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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I’ve made the following note in a couple of posts, including:
http://bobtisdale.blogspot.com/2008/07/polar-amplification-and-arctic-warming.html
http://bobtisdale.blogspot.com/2009/06/another-look-at-polar-amplification.html
Refer to RealClimate thread here:
http://www.realclimate.org/index.php/archives/2007/12/tropical-troposphere-trends
Real Climate writes, “Whether the warming is from greenhouse gases, El Nino’s, or solar forcing, trends aloft are enhanced. For instance, the GISS model equilibrium runs with 2xCO2 or a 2% increase in solar forcing both show a maximum around 20N to 20S around 300mb (10 km):”
#
The following are two illustrations from the RealClimate thread. The first shows the tropical enhancement and polar amplification for a doubling of CO2 and the second illustrates the same effects for a 2% increase in solar irradiance.
http://i33.tinypic.com/10fu8p2.jpg
http://i38.tinypic.com/w8l4c0.jpg
RealClimate continues: “The first thing to note about the two pictures is how similar they are. They both have the same enhancement in the tropics and similar amplification in the Arctic. They differ most clearly in the stratosphere (the part above 100mb) where CO2 causes cooling while solar causes warming. It’s important to note however, that these are long-term equilibrium results and therefore don’t tell you anything about the signal-to-noise ratio for any particular time period or with any particular forcings.
“If the pictures are very similar despite the different forcings that implies that the pattern really has nothing to do with greenhouse gas changes, but is a more fundamental response to warming (however caused). Indeed, there is a clear physical reason why this is the case – the increase in water vapour as surface air temperature rises causes a change in the moist-adiabatic lapse rate (the decrease of temperature with height) such that the surface to mid-tropospheric gradient decreases with increasing temperature (i.e. it warms faster aloft). This is something seen in many observations and over many timescales, and is not something unique to climate models.” [My Emphasis]
In any other case, such a disparity between theory and observation would lead to dismissing the theory, or reworking it. Not in this case.
Oops! Forgot the next paragraph from my posts…
To create the polar amplification profile illustrated in the above figures in the GCMs, there had to be a doubling of CO2 or a 2% increase in solar irradiance. Neither happened in the last 3 to 4 decades, so what created the polar amplification profile? Real Climate provides the answer. El Nino events.
M White – the media have been speculating about how badly security failed in allowing so many demonstrators to gain access to Westminster. It doesn’t take a rocket scientist to work out that security turned a blind eye. I figure it’s just an escalation of the Government’s pathetic anti-sceptic (ha ha) propaganda offensive.
Has anyone here ever seen the movie Braveheart?
It is a movie about a person that saw that the government that he believed in and lived under was wrong. And he tried to change it by force. And he was captured and killed in an evil way.
Oh…So you all have seen it! But some of you say that it is not factually true. That it is just a “movie”. And of course you would be right. Truth and action an uncomprendable in our modern society….”must move forward”…march , march , march.
P.S.
There is no such thing as a “global” temperature. So how does one measure something that is non-existent???
If you theoretically change atmospheric conditions (CO2 consentration for example) you surely are not able to calculate how climate conditions and temperatures are affected. That is simply far too complex task to do at exact level. Althought “green house effect” is surely seen strengthen if you add CO2 from zero to present consentration, it is completely different initial condition to increase consentration from present.
Models tell that temps at surface level should rise slower than temps in middle troposphere. However, what is happening is reverse. So either the models calculate wrong or measurements are wrong (UHI is not correctly removed from surface datasets). Or both. The intresting thing is that these scientific anomalies between theories and measurements seem not to cause any attention among mainstream climatologists or IPCC.
Truth and action an uncomprendable
S/B “action are” uncomprendable
tallbloke (00:39:01) :
…It ain’t rocket science.
I agree. It’s much more complex.
Stephen Skinner (02:58:13) :
tallbloke (00:39:01) :
…It ain’t rocket science.
I agree. It’s much more complex.
I was talking about propositional logic, which doesn’t seem all that complex to me. Are you talking about logic, or the complexity of climate?
I shared a graduate student office with another who’s project involved modelling.
His classic statement on reviewing another run was “Real knowledge doesn’t increase at the rate of computer output”.
It was immediately and eventually useful – immediately in helping to make a 3-student office look like it could only hold 2, eventually as he got his degree.
