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.

I really try to say things as they basically are and it so happens that it is a good message that things are getting better, but there are still problems.

Of course, the world is full of problems. But on the other hand it's important to get the sense... are we generally moving in the right direction or the wrong direction?

My suggestion is that we should first work to ensure the Third World has clean drinking water and sanitation.

The Kyoto treaty has an estimated cost of between US$150 and $350 billion a year, starting in 2010.

The second thing is, if you want to do something about global warming, you have to think much more long-term. There is something wrong with saying we should start using renewables now, while they are still incredibly expensive.

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