Warm air holds more water vapor than cold, and so the atmosphere is about 4% wetter than it was 40 years ago. This loads the dice for flood and drought, and we're seeing both in stunning abundance.

We've lost half the summer sea ice in the Arctic. We've wiped out an enormous percentage of the world's coral reefs. We see huge changes in the planet's hydrology already, the cycles of drought and flood both amped up because warm air holds more water vapor than cold. These things are happening with a one-degree increase and going to two degrees won't be twice as bad, the increase in damage won't be linear, it most certainly will be exponential. So it was precisely the wrong moment to elect Trump.

Global warming is no longer a philosophical threat, no longer a future threat, no longer a threat at all. It's our reality.

I'm far less a leader than a writer.

If we had about 100 years, that sort of slow cultural conversion would be exactly the thing to do. But physics is calling the tune here. We've got to respond to a timetable that physics has set for us.

But the truth is that we could win every other fight that we face and if we lose the climate fight, the other victories will be pyrrhic. I don't think even people who are worried about climate change quite understand the scale and speed with which we're now shifting the planet.

There is a tendency at every important but difficult crossroad to pretend that it's not really there.