Why the new Otto et al climate sensitivity paper is important – it's a sea change for some IPCC authors

Yesterday, WUWT was honored to have a guest essay by co-author Nic Lewis on the new Otto et al paper that pegs Transient Climate Response (TCR) at 1.3°C along with Equilibrium Climate Sensitivity at 2.0°C. Lewis , who had previously published a solo paper on his ECS estimate was roundly panned as a “single study” by the advocates over at “Skeptical Science” in a scathing post by Dana Nuccitelli, who will now have a hard time honestly reconciling the Otto et al paper, because it is co-authored by several IPCC authors who previously had considered higher climate sensitivity values to be likely.

While this isn’t an end-game paper for the overblown threat of AGW, this paper represents a sea-change in thinking of some prominent IPCC authors that will be hard to ignore, and even harder to criticize. Its timing is especially good since Cook and Nuccitelli just published a ginned up claim about “97% consensus” of climate science papers. With the broad author spectrum of the Otto et al, paper it seems the consensus is slipping at bit when you see authors of this caliber revising their thinking. I suspect this graph from the leaked AR5 draft also figures into some of this change of thinking:


Here are some comments from around the web: 

Dr. Judith Curry:

James Annan’s blog post starts with this sentence: “At last the great and the good have spoken.”  I.e., some IPCC lead authors are paying attention to the lower sensitivity estimates.  It will be very interesting to see how the IPCC AR5 plays this.  I suspect that the uncertainty monster will become their good friend, ‘not inconsistent with.’  It will be very interesting indeed to see if the IPCC budges from the 2-4.5 C range that has remained unchanged since the 1979 Charney report.


Dr. Matt Ridley:

New Nature Geoscience paper v significant. If just 1.3C temp rise to 2060, half of which has happened already… http://t.co/0SXCSaFwly


And Dr. Ridley in the Times:

The latest science suggests that our policy on global warming is hopelessly misguided

There is little doubt that the damage being done by climate-change policies currently exceeds the damage being done by climate change, and will for several decades yet. Hunger, rainforest destruction, excess cold-weather deaths and reduced economic growth are all exacerbated by the rush to biomass and wind. These dwarf any possible effects of worse weather, for which there is still no actual evidence anyway: recent droughts, floods and storms are within historic variability.

The harm done by policy falls disproportionately on the poor. Climate worriers claim that at some point this will reverse and the disease will become worse than the cure. An acceleration in temperature rise, they say, is overdue. The snag is, the best science now says otherwise. Whereas the politicians, activists and businessmen who make the most noise about — and money from — this issue are sticking to their guns, key scientists are backing away from predictions of rapid warming.

Yesterday saw the publication of a paper in a prestigious journal,Nature Geoscience, from a high-profile international team led by Oxford scientists. The contributors include 14 lead authors of the forthcoming Intergovernmental Panel on Climate Change scientific report; two are lead authors of the crucial chapter 10: professors Myles Allen and Gabriele Hegerl.

So this study is about as authoritative as you can get. It uses the most robust method, of analysing the Earth’s heat budget over the past hundred years or so, to estimate a “transient climate response” — the amount of warming that, with rising emissions, the world is likely to experience by the time carbon dioxide levels have doubled since pre-industrial times.

The most likely estimate is 1.3C. Even if we reach doubled carbon dioxide in just 50 years, we can expect the world to be about two-thirds of a degree warmer than it is now, maybe a bit more if other greenhouse gases increase too….

It is true that the “transient climate response” is not the end of the story and that the gradual warming of the oceans means that there would be more warming in the pipeline even if we stopped increasing carbon dioxide levels after doubling them. But given the advance of nuclear and solar technology, there is now a good chance we will have decarbonised the economy before any net harm has been done.

Full essay at the Times

Bishop Hill does some comparisons

ECS with Otto

Further to the last posting, and in particular the claim in the BBC article that the 2-4.5 range is largely unaffected by the Otto et al paper, here’s my graph of ECS curves with the incorporation of the Otto et al results – both the full-range and the last-decade curves. These are shown in black.  As previously, the other studies are coloured purple for satellite period estimates, green for instrumental, and blue for paleoestimates. The grey band is simultaneously the IPCC’s preferred range and the range of the climate models.

As you will see, it is fairly clear that the Otto et al results slot in quite nicely alongside the other recent low-sensitivity findings, with most of the density outside the range of the models. The IPCC’s preferred range looks increasingly untenable.


