Right now, we're going to just burn everything up; we're going to heat the atmosphere to the temperature it was in the Cretaceous, when there were crocodiles at the poles. And then everything will collapse.
He's not talking about the global ecosystem. That will adapt, as it has to more drastic changes before. He's talking about human society. Kolbert writes herself:
A disruption in monsoon patterns, a shift in ocean currents, a major drought—any one of these could easily produce streams of refugees numbering in the millions. As the effects of global warming become more and more apparent, will we react by finally fashioning a global response? Or will we retreat into ever narrower and more destructive forms of self-interest?
I'll let you guess which path we're on today. Think of it next time you fill your tank. I will.