> Suppose that it's significantly greater than predicted? Are you willing to bet your future happiness, and the health and wealth of the rest of humanity, that it isn't?

Yes. Of course I am. We make those sorts of bets constantly, because Pascal's Wager doesn't work. We can't not make those sorts of bets.

When somebody says "the end of the world is nigh!" it is almost always worth waiting a bit to see if in fact the thing they're worrying about is actually a problem. Hindcasting is nice and all but the real test is: Does the warming trend actually continue as predicted and if so, once it does get warmer, do we actually see negative effects from it that significantly outweigh all the likely positive effects of warming?

The warming trend is continuing, and the insurance industry is already seeing significant negative effects. See for example [0], [1], [2], [3], all from a single search on "insurance industry extreme weather trends"

[0] http://www.theguardian.com/sustainable-business/extreme-weat...

[1] http://www.foxbusiness.com/industries/2014/02/14/allianz-sto...

[2] http://www.theglobeandmail.com/partners/advinsurancetrends11...

[3]

Even if it's still "warming" at all - whether it is depends on what timescale you look at and how you average the data points - it's certainly not continuing as predicted, but rather at a lower rate than expected. Breathless media stories notwithstanding, nobody thinks the amount of warming we've seen thus far is likely to have generated measurably "more extreme" weather. One of your links is about Sandy, but atlantic Hurricane activity has been unusually LOW over the last decade, with 2013 one of the lowest yet. You should perhaps balance your diet with more stories like this:

http://www.climatecentral.org/news/what-happened-to-the-2013...

(Regardless, even if there were measurable negative effects you would need to balance them against the measurable positive effects to determine if the NET externality was positive or negative. It's silly to add up just one side - even the IPCC doesn't do that.)