGR paper also demonstrated that this decorrelation was not simply due to noisy data…”connecting the dots” (phase space plots) shows looping and spiral patterns, rather than the zig-zag patterns one gets with random noise.
In the big picture, what the satellite data suggest is a sort of meandering of the climate system through varying states of radiative IMbalance, with the temperature changes always trying to play catch-up with the radiative flux changes, …but then the atmospheric circulation causes another change in cloudiness, and the temperature then has to slowly respond to that, too, …etc. Radiative equilibrium is never actually reached.
Regarding Andy’s question of just what percentage of all of the variability is due to “forcing” versus “feedback” is still an open question. All I know is that the “forcing” so strongly decorrelates that data that doing linear regression to get a feedback estimate is going to result in a regression slope approaching zero, which is then commonly misinterpreted as strongly positive feedback.
(We also showed in our JGR paper that short satellite periods of record can even lead to a bias in the direction of NEGATIVE feedback…but this is much less likely than a bias in the direction of positive feedback.)
-Roy
Andy Dessler says “In my research paper, I showed that the energy trapped by clouds increases as the surface temperature increases, and concluded that there is a positive cloud feedback acting.”
Is that like the heat trapped in the cast iron frying pan on my hot plate? More heat gets trapped in the frying pan when I turn up the temperature on the hot plate. The positive feedback from the fry pan in turn raises the temperature of the plate.
This was not a debate but more a schoolyard wrestling match, each side trying to best the other by talking past each other.
When Dessler says “and we know that ENSO is not caused by clouds” how does he know that? I thought that one of the points Spencer has made in the past is that until he and Braswell did the phase space analysis, it was very difficult to separate cause and effect in the cloud/temperature relationships. (I see here that he is now saying that the time lag relationships of temperature change and radiation change that Lindzen has been doing are another way of separating cause and effect — although this may in reality amount to the same thing, since the phase space analysis is just another way, albeit a clever one, of illustrating tome lags in correlations.)
Another thing that strikes me about this discussion is that the two protagonists are essentially talking about very different scales. Dessler wants to talk about a “macro” phenomenon (ENSO) while Spencer is talking about “micro” details of temperature and radiation correlations over time. Spencer seems to be saying that before we try to explain something very complicated like ENSO, with lots of factors in play (including ocean as well as atmosphere dynamics and feedbacks on feedbacks), we need to be able to explain changes in observed correlations over time. Once we get the micro details sorted out we can return to try to explain more macro phenomena such as ENSO.
Another point that can be made about the analogy to beating a drum and the sun rising is that this illustrates that the empirical correlations alone are not enough to provide convincing evidence of causality — a link to a structural model also is required. As I understand it, however, that is also what Spencer and Braswell did by looking at both their “toy” climate model and actual climate models. They showed that when cloud changes cause temperature changes, the phase space diagram has loops, but when temperature changes cause cloud changes the points lie on a straight line. Since the real data has loops (and some straight segments) it follows that at least some of the real world correlations involve cloud changes causing temperature changes.
Science is about serving truth not justice. And, that’s the problem with the problem we have with the UN and the climatologists of government science authoritarianism: the AGW hypothesis is more social than science.
Within the scope of the 10 year data Roy is concluding that Cloud -> radiative flux – ENSO must be true. But there is no support for this in the literature, so Roy’s conclusion must be wrong. Or worse wants to “trap” Roy into saying something that would be “laughable” in the “climate” community.
To my “untrained” eye (as an engineer by training, I know enough about feedbacks to get into trouble) it seems that there might not be enough data to disentangle.
Roy should explain why Clouds -> ENSO is not a worthwhile conclusion, while Andy should explain why is it wrong to conclude Cloud -> temp is a wrong conclusion for this 10 year period
Debee,
You claim Dr. Roy says clouds cause ENSO. Please do not put words in his mouth. I do not believe either side has claimed they know what causes ENSO.
Heat trapped by clouds?
http://eosweb.larc.nasa.gov/EDDOCS/images/Erb/components2.gif
That big broad swath labeled “Incoming solar energy 100%” seems to be the independent variable in this scheme of things. That means, changes in solar energy changes everything. Could this be true?
I mean, nominally, isn’t NASA now saying it’s incoming ‘solar energy,’ stupid?
Also, more energy is reflected by clouds than is absorbed by clouds; nearly 7-fold. Could this mean, a change in cloud cover changes everything?
Isn’t that what the skeptics have been saying? And, what happened to a shadowy specter of a ‘greenhouse’ indicating that the green color at the bottom will slowly turn a firery red corresponding to changes in atmospheric CO2?
When the weather hits the fan, it’s always wise to remember (and, I think Drs. Spencer and Pielke, Senior will agree): global cooling is not evidence of global warming. The oceans are cooling and there is no end to the cooling in sight. And, in a period when the oceans are cooling, there is no global warming during that period.
Amen, to what you said about when the oceans are cooling, there will be no global warming.
