Colonialism of one kind or another, imperialism of one kind or another, and slavery, and on and on and on.

There is basically no one not on the payroll of Exxon Mobil or coal companies who any longer contend that this is not something to worry about.

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.

In the States we've had by far the largest demonstrations in the last few years. The largest civil disobedience actions about anything in US history in the last 30 years have all been centred around the climate.

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.

Those of us in the west have figured out a lot of ways to damage the lives of poor people in this country and around the world over the years.

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.