[zachrose]

Have I got this right? 8 K (8°C) is terrifying, but 1,200 ppm is almost 3x where we are now.

[lisper]

Correct. But the thing to remember is that we're going up by 2-3 PPM/year, and the arctic permafrost is almost certain to release its methane long before we get to 1200. Civilization is all but certain to collapse after that.