Joe Bastardi , had a great video on this subject a few days ago.
Global cooling has started, and it will be here for sometime to come. All the factors that control the climate are now in, or going toward a colder phase, those being AO,NAO, SOI oscillation,volcanic activity ,solar activity, pdo, with amo to follow by 2015.
The meridional cir. AO NEG 3 , as we speak, if it should continue, will evenually lead to more snow cover ,if so earth’s albedo could increase which could bring about further cooling. We will have to see how this, among solar,volcanic eruptions, oceanic temp etc etc all play’s out.
I predicted this circulation, as a consequence of low solar activity/high lat. volcanic activity.
Also, it must be pointed out that all the global warming models have been predicting a more positive AO,they are dead dead wrong. One of endless items ,they have forecasted wrong.
One thing is for certain, CO2 AIN’T GOT, AND WILL NEVER HAVE ANYTHING TO DO, WITH EARTH’S CLIMATE.
Pardon my English.
Roy and Andy are debating without stating clearly an explicit model of what they are talking about. They seem to assume that the use of the word ‘feedback’ is enough of a specification of their respective or perhaps common model. They are here continuing a fine tradition of muddle- generation that pervades this area of debate. The terms “forcing” and “feedbacks” as they are generally used facilitate miracles of confusion. Unless Roy and Andy fix this on this occasion, they will probably make little useful progress.
It would also help if they distinguished the terms ’causes’ and ‘is part of the mechanism of’. In ordinary language, ’causes’ often means ‘arises externally of and independently of but has causal efficacy acting on, and is not subject to feedback from’, while ‘is part of the mechanism of’ means ‘is involved internally in the dynamics of’. Use of the word ’cause’ is possible also in a sense that does not demand the just mentioned strict externality and absence of feedback, but great carefulness of expression is really necessary to get clarity with this; a clearly stated model is necessary for the purpose. Cavalier abuse of the word ’cause’ is another recipe for confusion.
Of course Roy and Andy here are also continuing the fine tradition of mixing up the four different senses of the word ‘feedback’ that are distinguished by J.R. Bates in ‘Some considerations of the concept of climate feedback’, at Q.J.R. Meteorol. Soc. 133: 545-560. I am not saying here that Bates has really fully sorted out this problem, just noting that he has made some points that Roy and Andy should attend to.
Why does the ocean change its motion? So far as I know, the external driving causes of el Niño and la Niña are entirely unknown to present day science. Their mechanisms are of course understood to a useful extent. It defies belief that clouds would not be part of their mechanisms of development. The idea that clouds themselves are an external driver verges on the preposterous, unless it is meant by that that some external driver (for example something in the sun) has a special effect on clouds that then trigger el Niño or la Niña. It might be claimed that el Niño and la Niña are manifestations of some deterministic chaotic climate dynamics, but then of course the idea of feedback being positive or negative is no longer available in a simple form, because a dynamic fixed point is incompatible with a chaotic régime while being necessary to define the sign of ‘feedback’.
Now this is a good start to how science is supposed to be done and seen to done, complete with valuable comments from others. This geologist of course thinks that the time frame is to short to in any way, shape or form tell is anything very useful. What we need is a wide application of the Multiple Working Hypothesis and a heavy dose of falsification. I must agree with Dr. Spencer that at this point in time we simply do not know enough to draw any firm conclusions, except we are ignorant.
There is a lot of sense in what Christopher Game says but this comment from Wagathon takes the cake for perspicacity from my point of view:
“Also, more energy is reflected by clouds than is absorbed by clouds; nearly 7-fold. Could this mean, a change in cloud cover changes everything?”
Give me an your email address Roy, and for Mr Dessler and I will demonstrate the point that sea surface temperature in the tropics is a creature of sea surface temperature in the mid latitudes where it is driven by the flux in ozone from the poles into the troposphere. In the mid latitudes anomalous warming between 200hpa and 500hpa is a direct consequence of warming in the stratosphere. I am talking about annular modes of intra-seasonal variation, a well recognized phenomenon following the work of Wallace and Baldwin. A warming troposphere means less cloud to reflect short wave energy.
The SST response is less at low latitudes because there is upper atmosphere cloud at low than at mid latitudes. So, you can look carefully in all the cupboards in the ENSO kitchen and just end up confused.
In short, SST in mid latitudes fluxes with the AO and the AAO with the added proviso that the former is currently by far and away the most important driver. And it will remain so while AAO persists with high values indicating the lowest polar pressure in the Antarctic since 1948, where the reliable reanalysis data begins.
You have to go back to the days before the climate shift of the late 1970′s to see a regular year after year sea surface temperature anomaly in mid year that is due to ozone flux from the Antarctic stratosphere at a time when pressure was higher and fluctuation in the AAO wider than today. The Antarctic also suffers from the great disadvantage that background levels of ozone are always low.
