Global warming less than we thought

Don’t have time to look closely, but here’s a taste of good news.

*abridged* New research from Oxford University shows the rate of global warming has been lower over the past decade than it was previously.

The paper, “Energy budget constraints on climate response”, to be published online by Nature Geoscience, shows the estimated average climate sensitivity – or how much the globe will warm if carbon dioxide concentrations are doubled – is almost the same as the estimates based on data up to the year 2000.

The study, which uses data from the past decade, also shows the most extreme rates of warming simulated by climate models over 50- to 100-year timescales are looking less likely.

The study used the most up-to-date information available to the AR5 from the IPCC, which is due to be finalised in September.

Victoria University climate scientist James Renwick said there was always a range of uncertainty and it had been hard to rule out the possibility that the climate sensitivity might be very large.

“Using the latest data shows that those very high sensitivities look much less likely, so we’ve been able to tighten the range of uncertainty, especially at the high end,” he said.

“We have much more comprehensive and reliable data on ocean heat content these days, and there haven’t been many large volcanic eruptions lately to obscure things, so that has allowed a better estimate of the range of climate sensitivity.”

via Lid lowered on global warming rate – Environment – NZ Herald News.

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Andy
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Andy

Victoria University climate scientist James Renwick said there was always a range of uncertainty and it had been hard to rule out the possibility that the climate sensitivity might be very large

Typical weasel words. The probability of high sensitivities are looking much less then previous studies. This study is an important one because many of the well-known names associated with CS studies are co-authors, including Myles Allen, Gabi Hergerl and so-called sceptic Nic Lewis

Andy
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Andy
Andy
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Andy

Judith Curry – mainstream ECS ~2 degrees C

http://judithcurry.com/2013/05/19/mainstreaming-ecs-2-c/

discusses the same paper

Andy
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Andy

Meanwhile, on Planet B

Climate change: human disaster looms, claims new research

Forecast global temperature rise of 4C a calamity for large swaths of planet even if predicted extremes are not reached

http://www.guardian.co.uk/environment/2013/may/19/climate-change-meltdown-unlikely-research

Andy
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Andy

There is more on Otto et al at Bishop hill with regards to the various reactions to this new paper

http://www.bishop-hill.net/blog/2013/5/20/reactions-to-otto-et-al.html

Richard C (NZ)
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Richard C (NZ)

>”….with regards to the various reactions to this new paper” None more astounding than that of Steven Sherwood I would have thought (although I’ll have a look at BH eventually). I’ve spammed the following far and wide including ‘Emotional knowledge’ by Mike Jowsey but I think it is worth putting on the table again in this thread (at the risk of incurring wrath):- I’ve emailed Joanne Nova to check whether my eyes are deceiving me because she is very familiar with what Steven Sherwood’s climate viewpoint is in OZ, his papers, and what the MSM has reported of him in the past:- Hi Joanne, I never, in my wildest dreams that sensibility would prevail eventually, thought I’d see this from Steven Sherwood, and NEVER in the MSM. **************************** University of NSW scientist Steven Sherwood – a lead author on the next IPCC report – said the Nature Geoscience study [Otto et al] had found oceans were capturing heat more rapidly than expected over the past decade. [that’s highly contentious (but beside the point of this communication) and the latest data doesn’t support it – Balmaseda et at was out of date ending their… Read more »

Richard C (NZ)
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Richard C (NZ)

>”Victoria University climate scientist James Renwick said there was always a range of uncertainty and it had been hard to rule out the possibility that the climate sensitivity might be very large.”

I take this to mean by (cynical) inference and the implication of ” hard to rule out the possibility” that the the range of uncertainty was convenient for those pushing “very large” CS.

>“Using the latest data shows that those very high sensitivities look much less likely, so we’ve been able to tighten the range of uncertainty, especially at the high end,” he said.

Latest data, and therefore an update of realism, is always a good thing IMV. A continuous, perhaps real-time data feed to CS algorithms would be even better if that were possible. I don’t see why not given Otto et al updates 2000 CS to present (or whenever the study ends, maybe 2010/11?) and CS seems to be a time-varying derived metric rather than a fixed figure.

Richard C (NZ)
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Richard C (NZ)

Did I read somewhere, Matt Ridley I think, that for a lower CS of 1.3 C by 2060, half has already occurred?

