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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tallbloke (01:05:25):
You’ve got the essential points entirely right. But oceanic mixing from near-surface thermalization of solar radiation readily extends downward only to ~100m, which is the ballpark thermocline level.
michel:
“By the way, these rants people are indulging in about socialism, world government, plans to wreck the economy, they add nothing whatever to our understanding of climate and the evidence.”
————-
I completely agree. If everyone thinks that the only people questioning AGW are rabid right-wingers (of a type which would make most UK conservatives wince) and/or the paranoid then everyone else (which includes, for example, most of the opinion-formers in Europe) will tend to ignore the message and shy away from the messenger.
It’s far too easy for warmists to point at the strident right-wing rhetoric of some sceptics in the US and put all sceptics in the same boat as creationists.
If anyone wants to have any credibility in Europe they certainly don’t want to be seen as similar to a creationist.
Not a single party of any size of the left or right in the UK is publicly sceptical of AGW and I think that’s true over most of Europe. That isn’t going to change as long as being sceptical is seen as a knee-jerk right wing political position rather than a considered opinion based on a disinterested examination of the evidence.
Shou’dnt’ the data cause hot spots where the NASA AIRS satellite shows higher concentrations? This would be two bands, not around the equator, but close to in each hemisphere. In short, the top two and bottom left would be the fingerprint. However the biggest band is at the equator, from the acute angle of incidence of the suns rays.
RW,
The observed stratospheric cooling is a fingerprint of ozone depletion.
The BBC only allowed that article to be printed so that they could increase their audience. Always follow the money! If the BBC wasn’t losing money hand over fist, they would never have run that story. It is their deparate attempt to increase their earnings.
Global warming hooey
Worries about climate are being manufactured by the international left
By MICHAEL COREN
http://www.torontosun.com/comment/columnists/michael_coren/2009/10/10/11363661-sun.html
Quite possible this is O/T, just didn’t know where to put it.
Today, I read a paper titled ‘ Possible Atmospheric Transparency Studies on the Basis of Cherenkov Light Measurements,’ Mishev A.L. et.al. Oct 2009.
Its a nice read. You can find it at eprintweb.org/S/article/physics/0910.1662 .
In it, there is a paragraph worth noting:”The Cherenkov Light undergoes extinction in the atmosphere because of absorbtion on molecules by Rayleigh and Mei scattering by aerosols.”
I have a question on this paper and maybe Dr. Svensmark could help answer (he was referenced twice) . Does the light spectrum analysis from the cherenkov light determine volume and density, between solar and cosmic spallation? I got a handle on most of the other statements from the paper, but I couldn’t determine exactly how much or how detailed the data would be from the telescope. Thanks in advance.
-David Alan-
“kuhnkat (08:42:43) :
The third part of the FINGERPRINT is the decrease in Stratospheric Temperatures. This is specifically caused by the increase in GHG’s. With more GHG’s in the Stratosphere to radiate away the heat, it cools due to the inability of the system to move the extra heat across the tropopause from the Hot Spot area into the Strat.”
I may be missing something, but this explanation does not make a lot of sense. It looks like the argument is that there is an impediment to conduction and convection transferring heat into the stratosphere and that the added CO2 in the stratosphere makes it a more efficient radiator. But heat also radiates from the lower layers of the atmosphere into the stratosphere, and the added CO2 in the stratosphere would capture more of that radiation. (And how does the CO2 get into the stratosphere absent convention)
Also, I question the other premise; the stratosphere should not become a more efficient radiator because of a higher CO2 concentration. If that were true, then why do the lower atmospheric layers not become more efficient net radiators with higher greenhouse gas concentrations. My understanding is that CO2 and other GHGs are absorbers of IR radiation and thus, to re-radiate the absorbed heat, they have to increase in temperature according to the equation R(out) = kT^4. If I add more CO2 to a balloon that is held in an environment that receives all radiative energy from bands outside its absorbtion spectrum, it should not cool.
