Nicholas Lewis (who with Jeff Id and Ryan O’Donnell rebutted Steig et al and the flawed Antarctica surface temperature analysis) writes in with a note about a post on Climate, Etc. (Judith Curry’s blog) related to the IPCC AR4 and their estimate of climate sensitivity.
The IPCC Third Assessment Report (TAR), said it was “likely to be in the range of 1.5 to 4.5°C” (from . “Technical Summary: F.3 Projections of Future Changes in Temperature”
More recent work continues to support a best-guess value around 3°C (from “The equilibrium sensitivity of the Earth’s temperature to radiation changes”)
There’s been a lot of talk about this as of late, and the number that I keep hearing repeated again and again is in the range of 1.1 to 1.4°C per doubling of CO2. Recently at ICCC6 in Washington, Dr. Roy Spencer suggested in his debate with Dr. Scott Denning that the value seems to be 1.3°C per 2xCO2 based on his analysis of temperature observations.
Nicholas Lewis has found what may be an error with IPCC’s calculation of climate sensitivity and writes:
I am hoping that its (correct) claim that the IPCC made an invalid alteration in AR4 of key evidence it cited as to climate sensitivity will get quite a lot of exposure, relating as it does to the core scientific basis of the AGW/dangerous climate change case. If you were willing to post on WUWT a link to the article on Climate Etc, that would be great.
… I am keen to bring the issue raised – about the major influence on observationally-based climate sensitivity estimates of ‘uniform prior’ probability distributions by the IPCC and many climate scientists – to the attention of mainstream climate scientists…
I have actually done a lot more work on the IPCC cited climate sensitivity estimates, and in particular the ‘uniform prior’ issue, than is covered in the attached piece. I have concluded that the IPCC AR4:WG1 Fig. 9.20 sensitivity PDFs are probably all substantially biased to high climate sensitivity.
Read it here:
The IPCC’s alteration of Forster & Gregory’s model-independent climate sensitivity results
Biosketch. Nic Lewis’ academic background is mathematics, with a minor in physics, at Cambridge University (UK). His career has been outside academia. Two or three years ago, he returned to his original scientific and mathematical interests and, being interested in the controversy surrounding AGW, started to learn about climate science. He is co-author of the paper that rebutted Steig et al. Antarctic temperature reconstruction (Ryan O’Donnell, Nicholas Lewis, Steve McIntyre and Jeff Condon, 2011, Improved methods for PCA-based reconstructions: case study using the Steig et al. (2009) Antarctic temperature reconstruction, Journal of Climate – print version at J.Climate or preprint here).
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Isn’t it remarkable how all these ‘mistakes’ tend to favor the alarmist cause? I suspect that there are some interesting statistics to be uncovered in computing the likelihood of so many mistakes occurring in one direction, ‘by chance’.
that the value seems to be 1.3°C per 2xCO2
========================================
That is….if things like a flipped over ENSO, the sun, Chinese coal, natural variability, clouds, contrails, soot, elves and gremlins, and …..
…don’t get in the way
Lies, damn lies, and statistics.
Just to short hand the study because its a pretty long a high on the technobabble.
The IPCC took eight studies on climate sensitivity of which one(Forster/Gregory 06) was the only study based purely on observational evidence, with no dependence on any climate model simulations threw said study in their voodoo math machines and basically 2x the results. It then put the study up in the graph with the other studies and basically pulled the “mikes nature trick/hide the decline” game.
Bayesian babble
Snookers policy makers.
Climate science mocks.
=================
So it is models, all the way down.
~1.1C per CO2 (including equivalents such as methane) doubling and 2-3C in concommitant water vapor amplification.
The bone of contention among the better informed has always been about the amplification and seldom about the baseline increase from CO2 sans amplification. 1.1C per doubling is nothing to worry about and everyone knows it. 4C per doubling is something even I would worry about and I don’t worry easily. Fortunately there’s not a shadow of doubt in mind that 4C is a complete fabrication without a shred of empirical evidence behind it while 1C per doubling is quite credible and supported by virtually all the observations and theoretical physics. So, no worries. We’ll run out of fossil fuels before we can pump enough into the atmosphere to even do something as positive as end the ice age. Hopefully we’ll have a replacement source of energy to keep us warm and fed when the glaciers begin their inevitable rapid advance. If not then civilization is going to collapse by ice not fire.
Regarding Roy Spencer’s recent sensitivity estimate that a doubling of CO2 would cause about 1.3°C of warming: note that this was accepting the IPCC’s assumptions that 20th century warming was caused almost entirely by CO2 only a tiny bit by solar activity. Roy:
To be specific, the IPCC assumes that CO2 has 14 times the warming effect of solar activity, a product of assuming that solar magnetic activity has no effect at all on global temperature. The only solar variable the IPCC includes is total solar insolation, which varies by about a tenth of a percent over the solar cycle. Solar magnetic variables, which can vary by an order of magnitude over the solar cycle and are highly correlated with climate, are all completely omitted.