The AO and the AAO are driven by shifts in the mass of the atmosphere between the poles and low latitudes and between the hemispheres assisted by changes in atmospheric heat content due to irregular patterns of warming between latitudes and across hemispheres.
But ultimately the atmosphere responds to electric currents generated by the solar wind, present in the upper stratosphere and ionosphere,that accelerate charged particles which carry the neutrals along and, depending upon the changing nature of the field, can hold the atmosphere against the force of gravity. It renews on a daily basis as the sun rises and it relaxes overnight as the sun disappears along with the extent of ionization. And it is more powerful when the sun is quiet and neutrals are in more intimate contact with charged particles.
Shifts in atmospheric mass between the poles and the mid latitudes govern the activity of the polar night jet which connects the surface with the mesosphere where ozone absorbing NOx is to be found.
Now, if there is no response from you I will understand that these ideas are just too exotic for mainstream urban transit passengers to contemplate.
But, I urge you to live dangerously, look outside the current areas of inquiry and forget about the models. The climate system has more modes of interaction than the designers of models can currently contemplate.
Contemplate if you will the effect of a 10hpa increase in the differential pressure driving the westerly winds in the southern hemisphere over the last sixty years, contemplate the effects of the collapse in the pressure driving the westerlies in the northern hemisphere in winter between 1948 and 1978, its recovery to 1997 and the collapse over the last three winters. Do the models build in the drivers of that phenomenon?
I believe that the models predict a continuously rising AO but it has been falling since 1990 and most strongly in winter.
Do you like cold winters? Can you put up with expensive orange juice as the Florida crop is frosted more years than not?
The closest study of the climate record of the last sixty years will not help meteorologists work out what is going to happen next.
Very interesting!Are You aware off the analys from Le Mouel about that topic?
I would be gratefull iff You would give here, off by other means, the full analysis.
Best wishes for 2011
So, it’s deadly cold outside. What do you do?
Do you prepare for more cold weather–perhaps for decades? Or, do you go outside and look to find where the global warming is hiding?
“The fact is that we can’t account for the lack of warming at the moment and it is a travesty that we can’t.” ~Kevin Trenberth (Lead Author IPCC – 2001, 2007)
Andrew Dessler (and anyone else who thinks the cloud feedbacks are positive),
If the cloud feedbacks are indeed positive and inline with the IPCC model predictions of about a 3 C rise in temperature from a doubling of CO2 (a 3.7 W/m^2 gross increase in radiative forcing; 1.85 W/m^2 net), then why doesn’t the same proportional amount of positive feedback amplification lead to 10+ C rise in temperature when the post albedo solar power at perihelion is about 7 W/m^2 higher?
What is so special about 1 W/m^2 of additional power from CO2 that it’s at least 5 times more powerful than each 1 W/m^2 of power from the Sun?
Meilleurs voeux pour l’année nouvelle Mr.Spencer, ainsi qu’à vos proches.
Merci pour vos articles “ravageurs”,qui sont appréciés ici également.
Bonne année
Jo Vdh
Erl Happ ,just a fantastic explanation of things. Your explanation is way better then what Dessler and Spencer ,are trying to do,whatever that is.
Just a great explanation. I am making a copy of what you said. Thanks.
Salvatore,
Your email please? Tell me at erl@happs.com.au I want to send you a paper so that I can get some feedback.
Nothing wrong with your English and you are obviously aware of the importance of the AO and the shifts in the atmosphere that change climate.
It is salmbswx@aol.com I will get back with you next week.
I hope you read my earlier post, on some of my thoughts.
I am of the opinion the sun sets the tables, and if the sun stays as is ,this will be the decade of global cooling.
I will send you some of my thoughts next week as well.
“On Sunday, 2010 July 11, a total eclipse of the Sun is visible from within a narrow corridor that traverses Earth’s southern Hemisphere. The path of the Moon’s umbral shadow crosses the South Pacific Ocean where it makes no landfall except for Mangaia (Cook Islands) and Easter Island (Isla de Pascua). The path of totality ends just after reaching southern Chile and Argentina. The Moon’s penumbral shadow produces a partial eclipse visible from a much larger region covering the South Pacific and southern South America”
Measure the incoming and outgoing radiation before, during and after the eclipse, on land, at sea and in the air using tracker ships and aircraft. Correlate the change in temperature, incoming light flux and cloud cover.
The track covers a lot of the pacific, where the only real differences between bits of ocean are going to be cloud cover.
It should be trivial to deconvolute out the feedback.An eclipse gives you a window where light flux falls and then rises, during the cause of the day.
One observation is for the N.H when solar activity is weak such as during the Maunder Minimum or Dalton ,the atm. circulation always seems to become more meridional. Not however so, for the S.H.
I think geography , the distribution of land and sea and how they are so opposite in both hemispheres plays a big role in this.
The impact of the circulation becoming more meridional in the N.H. explains to me in part why the temp. change in the N.H. can be much more dramatic ,while it is not the case in the S.H., even though the same process is effecting both hemispheres.
Do you concur ,Erl?