Answering my own question:-

Matt Ridley:

New Nature Geoscience paper v significant. If just 1.3C temp rise to 2060, half of which has happened already… http://www.thetimes.co.uk/tto/opinion/columnists/article3769210.ece

https://twitter.com/mattwridley/status/336384496712699904

Richard C (NZ)
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Richard C (NZ)

‘Earth to Met Office: check your climate facts’ Matt Ridley The latest science suggests that our policy on global warming is hopelessly misguided […] 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. That is to say, up until my teenage children reach… Read more »

Mike Jowsey
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Mike Jowsey

Richard, we all knew that the house of cards would crumble. This starts with the house being divided. This is a tipping point perhaps. 😉

Barry
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Barry

IMHO, this is the biggest (and best) news in the climate field since COP15 fell over. As Judy Curry points out, 2 of the 14 authors are lead authors of the all-important Chapter 10 of AR5 which will estimate climate sensitivity. It confirms a plethora of other recent studies which warmists were struggling to describe as outliers. The Otto paper reduces the “best estimate” for ECS from 3 to 2 – a massive 33% decrease. Even more importantly, its best estimate for the new-fangled TCR is only 1.3, suggesting that positive and negative feedbacks almost balance out during the 50-100 years after CO2 reaches 560ppm. Richard Tol and others have shown that the effect of global warming is beneficial on balance until it reaches 2.2°C above the pre-industrial level. Only then do the negatives outweigh the positives. Matt Ridley notes that this paper (if correct) means that the next couple of generations – including James Hansen’s many grandchildren – will experience exactly the same gentle warming trend that the earth has seen over the past 50 years. Forget about “catastrophic” or “dangerous”. Start thinking in terms of “benign” and “golden ages”. The Herald’s… Read more »

Andy
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Andy

Barry – I would agree with those sentiments. “Climate Sensitivity to CO2” is the cornerstone of the CO2-AGW theory, and this does seem like a fairly major paper.

I would also note that Nic Lewis is a co-author, who has doggedly pursued this issue, presumably as a hobby.

Skeptical Science refers to Lewis as a “retired accountant, not a climate scientist” or similar derogatory terms (not that being a retired accountant is a bad thing, I’m sure you know what I mean)

So presumably Nic Lewis can now call himself a “climate scientist”, having a paper in Nature co-authored by such luminaries as Myles Allen and Gabi Hegerl

Dave Frame was a colleague at Oxford with Allen. I would hope he might have something interesting to say about this paper in the NZ sphere at some point.

SimonP
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SimonP

It is good news that estimates are becoming more precise and that the more extreme projections ar looking less likely. Alexandar Otto has a good summary of his own paper rather than relying on less-informed sources:
http://www.metoffice.gov.uk/research/news/alex-otto-article
Nic Lewis’s paper is here:
http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-12-00473.1
All these new estimates do is delay the warming by roughly 15 years. Matt Ridley’s “rational optimism” has obviously been unaffected by the crash of Northern Rock. He probably should have stuck with evolutionary theory and survival of the fittest 😉

Andy
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Andy

James Annan seems to have different views

This looks like a pretty unreasonable attempt to spin the result as nothing new for sensitivity, when it is clearly something very new indeed from these authors, and implies a marked lowering of the IPCC “likely” range. So although the analysis does depend on a few approximations and simplifications, it’s hard to see how they could continue to defend the 2-4.5C range

http://judithcurry.com/2013/05/19/mainstreaming-ecs-2-c/#more-11727

Andy
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Andy

There is a very interesting paper from Nic Lewis at Bishop Hill which looks at where Otto et al differs from his study.

It turns out that both papers get 1.3 degrees c for TCS but the ECS values differ.
Lewis gets 1.6 to 1.7 for ECS whereas Otto et al get 2 degrees.

