By Roy W. Spencer, Ph. D., October 11th, 2009
It is claimed by the IPCC that there are ‘fingerprints’ associated with global warming which can be tied to humanity’s greenhouse gas emissions, as if the signatures were somehow unique like real fingerprints.
But I have never been convinced that there is ANY fingerprint of anthropogenic warming. And the reason is that any sufficiently strong radiative warming influence – for instance, a small (even unmeasurable) decrease in cloud cover letting in slightly more sunlight starting back in the late 1970’s or 1980’s– would have had the same effect.
The intent of the following figure from Chapter 9 in the latest (AR4) version IPCC report is to convince the reader that greenhouse gas emissions have been tested against all other sources of warming, and that GHGs are the only agent that can cause substantial warming. (The snarky reference to “proof” is my addition.)
But all the figure demonstrates is that the warming influence of GHGs is stronger than that from a couple of other known external forcing mechanisms, specifically a very small increase in the sun’s output, and a change in ozone. It says absolutely nothing about the possibility that warming might have been simply part of a natural, internal fluctuation (cycle, if you wish) in the climate system.
For instance, the famous “hot spot” seen in the figure has become a hot topic in recent years since at least two satellite temperature datasets (including our UAH dataset), and most radiosonde data analyses suggest the tropical hotspot does not exist. Some have claimed that this somehow invalidates the hypothesis that anthropogenic greenhouse gas emissions are responsible for global warming.
But the hotspot is not a unique signature of manmade greenhouse gases. It simply reflects anomalous heating of the troposphere — no matter what its source. Anomalous heating gets spread throughout the depth of the troposphere by convection, and greater temperature rise in the upper troposphere than in the lower troposphere is because of latent heat release (rainfall formation) there.
For instance, a natural decrease in cloud cover would have had the same effect. It would lead to increased solar warming of the ocean, followed by warming and humidifying of the global atmosphere and an acceleration of the hydrologic cycle.
Thus, while possibly significant from the standpoint of indicating problems with feedbacks in climate models, the lack of a hotspot no more disproves manmade global warming than the existence of the hotspot would have proved manmade global warming. At most, it would be evidence that the warming influence of increasing GHGs in the models has been exaggerated, probably due to exaggerated positive feedback from water vapor.
The same is true of the supposed fingerprint of greater warming over land than over the ocean, of which there is some observational evidence. But this would also be caused by a slight decrease in cloud cover…even if that decrease only occurred over the ocean (Compo, G.P., and P. D. Sardeshmukh, 2009).
What you find in the AR4 report is artfully constructed prose about how patterns of warming are “consistent with” that expected from manmade greenhouse gases. But “consistent with” is not “proof of”.
The AR4 authors are careful to refer to “natural external factors” that have been ruled out as potential causes, like those seen in the above figure. I can only assume this is was deliberate attempt to cover themselves just in case most warming eventually gets traced to natural internal changes in the climate system, rather than to that exceedingly scarce atmospheric constituent that is necessary for life of Earth – carbon dioxide.
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Sweet…
So when is this going to be published and put up to peer review?
I can’t wait!!!
Also, note the blatant personal attack on what are supposed to be his scientific peers in the last paragraph. Is he arguing science or running for a political office?
Publish your criticism and questions already….
danaappleloupe – did you see the offer to have your very own thread on WUWT? You seem to have missed that.
Yes I did, breifly and have not had the time to respond. I gather it is a place for me on here where I can teach your readers about statistics, and time scale on climate, and how belief in an intelligent designer is actually relevant to how one thinks critically about the natural world (Im done on that topic). I work full time , volunteer at non profits and wouldn’t have the time to do that.
I would yield to science.
There is a place for questions, doubt and skepticism. It is called the scientific method, a big part of it today is publication and peer review. That’s how we do it, and it works.
I have been look for this publication of RW Spencer, I can’t find a real title for it, just “Spencer et. al. 2007”. In his statement to Congress in March 2007 he mentions that it has been published for peer review. It has been over 2 years, plenty of time for this process…
All I want. Seriously all I want, is scientific discussion on this topic, because the truth is very important.