Convection, advection, radiative transfer, radiant flux, etc. might be interesting topics to research — especially by the Education Industrial Complex on some else’s dime –but, let’s not use the donkey to push the cart. Global cooling does not prove global warming.
It is nice always to think about and try to understand the nature of nature but AGW True Believers can never make their case going down this road of proving CO2 has some mystical property in nature that cannot be duplicated in the laboratory. Just the idea of a positive feedback is a nonstarter; otherwise, we’d have to understand the climate system as evidence of a perpetual motion machine.
A study of the Earth’s albedo (project “Earthshine”) shows that the amount of reflected sunlight does not vary with increases in greenhouse gases. End of story.
The “Earthshine” data shows that the Earth’s albedo fell up to 1997 and rose after 2001. What was learned is that climate change is related to albedo, as a result of the change in the amount of energy from the sun that is absorbed by the Earth. For example, fewer clouds means less reflectivity which results in a warmer Earth. And, this happened through about 1998. Conversely, more clouds means greater reflectivity which results in a cooler Earth. And this happened after 1998.
It is logical to presume that changes in Earth’s albedo are due to increases and decreases in low cloud cover, which in turn is related to the climate change that we have observed during the 20th Century, including the present global cooling. However, we see that climate variability over the same period is not related to changes in atmospheric greenhouse gases.
Obviously, the amount of `climate forcing’ that may be due to changes in atmospheric greenhouse gases is either overstated or countervailing forces are at work that GCMs simply ignore. GCMs fail to account for changes in the Earth’s albedo. Accordingly, GCMs do not account for the effect that the Earth’s albedo has on the amount of solar energy that is absorbed by the Earth.
Dear Drs. Roy and Andy
Please avoid any of these for the future.
http://www.searchlores.org/schopeng.htm
And pleasestick to the science insteadof beating wives or drums.
Salvatore,
Delighted to respond. You are a living national treasure.
The Northern Hemisphere and the Southern are like two planets within one. The pressure driving the winds declines from south to north.
Pressure driving the winds is greater in winter.
Low pressure in the Arctic robs the polar Easterlies of impetus there.
South westerly air stream in the north is dominant all the way to the Arctic but the Polar Easterly stream is episodically driven by a much higher pressure differential because pressure flux in the Arctic is much greater than in the mid latitudes.
There is no deep pressure trough at 60-70° of latitude as there is in the southern hemisphere to act as a wall between the westerlies and the easterlies.
The mid latitudes of the northern hemisphere derive atmospheric mass from the Southern hemisphere esp in northern winter when temperature plummets in the north. Between the Antarctic and 40°S latitude pressure has been falling for sixty years partly because of consistent warming, more kinetic energy in the air, fewer molecules.
The result of the change in pressure relations over time in the northern hemisphere has been 30 years cooling to 1978, 30 years warming to 2007 and cooling to come. The AO indicates the trend. It measures the balance between the pressures at the important latitudes. You can also characterize the AO in terms of flux in geopotential heights. That flux is driven by ozone flows.
Antarctic sea level pressure has bottomed. As it increases the westerlies in the south will reverse the growth trend of 100 years. Northern mid latitudes will lose atmospheric mass. The flux in polar pressure will see the Easterlies expand their zone of influence, but mainly in the northern hemisphere. More Arctic outbreaks.
Your analysis is correct. Wind flows in the north are much more meridional all the time due to the lack of that pressure trough at 60-70N and the changing balance of pressure between 30-40N and 80-90N.
AO and the AAO can be seen as a rough measure of pressure at the poles. The indices can be seen to move together. Atmospheric mass moves between high and low latitudes and across the hemispheres when these indices move apart. Implications of this are yet to be realized in climate science.
The flux of pressure is the gorilla in the climate change room.
As the westerlies and the trades blow harder (they move together) the ocean warms. It does not take too much imagination to work out why. These winds blow harder when pressure falls at the poles. As pressure falls at the poles stratospheric ozone levels build because less NOx arrives from the mesosphere. Ozone is being continually churned into the troposphere in the areas of both hemsipheres where 200hpa and 500hPa geopotential is consistently high. Ozone absorbs outgoing long wave radiation from the Earth. It warms the troposphere. Ice cloud evaporates.Look at the SST anomaly map right now. Compare to the map of 200hPa heights. Take out the desert areas where OLR is high and what is left.
As the wind blows harder the ocean should cool from evaporation and upwelling of cold water. It doesn’t. It warms in concert with the AO and the AAO. Two poles, one equator, a lot of people theorize that what happens at the equator drives what happens at the poles. Nonsense about planetary waves influencing the stratospheric vortex is ideologically driven. Many people want the Earth to be a closed system. It’s not.
There is nothing more debilitating than to believe that the atmosphere warms the surface via back radiation. Radiation begins from a point high in the troposphere where the air is already very cold. Air cools mainly by decompression. Radiative bands are concentrated where the air descends, warms and is cloud free. No feedback there. No feedback from the stratosphere either where there is the most potent greenhouse gas of them all, ozone. Convection rules.
