> Neither is a "long term" threat -- if we stopped emissions entirely the climate would be expected to return to a pre-civilization equilibrium on the scale of

> Neither is a "long term" threat -- if we stopped emissions entirely the climate would be expected to return to a pre-civilization equilibrium on the scale of decades. That only can be true if the resultant warming over those decades isn't significant enough to kick off other feedback loops or cause ecosystem collapse. For instance, the caps melting and lowering the planetary albedo, ocean acidification, etc. If these things happen too quickly, you're going to see a serious and nasty extinction event happen. Sure, not all life forms will die - archaea are pretty hearty after all, but it isn't going to be pretty for most complex lifeforms adapted to the climate of the current era.