Tuesday, December 09, 2008

Do solar/heliospheric changes affect the earth's climate?

That was the title of the keynote talk at a workshop held here last week. To save you the trouble of reading any further, I should just say now that the answer provided was "no, at least not to any significant extent since the middle of last century".

Based on the talks I attended, the field basically consists of little more than people data-mining for correlations that usually fail to hold when tested on out of sample data, and for which there is no real evidence or even plausible modelling to support the hypothesis that there may be a significant effect. Of course it is obvious enough that gross changes in solar output will have some sort of effect, such as the orbital changes at Milankovitch time scales, and a modest sunspot-related influence. But nothing of much significance in the context of anthropogenic global warming. The main speaker (Usoskin) even admitted as much, despite doing his best to present (in his own words) somewhat of an advocacy of the hypotheses rather than an impartial review. I mostly went along to see if there would be any sceptic-baiting fun to be had (remembering that Akasofu had been a previous invitee here, and having heard some vague rumours of scepticism in the higher echelons of Jamstec itself) but was rather disappointed by how weakly it was all presented. The only really interesting point was that Jamstec has apparently decided in its wisdom to sponsor a new big interdisciplinary project in this area.

To be fair, I don't know the exact scale of this project, although one person presented results from a high-resolution model that used fully half of the Earth Simulator to run, which certainly didn't come cheap. And I do think that it is worth providing a certain amount of support for somewhat speculative and innovative research - 5 years ago people told me that my ideas wouldn't work either. But I'd expect the resources could make a more useful contribution if they were focussed on climate science rather than being siphoned off on this wild goose chase.


Steve Bloom said...

A wild goose scheduled to be spotted in San Francisco this Monday:

"Recent satellite measurements reveal a recurrent 'breathing', or expansion and contraction, of the Earth's upper atmosphere. Researchers have discovered that this multi-day breathing mode is associated with solar wind high speed disturbances that originate at the sun. This new solar-terrestrial connection could help improve predictions of satellite drag and of characteristics of the ionosphere that affect radio communications and GPS signals. The new findings may also have a bearing on climate and climate change. The evidence for 'breathing' is found in upper atmospheric density and composition, and in gases responsible for cooling the atmosphere."

Why do I suspect that the bit about affecting climate is completely unsupported by the results?

James Annan said...

Sure, of course the ionosphere and stratosphere can be more significantly affected. The difficulty - which Usoskin and others openly admitted to struggling with - is working out how any of this can have much bearing on the troposphere...

Steve Bloom said...

BTW, how's Piers doing? AFAICT the last month you looked at was August.

James Annan said...

Funny you should mention that, I had just made a note reminding myself to deal with it. Some of his forecasts seemed to be missing in action but I'll see what I can dredge up.

cce said...

Totally off topic.

Given the resurging popularity of "tropical troposhere warming", would it be useful to create a profile of tropospheric warming using fancy Bayesian techniques? That is, take all of the various methods and their uncertainties and come up with a tighter range of values? Would there be value in that, or would it not tell us any more than we already know?