Climate change is the single biggest thing that humans have ever done on this planet. The one thing that needs to be bigger is our movement to stop it.

In the end, climate change is a math problem.

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.

We spend a lot of time playing defence against bad things. So, in the US, one of the focusses has been this huge Keystone Pipeline project, another has been the coal ports on the Pacific Ocean.

In the States, the movement's actually gotten much much much stronger. There really was no climate movement so to speak before that - I think because everybody assumed that reasonable heads would prevail and do the right thing - and why would you need to have a huge movement in order to cause our leaders to deal with the most serious problem that they face. In a rational world you wouldn't. They would deal with it.

Climate change is the single biggest thing that humans have ever done on this planet. The one thing that needs to be bigger is our movement to stop it.

Alone among businesses, the fossil-fuel industry is allowed to dump its main waste, carbon dioxide, for free.