They spend most of their time on sea ice, this cap of ice that is floating around on the surface of the Arctic Ocean.

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Are you terrified by the melting polar ice cap, rising sea levels, extreme weather, and other growing threats from global warming?

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Jack Hall (Dennis Quaid) is a climatologist who realizes, as a slice of the polar ice cap slides into the sea, that the end of the world (or, at any rate, of that half of the world that drives S.U.V.s) is nigh.

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Increased evaporation from the exposed sea should also mean more snowfall to compensate for the ice cap's losses (though together with rapid erosion at the margins this could increase the gradient of the ice cap, making it less stable.) But this is small consolation for another big fear: rapid thawing of the Arctic permafrost.

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If the climate stabilises soon, the ice cap might resettle at a slightly lower mass than it has now, raising sea levels by only a few centimetres.

ECONOMIST: The science