If anyone has information on what happened to the frequently mentioned in skeptic blogs (no mention in any journals) to “Spencer et. al. 2007” please let me know. *Usually research, etc going out for publication and peer review have titles.
The lack of peer reviewed research from climate change skeptics is shocking.
REPLY: So I take that is a no?
Hey Guys…
Lysenkoism was politically endorsed “Real Science” for at least 30 years… At least as far as the Russians were concerned.
Any claim to being the “Real Science” needs to keep that one in mind.
“[…] authors are careful to refer to “natural external factors” that have been ruled out as potential causes […] deliberate attempt to cover themselves just in case most warming eventually gets traced to natural internal changes in the climate system […]”
…so they appear doubly-wrong.
John S. (17:02:44) :
tallbloke (15:20:15):
Downward mixing well below the thermocline, which is seldom found much deeper than 100m anywhere before disappearing completely at high latitudes , is a very sluggish process, quite inconsequential in its climatic effect. Widespreasd subduction of surface waters is a red herring, accepted only by ignoranti in physical oceanography, such as Al Gore. What little sinking occurs is due purely to density differences developed in limited areas, under rather special conditions. The wind-driven circulation is orders of magnitude more important than the thermohaline in redistributing near-surface heat poleward, rather than downward.
Hi John S, I ws going by the following which I found on the net. I’m a learner so feel free to set me straight.
http://www.esr.org/outreach/glossary/thermocline.html
Thermocline: definition.
… In the tropics, the thermocline can be quite shallow on average, as in the eastern Pacific (50m), or deeper as in the western part (160-200m). In extra-tropical regions a permanent (or main) thermocline is found between 200m and 1000m.
And:
http://books.google.co.uk/books?id=bOg0EqqrDRgC&pg=PA149&lpg=PA149&dq=depth+of+thermocline&source=bl&ots=X8ZvDPmUi2&sig=N4n7JHLZX9FyEczf_LRNtIQjBkQ&hl=en&ei=2S3UStznNNzajQe18vn2Aw&sa=X&oi=book_result&ct=result&resnum=8&ved=0CCcQ6AEwBzgU#v=onepage&q=depth%20of%20thermocline&f=false
200-800m tropical and 400-1100m extra tropical according to this book.
Cheers
danappaloupe: “If anyone has information on what happened to the frequently mentioned in skeptic blogs (no mention in any journals) to “Spencer et. al. 2007″ please let me know. *Usually research, etc going out for publication and peer review have titles.
The lack of peer reviewed research from climate change skeptics is shocking.”
Spencer et. al. 2007, you say:
Spencer, R. W., W. D. Braswell, J. R.
Christy, and J. Hnilo (2007), Cloud and radiation budget changes
associated with tropical intraseasonal oscillations, Geophys. Res.
Lett., 34, L15707, doi:10.1029/2007GL029698.
Joel, the best Dessler paper I have found so far is here:
http://geotest.tamu.edu/userfiles/216/Dessler2008b.pdf
What is says is, yes, the UT is moistening, but it also says it is drying in other places. He and Soden then make the leap that it is ok to put constant RH into their models since they get the same result.
The problem with that approach is that it can’t be used to conclude anything about future climate. How do we know what the NH subtropics will do with even more CO2 warming? Right now there is negative water vapor feedback (undoubtedly due to the land masses). What will the weather be like with more CO2 warming?
danappaloupe (23:10:27) : “The lack of peer reviewed research from climate change skeptics is shocking.
You know, I was thinking the same thing about anything that comes out of the mouth of Al Gore.
Pamela Gray: You are right about my over-the top phrasing. It was a bit of rhetorical flourish…Smokey tends to get my blood boiling.
