Wednesday, July 26, 2006

New Nature manuscript on climate sensitivity

I was on the verge of posting to say what a damp squib the Nature peer review trial had been. There had been no manuscripts of any interest to me, and no comments either. (I'm not blaming Nature for this, just making an observation. The essays on peer review are good though, and well worth a browse.)

But then this appeared on the RSS feed. Someone has produced a new estimate of climate sensitivity, based on some sort of optimal fingerprint of the solar cycle on global temperatures. They claim a lower limit for S of 2.3C, and a rather vague upper limit of 6.4C (although they say they think it is more likely close to the 3C+-0.7C estimate that they deduce for the periodic response). I guess I might as well make it clear that this is purely at the "submitted" stage - not yet refereed, but it obviously got through the initial editorial vetting.

Comments are invited from institutionalised people only - that's Nature's policy, anyone can comment here of course! I'll keep my powder dry for the time being...

6 comments:

Anonymous said...

Since no-one else has asked the obvious question...

Does keeping your powder dry mean there are going to be suprises or is it just going to be more of the same old

'Why are you answering "What would we estimate climate sensitivity to be, if we had no information other than that considered by this study." rather than "What do we estimate climate sensitivity to be" '

stuff?

crandles

James Annan said...

Chris,

Mostly it just meant that I hadn't read the paper properly! Now I've had a more careful look I'm even less impressed, for a number of reasons which go well beyond what you suggest. But I'm not sure I can be bothered commenting officially. The refs will surely bin it anyway (or at an absolute minimum suggest a heap of new work if they think it might be salvageable).

Phil Hays said...

Even in the bounds of the methods used, the paper should have at least mentioned Mt. Agung, 1963, which was both significant in climate impact, and is in the period of this study.

http://vulcan.wr.usgs.gov/Glossary/VolcWeather/description_volcanoes_and_weather.html

Kooiti Masuda said...

Oh, I find "good old" climate sensitivity again here. (Decades ago, if there can be _the_ parameter of climate sensitivity, it is the response of global mean surface temperature to fractional change of so-called solar constant. At least, so did I write in 1993 in a review article on the role of ice to climate sensitivity....)

Though I think the paper very interesting, I think that there are two weak points in the logic. (I have not examined the logic of the paper to the limit of my capability and thus I do not dare to be an official reviewer....)

The first is that translation between solar-climate sensitivity and CO2-climate sensitivity, perhaps by way of global mean change of radiative flux at the tropopause. The authors admit that it is controvertial. I think, from the experiences of many researchers, it is correct as a matter of order-of-magnitude. (The climate system cannot be very sensitive to solar activity while very insensitive to CO2). But the vertical distibution is different (solar activity warms stratosphere while CO2 cools it). Horizontal and seasonal distributions are also different. Thus it is possible, for example, that factor of 2 difference between them.

The second thing is translation between the "filtered" temperature and the global mean temperature. The fact that the temperature response to solar forcing contains some meridionally inhomogeneous but zonally homogeneous component is consistent with the work by Ogi et al. (2004). I think that many researchers who study annular modes (not necessarily the typical one) view the variation of global mean temperature as something separate from the mode. Tung and Camp, on the other hand, seem to consider that they are essentially the same. I do not say that that is wrong, but I think that more confirmation is necessary whether they really go together.

Reference
Ogi M, Yamazaki K & Tachibana Y 2004: The summertime annular mode in the Northern Hemisphere and its linkage in the winter mode. J. Geophys. Res. 109, D20114.

Hank Roberts said...

What became of that in the end?

Found this thread while looking this up:

http://www.realclimate.org/?comments_popup=3349#comment-167743
pointing to
http://www.jamstec.go.jp/frsgc/research/d2/masayo.ogi/2009GL042356-pip.pdf

James Annan said...

No idea. If I could even remember who the authors were I could see what else they published. I assume it was binned by Nature, correctly so according to my earlier comments here.