Friday, April 14, 2006

Never mind

Here's the BBC paraphrasing Professor David King, Tony Blair's Chief Scientific Advisor:
The world is likely to suffer a temperature rise of more than 3C, says the government's chief scientist.
The context seems to indicate that King is referring, effectively, to the impact of a doubling of atmospheric carbon dioxide concentration.

Here is James Annan, climate scientist and author of a recent paper on climate sensitivity (defined as average global temperature rise as a function of doubled atmospheric carbon dioxide concentration), saying, in response to a comment on his blog:
We said that a more optimistic (but not completely unrealistic) view might give an upper limit of about 4C at 95%. If I was giving round numbers, I would simply say 3+-0.5 (at 1sd, Gaussian) is a pretty good estimate - that makes
2.5-3.5C is likely (68%)
2-4 is very likely (95%)
Well, I'm interested in climate change, and I have very good impressions of both men, so I thought I'd better check into what appeared, at first look, to be a conflict between their statements. Annan's position seems to be that climate sensitivity is 3 degrees Celsius, give or take a little, while King's position seems to be that the number is higher. How interesting.

So I started to look into it some more. First to look up Bayes Theorem, which is how Annan studied the question.

Then the damned cat distracted me with its prey. By the time I was done with that, I guess my subconscious mind had taken care of the issue for me. I no longer wanted to follow up on the apparent discrepancy above, having concluded that it doesn't matter to me (which is not to say that climate change is unimportant, and is not to denigrate either man's work).

One of my favorite movie lines is from one of the Eastwood cop flicks, something to the effect of, "A man's got to recognize his limitations." Well, it would take a great deal of time and energy for me to come to understand what Annan has done to reach his conclusion (there's a reasonable chance of discovering I can't get there from here anyway). Then, to investigate what King bases his assessment on would be another major chore. All of this effort to what end?

It is crystal clear to me that humankind is trashing the atmosphere (and the planet in general), and this is consistent with what Annan and King are both reporting. End of story.

Now maybe I can make a little progress on one of the three or four books I've got open at the moment, rather than giving up on them as I've been prone to do lately.

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