Eric (skeptic): Yes, Dessler finds that overall the UT is moistening but that the behavior is not uniform everywhere, either in the real world or in the models. However, I don’t see where he or Soden say, “It is ok to put constant RH into their models since they get the same result.” What they do say is that the results for the strength of the water vapor feedback do seem to be about the same if you make the RH constant everywhere. However, the models are not normally run with that constraint and I don’t see where either Dessler or Soden is advocating that they be run with that constraint in the future.
danappaloupe: To Spencer’s credit, he has been publishing or submitting for publication his work on the cloud feedbacks.
danappaloupe (23:10:27) :
Are you seriously incappable of putting “Spencer et al. 2007” into Google and pressing “search”? Because if you did, you would find this:
Cloud and radiation budget changes associated with tropical
intraseasonal oscillations
Roy W. Spencer,1 William D. Braswell,1 John R. Christy,1 and Justin Hnilo2
Received 15 February 2007; revised 30 March 2007; accepted 16 July 2007; published 9 August 2007.
GEOPHYSICAL RESEARCH LETTERS, VOL. 34, L15707, doi:10.1029/2007GL029698, 2007
http://www.drroyspencer.com/Spencer_07GRL.pdf
http://www.agu.org/pubs/crossref/2007/2007GL029698.shtml
No, it wasn’t just mentioned in a journal, it was printed, too. Knock yourself out.
tallbloke (00:40:24):
The permanent thermocline has little to do with downward diffusion of near-surface heat, being unaffected by seaonal cycles. It is developed by advection of warmer water poleward and colder water equatorward. For active vertical heat transfer you have to look at the seasonal and diurnal thermoclines, which are always much shallower.
Joel, if constant RH is false, then why mention it? It is the distribution of RH (which is weather at the small scale) that will determine climate sensitivity along with forcings like CO2 and unpredictable, but still modelable factors like PDO. Everything can be modeled to some extent, there is no need to ever mention or assume constant RH.
The political dimension of AGW is very important. But not because it is about plots for global domination by shadowy forces.
The important thing is the scale of the public policies being advocated, and the lack of any analysis of either their risks or their chances of success. This is the thing one should focus on. Motives and so on are difficult to prove and are not very material. The lack of evidence based justification for many of the proposals is fairly easy to prove.
As an example, take the enormously valuable number of 1.8 million. This is the number by which you divide a given number of gigatons of CO2, to find out how much of a difference a reduction of that many gigatons would make to the global average temperature – in the view of the IPCC.
You rapidly see if you use this number a few times that most proposals to do things to save the planet and avert global warming will have no such effect. The problem with Kyoto, for instance, was not that it was a plot for world domination. The problem was that it would have no more effect on future temperatures than if we all did 20 pushups every morning. Similarly the problem with Cap and Trade is not that its a filthy Democratic plot. The problem is it will at enormous expense make no difference that anyone will be able to measure to global temperatures. But the costs will be enormous.
The problem with plans for huge reflecting mirrors in space or whatever is that the risks associated with doing projects with this level of effect on climate are simply huge.
The problem with covering the West with windmills is that they do not generate any significant amounts of usable electricity, and cost a bomb. And probably be more dangerous than coal mining to the workers servicing them.
The problem with proposals for draconian carbon emission reductions, and forecasts of it happening, is that they conflict with all the evidence we have of what industrial countries can actually do, and with what their policies say they are actually going to do. Pielke has made excellent contributions to the debate in this area, and he is a model of how to focus the debate on rational considerations, which, when you look at them calmly, all add up to the same thing: it ain’t going to happen anyway. One fact based posting from Pielke outweighs in usefulness and convincingness 1,000 rants about world government plots by shadowy groups.
It is very important to assess public policy choices that are being urged on us on the basis of, initially, whether they are rationally justifiable in their own terms. If not, they fall at the first fence. If they make some kind of sense in their own terms, we can then start to discuss whether the terms are correct, what the risks are, what the alternatives are, are they cost effective, doable. But most of these hare brained schemes are non starters in their own terms.
The really important public policy issue, which everyone involved needs to be called on, over and over again, is that anything labeled carbon reducing or green is given a free ride. If it were a proposal to build a new nuclear plant, or if it were put forward by Exxon, it would get intensive scrutiny as to safety, cost effectiveness, efficacy. If it is some totally unproven scheme to generate power in some untried way, to save the planet, it seems to get a free ride. The consequences, as with the disaster of the ecological consequences of the biofuel movement, while the corn lobby laughs all the way to the bank, are horrendous. Ask yourself, for instance, what the accident rate will be on the servicing of the 8,000 off shore windmills the UK is proposing to build. Has anyone even mentioned the idea that this might be a rather dangerous sort of thing to be doing?
