> already dealt with problems much bigger than the average temperature going up by a couple of degrees and sea level rising a couple of feet

With respect, I think you may be underselling the effects! The chaotic knock-on of species loss; water pressures causing human migration; a loss of half of the ice on the third pole (the Himalayas) that provides water to over a billion people; acidification of the oceans. We could go on but the point I'd like to hammer home is this isn't anything at all like the previous crises in our brief 60k year sojourn: the anthropocene is an apocalyptic event that will wipe out half of the species on earth (probably).