One way that stratospheric cooling with more GHG emissions might make sense is to start from the premise that the radiation leaving the outer boundary of the stratosphere is unchanged with GHG emissions, under the equilibrium assumption that radiation into the earth equals radiation out, and if radiation in is unrelated to CO2 concentrations then the net radiation leaving the earth also must remain unchanged with CO2 concentration. If CO2 concentrations in the lower layers of the atmosphere grow at a faster rate than that in the stratoshpere, due to convention constraints, the large warming below produces more of an outbound (upward) radiation increase than can be captured by the stratosphere. Therefore, of the fixed amount of radiation exiting the atmosphere’s boundary into space, more of it becomes pass-through radiation from the lower atmoshpere, through the stratosphere, as opposed to radiation captured by the stratosphere and re-radiated into space. For the stratosphere to radiate less into space, it has to cool. But this is not a function of higher GHG concentrations in the stratosphere, it is a function of the stratosphere losing ground in relative CO2 concentration to lower levels of the atmosphere.
kurt (12:59:57) : As I posted above:
We must always remember that that CO2 tale is impossible:
Air can not hold enough heat as water.
Air volumetric heat capacity: 0.001297 J cm-3 K-1
Water volumetric heat capacity: 4.186 J cm-3 K-1
Would you warm your feet with a bottle filled with hot air or hot water?
All of this makes for a very interesting discussion. But yet, no one contributing to this blog has published any of these refutations to AGW warming in a reputable peer review journal. If all of this is so obvious and easy to prove then who here is going to write and publish the refutation?
Until that is done, then what we have here is people expressing their opinions and everyone has one of those. I look forward to the published article.
Shiny
William
Adolfo Giurfa (13:25:52) :
Would you warm your feet with a bottle filled with hot air or hot water?
Adolfo,
Isn’t the total volume of available air much larger than the total volume of water?
Until that is done, then what we have here is people expressing their opinions and everyone has one of those. I look forward to the published article.
Shiny
William
William,
In case You haven’t noticed, I can read the published words right before my very eyes, right here at WUWT, on Climate Audit, and other non biased places right before my very eyes right now.
Adolfo Giurfa (13:25:52) :
“Would you warm your feet with a bottle filled with hot air or hot water?”
Adolfo,
Isn’t the total volume of available air much larger than the total volume of water?
Adolfo,
Isn’t the total volume of available air, much larger than the total volume of water?
Michael (11:00:51) :
Should we entitle that “The Return of the MSM”??
The ideal situation in the debate is for ordinary people to be prepared, not scared.
william (13:46:47):
Refutation of AGW: click
Show us that runaway globaloney, why don’t you. And enough appeals to authority. The climate peer review system has been gamed by a small clique of rent-seeking insiders. See the Wegman Report to Congress. Or John Daly on peer review. Or Bishop Hill on peer review.
There are several others showing the same thing: we can not depend on what comes out of climate peer review. The real climate peer review happens right here. But since you claim, wrongly as it turns out, that there is no peer reviewed study falsifying AGW, see here: click. Climate models, on which the entire AGW edifice rests, have been discredited.
Be prepared, not scared.
Animals hibernate or migrate.
Man adapts.
Be prepared, not scared.
Smokey
1) I don’t believe there will be “runaway” global warming, but I do believe there will be warming caused by the CO2 we are dumping into the atmo. There are consequences for putting that CO2 into the air and we should not ignore those consequences the same way we did not ignore the consequences of polluting our waters until the clean air and water acts were enacted.
2) So the peer review process is gamed? So it’s like a big “left wing conspiracy”? Let’s use Occam’s razor, skeptical articles don’t get published because there are so few skeptics, so few valid skeptical arguments and som many scientists across dozens of disciplines that do not agree with the skeptical argument. I’d suggest that it’s more likely that the skeptical argument does not “hold water”.
3) Much as I love this site, CA, the Air Vent and the Pielke’s blog sites, that is not where science is being published and distributed to the rest of the world. Until skeptics can meet the AGW head to head in the journals these sites will just be nipping at the heels of what gets published and what the IPCC compiles next time around.
As I have stated before, I’m a warmer in that I believe CO2 will cause some warming and the level of that warming will depend on feedbacks. If cloud feedbacks turn out to be positive then it will be game over for the skeptical argument. I do trust Dr. Spencer to get to the bottom of it but don’t be surprised if his findings in the long run validate the GCM’s and increases in temps over the next century.
