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Thursday
Apr182013

Still more on the political sensitivity of model recalibration

Larry placed this in the comment thread for last post on this particular topic (a few back) but I am "upgrading" it so that it doesn't get overlooked & so debate/discussion can continue if there's interest. In response to last line of Larry's report -- a bet on the river, essentially -- I check raise with an older post from Revkin!

Larry says:

Late, but still pertinent, here's Judith Curry's own scholarly rejoinder, including Mann/Nucitelli, the Economist, and a variety of other papers on both sides of the climate sensitivity issue -- her synthesis:

Mann and Nuccitelli state:
 

"When the collective information from all of these independent sources of information is combined, climate scientists indeed find evidence for a climate sensitivity that is very close to the canonical 3°C estimate. That estimate still remains the scientific consensus, and current generation climate models — which tend to cluster in their climate sensitivity values around this estimate — remain our best tools for projecting future climate change and its potential impacts."

The Economist article stated:

"If climate scientists were credit-rating agencies, climate sensitivity would be on negative watch. But it would not yet be downgraded."

The combination of the articles by Schlesinger, Lewis, and Masters (not mentioned in the Economist article) add substantial weight to the negative watch.

In support of estimates on the high end, we have the Fasullo and Trenberth paper, which in my mind is refuted by the combination of the Olson et al., Tung and Zhou, and Klocke et al. papers. If a climate model under represents the multidecadal modes of climate variability yet agrees well with observations during a period of warming, then it is to be inferred that the climate model sensitivity is too high.

That leaves Jim Hansen’s as yet unpublished paper among the recent research that provides support for sensitivity on the high end.

On the RealClimate thread, Gavin made the following statement:

"In the meantime, the ‘meta-uncertainty’ across the methods remains stubbornly high with support for both relatively low numbers around 2ºC and higher ones around 4ºC, so that is likely to remain the consensus range."

In weighing the new evidence, especially improvements in the methodology of sensitivity analysis, it is becoming increasing difficult not to downgrade the estimates of climate sensitivity.

And finally, it is a major coup for the freelance/citizen climate scientist movement to see Nic Lewis and Troy masters publish influential papers on this topic in leading journals.

Should indicate, if nothing else, that debate over this significant point continues, and that climate ideologues committed to heightening alarm in order to achieve political (and these days often financial) ends indeed have cause for concern.

Me:

Oh yeah? Well, consider what the sagacious science writer Andy Revkin says. I think he is seeing more clearly than the climate-policy activists who seem to view the debate featured in the Economist article as putting them in a bad spot. He concludes that if sensitivity is recalibrated to reflect over-estimation, the message is simply, "hey, there's more time to try to work this problem out ... phew!" So my sense of puzzlement continues.

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Reader Comments (11)

Me?

I don't see a conflict. If there are people who are using CC alarmism for self promotion, I would agree that they should be concerned. I agree, "Whew!, but we should not lose sight of future challenges and end up in the same position 50 years from now."

I see a conflict brewing due to the history of events. The "it is worse than we thought and if you don't agree you are a denier" will become ammunition. I expect that after temperatures start climbing again, if they do, it is unlikely that either side of the heavily invested players will see that they would be more effective by not engaging in scorched earth policies. Hopefully I am wrong

I expect that the new studies which indicate that those who studied the climategate emails were correct in their assessment of bias and advocacy will not help in getting this point across, but will serve as ammunition in the continued PR war. Denial of any worth of the opposition's position continues, and history will once again be ignored to the potential detriment of all.

I expect that the IPCC will continue to rely on NGO advocates and cater to their concerns even if it is 10 more years before temperatures increase substantially. I also expect that advocates of mitigation will try using discount rates even more agressively and claiming a moral responsibility to future generations to do so.