The more that 20th century warming is actually attributable to the 80 year grand maximum of solar activity (from 1923-2003) the less warming is attributable to CO2 and the lower the climatge sensitivity (the warming that a doubling of CO2 would create). If it is only 1.3 when all warming is attributed to CO2, it would pretty much have to be less than 1 when solar effects are properly accounted, meaning that feedback effects tend to dampen rather than amplify temperature forcings.
A 1.3°C rise due to 2XCO2, if added to a natural out-of-LIA of another 1.2°C will bring the total to 2.5°C, close enough for the warmists to say observations “prove” their hypothesis. The only hope we have is that the coming solar minimum (as proposed) has a cooling effect. That amount of cooling, however, seems to be in the 0.3° – 0.5°C level (relative to pre-1820 estimates). A further rise of perhaps 0.8° – 1.0°C would then occur even with a modest CO2 input. More “proof” that we are endangering the planet by the warmist meme.
Of (serious) note is this: according to the warmist/Mann temperature history, we are already far warmer than the MWP, when the Vikings colonized Greenland. According to some recent report (in WUWT, June 2011), Greenland at the times of Viking settlement and farming was about 4°C higher than today. So we have a disconnect here.
Again it goes back to the temperature record: if the MWP was cooler than today, then the non-Greenland, non-Britain areas were far cooler than today, as the northern latitudes appear to have been warmer in the MWP than today. Does that show up?
It is one thing to argue that the MWP was cooler than today, but since we know places were warmer then than now, we have to have those cooler places. Or should we be setting sail (with combines) for Thule?
Bias at the IPCC?! Say it isn’t so…. (Head explodes….)
A year ago people here would be swarming all over this post by now. Nic Lewis, it appears, has pretty much knocked down the central pole of the Catastrophic Anthropogenic Global Warming tent, by showing how the IPCC used statistical tricks and mis-applied Bayesian analysis to skew projections of climate sensitivity to CO2, more than doubling the projected sensitivity arrived at by the only instrumental study of this phenomenon, and applying the same statistical measures used for purely modelled projections. It’s hard to get frightened by a likely 1.2 degrees C warming from a doubling of CO2, with diminishing results over that initial doubling due to the exponential relationship between CO2 and radiative forcing. Well done, Mr. Lewis.
There are several challenges this new analysis will have to overcome:
1) Forster and Gregorey’s apparent acquiescence to the IPCC’s misuse of their study. Hopefully they will respond to Nic Lewis’s invitation to comment.
2) The complicity of the lamestream media and government bureaucracies in the global warming scam. Media types will not be motivated to provide a translation of this technical criticism of the IPCC AR4. The few exceptions such as Lawrence Solomon of the National Post will take note, but will be preaching to the choir.
3) Getting the message to the scientific community – can this be submitted to a peer-reviewed journal so that the inevitable criticisms may be overcome?
My prediction – the global warming zombie will rise again; we still have a way to go before it’s starved out of existence. (I’ve just had to look up how to kill zombies, and none of the other methods seem particularly appropriate to this particular species of zombie, except perhaps setting it on fire.)
This is another example of how confirmation bias works. When the outcome of their work supports their theory or preconception, it must be right and therefore does not require that their methodologies or math be reviewed for errors.
I liken the IPCC to a population of animals too small and confined to have a diversified gene pool. They’re just passing the same bad genes (bad math and biased results) back and fourth as they borrow from each other. With each new paper that builds uncritically upon the results of previous work, the errors compound and become more generalized with a predictable end result. If the IPCC were to have any hope of avoiding extinction, they will need to pull in a new stock of scientists who aren’t all first cousins.
My understanding of the “~1.3C” sensitivity it that this is deduced assuming, like the IPCC does, that all recent warming is predominantly caused by increases in CO2, and applying this to the major temp records, not questioning whether their “adjustments.”
So, assuming IPCC theory is correct, even Jim Hansen’s records indicate a ~1.3C sensitivity with doubling from pre-industrial levels. This fact is very scary to Climate Science because 1.3C is not scary. If the fear is not there, the money will dry up. The junkets, the honorariums, the grants, all go bye. The game therefore is to make it seem like there is important scientific progress being made by their new models (5C!…8C!) and distract applying their “co2 mostly” theory to actual temp records.
Clowns are very good at juggaling balls at the International Parade of Climate Clowns (I appreciate when typing this that most scientists connected witht he IPCC are honest and they believe in the scientific method and they should appreciate an open debate on the conclusions that the IPCC have made but there are a lot of careers that rest on such conclsions, it is the response that will interest me).
vigilantfish asks:
“can this be submitted to a peer-reviewed journal so that the inevitable criticisms may be overcome?”
