There are so many symptoms of this disease it's hard to know where to start to catalogue them, but just look at the effects on hydrology - on the way water moves around the planet.

We have to figure out ways to scare and entice our leaders more effectively than the fossil fuel industry has managed to scare and entice them. They've got the big checkbooks. We've got to have the big crowd.

Global warming is no longer a philosophical threat, no longer a future threat, no longer a threat at all. It's our reality.

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.

We also have to engage - and I think this is important - in national politics because there is no way to address questions of this scale in the short time that we have to address them without engaging in real political change.

All the signs of incipient activism and uprising, from Tahrir square to Zuccotti Park to [the recent] shutdown of the Internet to protest web censorship. People are getting smart and getting connected.

It is a complete embarrassment and literally shameful that the country that first of all invented environmentalism and gave it to the world, and second of all did all the science originally around climate and global warming and presented that to the world, has been the country that has refused to participate in a constructive way to the solution.