Excerpts from The Register, coverage of the Nic Lewis paper.
This graph below from Bishop Hill shows that it isn’t just one paper, but several now that show lower climate sensitivity to a doubling of CO2.
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More and more likely that double CO2 means <2°C: New study
Yes, it warms the planet – just not as much as thought
The results of a new approach to calculating the effect of CO2 – using empirical observations – suggest it has a lower impact on the climate than previously thought, and its effects are being over-estimated by the IPCC.
Publishing in the American Meterological Society’s Journal of Climate, a new paper called An improved, objective Bayesian, approach for applying optimal fingerprint techniques to estimate climate sensitivity, Nicholas Lewis applies objective Bayesian techniques and uses more up-to-date observational data to derive his conclusions.
…
Very few people disagree with the basic fact that the greenhouse gas CO2 warms the climate, but without some kind of positive feedback mechanism, it doesn’t add very much: around 1°C-1.2°C per doubling of CO2. (See this discussion on no-feedback sensitivity). The global warming “crisis” emerged from a belief that small rises in CO2 concentrations result in large knock-on effects, or strong positive feedbacks. These remain conjectural, as the forcings and feedbacks are poorly understood. Just how much of an effect does a rise in CO2 have – a little, or a lot? Hence the importance of new and better studies in the area of climate science dealing with “attribution”.
Lewis finds that in recent years neither the global temperature nor ocean heat uptake have changed very much, while CO2 concentrations have continued to rise. Therefore, the climate sensitivity must be lower.
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Full article here: http://www.theregister.co.uk/2013/04/22/climate_sensitivity_down_down/
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I think it is also important to keep reminding people that the IPCC claimed, as the very foundation of the agw theory, that there was a proven causal correlation between CO2 and temperatures. But finally, circa 2004 the ipcc was forced to retract their claim. Al Gore later repeated the bogus ipcc claim in his 2005 movie, see an outstanding rebuttal of Al Gore’s dishonestly in this clip:
There is another, Annan and Hargreaves 2009. They derived a mode of 1.9 twice in the course of using informed priors to constrain the ECS sensitivity tail. See figure 1. And NEVER mentioned the fact once in the paper or in the abstract, which is perhaps why it is obscure. Why they did not mentionn the mode? Perhaps because their 2006 GRL paper using uniformed priors contributed to the mainstream ( but wrong) ECS consensus of 3, and these two authors were (until Annan broke ranks in 2012 over the temperature pause) part of the Climate Club.
“Yes, it warms the planet – ”
No it does not!
The longer the warming is “on hold” while CO2 concentrations rise, the lower value comes out of statistical analysis. Even Nic Lewis gets the lowest value only after processing up to date data. So it’s both better analytical methods and time what is finally proving what skeptics had “gut feeling” about for a long time.
It is interesting that if you just take pre-industrial temps & pre-industrial CO2 concentrations , along with current temps & current CO@ur momisugly concentrations & don’t assume anything other than the change in temps is a function of the change in CO2 & fit these observations , I calculate a sensitivity of 1.5 °C/ doubling , which sits right in the middle of all the above estimates.
See :
http://wattsupwiththat.com/2013/04/18/numeracy-in-climate-discussions-how-long-ill-it-take-to-get-a-6c-rise-in-temperature/
and
http://wattsupwiththat.com/2013/04/18/numeracy-in-climate-discussions-how-long-ill-it-take-to-get-a-6c-rise-in-temperature/#comment-1279353
fore relevant math.
assuming all this is true…….1 degree above the little ice age?
but what happened too spring coming sooner? all the banana plantations in Cleveland??
Another hugh crack in the Berlin Wall of climate denial.
Hmmm, so a 1 C raise in average global temp causes a doubling of CO2.
One of the things I remember about physics from school was that the specific heat capacity of water is so much higher than just about any other substance. Given that there is so much water in the oceans, and to paraphrase Hilary… does the atmosphere really matter?
Kasuha:
At April 24, 2013 at 8:56 am you say
No, not “gut feeling”. Empirical determinations which climastrologists have ignored..
As the above article says, no feedback sensitivity is “around 1°C-1.2°C per doubling of CO2.”
So
If feedbacks are positive then the sensitivity will be more than ” around 1°C-1.2°C per doubling of CO2″
and
If feedbacks are negative then the sensitivity will be less than ” around 1°C-1.2°C per doubling of CO2″.
All the values cited in the above article are amendments to model-derived values which assume positive feedbacks.
But empirical measurements indicate the feedbacks are negative so the climate sensitivity is less than 1°C.
Climate sensitivity less than 1°C is indicated by the studies of
Idso from surface measurements
http://www.warwickhughes.com/papers/Idso_CR_1998.pdf
and Lindzen & Choi from ERBE satelite data
http://www.drroyspencer.com/Lindzen-and-Choi-GRL-2009.pdf
and Gregory from balloon radiosonde data
http://www.friendsofscience.org/assets/documents/OLR&NGF_June2011.pdf
Negative feedbacks mean that the man-made global warming from man’s emissions of greenhouse gases (GHG) would be much smaller than natural fluctuations in global temperature so it would be physically impossible to detect the man-made global warming.
Of course, human activities have some effect on global temperature for several reasons. For example, cities are warmer than the land around them, so cities cause some warming. But the temperature rise from cities is too small to be detected when averaged over the entire surface of the planet, although this global warming from cities can be estimated by measuring the warming of all cities and their areas.