Some outlets though are playing the same kind of game that SkS does though, trying to diminish the significance of this paper.

At the Guardian, Fiona Harvey is over the top. She’s putting the ridiculous spin out that the Otto et al TCR figure of 1.8°C is a “human disaster looming“.


She goes on to say:

That would still lead to catastrophe across large swaths of the Earth, causing droughts, storms, floods and heatwaves, and drastic effects on agricultural productivity leading to secondary effects such as mass migration.


Oh right, climate refugees again. IMHO this is the journalistic equivalent of saying “Look! A squirrel!”. With the modest rate of warming stated by Otto et al, the impacts of global warming are more likely to be positive than negative for humanity in the foreseeable future; increased crop yields for example. The impacts of regulation are likely to be far more problematic, i.e. the cure is worse than the disease.

The BBC says they had it all covered before and this new paper is “consistent” with previous works. Oh, sure.

…when it comes to the longer term picture, the authors say their work is consistent with previous estimates. The IPCC said that climate sensitivity was in the range of 2.0-4.5C.

This latest research, including the decade of stalled temperature rises, produces a range of 0.9-5.0C.

“It is a bigger range of uncertainty,” said Dr Otto.

“But it still includes the old range. We would all like climate sensitivity to be lower but it isn’t.”

So far the spinmeisters at “Skeptical Science” have yet to acknowledge the paper, when and if they do, we’ll all have a good laugh. We’ll probably see it somehow being “consistent” with that 97% consensus. Meanwhile, in lower sensitivity land, “the pause” in global temperatures continues, and is approaching the Santer definition.

Our results show that temperature records of at least 17 years in length are required for identifying human effects on global-mean tropospheric temperature.

If “the pause” reaches 17 years, what then?


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Jimmy Haigh.

The Consensus disappoints. – gavin

Nic Lewis

There seems to be a general assumption at most blogs that because the new Nature Geoscience paper has only just appeared, it is too late to be cited in AR5. That is wrong. The paper was accepted by the journal, after peer review, by the AR5 WG1 acceptance deadline (15 March 3013). It will be cited in AR5 WG1.


The smartest of the bunch have woken and up smelled the coffee and now have begun to pedal back to save their bacon. Another five years of no warming or even cooling and they suddenly discover negative feedback that cancels out the CO2 effects.

The Carbon Climate Forcing Hypothesis….
is within the historic variability….
of Dogmatic Orthodox Stupidity….

The Ghost Of Big Jim Cooley

Someday soon, someone big in the name if AGW is going to admit that they were wrong. It may turn out to be someone who, up until that point, has argued that AGW is true. In my life I have come across big people who have admitted they were wrong when faced with the evidence. And given that this is the world of science, then the prospect is good that someone firmly in the AGW camp stands up and says it’s obviously incorrect. It won’t be someone like Hansen – people like that will choose to fade away rather than admitting to be wrong. The next five years is going to be oh so interesting…

Here is the consensus:
97% of scientists who make their living studying global warming believe in it.
97% of scientists who got grants to study global warming and think their study proves global warming is real believe in it.

And when the AMO finally turns negative again, the numbers will end up being close to 0.


I quite like the Guardian article. The anxiety levels on display weren’t about the climate but about the fact that the alarmist tide is going out. They are paddling ever harder but the winds of uncertainty keep blowing them backwards and they hate it.
SkS will no doubt do some fine arabesques in trying to show that “it’s worse than we thought” but after the hilarious 97% nonsense they are sliding into ever more irrelevance. In fact the sum total of their supporters are the ones who make the risible comments on CiF over at the Guardian. That nasty little triumvirate, the BBC, Guardian and Sks ( sub branch of UWA).

Lance Wallace

Ghost of Big Jim–
Someone “big in AGW” has already done that–James Lovelock, creator of GAIA, some months ago. Agree with you about Hansen, though–too much skin in the game.

Les Johnson

Anthony: technically, the paper does fall in the 97% consensus.
The problem I have with Cook et al, myself being a lukewarmer, is that there is no C in the AGW ratings Cook did. Even though most of the CO2 is probably anthro, how much effect will there be for a doubling of CO2? With this paper, and others, not much.
As Tol suggested in his paper, a temp increase of up to 2 deg will be beneficial, in terms of economics. Or at least neutral at the 2 deg mark.