It turns out this difference is due to use of Leviticus et al.

http://www.bishop-hill.net/blog/2013/5/24/updated-climate-sensitivity-estimates-using-aerosol-adjusted.html

Richard C (NZ)
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Richard C (NZ)

>”It turns out this difference is due to use of Leviticus et al” Levitus et al Andy – Leviticus et al is the Bible. But yes, Levitus et al’s pentadal data is highly problematic as Bob Tisdale has exposed. My question though is: the premise/assumption used for “heat-uptake estimates” in respect to CS methodology, specifically the “heat-uptake” part. SkS have a recent post on this and although there’s some sense in comments – Gates, Painting, Brookes – except they miss-attribute a posited change (unsubstantiated) to the output side of the sun-ocean-atmosphere system when the change has been on the input side, they also neglect Trenberth’s lags. Rob Painting’s conjecture however, IS on the side of conventional thermodynamic energy flows, laws of convection, energy gradients, observational scientific literature etc, they just don’t have the observational or calculated evidence to support it (I’m keeping an open mind in case it turns up). The SkS post title is (and actually Nuccitelli’s POV is contrary to the Gates/Painting faction’s POV, see below and my 3 part series):- ‘Another Piece of the Global Warming Puzzle – More Efficient Ocean Heat Uptake’ http://www.skepticalscience.com/watanabe-et-al-2013-another-piece-of-the-puzzle.html Basically what they (the SkS/Nuccitelli faction… Read more »

Richard C (NZ)
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Richard C (NZ)

I also note that Otto et al and Lewis appear to be making the same error as Balmaseda et al (and Thomas) in that they assume global aggregate data (e,g, 0-700m) is typical of all 3 ocean basins when in fact the 2002–11/12 (Lewis) “differences in the heat-uptake” have been due to the skew in the global aggregate data from the Indian Ocean (upper Indian warming spectacularly, upper Pacific and Atlantic cooling).

If Lewis carried out the same CS analysis but separated into 3 ocean basin sets, he would get 3 totally different CS figures. The Indian set would return a figure close to his estimate because that data predominates the global aggregate dataset but I don’t even know how CS methodology deals with cooling for him to arrive at a figure for the Pacific and Atlantic.

Similarly, if atmospheric AND ocean cooling occur post May 2013 (already indicators over the last decade in GMAST and SST) how will CS methodology deal with that?

Richard C (NZ)
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Richard C (NZ)

>”Are the CS guys making a similar miss-attribution (as I contend) Andy?”

Just spotted this:-

“The 0.16 W/m2 estimate – half natural, half anthropogenic – seemed reasonable to me”

Definitely NOT reasonable to me.

Richard C (NZ)
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Richard C (NZ)

Does CS methodology account for the thermal lag in the sun-ocean-atmosphere system Andy?

Trenberth 6 and 10 – 100 years, Abdussamatov 14 +/- 6 years, Scafetta 1 and 12 years.

Andy
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Andy

The lay-person’s summary by Bishop Hill in comments is useful

It was surprising that the Otto paper came up with very low TCR but only low-ish ECS. This turns out to be due to the choice of dataset for top-of-ocean heat content. For ocean heat, Otto et al used the Levitus dataset, but for the top of the ocean they replaced Levitus’s data with an alternative – Domingues et al.

Nic has reworked Otto et al’s calculations using the original Levitus top-of-ocean data and also with a variety of alternatives (he also updates to slightly more recent data) and found that in every case the estimate for ECS value obtained is lower than the one reported by Otto.

He finds a value of around 1.6-1.7C, close to his own paper and also those of Aldrin et al, Forster and Gregory etc. Otto et al reported 2.0C.

Magoo
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Magoo

An article in the Herald about a lowering of climate sensitivity. A few comments for Renwick thrown in as well:

http://www.nzherald.co.nz/climate-change/news/article.cfm?c_id=26&objectid=10884739

Andy
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Andy

Just for clarification, the link you post is what the blog post is about, I.e Herald coverage of Otto et al

Magoo
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Magoo

Oops.

Mike Jowsey
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Mike Jowsey

Professor Reto Knutti of ETH Zurich said even at the low end of the range warming would be well over the two-degree goal that countries had agreed to.


It seems so silly that countries can agree to a certain level of warming. Too silly for words.

Andy
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Andy

Mike – I think this agreement of 2 degrees came from one of the COPs (Copenhagen?). This was a side-effect of the other agreement that 2 degrees was “dangerous”.

These arbitrary agreement levels are then dependent on the climate sensitivity models and calculations, and also the emissions pathways models, of which there is some agreement

A veritable bureaucrats dream, I think we are in agreement on that.

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