Wednesday, March 25, 2009

Mark Campbell gives 33% chance that IPCC is right, and no betting will happen

(UPDATE: some overlooked email correspondence going on now, I will repost later after it's resolved.)

I'm not sure how important it was to see if Naval Academy chemistry professor Mark Campbell would bet over his position. He only wrote one letter to the editor denying the mainstream consensus that I'm aware of, but it was a fairly aggressive one that was trumpeted by Marc Morano:

....If we are going to stoop to name-calling, an appropriate name for
people with the view The Baltimore Sun endorses could be "Chicken Littles." But
instead of claiming that the sky is falling, they claim the sky is burning....
To many of us, there is no convincing evidence that carbon dioxide produced by
humans has any influence on the Earth's climate. Arguing that our country should
decrease its use of fossil fuels is a laudable goal, but the reason to do so
should be to reduce our reliance on energy from foreign sources, not to reduce
the danger from some imaginary boogeyman.

In any event, Campbell is one of the few non-retired science professors who's willing to say this stuff, so I thought it worthwhile to contact him. He exceeded 95% of the denialists out there by responding to my email and actually exploring a bet, but unlike David Evans or Bill Gray, he never lost the aggressive tone. I wonder if that hostility has anything to do with being so catastrophically wrong.

Anyway, his first bet offer was fine - it was to take 1980-2000 warming and project the same amount for 2000-2020. If 2000-2020 meets or exceeds the 1980-2000 warming rate then I win, and if it's half or less of the 1980-2000 warming rate then he wins. The idea was fine but the data he used was wrong (he got it by eyeballing a graph), and when I supplied correct data he began backing away. Ultimately the only bet he would offer against the IPCC position had to favor him by 10:1 odds over a twenty-year period.

Seeing as I give 20:1 odds or better that the IPCC is right, 10:1 odds might sound fair, but the odds that the IPCC is right overall doesn't translate directly into the odds of the outcome for any particular period matching what the IPCC says. Also, I don't have the money to make my betting partner put out a significant bet if I have to bet ten times as much.

Here was my email to Campbell:

Mark,

I'm sorry you don't consider your own previous bet offers as fair ones.
The idea is that both sides perceive different odds of an event and can reach a
bet point where each side thinks it's likely to win.I believe there's been some
utility in this discussion in that you acknowledged to me at least a 33% chance
of the IPCC position being right
(see update below). I think in any policy claims you make against controlling emissions, you might want to acknowledge that too, given the downside of what will happen if the IPCC is indeed right and we continue our path of doing very little to control emissions....The 4:1 bet offer you've made,
by the way, doesn't contradict the IPCC range because I can only win at a rate
significantly higher than the IPCC predicts for the next few decades. And
the Wrigley-Raper paper has been criticized as inappropriate melding of
different scenarios (as I recall, it was a long time ago).

Brian

I had also said I would only summarize but not quote him without permission. I just now discovered that he's misrepresented our negotiations, so I've reproduced the relevant correspondence, here.

I really expect better from someone lucky enough to teach at the Naval Academy.

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