Quote from Ned if he reads this.
It has always been the case in the scientific method that while a theory can never be proved, a single falsification can render it invalid (Popper). As several posters have already remarked, the fact of the matter is, not only would the “fingerprint” not be unique to greenhouse gases, but the fact that it doesn’t exist, would count as a falsification.
Of course, we don’t know that it doesn’t exist, and therein lies the rub. It may simply have escaped detection. This is the favoured explanation from the warmists, and have led to attempting to use windspeeds as a proxy for temperature, with some degree of success, if the results are to be believed.
But there are no more reasons to believe that windspeed proxies indicate higher temperatures than there is to believe that radiosondes and satellite data indicate no higher temperature. In fact less so, since the windspeed proxies and another layer of uncertainty.
However, if the windspeed proxies are in fact correct, indicating a net positive radiative imbalance, then the heat must be accumulating in the system, but this too has escaped detection. Roger Pielke snr. has already shown that the warming theory predicts that the ocean energy anomaly should now be showing (since 2003) somewhere between 10^22 tor 10^23 joules. But according to Argo based data, no ocean warming has been observed since 2003. So each predicition leads in turn to more and more contradicitory observations.
Of course, the missing heat could have gone below the 750m Argo floor. It could have, maybe . . . just maybe.
Natural cycles are all around us. Fact that proxies are not ideal, and do not correlate 100% to each other, it is no reason to reject them. I am inclined to take as good guide graphs produced pre 1990’s, before whole of AGW hysteria took off.
erlhapp:
The heating in the upper troposphere is not from water vapor at that level, but rising from below condensing and releasing latent heat. It is BECAUSE the specific humidity is limited at 200 mb that water ascending to the level must be precipitated out. Also, remember the heat capacity of air at 200 mb is only 20% of that at 1000 mb (less air to heat), which helps amplify a temperature rise.
If a hotspot were to exist, however transient, it is comprised of water vapor, no? There isn’t enough C02 to create it. So, with the GE due to water vapor present in orders of magnitude beyond C02, one should think a doubling of C02 would behave like nothing more than a slight increase in humidity, which happens all the time.
Bob Tisdale (01:42:58) :
Real Climate writes, “Whether the warming is from greenhouse gases, El Nino’s, or solar forcing, trends aloft are enhanced. For instance, the GISS model equilibrium runs with 2xCO2 or a 2% increase in solar forcing both show a maximum around 20N to 20S around 300mb (10 km):”
—
I am constantly amazed that people (climate “scientists”) actually use AOGCMs as poorly written and undocumented as Model E as proof of anything. For those who want to see how bad Model E is, please go here:
http://www.giss.nasa.gov/tools/modelE/modelEsrc/
They want our tax money, that explains everything. The hoaxers believe they can get the taxes by guilt tripping. Remember the post racism gag?
It’s going to be a bad winter for the hoaxers, if the sun keeps to it’s current plan, it will soon be so cold, the snow piled so high, the ice extent so large, that Al Gore will be the last true believer on the planet.
Watch the food crops closely … http://www.missoulian.com/news/state-and-regional/article_c1c13d5e-b6a4-11de-a09c-001cc4c002e0.html
michel (01:09:57) :”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.”
Unfortunately, Michel, this is also a political debate. The IPCC is a political entity. It stands for “Intergovernmental Panel on Climate Change”. It’s organizational statement claims: “Because of its scientific and intergovernmental nature, the IPCC embodies a unique opportunity to provide rigorous and balanced scientific information to decision makers”
http://www.ipcc.ch/organization/organization.htm
Note the wording, “to provide rigorous and balanced information to decision makers”. That means the decisions makers will use the information, correctly or incorrectly, to inflict their policies on us. When Al Gore, a political figure, makes statements like “the science is settled” and wants us all to follow him without question, that is political. But the bigger question is why do they want to stifle open debate? Certainly not to increase our understanding of climate. No, the politicians have hijacked the scientific debate to force their agenda on us. The institution of cap and trade policies do nothing to further the science. It only redistributes wealth.
Using a scientific agenda to force taxation on us is always political.
michel (01:09:57): “It must be quite probable (moderators please note) that these are in fact trolls. I have long suspected that the most plausible explanation for some of the wilder and more frenzied postings on Tamino and RC is that those who appear the most fanatical proponents of AGW are in fact trolls seeking to undermine it. ”
May I suggest that it appears the pot is calling the kettle black!