Wagathon, you should promote your observations to more people. You have one hell of a lot of uncommon good sense.Another living national treasure.
excellent,this is great! take care
Interesting debate, but as stated by many Roy and Andy are missing each other.
As I understand the issue Andy originally wrote about cloud feedbacks and el Nino while Roy’s views were of a broader nature.
It is most obvious that ENSO is not driven by clouds but by warm waters being blown westward and awaiting a slack wind to flow back eastward and increasing the SST off S-America (el Niño).
Theodor Landscheidt used to predict next el Niños based on his study of solar activity, etc.
Furthermore Wagathon is on the right track when stating: “A study of the Earth’s albedo (project “Earthshine”) shows that the amount of reflected sunlight does not vary with increases in greenhouse gases. End of story.”
It seem logical to accept the views of Henrik Svensmark almost a decade ago that variations in solar activity lead to changes in cloud cover. There is no single mechanism active but is probably a cocktail of cosmic radiation, solar mass ejections, planetary influence and many others not yet identified.
Anyhow, Svensmark suggested that a 3% decrease in low altitude cloud cover could more than well compensate for the possible temperature increase assigned to anthropogenic greenhouse gases () assuming that man made GHG would have the forcing effect following IPCC argumentation.
Boris Winterhalter says:
January 2, 2011 at 4:06 PM
“It seem logical to accept the views of Henrik Svensmark almost a decade ago that variations in solar activity lead to changes in cloud cover. There is no single mechanism active but is probably a cocktail of cosmic radiation, solar mass ejections, planetary influence and many others not yet identified.”
Well said, Boris. Some combination of all these things seems most likely. The Svensmark theory of clouds controlling climate rather than climate controlling clouds is quite intriguing.
To me though, the biggest hole in the AGW theory that I’ve yet to see adequately explained is that it treats each 1 W/m^2 of increased radiative forcing from 2xCO2 as being at least 5 times as powerful as each 1 W/m^2 coming from the Sun. In effect, the AGW theory is claiming that the climate system is all of the sudden going to respond to less than a 2 W/m^2 increase radically differently than it does the original 99+%. While I suppose that is theoretically possible, it’s seems physically illogical, especially in a system that is changing spatially and in time…all the time.
Gosh is there anything in climate science that isn’t frustrating? Like others I can’t help thinking both here are talking passed each other. Do Spencer or Dessler think this discussion has been productive because I can’t see anything positive here?
Anyway I’ve got a specific question to Dessler.
Spencer seems to make specific claims about his phase space plots which give us more information than a simple correlation. It seems to me that Spencer suggests it’s the results from this method that’s highlighting the relationship between temperature and forcing. If I’ve got this right I’d like to know what Dessler thinks this method and Spencers results are telling us?
HR has it right. This ‘debate’ will not progress unless someone is able to pose a closed question which is relevant to both sides. I appreciate the discomfort in accepting that the phase space plots have any causal significance – since that could be mis-used as a claim of victory.
Is there some space (models, new data, possible scenarios) where some predictions can be made to provide some agreement?
The argument that the correlation is insignificant only because it is not explained seems weak, but how to progress? Can we say something about IF temperature in the next 5 years shows a specific pattern?
@Christopher Game
Hey Chris, I really like the analysis you have done here on many occasions. Could you please tell me what you think of William Happer’s opinion on global warming? I find it interesting that he and only a few others openly state that more co2 in the atmosphere will be beneficial to mankind. Also, do you have any ideas as to why global warming advocates use 1979-present and use this time period to claim extreme temperatures? Shouldn’t they be using a historically averaged GAT to compare the present temperatures? I have always suspected that historic GAT is higher than todays temperatures and so they do not use it.
The importance of Dr Roy is indisputable.
I would like to master the English language enough to philosophize.
I’ll try to summarize in a few fragments.
a-No one theory is able to define the planet’s average temperature in real time.
b-No one theory is able to define the importance of the concentration of CO2 in the Earth’s mean temperature.
After four years of devoting as much time as is available in this activity.
My conclusion is, clouds are the key factors.
I live on the Tropic of Capricorn. I can confirm without fear of making mistakes _ Statistically, no significant warming since 1995. (Phil Jones, also says this).
Dr Andy. I’m glad for the ability (tastefully) in playing chess. (even though the board is composed of fractal grids).
Overall conclusion:
a-It is reasonable to return all the drawing board.
b-It is reasonable to go back to doing science.
c-It is reasonable that it is not necessary to invoke the spirit of Bohr. To put the same bag as notable figures (Erwin Schrödinger, Werner Heisenberg, Wolfgang Pauli and others ..).
Andy. The elements in the evolution of climate science are locked in the hypotheses of CO2 concentration and solar activity.
Dear Andy.
Happy 2011. (hot?)