Hal Javert

I, too, am pleased that analysis of real data (Otto et al.) is shining a bright light into dark academic holes (IPCC drafting conclaves). Your post refers to this as “…when you see authors of this caliber revising their thinking…”, the clear implication being these are honorable scientists in the process of changing their minds based upon significant new scientific analysis.
With all due respect (to you, not the IPCC authors), this is crap: these individuals have been complicit in an intellectually dishonest endeavor for almost half their professional careers (it would be interesting to know if any one of them had ever actually seen the unabridged UEA climate data before Mann, Jones et al. “lost” the data set). Frankly, “authors of this caliber” have sold their souls to the politically correct IPCC devil, and the only caliber they have is zero.
Actions have consequences; years of intellectual dishonesty result in loss of credibility & reputation. Yes, they are responding positively to the Otto et al. data, but then this is the minimum you’d expect of a 1st year hard-science grad student at a second-tier school.
Please advise if I have misunderstood this aspect of your post.

Jim Cripwell

Kaboom, you write “they suddenly discover negative feedback that cancels out the CO2 effects.”
You seem to be assuming that CO2 has any affect at all. This is far from proven, and it is more that likely that adding CO2 to the atmosphere has a completely negligible effect.

Bill Illis

I think the tide has now turned; at least in terms of backing off the 3.0C per doubling doctrine which the science would not allow to be tested/evaluated or even discussed critically before.
It now allows more realistic/objective analysis to be done in the field. This is just step one. Maturity to follow later.

Gary Pearse

Nic Lewis says:
May 20, 2013 at 7:25 am
“There seems to be a general assumption at most blogs that because the new Nature Geoscience paper has only just appeared, it is too late to be cited in AR5. That is wrong.”
Imagine that such blogsters think it would be okay to ignore a paper like this because of lateness for AR5 – it underscores that these folks are not interested in science or truth. I am considerably relieved that there are a number of lead authors seeking the truth and admitting their earlier estimates were too high. It tells me that they were honest researchers after all. I think skepticism is good, necessary and healthy but, for a guy who has (had?) the propensity to trust the motives of scientists, the egregious acts of self-serving dishonesty by scientists, institutions, journals and the press and the silence of the majority of scientists (I’m relieved its not really 97% – that would be irredeemable) in the face of it, had pushed me to a deep cynicism – this is not healthy or good.
The benefits of skepticism in science has certainly never had such a thorough test in the history of science as that probing mainstream climate science, which was practiced by climate Knights Templar behind closed doors. Without the apparent small minority of thoughtful skeptics, climategate would not have happened. The constant debunking of shoddy and dishonest science and finally, with aid of nature’s noncompliance with the consensus’s program, the tide began to turn. It can be argued that the stakes were never higher. Whether Galileo was right or not didn’t have the terrible consequences for mankind that the CAGW agenda has. It’s not over yet by a long shot – it can never relax- but much vilified skepticism can now take a small bow or two.

sunshinehours1 says:
May 20, 2013 at 7:48 am
And when the AMO finally turns negative again, the numbers will end up being close to 0.
the number cannot be zero.

As important as this finding is to bring sanity to the madness of climate change fear, it seems almost moot alongside Professor Malby’s finding that total atmospheric CO2 is nearly unrelated to human emissions. Has his paper ever been published or his findings proven in error?

John G.

“The most likely estimate is 1.3C. Even if we reach doubled carbon dioxide in just 50 years, we can expect the world to be about two-thirds of a degree warmer than it is now, maybe a bit more if other greenhouse gases increase too….”
Shouldn’t that be “two-thirds of a degree warmer than it would otherwise be?” Or did they take into account all of the natural cycles due to orbital mechanics, solar fluctuations, cosmic rays, various earth and ocean cycles etc. that might also move the climate?


Lord Ridley says:

there is now a good chance we will have decarbonised the economy before any net harm has been done

And on the same day, Rossi’s ECAT gets independant confirmation here.

Ken Hall

The consensus on global warming is looking more and more like saying that there is a consensus amongst humanity that Jesus is the real flesh and blood embodiment of the Lord God, because 97% of Catholics believe it, so ALL humans must.
These alarmists just ignore the majority of scientists who no longer believe that we are headed towards climate induced catastrophe.
The problem we all have now is that we are headed towards human induced catastrophe at the hands of the politicians who are hell-bent on spending and legislating us back to the stone age, all in order to avoid a non-problem.

Ken Hall

The Ghost Of Big Jim Cooley, did you miss the Author of the Gaia hypothesis recant his previously extreme view and admit that he was wrong? scientist Dr James Lovelock has recently stated that the alarmist view is completely wrong.

Juraj V.