I have been reading this site for almost 2 years. I have learned such a great deal. But also, I always question government and their authority over us. Being forced to do anyting by anyone goes against my nature. Especially when I am told by our “leaders” to simply trust and not to question. This is how freedoms are lost and dictators win. So as long as the stated solution to climate change involves government control and taxation it will remain political and we need to remain vigilant.
michel (01:09:57) :</i?
…I have long suspected that the most plausible explanation for some of the wilder and more frenzied postings on Tamino and RC is that those who appear the most fanatical proponents of AGW are in fact trolls seeking to undermine it.
I take it you haven’t had the misfortune of being personally subjected to said fanatical proponents — I could introduce you to a few, but you’d probably try to strangle me afterwards…
Roy – I came to the same conclusions in my book ‘Chill’. As a scientist, but an outsider in relation to climate, I simply could not believe the simplistic stance of the IPCC – they had a graph of their computer validation showing no increase in global temperatures from 1950 to 2000 if there had been no CO2 (and hence only natural variability – they did not really highlight the existence of ‘cycles’) – and then a match to the observed temperatures when CO2 was factored in. Yet in another section, they admit that their knowledge of natural cycles is very poor!
Yet – this has been called ‘mainstream’ and ‘consensus’ and ‘authoritative’ by huge numbers of commentators as well as science institutions.
It seems the BBC is turning and looking at the arguments instead of the ‘authority’. Hopefully, other TV channels will follow. But many are afraid to put their toes in the water – for fear of repeating Channel4’s mistakes and getting the backlash.
There has been absolutely NO coverage of the Yamal controversy here.
The grip of authority in the UK is really very disturbing – but more so because it now includes Friends of the Earth, Greenpeace, WWF, Oxfam and even the lowly Royal Society for the Protection of Birds. These organisations have all jumped on the bandwagon and colluded with authorities they would have historically been very wary or critical of. I know that WUWT readers tend to take a somewhat jaundiced view of the ‘green’ movement – but it consists very largely of decent folk concerned about their environment, and who rely upon the campaign offices to do a decent job of monitoring government actions and justifications. This ‘rank-and-file’ have been seriously let down and misled – but they get virtually no dispassionate analysis – all the normal channels of communication are subject to the collective spin of global warming and its deniers.
Michel,
>So, moderators, why not follow Steve M’s example, and just snip all this irrelevant silliness? You’ll improve the quality of discussion and raise the credibility of the site, and avoid being taken in by trolls.
I see it differently.
The reason that many people read and participate in discussions on this very fine site is that the political and social consequences are so important. When one side of a controversial issue uses “scientific” justifications for its political initiatives, the other side will counter with both “scientific” and political responses. (I used quotation marks because many high profile people spouting “science” on either side are not experts in the topics and most of the experts are not high profile. Or so I believe.)
The science matters most when the consequences matter most. If this were a debate about the mating habits of the snail darter and our potential impact on them, the most vocal and committed debaters would be those who live near the habitat of the snail darter and those who depend on the snail darter for some part of their existence. The “global” nature of global warming means that everyone feels entitled to pronounce on the science, the forecasts and the policy responses.
I love chaos-rich systems when they provoke debate, because we witness people hoping to comprehend based on simplistic interpretations and our insight grows as their models are debated. I fear when some of those simplistic interpretations are taken to be timeless truth and wisdom. If you want non-climate-related examples, think of OTC derivatives in the world’s economic markets, or failed models of organizational behavior, or any religious fanaticism at any period in human history.
So I think your request that moderators begin suppressing the political comments that pop up on this site is mis-guided. The site is popular BECAUSE of the political implications of its topic, as well as its dedication to debate about the data, the science and the incomprehensible complexity of our climate. This stuff all matters, and while I can skim over the rants of the paranoid and the power-grabbers, I am shirking my duty as a citizen if I ignore the reality of the political currents that affect us all.
Moderators, please stay the course.
From Santer (G. Schmidt) et al 2005
Amplification of Surface Temperature Trends and Variability in the Tropical Atmosphere
“Tropospheric warming is a robust feature of
climate model simulations that include historical
increases in greenhouse gases (1–3). Maximum
warming is predicted to occur in the middle and upper tropical troposphere.”
