[extropy-chat] A Bayesian Looks at Climate Change

[Martin Striz]

On 4/19/06, Eliezer S. Yudkowsky <sentience at pobox.com> wrote:
> Hal Finney wrote:
> > I ran into an amazing blog entry from last month which sheds new light
> > on global warming from an unusual perspective:
> > http://julesandjames.blogspot.com/2006/03/climate-sensitivity-is-3c.html
> > The blog entry is by James Annan and describes a paper he coauthored with
> > J.C. Hargreaves that is being published in Geophysical Research Letters:
> > http://www.jamstec.go.jp/frcgc/research/d5/jdannan/GRL_sensitivity.pdf
> >
> > The bottom line is that when you combine all these different papers
> > using Bayesian analysis, you get that climate sensitivity is 3 +/- 0.5
> > degrees C, an astonishingly narrow estimate given the state of knowledge
> > in the field.
>
> This sounds highly suspicious to me.  What if there are correlated
> errors in the studies?
>
> No one in China has ever seen the Emperor of China, but everyone can
> guess his height to within plus or minus one meter.  Therefore, by
> polling a million Chinese and averaging their estimates, the law of
> large numbers says we can get an estimate of the Emperor's height that
> is accurate to within one millimeter.

But I think that's the point.  You sampled a billion people in exactly
the same way.  If you start with a number of studies, each with
different methodologies, then you hope to minimize the  bias in each
one.

Martin