Sorry for de bad english…
EEWALT says:
Roy:
REF Your emails w/ Andy Dessler
I am a retired electrical engineer, very rusty on thermal, but I have designed very many feedback circuits. The question here is does the presence of clouds represent a positive, or a negative feedback system?
The answer is if the clouds, no matter how they got there, through some mechanism causes more clouds then it is a positive feedback system. If the clouds, through the same mechanism causes fewer clouds, then it is a negative feedback system. Here we have two cases to consider: Day and night. If the feedback sense is different day vs night, then you have to assign power numbers to get the net feedback sense. This is probably not what you want to hear, but that’s the best I can do without more study.
I notice there has been some confusion in the blogs about Bode plots, etc. I can shed some light on this, why and how we use them, what do they mean, etc.
I also got the feeling that the two respected Doctors were talking past each other. However I do wonder if this was more from trying to keep the complexities of the conversation at a level we laymen can understand.
Gentlemen, I do urge that such conversations be continued. Debate strongly and without thought as to whether we onlookers can understand. (Although it would be nice to be able to ask for clarification on some points)
Many of us lay sceptics are in good faith simply trying to understand the science better. In this net age that we live in, the world is a classroom and many are here to be educated. Areas of highly technical debate that we don’t understand simply show the areas that we need to improve on so that we can.
Don’t pander to us or make allowances by trying to keep it simple. Go for it. We’ll just have to catch up.
John B,
I think the issue fundamentally boils down to whether the increased heat trapped by incrementally more clouds is greater than the increased energy reflected off of them.
This is likely where Dessler, among other things, is wrong in his analysis.
Clouds, causing feedback, satellites measuring I assume average cloud cover, big problem, are we talking tropical clouds or those at say 30 degrees north and south, and are we talking average cloud cover or actually taking into acccount what time of day that cover appears?
Tropical clouds appear in response to warming from the sun. The morning is clear, the sun then warms the earth (and sea), evaporation occures, this creates thunderstorms by afternoon, moving large amounts of hot air from the surface to the upper atmosphere, whee it cools, resulting in rain, cooling the surface. In addition, the thunderclouds reflect the sun during the hottest part of the day, and all that hot air moved upwards radiates out some of its heat into space. Put the two together and you get cooling. At night, after the sun goes down, the eveporation stops, the sky clears, and the heat from the surface radiates out into space, result, cooling. Thus, the tropical claouds result in a net cooling effect. A satallite might see average cloud cover for a 24 hour period, but average over 24 hours is not what is relevent in tropical clouds, what IS relevant is WHEN it is cloudy and not cloudy here. If cloudy in afternnons and not cloudy at night and in mornings, then net cooling. Thus, any study of clouds and temerature and such in the tropics MUST take into account WHEN during the day it was and was not cloudy.
At 30 degrees north and south, clouds tend to hang around in a thinner layer all day, thus, they tend to trap heat, especially at night 09thay also seldom rain, thus not cooling the surface). Many of these clouds came from the tropic air, warmed and then stripped of some of it’s moisture, result, the desert belts of this lattitude. Thus the clouds here act differently than tropical clouds, especially in regards to radiative heat and warming at the surface.
Typical studies like this one seem to mainly be a lot of averaging, abstract numbers, and suchlike that bear little resemblence to the actual effect felt by actual people actually living in these locations. People living in the tropics can FEEL the fact that clouds there result in lowered surface temerature, especially in the afternoons when it would be unbearably hot without that thundderstorm either dumping cold rain right on them or sucking in and up air and fanning them. Thus, these sort of abstract studies tell nothing about actual temepratures UNLESS the people making them know how clouds actually work in the specific locations in regards to temerature at that location. Different kinds of clouds at different types of day or night at different locations in regards to such things as the angle of the sun make all the difference on whether the clouds will result in net heating or cooling. An abstract study that does not include actual hour by hour details, but tries to treat all clouds as the same, and all locations as the same, is sure to get it wrong.
So, did this cloud study take into acount whether the clouds it was studying were there all day or only appeared in the afternoon? Did it take into account what type of clouds, and where latitude wise they were. Did it take into acount whether that cloud rained or not? Or is it just another computer model that treats all clouds everywhere the same, and assumes that tropical clouds are the same as desert belt clouds, only measures average cloudyness over 24 hours rather than actually telling us what time of day it was or was not cloudy, does not even notic rain, and doesnt care what type of clouds they were, at what altitued they were, how much moisture they had, etc?
In short, did they actually do their homework or is this just another meaningless argument over largely irrelevent abstract numbers and graphs that have little or even no relevence to actual temeprature or whether clouds cause or do not cause increased temeratures?
The evidence seems to suggest that ENSO causes cloud changes rather than the other way around.
