Policies that engage us again in the international fight for real climate protection.

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 don't spend a huge amount of time fixated on climate denial because I don't think that their objections, though sometimes couched in science, are based in science. I think they're based in ideology. And I don't think there's anything you can do.

There's always the danger that people will simply sign online petitions, the way they used to just mail in checks, and there's the greater possibility we'll just spend our whole lives staring at screens and never get anything done.

You think OWS is radical? You think 350.org was radical for helping organize mass civil disobedience in D.C. in August against the Keystone Pipeline? We're not radical. Radicals work for oil companies. The CEO of Exxon gets up every morning and goes to work changing the chemical composition of the atmosphere. No one has ever done anything as radical as that, not in all of human history.

With each month that passes, a solar panel gets 2 or 3 percent cheaper. So while we're holding the fossil fuel industry in check, the engineers in the renewable energy world are undercutting them from the other side.

We're putting more carbon into the atmosphere than the atmosphere can absorb. And everybody told us when we started, coz we knew nothing when we started - we still don't know very much - but everybody told us 'this is crazy, you don't use a scientific data point, it's a number, people don't respond to numbers'.