Well, first there are people mitigating (or at least attempting to mitgate it) and secondly, a drastic reduction in human population is a bad thing (asking from a global perspective)?
I'm not advocating a reduction in population, I'm saying based on the current direction we're going the world's major nations are already preparing for wars that will kill many of us in a fight for dwindling resources as the worst effects of climate change kick in...especially when it comes to water security.
The way we're going we're going to create the conditions that will cause a massive loss in population, that's the ugly little not-so secret behind climate change denial. The people behind it keep talking about being concerned about other people but it's nonsense. Many people will be left without the means to live if we keep forcing the climate into a radically new state.