This is the right way to object to some of these outlandish and dangerous public policy proposals. It gets the debate down to concrete details, it focusses on the facts and the science and the uncertainties involves. Ranting about conspiracies and socialism is counterproductive. By all means think it. Just do not mistake such thoughts for serious arguments about what proposals should or should not be done. People in the end make decisions on the facts about particular proposals, not on the basis of our feelings about the motivations of the proponents.
Nasif Nahle (20:13:45) :
I didn’t say it was saturated in the troposhere – Its peaks are saturated in the lower troposhere whilst in the upper troposphere, its shoulders absorb radiation even beyond the troposhere. Shoulder molecules only do what nitrogen and oxygen do – 5% as effective as at lower tropospheric level – and there are nearly a million more nitrogen & oxygen molecules at this level
Nasif Nahle (20:21:05)
Its been a few years since I read it – so think is was called “celestial rays and climate change. “. The analysis extended over the 400, or 800,000 year period of the vostok ice core legend
this might be useful:
http://pdfdatabase.com/index.php?q=jan+veizer+&filetype=0
John S. (17:02:44) “The wind-driven circulation is orders of magnitude more important than the thermohaline in redistributing near-surface heat poleward, rather than downward.”
Thanks for this note. I know little of oceanography (at this stage), but my instinct (based on detailed analyses of many terrestrial time series over the past 2 years) has moved towards believing that much of what many around here seem to assume “must be ocean cycles & currents” is actually related to sustained patterns of atmospheric pressure, wind, clouds, & precipitation (and I believe Yu.V. Barkin is pointing us in the direction of the bull’s-eye – there are many miles to go with the math, which will have to push into the seemingly-intractable to go where he suggests).
Eric (skeptic):
Ah…Spoken like a typical engineer! 😉
Seriously though, they mention it because it is interesting to see that a simpler way of looking at things appears to give an excellent approximation to the answer for the strength of the water vapor feedback that one gets by considering the system in its full complexity.
And, it is also true that climate calculations themselves are carried out at various levels of complexity (including one-dimension), so there may be sufficiently simple models that give more insight where it would be useful or even necessary (e.g., if you only have one dimension) to make an approximation like that of constant RH. Not everyone wants to do every calculation on one of the world’s largest supercomputers; sometimes you even want to do a calculation on the back of an envelope!
“Scott Mandia (17:12:24) :
EXACTLY! It never ceases to amaze me that if the anti-AGW points were so obvious then why do they not appear in journals? Most of the anti-AGW arguments are analogous to: “I see a bird flying so I just proved there is no gravity!”
You have it completely backwards. Most of the arguments here are analogous to “just because a bird flies, doesn’t mean that there is no gravity.” I for one, have repeatedly argued on this site that the sum total of all AGW research is based on the illogical conflation of the validity of the scientific or mathematical procedures underlying a study or paper, with the accuracy of the result of that study or paper. Just because your methods are sound, by itself, tells you nothing about whether your answer is right, any more than the exposure of a methodological flaw demonstrates that the result is wrong.
In truth, the measure of our knowledge of a system is what you are able to do with that knowledge. You don’t presume some level of knowledge and thus conclude that you have the ability to apply that level of knowledge to a particular problem. The flaw with climate science is that there is no practical application with which to adequately measure the level at which we really understand the climate. Certainly you can’t believe that a group of climate scientists gathered together in the Nevada desert on a star-filled night and called down a thunderstorm. Nor, given the fact that it takes decades to even measure changes in climate, from whatever origin, is it plausible that climate scientists have developed, or will develop in the forseeable future, a measurable track record of predicting climate change. It isn’t feasible for any climate scientist to demonstrate expertise at attributing a particular change in climate, once measured, to a particular cause given that there is no measurement instrumentation to test that expertise.
The argument that greenhouse gasses significantly contribute to climate change boils down to the logical fallacy of the appeal to authority. We look at the letters after a person’s name, and assume that because they are very intelligent that they are ultimately right, even though we have no objective measure of that person’s actual expertise, and in fact objective evidence of their non-expertise.