‘Tropical and subtropical low-level marine clouds consist of optically thick stratocumulus clouds, which usually form over the regions associated with relatively cold sea surface temperatures (SST) and atmospheric subsidence, and optically thin shallow cumuli in the tradewind regime. These low-level clouds play a pivotal role in the global climate system not only by affecting radiative budgets but also by promoting heat and moisture exchange between the sea-surface, the boundary layer, and the overlying troposphere.’ (Zhu, P., Hack, J., Keilh, J and Zhu, P, Bretherton, C. 2007, Climate sensitivity of tropical and subtropical marine low cloud amount to ENSO and global warming due to doubled CO2 – JGR, VOL. 112, 2007)
I would note also the Clement et al study on decadal changes in Pacific cloud cover(Clement, A., Burgman, R. and Norris J (2009), Observational and Model Evidence for Positive Low-Level Cloud Feedback Science325 (5939), 460. [DOI: 10.1126/science.1171255] – the positve feedback is over decades).
I am inclined to think that top down solar forcing (as in Lockwood, M., Harrison, R., Woollings, T. Solanki, S., (2010)Are cold winters in Europe associated with low solar activity? Environ. Res. Lett. 5 (2010) 024001 (7pp)) is the primary driver of ENSO through interactions of wind and currents driving cold water up the Antarctic Penisula to the South American coastline and influencing upwelling in the Humboldt Current. It seems a reaonable way of explaining the many observations of linked ENSO/solar cycle processes.
ENSO is so obviously a primary driver of global climate that we neglect it at the expense of understanding climate.
There is an article here -
http://sciencefile.org/SciFile/component/content/article/2297-how-the-pacific-ocean-influences-global-climate-a-review-of-the-physical-evidence-
ENSO is a complex and dynamic system – but you have to understand something of chaos theory to understand what is meant by this. We tend to think in terms of simple cause and effect but climate doesn’t work like that at all. Instead climate is characterised by abrupt changes at all timescales – see for instance the 2002 PNAS report (Abrupt Climate Change: inevitable surprises) or the 2007 and 2009 network analysis of Tsonis and colleagues. This is by definition a nonlinear response to small initial changes and is a primary reason why both sceptics and warmists are full of shit. They simply don’t understand chaos theory.
We could define climate risk as a probability density function by using climate models to systematically explore climate phase space – remembering that climate models are themselves chaotic. But this has not been done because so very few scientists even have any clue at all. It is on the modelling agenda but hasn’t progressed very far because the IPCC is tranfixed with climate being the ‘statistics of weather’. Weather may flucuate but climate will on average be warmer with more CO2.
But the essence of chaos theory is that small initial changes result in a nonlinear climate response as a result of energy cascading through powerful and multiple climate systems. The nonlinear response is not predictable from consideration of greenhouse gas concentrations alone.
Cheers
Robert
Is it not obvious that even totally random fluctuations (which surely must be present) in clouds should cause temperature changes? Then why would Andy insist that one must definitively prove that this ever happens, when in fact it must surely happen at least sometimes. Why does he seem to think that it is more reasonable to revert to assuming clouds are a response only, than to logically acknowledge that sometimes they aren’t, based on the fact that it is completely reasonable to think they wouldn’t always be, and the fact that evidence that is consistent with that notion appears?
I can’t even understand what Dessler is trying to argue anymore…
I agree with Andrew here, that they are both talking past each other. Mr. Spencer drew first blood, and then owned up to it. Mr. Dessler then struck back, pandering to a press outlet to show that he was “engaging the doubters” [enemy] – he seemingly just wanted to over-shout Mr. Spencer and call him a big fat dummy in front of everyone. It’s unfortunate. I’m not sure there was any real scientific debate that arouse out of this, just a playground argument in front of everyone; both parties bear responsibility for it. Mr. Spencer initiated it and Mr. Dessler was all to eager to stick his tongue out, followed with a neener neener neener.
Andrew is right. Have a real debate in your own language and we’ll catch up.
It seems to me that the r^2 of 2% in Dessler’s paper for Figure 2a is a HUGE fundamental problem. I don’t see much mention of this and I wonder why. There are a few outlier points at the left of the plot that to my understanding of basic correlation, dictate the result. These few points may have error and a result of r^2=2% should cause everyone including Dessler to reject his conclusion of slightly positive slope in that plot. He even admits this but then proceeds on to make all his claims. It is stunning to me that this paper was published even by pro-AGW editors. Am I missing something here?
Brian V, I was puzzling about the same thing myself. And since the conversation has stopped and Andy has not reposnded to this key point by Spencer
“In contrast, feedback (temperature causing cloud changes, which is what Andy believes is going on) is much closer to simultaneous, which would lead to strongly correlated data (which is seldom observed…except on month-to-month time scales).”
I suspect Andy now knows knows why he is on the loosing side of the argument.
Well Roy and Andy (please excuse the familiar address form); I suggest that we need to start with the first things first.
So let us start with the incoming Solar radiation; at its now new level of 1362 W/m^2 adn let’s take it as simply a black body spectrum at say 6,000 K with a 0.5 micron peak wavelength.
