The only thing that will really change global warming in the long run is if we radically increase the speed with which we get alternative technologies to deal with climate change.

In the rich world, the environmental situation has improved dramatically. In the United States, the most important environmental indicator, particulate air pollution, has been cut by more than half since 1955, rivers and coastal waters have dramatically improved, and forests are increasing.

We've had the U.N. for almost 60 years, yet we've never actually made a fundamental list of all the big things that we can do in the world, and said, 'Which of them should we do first?'

If every country committed to spending 0.05 per cent of GDP on researching non-carbon-emitting energy technologies, that would cost $25 billion a year, and it would do a lot more than massive carbon cuts to fight warming and save lives.

Surely the biggest problem we have in the world is that we all die. But we don't have a technology to solve that, right? So the point is not to prioritize problems; the point is to prioritize solutions to problems.

Wishful thinking is not sound public policy.

I'm an old member of Greenpeace. I worried intensely, as I think most of my friends did, that the world was coming apart.