In the scientific community, the debate is over, for all intents and purposes, about whether or not the planet is heating and who is causing it. In fact, it's more or less been over since 1995.

Scientists are telling us that 350 parts per million [of carbon] in the atmosphere is the upper limit. We're at 387 parts per million now, and we're up in that zone where the risk of going past irrevocable tipping points is elevated. It's no different than going to a doctor and learning your cholesterol is too high, and you're at risk for a heart attack. You have to work to lower your cholesterol and hope to get there before the heart attack comes.

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.

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.

There hadn't really been a climate movement, per se. I think everyone spent twenty years thinking that if we just keep pointing out that the world is on the edge of the greatest crisis by far it's ever come to, then our leaders will do something about it. And it turned out that was wrong. They weren't going to do anything about it.

Oil companies are radical because they're willing to alter the chemical composition of the atmosphere.

There are many places where we need to fight important battles to make sure that customers have access to solar.