April 18, 2013 | Unregistered CommenterJohn F. Pittman

I was going to say I call you, Dan, but then I don't see the Revkin article as much of a raise. In this opinion piece, he seems to be making an effort to keep fear alive, I'll grant you, but he quite commendably recognizes the possibility that this may be due to what he calls his own "reverse tribalism" (part of the article omitted in the above clip), and his concluding line seems to me to recognize the damage science has done to the hopes of "some climate campaigners, writers and scientists" (but not, of course, to those scientists "best known [by whom?] for their relationships with libertarian groups"!). In other words, he doesn't appear to share your puzzlement, Dan.

I'd add one other note: Revkin, like you, seems to think that reduced sensitivity only means that the timescale toward "substantial, prolonged and disruptive climate change (and changes in ocean chemistry)" is extended -- but surely it means that the change involved is simply not as substantial or disruptive as had been feared. And finally (okay, another note), I notice that he too seems to be entirely focused on substantial, prolonged, and disruptive economic forcing as the only answer to the problem, whatever its magnitude -- ignoring completely the possibility of active climate control, an omission that always seems to me to give the game away.

April 18, 2013 | Unregistered CommenterLarry

The weight being put on the papers of Lewis' is grossly exaggerated. I have counted at least 12 papers published recently (or forthcoming, like Masters') - papers by Hargreaves, Padilla, Gillett, Bitz, Schwatrz, Schmittner, van Haveren, Aldrin, Masters (Forthcoming), the PALEOSENS team (a compendium of dozens of papers) and Hansen (Forthcoming), and in each of these Lewis' paper is an outlier, though there is agreement that the value of the CS is >1C.

In fact, Gavin Schmidt called it right in RealClimate, and there are (yet) no grounds to rush to setting CS less than 2 and proceeding to burn all the fossil fuel in sight. I would love it to be so, but Andy Revkin is dead right when he talks about "single-study syndrome".

April 19, 2013 | Unregistered Commentertoby

"... Andy Revkin is dead right when he talks about "single-study syndrome""

But here's what Andy Revkin actually wrote (my emphasis):


This is also not a “single-study syndrome” situation, where one outlier research paper is used to cast doubt on a bigger body of work — as Skeptical Science asserted over the weekend. That post focused on the as-yet-unpublished paper finding lower sensitivity that was inadvisedly promoted recently by the Research Council of Norway.

In fact, there is an accumulating body of reviewed, published research shaving away the high end of the range of possible warming estimates from doubled carbon dioxide levels.

April 19, 2013 | Unregistered CommenterLarry

No one accused Andy Revkin of "single study syndrome". I was referring to this label on his website at revkin.net:

Single-Study Syndrome Label. Use when someone focuses too hard on cherry-picked study of questionable quality.

http://revkin.tumblr.com/post/41559928775/single-study-syndrome-label-use-when-someone

Ok, ignore the "questionable value" bit at the end. Lewis contribution is valuable, IMHO.

The point I was making is that the "shaving away" has mostly been at the top end of the climate sensitivity range of estimation, and a current meta analysis would place the probable value between 2 or 2.5 and 3C. That is based on a crude view of the 12 or so papers I have looked at, the vast majority of them published in the last 12 months. Lewis' is just one of many.

Not that Lewis is wrong but I suggest there is work for the scientists to do synthesising all these results. As far as I can see, estimates based on current warming show lower values for CS than estimates taken from paleoclimatology, and both in turn are different from values estimated from climate models.

In particular, see the extensive PALEOSENS review http://www.nature.com/nature/journal/v491/n7426/full/nature11574.html

What I want, and what we need, is for science to run its course. Lewis' paper has been given an interested response, a bit different from what Shaun Marcott received recently. Synthesising this reserch will not happen overnight.

April 19, 2013 | Unregistered Commentertoby

Toby,

If you are trying to argue that "the science is not settled" in favour of Lewis and low climate sensitivity, I would agree. These are early days, and the results have yet to be examined and tested. While I'm no fan of meta-analysis - judging the validity of arguments by the number of people supporting them - it's quite true that this is not the only argument on the table.

What has got the sceptics excited is that for the first time the lower estimates *are* on the table, getting published, and being discussed seriously. That is a dramatic shift. They cannot any longer be simply dismissed or rejected without a very good argument, and neither can the people putting them forward.

