“The latest computer modeling I’ve seen indicates that at mid-century, there might be 150 million people classified as “environmental refugees.””

But tolerance by itself can be a cover for moral laziness.

I’m probably the wrong person to ask. My partner in much of this work [climate movement], who really came up with the divestment campaign with me, Naomi Klein, I think has written powerfully about this.

[Barack Obama] done some good things, he’s done a couple of bad things. He’s obsessed with this all of the above energy policy and… lots and lots of drilling in the States, so he’s been weak on it.

What makes us different? We’re the creature that can decide not to do something that we are capable of doing.

Probably more than anything else, the place that we really see the effects of the power of even the relatively mild temperature increases so far is in the melting of everything frozen on the planet.

The movers and shakers on our planet, aren’t the billionaires and generals, they are the incredible numbers of people around the world filled with love for neighbor and for the earth who are resisting, remaking, restoring, renewing and revitalising.

If you were running a solar company you may be okay – you may be able to keep growing. The question for physics is: Can you grow fast enough to begin to catch up with the damage?

I think we need to think of lots of ways to communicate. And we tried some at 350. We organised what they called the largest art project in the planet’s history. We do a lot with art and music and things.

We’ve been in lots of places that I suppose, by Oxford standards, would be considered illiterate, but everyone’s completely conversant with the idea that here is a number, and that number is above it, and that’s too high. It’s not a very complicated idea.

In the States, I think, the syllogism goes like this: ‘free markets solve all problems. Free markets aren’t solving global warming, QED global warming is not a problem’. It’s not a very good syllogism but it’s emotionally comforting if you’re in that world.

The ability to write compelling emails may be the single most useful talent an organizer can possess.

The world is on fire, and I’m doing my best to help steer the firetruck.

There is a tendency at every important but difficult crossroad to pretend that it’s not really there.

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.

Look – every time is the wrong time and the perfect time to have a kid, and you just do it when you can.

The laws of Congress and the laws of physics have grown increasingly divergent, and the laws of physics are not likely to yield.

I am passionate about exploring the confluence of environmental and human health. I believe that the goals of conservation must constantly revisit a stated purpose.

We have forgotten how to be good guests, how to walk lightly on the earth as its other creatures do.

Finally, since human beings are uniquely capable of producing materials not found in nature, environmental degradation may be due to the resultant intrusion into an ecosystem of a substance wholly foreign to it.

The environmental crisis is a global problem, and only global action will resolve it.

When you fully understand the situation, it is worse than you think.

Environmental pollution is an incurable disease. It can only be prevented.

The environmental crisis is a signal of this approaching catastrophe.

In all matters moderation is desirable. If a thing is carried to excess, it will prove a source of evil.