In 2007, Scott Armstrong proposed a ten-year wager to Al Gore -- no warming (Armstrong's prediction) vs. warming (Gore's prediction). Gore declined, saying he doesn't gamble. And there was no wager, so that was the end of it. Kidding! What happened was that it became a minor myth picked up by the likes of Intrade and followed on http://www.theclimatebet.com/. Denialists like to claim that Gore is "losing the bet," a claim that interested me because of the number of lies packed into a simple declarative sentence. I will delve into this at greater length later, but here is a thumbnail sketch of the fallacies involved that sentence:
1. There was no bet, as Gore declined the offer.
2. Gore hasn't given an estimate for future warming, so the denialists chose 0.03C per year, which they claim is the "linear trend" predicted by the third IPCC report.
3. The trend predicted by the IPCC is not linear.
4. The trend is not 0.03C per year. The third IPCC report predicted a warming trend of 0.15C-0.30C/decade over the next several decades. Not only does the "bet" ignore the time frame (see #6), but rather than chose the middle of the range, the deniers have chosen to pretend the higher end of the estimate, the maximum possible, is the "projection" of the IPCC report.
5. The "bet" was proposed in 2007, when the fourth IPCC report came out -- but the denialists went to the out-of-date report for their estimates of warming. (The fourth report does not change things much -- it estimates warming of about 0.2C in coming decades.
6. It's a ten-year bet, yet denialists are tracking meaningless figures like who "won" the year or even who "won" the month (of course, short-term variations caused by solar activity, ENSO, and the like make it impossible to translate a prediction of 0.2C/decade averaged over several decades to a prediction for one decade, let alone a single month or year. Scott Armstrong himself has warned the denialists that this makes no sense, but they persist.
7. Even with these cherry-picked conditions, Gore has "won" six of the last seven months. Intrade gives him a 75% chance to "win" the year. Coincidentally, http://www.theclimatebet.com/ stopped posting updates on the status of the "bet" . . . exactly six months ago.