Shiny
William
Tom in Florida (05:40:29)
…very well put. Sceptics have known for years that the science of AGW is certainly not settled, and have been aware that the most strident political proponents of AGW have a radical ideological axe to grind. Answering their increasingly hysterical announcements and climatastrophe predictions has necessitated taking them on politically too.
rbateman (13:57:11) :
Michael (11:00:51) :
“Should we entitle that “The Return of the MSM”??
The ideal situation in the debate is for ordinary people to be prepared, not scared.”
Never let your guard down when it comes to the MSM. They do not have your best interest at heart.
The (BSM) Blog Stream Media is the new authority, even though you have to pick through it to find the nuggets of truth and intricate details the MSM does not have to offer.
William,
“1) I don’t believe there will be “runaway” global warming, but I do believe there will be warming caused by the CO2 we are dumping into the atmo. There are consequences for putting that CO2 into the air and we should not ignore those consequences the same way we did not ignore the consequences of polluting our waters until the clean air and water acts were enacted.”
What has the Clean Air Act done to stop the airplane emissions that cloud up the sky’s and makes a gray haze that lingers all day long. Have you looked up at the sky lately?
Here is something most people don’t know – the use of fingerprints to prove guilt… is not a science. So when they say they have the fingerprint of Man Made Global Warming, they are not conducting science. 🙂
“kurt (12:59:57)
One way that stratospheric cooling with more GHG emissions might make sense is to start from the premise that the radiation leaving the outer boundary of the stratosphere is unchanged with GHG emissions, under the equilibrium assumption that radiation into the earth equals radiation out, and if radiation in is unrelated to CO2 concentrations then the net radiation leaving the earth also must remain unchanged with CO2 concentration. If CO2 concentrations in the lower layers of the atmosphere grow at a faster rate than that in the stratoshpere, due to convention constraints, the large warming below produces more of an outbound (upward) radiation increase than can be captured by the stratosphere. Therefore, of the fixed amount of radiation exiting the atmosphere’s boundary into space, more of it becomes pass-through radiation from the lower atmoshpere, through the stratosphere, as opposed to radiation captured by the stratosphere and re-radiated into space. For the stratosphere to radiate less into space, it has to cool. But this is not a function of higher GHG concentrations in the stratosphere, it is a function of the stratosphere losing ground in relative CO2 concentration to lower levels of the atmosphere.”
Very similar to my climate description which suggests amongst other things that air circulations in the stratosphere regulate the rate of energy release to space whilst the speed of the hydrological cycle regulates the speed of energy transfer from the surface to the tropopause.
The former ensures overall radiative balance so that energy from the sun always matches energy lost to space.
The latter ensures that there is always an approximate equilibrium between sea surface and surface air temperatures.
Both processes oppose each other and the tropopause is the region where each process fights for dominance.
The end result is that variations in energy flow from ocean to air are countered by an equal and opposite response in the air to retain overall equilibrium.
Hence climate variability, apparently most of the time a wholly internal process.
william (14:12:31),
I provided five links that show you’re wrong about peer review. I doubt that you read them. If you had, you would not have made the comments you did.
Since you’re just winging it, I guess you’re not interested in how shoddy the peer review process is. There’s the Jan Hendrik Schön peer review fraud. Or the Wei-Chyung Wang shenanigans. And the fact that Michael Mann’s Hokey Stick was thoroughly peer reviewed — and later just as thoroughly debunked. And Briffa’s Yamal proxy was peer reviewed, and is in the process of being debunked.
Skeptics’ papers have to jump through flaming hoops to be considered and then they don’t generally get published, while climate alarmist papers are simply hand-waved through with little or no scrutiny. Even getting a comment published is like pulling teeth if you’re not on the true believers’ side.
Appealing to a peer review authority won’t always get you to the truth. Instead, think for yourself. The planet is cooling as CO2 rises. What does that tell you?
Pascvaks (10:23:07) :
For those who haven’t seen this entry (or same elsewhere), now Department of Energy’s Oak Ridge National Laboratory and the National Center for Atmospheric Research have published in the current issue of Biogeosciences, “Key new ingredient in climate model refines global predictions”. Link at Brightsurf.Com for press release: http://www.brightsurf.com/news/headlines/49366/Key_new_ingredient_in_climate
I’d like to read the methods for that paper. Got links?