I may be able to do so, as part of a more thorough analysis of the whole uniform (or other) prior issue, particularly if I can find a willing statistician to team up with to do so.
I appreciate your thanks and agree with your comments.
@Bloke down the pub
says:
and where is the difference ?
Your correspondent misses a crucial point, namely: the IPCC does not do research. They report on the collected findings of hundreds of researchers, finding a consensus where this exists. There is a ton of observational and satellite data confirming warming in the North. The loss of ice results in a diminished albedo effect, thereby enhancing a further loss of ice. Anyone with eyes can see this for themselves!
BTW, re: my post immediate above, I used ~1.3C not related to Lewis’ article re:ipcc above, but the other earlier stories and such putting sensitivity in the low 1 point 0s. 🙂 “1.1-1.4” I have now read Lewis’ article and it is good, but the prior paper he believes IPCC misrepresents indicates a median of 1.6C.
Nic Lewis says:
July 5, 2011 at 4:12 pm
vigilantfish asks:
“can this be submitted to a peer-reviewed journal so that the inevitable criticisms may be overcome?”
I may be able to do so, as part of a more thorough analysis of the whole uniform (or other) prior issue, particularly if I can find a willing statistician to team up with to do so.
=============================================================
Hmm, now who do we know that could fit that bill?…….. Hmmm?
BTW, Great work Nic! While I can with much effort follow the maths in some of these statistical dust-ups, I lack the skill of discernment as to what are appropriate applications of what approaches vs others. I’m thankful for guys like you and Steve McIntyre being there to guide us through these very obscure missteps. I could have read that part 100 times and never found this.
Storm in a tea cup, everyone knows the right number is ~3 from the models.
/sarc
The 1.1 to 1.6 (or whatever) range is certainly itself high by some significant multiple, given the plethora of ignored natural variables. Don’t get into the habit of ceding it as a given, or taking it for granted. Note that the reversal of water vapour’s negative feedback effect on top of that is then necessary to get us back to the actual MWP levels. It’s errors all the way down.
And then come the economic-political misrepresentations piling on, which are Godzilla-comic hypertrophied “scenarios” fueling demands for money and power to ‘save us all’.
Aside from the grotesque exaggerations of downside warming consequences (hypothetical) and Denial of the upside ones (which actually have abundant historical evidence), it’s really too bad the AGW mechanism is a house of cards built on scientific sand. I’d love to see the MWP again, personally. But it’s hard to resist the conclusion that the tremendous boost a return to it would provide humankind is itself the real problem for the misanthropist Watermelons.
Doug Proctor says:
July 5, 2011 at 1:39 pm Your comments on “the temperature” of whatever, to me seems the key. I see each revision of global land surface temperatures push down old values, and increase recent values. I frankly (Mosher be damned) think this is fraudulent. So how many degrees have we come out of the LIA? Perhaps CO2 forcing is considerably less than 1C.
JN says:
July 5, 2011 at 3:01 pm Good post. You, me and probably Willis would be in accord on this issue of keeping the gravy train going. I just hope when the scam is revealed for what it is, we still use “the perp walk.” Hanson and Mann and a number of others will look good – to me at least – in bright orange on their way to face the judge. And no white collar prison for them – I think they should go to one of those ordinary prisons, for hardened criminals, given their premeditated attempt to kill or seriously harm a few billion people.
When one adds the cooling effect of GHGs to the warming effect of radiation blocking, the total effect value comes down fast. My estimate is the total effect is in the .6C range per doubling. That means even strong positive feedbacks could only push the number to 1.5C. Hence, the estimate of 1.3C still seems a little too high.
All of the empirical data points to the low 1.5C per doubling or less sensitivity.
There has to be energy accumulating somewhere that we have not found yet and cannot even guess where it is, or sulfate Aerosols are bigger than can be measured so far or the theory about the heat trapping/radiation slowing properties of CO2/GHGs are over-estimated.
Find the missing energy – or show how sulfate aerosols are indeed reflecting more sunlight than measured so far – or face the facts about how the real climate system works.
And quit playing around with the numbers, climate scientists and the IPCC alike – you are getting caught more and more often now. Wiki 2050 biographies will tell the true story about what was done in the decade coming up.
Bill Illis says:
July 5, 2011 at 7:40 pm “…Find the missing energy – or show how sulfate aerosols are indeed reflecting more sunlight than measured so far – or face the facts about how the real climate system works….”
Jeez, that’s asking a lot. Let me just use the upside-down Tiljander sequence another time, and those lovely strip-bark bristlecone cores, and I’ll show you something unprecedented! Now off with you: I have really important things to do! I’m jetting off to Tahiti to present the nitty-gritty bad news to the WWF (you know that those loong flights are a PITA, but international first-class makes it just barely doable). And of course the bordeauxs and burgundies and late-night Tahitian treats are a real stress to the system, but, by God, this is important stuff. Who are you to question a settled science!?