Similarly, the global warming from man’s GHG emissions would be too small to be detected. Indeed, because climate sensitivity is less than 1°C for a doubling of CO2 equivalent, it is physically impossible for the man-made global warming to be large enough to be detected. If something exists but is too small to be detected then it only has an abstract existence; it does not have a discernible existence that has effects (observation of the effects would be its detection).
Richard
Gosh. A consensus of models.
– using empirical observations –!!!!!????!!!??
Can we, at least, use a computer model to decide if that’s a good idea?
“The results of a new approach to calculating the effect of CO2 – using empirical observations – suggest it has a lower impact on the climate than previously thought, and its effects are being over-estimated by the IPCC.”
I find that paragraph screamingly funny. My hat is off to you, Anthony.
No doubt the trolls will soon arrive and begin their pontifications about Trenberth’s unobservable observables in the deep ocean.
Were Jane Austen alive today, would she be writing Sense and Sensitivity, a novel set in the modern era about climate scientists and their relationships to their acolytes in politics and in the press?
here is another
http://link.springer.com/article/10.1007%2Fs00382-012-1375-3
and here is a reasonable starting point for the debate.
http://rankexploits.com/musings/2011/a-simple-analysis-of-equilibrium-climate-sensitivity/
Beta Blocker says:
April 24, 2013 at 10:34 am
The heroine is attending a conference on CAGW and finds that a comment she made during a seminar attracts the attention of a notable climate scientist that she greatly admires. (This adaptation is going to be difficult.)
‘Jeff L says
April 24, 2013 at 9:00 am
It is interesting that if you just take pre-industrial temps & pre-industrial CO2 concentrations , along with current temps & current CO@ur momisugly concentrations & don’t assume anything other than the change in temps is a function of the change in CO2 & fit these observations , I calculate a sensitivity of 1.5 °C/ doubling , which sits right in the middle of all the above estimates.”
Yup. That is a good starting point for the debate.
There other thing you can see is that arguments over the temperature record don’t play a big role in the estimate.
Other thing to consider is that c02 forcing is not 100% of the change in forcing.. so you need to add in all the other forcing ( neg and positive)..
Bottom line. Arrehenius predicted that increasing c02 would raise temperatures. The evidence suggests he was right. pretty damn simple. Now he predicted 5C.. the evidence suggests his estimate was high.
If CO2 concentration in the early 1700’s was about 280 ppm, and currently 390, gives ratio of 1.4.
CET across two 50 year periods
http://www.vukcevic.talktalk.net/CET1690-1960.htm
here temperature difference is 0.6 degree C.
Thus doubling of CO2 with a linear law gives sensitivity of 0.84C as shown here http://www.vukcevic.talktalk.net/CO2-S.gif
Logarithmic law would produce a bit less.
Since we are just coming off the top of natural cyclic warming based on the oceans I suspect we will see the actual sensitivity to increases in CO2 come in much lower. Probably less than .5°C at our current global temperature. Keep in mind that sensitivity is probably different at different global temperatures and is not linear in nature.
@ur momisugly Theo Goodwin,
Thank you for mentioning Trenberth and his “unobservable observables in the deep ocean.”
“There’s heat in the oceans, heat in the rivers,
Heat in the lakes, and heat in the sea,
Big grants are waiting for men who find it,
But only a travesty’s waiting for me.”
Val Doonican’s version is here:
Cheers,
Neil
Re Beta Blocker comment about Jane Austen, Nic Lewis lives in Bath where Austen lived for a while. Many of her novels revolve around life in Bath. The Jane Austen museum is there. There are Roman bath ruins in Bath and those baths must have been quite pleasant since the world was warmer during the Roman Period. Probably similar to today’s temps.
Without reading all of those papers, I suspect that they assume that all or virtually all warming is caused by CO2. This would make their numbers more like an upper bound than an estimate.
Apart from the obvious mistreatment of UHE (UHI), It is disgraceful that the IPCC justifies its very high ECS (sensitivity) estimate by “finding” still-not-understood indirect effects such as “cloud feedback” in order to make the numbers add up. At the same time, they dismiss the possibility that there could be any indirect effects related to solar activity, in spite of a known mechanism and concrete experimental evidence (Svensmark). Peer-reviewed, too. The unequal treatment is unjustifiable extreme confirmation bias at best.
On UHI – it is often stated that the urban areas are a very small part of the world’s surface, so can’t have a significant effect on global temperature. That’s not the point. The point is that the majority of thermometers are in or near urban/developed areas, so their UHE component gets extrapolated over a large proportion of the world’s area.
If atmospheric CO2 levels are an effect rather than a cause of warming, there is a 99% probability that climate sensitivity calculations are b.s.
As a layman I don’t understand how climate sensitivity can be determined using observations since all the forcing factors (e.g. clouds) are so poorly understood.
Nonetheless I can see how a maximum figure can be inferred from observations by assuming all of the observed warming since, say, 1950 was due to increased CO2.
From The Register article: ” … any changes will be slow, giving policy makers and technologists a long time to prepare, and develop economical low-carbon alternatives … “.
As always the assumption seems to be that a warmer CO2 enriched atmosphere is something to be avoided merely because it is not ‘naturally’ induced.
Christopher Hanley:
I write in hope of helping. At April 24, 2013 at 2:43 pm you say
As a start for a “layman” I suggest that you start by reading Idso’s 8 “natural experiments”.
It is a technical paper but I suspect you will find it is understandable.
It can be read at
http://www.warwickhughes.com/papers/Idso_CR_1998.pdf
Richard