TV is sometimes accused of encouraging fantasies. Its real problem, though, is that it encourages-enforces, almost-a brute realism. It is anti-Utopian in the extreme. We're discouraged from thinking that, except for a few new products, there might be a better way of doing things.

Very few people on earth ever get to say: 'I am doing, right now, the most important thing I could possibly be doing.' If you'll join this fight that's what you'll get to say

These things are happening in large measure because of us. We in this country burn 25 percent of the world's fossil fuel, create 25 percent of the world's carbon dioxide. It is us - it is the affluent lifestyles that we lead that overwhelmingly contribute to this problem. And to call it a problem is to understate what it really is. Which is a crime. Crime against the poorest and most marginalized people on this planet. We've never figured out, though God knows we've tried, a more effective way to destroy their lives.

We don't know exactly where all the tipping points are in the physical world for inescapable damage, but we're clearly reaching close to some of them.

To me, it's more important to take the 60-70% of people who really understand that there's a problem [of climate change] and get some percentage of them active than to try and stamp out the last embers of pre-scientific thought.

There's no happy ending where we prevent climate change any more. Now the question is, is it going to be a miserable century or an impossible one, and what comes after that.

In the last two years 24 countries have set new all-time temperature records. We've seen flooding on an epic scale in every continent .