1910-1945 warming was steeper than 1975-2002 warming. It means that CO2 has cooling effect. No kidding.


Now we can continue to wreck our economies with half the speed we planned to, which is very nice indeed, as they are almost entirely wrecked already.


The Ghost Of Big Jim Cooley says:
May 20, 2013 at 7:45 am
“Someday soon, someone big in the name if AGW is going to admit that they were wrong. It may turn out to be someone who, up until that point, has argued that AGW is true. ”
Already happened. Lovelock. The quickest of the weasels.


I have a theory (or should that be hypothesis?).
Activist-scientist types (we know the names, so no need to mention them here) were very keen to suppress uncertainty and overstate ‘dangers’ from AGW because the policy cure, as they prescribed, happened to fit in with their left-of-centre worldview. More centralisation of power, greater redistribution from richer nations to poorer, restrictions on individual freedom and on conspicuous consumption have long been aims of the Left, so a global emergency necessitating just these policies was perfect.
The activists perhaps didn’t bank (pun intended) on their chosen enemies – global finance, oil majors and wealthy landowners – first jumping on the bandwagon and then hijacking it. Sure, there’s a big issue to deal with, they agreed, but let’s look at how to deal with it. How about massive subsidies to landowners and multinational energy companies from the taxpayer and utilities customer to put towards the cost of erecting wind turbines on one’s estate? Maybe a carbon tax and emissions trading scheme working hand-in-hand to hasten the move to outsource First-World manufacturing to the Third World, bringing unemployment to the manual workers of the West, exploitation and collapsing buildings to the manual workers of the East and greater profit margins to the boardrooms of the industrialists so despised by the Left? A whole new commodity for banks to trade too. Oil companies getting subsidies for their new products and an artificially-higher price for their existing ones?
This wasn’t what the old cabal of activist-scientists had in mind at all. How could they row back from the alarmism without losing face? Maybe they were right about the theoretical risks, and that there’s still the potential for disaster at some levels, but not the extreme scenarios painted in previous years? Heaven knows the real-worl data isn’t playing ball. OK, maybe those wind turbines can be taken down from landowners’ estates as they don’t make much difference to anyone save the bank balances of those already quite comfortable. Those emissions trading schemes seem a bit unnecessary too, when a simple regionally or globally-administered tax could keep CO2 levels from spiralling out of control. Perhaps even drop the opposition to fracking, bit by bit, if it helps keep the lights on, the factories open and corporate taxes flowing to progressive Western governments?
I won’t be surprised to see this scenario play out, as the marriage of convenience between hardline environmental activists and global big business begins to break down. This ‘official’ downplaying of the Doomsday scenario, though maybe being misread by the usual media voices who haven’t read the memo yet, could be a play by the activists to reclaim the agenda from their ideological foes.


So they adjust the figures, but after the event. Doesn’t this just show they don’t know what causes the event?
One of the key tests of a good theory is that it gains a measure of predictability. In other words, when one gets confident that a theory is solid, one case use it to make testable predictions, and then see if these predictions turn out to be correct. The bolder and more often the predictions are on the mark, the more accurate the theory. This style of thinking is routinely used, for example, in mineral exploration, an iterative process that is used to find most mineral commodities at variable depths in the earth’s crust, based on both location-specific and more standardised geological models. A drillhole is essentially testing a theory’s prediction. But if the prediction turn out to be consistently wrong (as in 4 times out of 4 IPCC reports), or needs constant revision and adjustment, then the theory is deemed to be weak, or plain wrong, and the reasons underlining it need to be reviewed and/or discarded.
All this escapes the current brand of academic alarmism, primarily because they dont’ have to test their theories in the real world in the first place.

John West

Steven Mosher says:
“the number cannot be zero.”
Why not?
What’s the temperature response to additional heat being added to boiling water? Zip, zero, nada. An atmosphere with thunderstorms may be more like a boiling pot of water than a pot of water that’s not boiling. I’m not saying it is, just that it might be. Not only that but there’s a host of other ways the number could end up being zero, like negative feedbacks. At this point I don’t think we know enough to absolutely rule out anything, but personally I doubt very seriously its a number at all, more likely a function. JMO.

kadaka (KD Knoebel)

Ridley: But given the advance of nuclear and solar technology, there is now a good chance we will have decarbonised the economy before any net harm has been done.
Hopefully this means the 99% whom could never be affordably supplied with “decarbonized” energy and/or afford it themselves, will be such a tiny part of the world economy that it is considered effectively decarbonized, rather than that 99% be denied “carbonized” energy and sent to a path of “planned obsolescence” in service to the planet.