Nowhere in the entire article is mention made of solar amplification. In fact, the crux of the article is the likelihood of observational error, not “warming can be from any source”.
Wasn’t the whole purpose of Santer 08 to support the GCM “hot spot”?
What is so hard to understand about this figure? It does not show the expected response to theoretical forcings. It does not show “that GHGs are the only agent that can cause substantial warming”. It shows the expected response to observed forcings.
“a natural decrease in cloud cover would have had the same effect.”
No, it wouldn’t. It would not cause cooling of the stratosphere. If we want to talk about ‘fingerprints’, then as you say, a tropical hotspot is not a useful ‘fingerprint’ because any positive forcing would be expected to result in a tropical hotspot. Stratospheric cooling is a fingerprint; positive solar forcing would cause stratospheric warming; positive greenhouse gas forcing would cause stratospheric cooling. I’m sure you know what is observed. Perhaps you can tell us what decreasing cloud cover would do?
“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”.”
Would you prefer that they had said ‘proof’? If so, why? If not, what exactly is your problem with the term ‘consistent with’?
anna v (22:49:44) : … proof requires conditions called necessary and sufficient.
According to the authors of the IPCC reports, the hot spot is a necessary condition coming out of the model runs that give all the dire predictions that are stampeding politicians to destroy the western economies.
..They have not ..given us runs that show no hotspots and at the same time give dire predictions for the next 100 years…
Bob Tisdale (01:42:58) :
I’ve made the following note in a couple of posts, including:
http://bobtisdale.blogspot.com/2008/07/polar-amplification-and-arctic-warming.html
http://bobtisdale.blogspot.com/2009/06/another-look-at-polar-amplification.html
RealClimate .. “Whether the warming is from greenhouse gases, El Nino’s, or solar forcing, trends aloft are enhanced. .. the GISS model equilibrium runs with 2xCO2 or a 2% increase in solar forcing both show a maximum around 20N to 20S around 300mb (10 km):..The .. two pictures .. how similar they are. …that implies that the pattern really has nothing to do with greenhouse gas changes, but is a more fundamental response to warming (however caused). Indeed, there is a clear physical reason why this is the case – the increase in water vapour as surface air temperature rises causes a change in the moist-adiabatic lapse rate (the decrease of temperature with height) such that the surface to mid-tropospheric gradient decreases with increasing temperature (i.e. it warms faster aloft). This is something seen in many observations and over many timescales, and is not something unique to climate models.”
I agree with Anna v. If the hypothesis fails in a condition that is necessary for it to be true, then the hypothesis has to be rejected.
According to Bob Tisdale/ RealClimate, however it seems that, in agreement with what Dr Spencer has written, this is not a necessary condition (in the sense unique condition) for CO2 induced warming, but would be a necessary condition for ANY induced warming, CO2, El Nino or Solar. Why? because “the increase in water vapour as surface air temperature rises causes a change in the moist-adiabatic lapse rate (the decrease of temperature with height) such that the surface to mid-tropospheric gradient decreases with increasing temperature (i.e. it warms faster aloft).”
So what happens when this necessary condition for warming (any warming) doesnt appear? Doesnt the basis assumption that “the increase in water vapour as surface air temperature rises causes a change in the moist-adiabatic lapse rate (the decrease of temperature with height) such that the surface to mid-tropospheric gradient decreases with increasing temperature (i.e. it warms faster aloft)” be called into question? Either that is not true or else something else (maybe clouds) is happening to nullify that simple assumption?
To my mind all this may not “prove” that the AGW hypothesis is wrong, but it would cast serious doubts on the reasons why IPCC (now) and the warmist alarmists are so sure that the warming is due to CO2 and nothing else.
There is another bit of fundamental science, and the most important bit – if the predictions of your experiment fails, then the hypothesis on which these predictions are based, also fails.
Has the warming been in consonant with the IPCC predictions? No.
Normally the hypothesis should be rejected on these grounds, but the warmist / alarmist high priests, whose wealth and power depends on the tithes accruing from these prophesies of doom, and sacrifices demanded to appease the demon, are scrambling to say apocalypse is merely delayed not cancelled.
“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. ,,, So, moderators, why not follow Steve M’s example, and just snip all this irrelevant silliness?”
I agree.