Climate policy activists who have relied on universally high estimates and the casual dismissal of opponents understand very well the significance of these developments. It's true that from a scientific point of view it's not that big a deal, or it shouldn't be. Sensitivity has always been very poorly constrained by the evidence, and previous estimates have been heavily influenced by high priors. Credible evidence for a lower number has been put forward, and that evidence will be assessed and the estimate revised accordingly. But the activist case was never run along scientific lines, and reverting to the science will now involve a major retreat. Activists are right to be concerned, and sceptics have reason to be pleased. But it's certainly not 'game over'. It is perhaps a step in the right direction.

April 19, 2013 | Unregistered CommenterNiV

@toby: "No one accused Andy Revkin of "single study syndrome". No, what you said was that he was "dead right" when he talks about "single study syndrome". So when he said, in the relevant article here, that this issue of lowered climate sensitivity was not a case of single study syndrome, are you saying you agree with him on that? That this result is NOT just based on one paper, as the poorly named Skeptical Science site alleged?

April 19, 2013 | Unregistered CommenterLarry

NiV,

Perhaps we will all end up as Lukewarmers, whose main point was a value for CS less than 3.5C. Spencer & Braswell (2011), who found a value of 0C more or less, and LIndzen&Choi, who found a value ~0.6C, are gone by the board as well.

AFAIK, Lukewarmers accept the temperature record, the paleoclimate reconstructions, the Arctic ice data, the glacier/ ice-cap data, the sea level data and the ocean acidification data. There is enough to show a problem up ahead, perhaps not in our lifeitmes, but soon enough to be of concern.

The good news is that there is agreement over what to disagree about. Debates about CS have to related to the assumptions made, the method used and the data available, not ideology. That is progress.

In the end, I think it will end up as a debate about the places after the decimal point. I tend to look at the pessimistic side. We may have more time to avert looming problems, but I see little chance of it being used productively.

Larry, what I wrote I wrote and stand over. The sense I have is that a single study still needs confirmation and replication from many, not just a few, directions. No study has special priveleges, and every published paper must stand the test of fresh eyes, new data and different approaches. That is the sense of the Andy Revkin quote. And yes, I saw it on the SkS website. So what? If you want to take issue with that triviality, fire away, but I have no time for web tennis.

April 19, 2013 | Unregistered Commentertoby

Sorry, toby, I don't mean to engage in "web tennis", but this isn't a triviality, it goes to the heart of the post that Dan put up. You say, "No study has special priveleges, and every published paper must stand the test of fresh eyes, new data and different approaches." Fine, but that's simply not the sense that most people would make of the Andy Revkin quote -- that this is not a "single-study syndrome situation" -- and not the the sense that Revkin himself seems to imply when he goes on to say "In fact, there is an accumulating body of reviewed, published research shaving away the high end of the range of possible warming estimates from doubled carbon dioxide levels." In other words, he's explicitly stating that this issue of declining climate sensitivity goes beyond a single study, which was implied in the Economist article that started the thread as well.

So, as you say, we may all end up "lukewarmers", and then we can divide into glass-half-full/half-empty factions.

April 19, 2013 | Unregistered CommenterLarry

Larry, finally, the quote from Revkin you keep repeating is not the one I cited above, and gave a link for. So your interjections in a useful discussion have been totally irrelevant.

April 19, 2013 | Unregistered Commentertoby

Toby, there is some confusion here.

Dan cites an article of Revkin's in which Revkin says this is not a case of single-study syndrome, because it's not a single study. You say that Revkin was dead right when he talks about single-study syndrome. But in this you was referring to a different post? One where he defines it using the terms 'single', 'cherry-picked' and 'of questionable quality'? None of which describes the Economist article or the papers and recent discussion cited in it? Is that right?

What was Revkin "dead right" about, and why is it more relevant than what Revkin said in the article Dan cited, on this specific topic of lower sensitivity estimates, and that Larry was talking about? Relevant to what? I'm struggling to understand.

April 19, 2013 | Unregistered CommenterNiV

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