"In the minds of most experts, the chief worry is not that the carbon in the permafrost will break down quickly — typical estimates say that will take more than a century, perhaps several — but that once the decomposition starts, it will be impossible to stop." That's Justin Gillis in the New York Times.
Back in 2008 both Barack Obama and Hillary Clinton and John McCain and Mitt Romney all seemed to agree, in principle, that it ought to be a high priority to enact some kind of binding limit on American greenhouse gas emissions. Even given that, the path to a binding workable global agreement was clearly frought with peril since there's a divergence of perspectives between newcomers to the high emissions party (China) and those who've been there a long time (United States). But in the intervening three years, the politics of this have been totally transformed in a way that's not even slightly backed up by the scientific information that's come in over this time. Instead of debating whether or not emissions will be limited or reduced, we're debating the Keystone XL pipeline as a kind of proxy war over fossil fuels.