I don’t know how often I’ve seen climate scientists premise a study based on an “average” of the predicted results of computer models, which are basically the only evidence relied upon to quantify the effect of CO2. One particular instance was a study that predicted that Lake Mead would dry up in a couple decades, by first assuming an average of regional preciptation forecasts of the IPCC climate models. The IPCC itself, if I recall correctly, does nothing more than present the results of a number of models and just wave their hands to take the average as the “likely” result. This kind of averaging is a show of weakness, not of strength, the way a college football fan bets on a game by “averaging” the predictions of people they presume to be the experts. But in this case, the climate scientists, lacking the expertise to distinguish the accuracy of one model relative to another, just say, “hell, just take an average – don’t know what else to do.” But if they lack the expertise to evaluate the efficacy of one model relative to anther, how do they have the expertise to evaluate the efficacy of any model in absolute terms?
Similarly, judging a model based on comparing its output to what is believed to be past climate is again an exercise in futility. NASA, prior to the start of solar cycle 24 issued two predictions of the beginning of, and strength of, solar cycle 24 using two models, both of which were calibrated to reproduce the past solar cycles to 90% accuracy or so. We all know how well those models turned out.
Now, your logic seems to be that these arguments must be wrong either because I haven’t submitted them for publication in Nature, or that they did not or would not accept them if I did. Once again, this demonstrates the logical fallacy of the appeal to authority – since the arguments weren’t accepted by the experts, they must be wrong. But, of course, no scientific journal is going to bother publishing something that has the sole point of arguing the futility of relying on its prior content due to its status as unadulterated conjecture.
kurt (16:13:39) :
Hear! Hear! Very well said!!
****************
Joel Shore (15:07:01) :
Seriously though, they mention it because it is interesting to see that a simpler way of looking at things appears to give an excellent approximation to the answer for the strength of the water vapor feedback that one gets by considering the system in its full complexity.
******************8
So, Joel. Which climate model has modeled water in all its complexity. It’s my understanding that none can and it will be 10 – 40 years before computers are powerful enough to do it. What say you, Joel?
I must go back to a comment made by Bob Tisdale (01:42:58), quoting RealClimate and seconded by RW, Joel Shore and Scott Mandia- That the tropospheric “hot spot” is simply a signature of any warming including Solar warming and not a specific signature of Anthropogenic Global warming.
The explanation for the hotspot given was that an increase in water vapour as the surface air temperature rises causing this.
This statement (that the tropospheric “hot spot” is simply a signature of any warming) was generously offered Dr Spencer and seized upon by all the warmists, as it this “hotspot” that is supposed to exist, does not.
RW (06:12:35), Joel Shore (17:40:35), Scott Mandia (17:12:24)
There are 2 points that have not been addressed:
1. That I raised at Richard (06:24:21) – If the hotspot does not exist then either the basic assumption/ explanation is wanting OR something else is happening to nullify that explanation.
This is very important as it points to a negative feedback – something that the warmists say doesnt exist and are very uncomfortable with, as it may nullify any dangerous warming claimed due to CO2.
2. Real Climate may claim (to the hear hears, amens and head noddings of RW, Joel Shore and Scott Mandia) that the tropospheric “hot spot” is simply a signature of any warming, but the IPCC AR4 report says that that this hotspot is a SPECIFIC signature of Anthropogenic Global Warming.
This was in fact pointed out in the first sentence of Dr Spencer – “It is claimed by the IPCC that there are ‘fingerprints’ associated with global warming which can be tied to humanity’s greenhouse gas emissions…”
The graphs shown above are from the IPCC AR4 report which SPECIFICALLY show this.
The models in these graphs show “the effect of GHG’s as distinctly different from that of solar or volcanic forcings. In particular: The tropical tropospheric hotspots appears in the plate discussing heating by GHG’s and does not appear when the warming results from other causes”.
For a more complete discussion/ explanation see here
If IPCC is wrong here – could they possibly be wrong elsewhere? Maybe the science is NOT settled after all?
