Tuesday, February 28, 2006

Guardian Unlimited: Climate scientists issue dire warning

There's an interesting article by David Adam in the Grauniad today, entitled Climate scientists issue dire warning:
The Earth's temperature could rise under the impact of global warming to levels far higher than previously predicted, according to the United Nations' team of climate experts.

A draft of the next influential Intergovernmental Panel on Climate Change (IPCC) report will tell politicians that scientists are now unable to place a reliable upper limit on how quickly the atmosphere will warm as carbon dioxide levels increase.
So apparently one of the lead authors has been "leaking". However, later the article says:
According to sources who have seen it, the draft now assumes a doubling of carbon dioxide would cause a likely temperature rise of between 2 and 4.5C, but says higher increases are possible.
Peter Cox describes this as a "significant" move, but it doesn't actually sound like much of a change at all to me. The previous 1.5-4.5C range was only confident at the "likely" level, obviously implying a significant chance of a higher figure. Maybe something got a bit lost in translation, or maybe he knows of some more details not reported here. Anyway, us mere mortals will have to wait another month or so before we get to see the second draft (even though I was listed as a "contributing author" on the first draft of one of the chapters). It will be interesting to see how the lead authors attempt to reconcile the various opinions expressed in the literature.

Further on in the article, Peter Cox is quoted as making this strange statement:
"The scientific agenda has moved from improving the predictions to thinking about what are the chances of something awful happening."
and Dave Stainforth talks about the "destruction of society". I think that amply vindicates my comment about people "talking up the possibility of disaster".


William M. Connolley said...

I upgraded your wiki article, oh skeptic poster-boy :-)))

Anonymous said...

Keep a close eye on that second letter in the "S" word, James -- it's been known to be a tasty snack for weasels. :)

But seriously, the article didn't illuminate very much the distinction between the risk of meeting/exceeding 4.5C vs. the risk of abrupt changes that may result as we tend toward the 4.5C level. I'm far more concerned about the latter.

EliRabett said...

I am curious as to whether the predictions are symmetric, ie, is it equally likely that the actual change will be less than or more than...

James Annan said...


Yes it will be interesting to see if there is any nuance about the uncertainty being mostly on the upper end, as this BBC report seems to imply. I note that this article make the traditional error of confusing climate sensitivity with 2100 projections :-)

Anonymous said...

'make', 'makes' or 'did make'?


Is it worse now?


James Annan said...

OK, that's better now!

Anonymous said...

No the predictions are not symetric, climate models constrain 1/S to be a symetric roughly normal distribution. 1/S is about 0.3 +-0.1 So S has a skewed distribution with a long tail at the high end, e.g. see the ClimatePrediction.net or MIT results.

Mike Atkinson

Anonymous said...

The other classic "error" is to use "the last century" as though global warming did not have an anthropogenic contribution before, and that temperatures have not risen since.

James Annan said...

Not meaning to pick on you, Mike, but talking about "the distribution" as if it is some specific shape te be estimated is precisely the category error that has resulted in the recent confusion.