Various and sundry things attenuate this (air mass = zero) radiation spectrum; first of which is the Raleigh scattering in the spectral peak blue green region, which drops the peak spectral irradiance by about 25%.
Now various so-called GHG species also attenuate this incoming solar energy by straight foward molecular absoprtion. Ozone of course does in the UV and also near the peak around 500-650 nm.
H2O vapor starts absorbing solar energy beginning at about 700 nm and then in multiple bands out to and beyond 4 microns. Roughly 98% of the solar energy lies between 0.25 microns, and 4.0 microns (0.5-8.0 times peak wavelength) with 1% beyond each end. The region addressed by H2O contains about 45% of the total solar energy (AM=0) and H2O absorbs across about half of that total range, so could account for 20% or more of the total incoming solar. CO2 also has some near IR absorption bands in the 2.7 micron region notably and around 4.0 but to a much lesser extent than H2O.
So somewhere in the 20-25% maybe range of incoming solar energy can be absorbed in the atmosphere directly; SO IT DOES NOT REACH THE GROUND and 70+% of the ground is actually the deep ocean into which solar spectrum energy can penetrate hundreds of metres. The 1/e absorption depth at the peak of the solar spectrum is about 100 metres; 10^-4 cm^-1 absorption coefficient, so about 500 metres for 99% absorption.
The loss of that direct solar energy from the ground, must cool the ground; but of course the absorbed energy will heat the atmosphere. That heated atmosphere will in turn radiate its own (elevated) thermal spectrum of LWIR radiation (in an isotropic radiation pattern). So only half of that thermal radiation heads towards the ground and the other half heads towards escape to space. An analysis of the change in line width of the molecular absorption bands with altitude (Temperature and density broadening) shows that the escape path is favored over the return to earth path; so maybe more than half escapes.
In any case regardless of what subsequently happens to that earthward directed LWIR from the atmosphere due SOLELY to direct heating from the sun; the ground level sunlight MUST be reduced by the captured solar energy that escapes to space as LWIR. Now that is true regardless of where those GHGs are in the atmosphere; specially the H2O which is the biggest contributor to the capture.
So now let’s get to your clouds; which are just my H2O condensed into a different phase (or phases). Once again; no matter where those clouds are as to location or altitude or type, they pseudo reflect (actually scatter) sunlight back out into space (albedo), and they further block through absorption additional sunlight from reaching the ground.
No matter what else those clouds do; they ALWAYS REDUCE the amount of direct solar spectrum incoming energy from the sun that can reach the ground.
Now if the AMOUNT of cloud cover should INCREASE, and please for a climatically significant time frame; not last night’s weather; no matter where those clouds are the net ground level solar insolation MUST be reduced, and the total incoming energy budget of the earth must be less.
Now argue all you want about what the various transportations of the atmospheric and surface generated LWIR thermal spectrum energy does or does not do, vis-a-vis clouds; that doesn’t change the simple irrefutable, and incontrovertible fact that H2O molecules in any form, in any phase, at any altitude, at any atmospheric location on earth, MUST reduce the total solar energy received from the sun, and any climatic time frame increase in that H2O MUST result in the Temperature eventually going down.
And I’m NOT impressed with what the return LWIR may do, because that is completely absorbed in about the top 50 microns of water surfaces (even in the soil) and that should result in rather prompt evaporation of even more water into the atmospehre; along with the return of a lot of latent heat of evaporation; so I don’t see that LWIR conveying much net energy to the ocean or earth storage system.
So aregue all you want about whether it is the highest whispiest of clouds that heat the earth through GHG capture and positive feedback, and don’t block much sunlight; hey they also don’t block much outgoing LWIR because of their low density not to mention the optical losses from ground to sky.
If you can convince me that some positive feedback due to water in any cloud form, can overcome the loss of direct incoming solar spectrum energy from reaching the surface storage sytem; then I may change my opinion. I don’t think you can; but give it your best shot.
Sorry to be so long winded.
REF: George E. Smith Comments
Spectacular comments. I wish you had been more long winded. Your comments are the best I have seen on these blogs.
I have suspected for a while that the positive/negative feedback issue is part of a delaying tactic of the warmers. You will notice Dr Dessler jumped on a ENSO question because Roy said this, but actually said that, ad infinitum, and conveniently never got around to what Roys point was in the first place: cloud feedback is positive.
The real question is whether Dr. Dessler and the IPPC are delivering accurate information despite their misunderstanding of cloud feedback?
REF: George E. Smith Comments
Sorry, I meant Roys point was: cloud feedback is negative.
“A study of the Earth’s albedo (project “Earthshine”) shows that the amount of reflected sunlight does not vary with increases in greenhouse gases. End of story.”
Some links to time series and data would be greatly appreciated. And, to help me understand the comment – is it not the case that sunlight passes through GHGs, and that it is upwelling, long-wave IR that is hindered? If that is the case, we should see little change in Earthshine from GHGs, and more likely from albedo changes (clouds, ice etc).
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