PS
The corollary to my argument above, Richard (04:28:03), is :
If IPCC is correct that the appearance of a tropospheric “hot spot” is specifically due to Anthropogenic Global Warming and does not appear when the warming is due to other causes, and since the hot spot has not appeared, then our current warming is not due to Anthropogenic Global Warming and is due to “other causes”.
According to the IPCC.
I wonder what the warmists have to say about that?
@ur momisugly kurt (16:13:39) :
Just open your eyes to what is happening in the past few decades and what has happened in the past 2,000 years. What you will see today has not happened in the past 2,000 years.
It is easy to criticize the models but they represent the best knowledge that scientists have to date and they predict many aspects of climate change quite well.
Because we cannot create a new planet and test climate change on it, we must use models. They are far from perfect but they are much, much better than chance.
BTW, there have been measurements of the greenhouse effect and they do match models fairly well. See:
http://www2.sunysuffolk.edu/mandias/global_warming/greenhouse_gases.html
and go to the section titled: Measuring the Greenhouse Effect
@ur momisugly Richard (04:28:03) :
Regarding the “hot spot” controversy please see Chris Colose’s thread which is the best I have seen on the subject:
http://chriscolose.wordpress.com/2008/12/20/skepticsdenialists-part-2-hotspots-and-repetition/
Jim says:
As I have noted, the models seem to be modeling water vapor well enough to be in very good agreement with the available satellite data that can be used to study water vapor in the troposphere and hence provide strong evidence that the water vapor feedback is being modeled correctly. Clouds are much more difficult to model.
But the larger point is that models are never perfect. I don’t think even in 40 years we will have perfect models. The only perfect model is a complete duplicate earth. That doesn’t however mean that models are useless…in fact, far from it.
Richard says:
As I have pointed out, the most direct implication of the “hot spot” not being there would in fact be that a negative feedback that is currently included in the models, the lapse rate feedback, should not be there. The lapse rate feedback occurs because, under the assumption that the warming is larger in the upper troposphere than at the surface, the earth’s surface doesn’t have to warm as much as the effective radiating level in the upper troposphere does in order to restore radiative balance. If the assumption is wrong, the models have a negative feedback in them that should not be there.
Now, it is true that a lot of the same convective dynamics that are expected to control the lapse rate feedback also control the water vapor feedback. So, in principle, one might expect that the lack of the “hot spot” could also mean the models are wrong about the water vapor feedback. However, this is a more indirect consequence of the hot spot being absent and, furthermore, it seems to be contradicted by the satellite evidence of upper tropospheric moistening.
I don’t think that is correct. You can tell me where you think that they say that but I seem to recall that this claim involves considerable interpretation of what they actually say. I agree that the IPCC should have been clearer in explaining how the hot spot arises but I don’t think they said anything directly incorrect about it.
This is absolutely incorrect. The technical definition of the “hotspot” is that it is amplification of the surface temperature trend or fluctuation as you go up in the tropical troposphere. The graphs that the IPCC shows are simply not sufficient to resolve the spatial pattern of the warming for the mechanisms that are not believed to have contributed very much to the 20th century warming. For example, if you look at the solar mechanism, the color shading indicates a warming of between 0 and 0.2 C at the surface and 0.2 to 0.4 C at altitude in the tropics. That is compatible with any amplification factor between 1 and infinity (and, in particular, is not incompatible with the factor of about 2 or 2.5 that is expected for greenhouse gas mechanism). That is why Gavin Schmidt did an experiment where he ran the models with solar and GHG forcings that produce about the same magnitude of response and showed how the pattern through the troposphere is nearly identical…with the only dramatic distinction being the pattern in the stratosphere ( http://www.realclimate.org/index.php/archives/2007/12/tropical-troposphere-trends/ ). [The second largest forcing in that figure is the negative forcing due to aerosols and you can in fact see a little clearer evidence than for solar how there is indeed an amplification of the temperature response in the upper troposphere of the tropics relative to the surface. (In this case the temperature response is, of course, a cooling.)]
People are using that figure from the IPCC AR4 report to try to determine something that it simply was not designed to distinguish…and are getting confused because they don’t understand the subtleties of contour plots.