The latest computer modeling I've seen indicates that at mid-century, there might be 150 million people classified as "environmental refugees."

Probably nothing that we have ever managed to do quite equals the basic undermining of the physical stability of the planet on which most of the world's poor people depend.

I can't tell how moving it is to open my email and see a picture of 1,500 Buddhist monks and nuns in the Himalayan kingdom of Ladakh forming a human 350 against the backdrop of the melting glaciers. This is not their fault, and yet they're stepping up to be part of the solution.

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.

The fact that Washington has been a complete logjam for anything for the last six years has got to change because we need to have federal policy that really allows us to move quickly and nimbly.

My guess is that liberating the fossil fuel industry to frack anywhere they want will drive down the rate at which we're converting to sun and wind. And it's entirely a rate problem at this point.

To me, it's more important to take the 60-70% of people who really understand that there's a problem [of climate change] and get some percentage of them active than to try and stamp out the last embers of pre-scientific thought.