I'm travelling and won't be blogging until sometime next week. I may have a development on the climate betting front by then, and will be sure to post when that happens.
Meanwhile, I recommend taking a look at James' post on the Intrade prediction market for a near-record temperature in 2008. From James' analysis, it sounds like the 20% odds are high. I think it would be interesting though to calculate the odds if temperature changes were random instead of forced, and that would indicate something about this market's belief in global warming.
Also on betting, I agree with William that a climate change bet where all the money goes to the same charity no matter who wins isn't much of a bet. However, a bet where the money goes to different charities depending on who wins is a different matter, especially if the charities work to cross purposes, like a climate-crisis charity versus a right-wing denialist think tank.
UPDATE: fixed the mistake in the post title - I knew what I meant to say!