There’s a paper been written by Otto,
Makes climate alarmists go blotto.
And now Lord Matt Ridley
Tells us there ain’t diddly
To fear. Mine’s a Curry risotto!

Mike jarosz

The economics of their actions are starting to take their toll on the European citizens. Actions have consequences( not part of liberal thought process). The political power play to control our lives is going down the tube. Special thanks to the 1997 U.S. Senate for voting 95 to 0 against surrendering the U.S. economy to these socialist pukes.

Mike jarosz

[snip -pointless -mod]

Douglas Proctor

Nic –
Re graph temp AR5:
For Scen. A or B to be real by 2100, we have to have a way to get from here to there. Is there enough flexibility in the models to do that?
If climatology is a mostly linearly connected series of determinative processes, with little input from unknown natural factors, should not the last 25 years of observation remove the top end Scenarios?
Does Scenario A actually include a profile that takes us to >3*C at 2100?


That 1.3 degrees is quite close to the Planck response of CO2 of 1.23 degrees per doubling.

A climate sensitivity lower than 2 K was already demonstrated here:
Scafetta N., 2008. Comment on ‘Heat capacity, time constant, and sensitivity of Earth’s climate system’ by Schwartz. Journal of Geophysical Research 113, D15104.
The real climate sensitivity is very likely about 1.0-1.5 K, as demonstrated by geometrical constrains here:
Scafetta N., 2012. Testing an astronomically based decadal-scale empirical harmonic climate model versus the IPCC (2007) general circulation climate models. Journal of Atmospheric and Solar-Terrestrial Physics 80, 124-137.

son of mulder

You can buy a very good condition copy of Six Degrees: Our Future on a Hotter Planet By Mark Lynas for 1 Uk penny on Amazon UK. Nuff said.

Werner Brozek

The two dots at the end are for 2011. 2012 was just a bit warmer, however it was almost identical to 2004 which shows up as a little dip 7 spaces to the left of 2011. So if 2012 were added, the top of the black squares would still be below the bottom green line. The first three months of Hadcrut4 for 2013 are virtually identical to the 2012 average, so the divergence from the projections continues to widen from 2012 to 2013.

What are they gonna do? What are they gonna do! They won’t be sleeping much, I can tell you that. What’s the betting the IPCC will try to ignore it, at least this time through. It gives them a little more time. Maybe they can turn the air conditioning off all over the world…
I don’t need a /sarc off, do I?

david elder

Not the end, not the beginning of the end, but the end of the beginning. No serious exponent of CAGW will credibly be able to ignore or dismiss curtly the presence of a substantial alternative interpretation of climate change.

I hear the sound of something breaking up. Could it be a consensus? Or Nenana? Or both.

Mosher: “the number cannot be zero.”
Which is why I said “close to 0”.
Of course I won’t rule out negative feedbacks.


But surely we’re still doomed. Please tell me we’re still doomed.

Mike Jowsey

First there was Global Warming. Then, because it wasn’t warming, Climate Change. Then, Climate Disruption, because we could be sure that somewhere in the world every year there would be a storm, flood, wildfire, drought for which to blame Disruption. Now we have Ocean Heating. Because it’s a travesty if we can’t find that missing heat. And when all else fails, we have Delayed Warming. Whereby we lower our projections of warming, increase our uncertainty bands and say something like, “This temporary slowdown in accelerated warming is something we can’t explain, but is in line with our original projections and it may take a little longer for the world to fry, but it will happen!” Have we now entered the chapter “Revised Global Warming”? Wherein it will be in a state of continual revision and always in line with projections, and always seeking more grants for more research. Oh, wait…. nothing’s changed.

Dodgy Geezer

@Ken Hall says:
“…The Ghost Of Big Jim Cooley, did you miss the Author of the Gaia hypothesis recant his previously extreme view and admit that he was wrong? scientist Dr James Lovelock has recently stated that the alarmist view is completely wrong…”
Actually, he didn’t completely reject the Global Warming theory. He said that he had been alarmist, and that the frightening things he had earlier proposed would not come to pass (They included the last few humans sitting on a melting iceberg in Antarctica!), but he did say that he still believed that humans were affecting the climate.
That lets him play both ends quite nicely…

Brian H

Green jelly beans cause acne.
“Likely” my rosy red patootie.

Brian H

You won’t get out alive. You can relax.