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.
Bishop Hill does some comparisons
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?