All the things that we've done as a species have had a limited scope. We're talking about melting the ice caps, raising the level of the seas dramatically, changing the distribution of every other species on Earth, perhaps wiping out one-third or half of them. The changes at work are geologic in scale. The level of change required to deal with it is enormous, too. It will require change in every country. It will require a degree of global cooperation that we haven't seen before.

I'm guessing the most efficient way would be to transfer an awful lot of technology, but also direct aid to deal with climate emergencies already underway. Hillary [Clinton] has already said $100 billion a year would be appropriate.

We have to get our states to adopt what are called "renewable portfolio standards" pledging to use a lot of renewable energy by 2015 or 2020. We have to work with businesses and shops to get them engaged in the same way.

The idea that China and India will just abandon climate action is not true, because they're doing it for more reasons than we are.

I think that some of it is electoral - helping candidates that are willing to take dramatic actions, not just to say a few words about how climate change might be a problem.

When we work all over the planet, it's mostly poor and black and brown and young people, because that's mostly what the world [environmentalism] is.

I've got no advice. You guys know where you are and what will work. Just know that there are people all over the place working on this and that there's a great deal of solidarity around the world and we should try to build this big, sprawling movement that looks like the kind of energy system that we want - building lots of solar panels on lots of rooftops that are all interconnected.