These things are happening in large measure because of us. We in this country burn 25 percent of the world's fossil fuel, create 25 percent of the world's carbon dioxide. It is us - it is the affluent lifestyles that we lead that overwhelmingly contribute to this problem. And to call it a problem is to understate what it really is. Which is a crime. Crime against the poorest and most marginalized people on this planet. We've never figured out, though God knows we've tried, a more effective way to destroy their lives.

Delhi is locked in a complete choking smog at the moment - they've had to close schools in one of the world's biggest cities. They have their own reasons for needing to get off fossil fuels fast.

Do I think that people should in the best of all possible worlds have to go to jail for wanting the US government to pay attention to the warnings of scientists about climate change? Not really. I mean, in a rational world, if all the scientists said, "The worst thing that ever happened is about to happen and here's what you should do to stop it," you would expect any rational system to say, "Oh, sure, OK, let's do something about it." But that's not the world we live in. In the world we live in, you do need people willing to stand up, fight, march and sometimes go to jail.

We have built a greenhouse, a human greenhouse, where once there bloomed a sweet and wild garden.

A spiritual voice is urgently needed to underline the fact that global warming is already causing human anguish and mortality in our nation and abroad, and much more will occur in the future without rapid action.

I think fracking for gas will reduce the incentive to turn to renewables, and I think it will do a lot of other damage across the countryside.

I don't know how to make people who absolutely have to be obsessed with paying a week's energy bills... obsessed with climate change... It's very hard.