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

We worry about the seemingly ever-increasing number of natural catastrophes. Yet this is mainly a consequence of CNN - we see many more, but the number is roughly constant, and we manage to deal much better with them over time. Globally, the death rate from catastrophes has dropped about fifty-fold over the past century.

When thinking about the future, it is fashionable to be pessimistic. Yet the evidence unequivocally belies such pessimism. Over the past centuries, humanity's lot has improved dramatically - in the developed world, where it is rather obvious, but also in the developing world, where life expectancy has more than doubled in the past 100 years.

I think it's great that we have organisations like Greenpeace. In a pluralistic society, we want to have people who point out all the problems that the Earth could encounter. But we need to understand that they are not presenting a full and rounded view.

I feel privileged to be a U.N. ambassador. It gives me an opportunity to use my voice to help raise awareness about important social and environmental issues.

There is a triple layer of jargon when writing about climate change. You have the scientists, who are very cautious now because of the amount of climate denial. Then you have the U.N. jargon - I had to carry around a glossary of terms. It was like an alphabet soup.

Our weather patterns are mercurial. What you must remember about Great Britain is we have a uniquely temperate climate not shared by any other country in Europe. We can grow plants from every country in the world. The result is 90% of the plants in our gardens are from other parts of the world.

Why should we not expect self-designated environmental leaders to practice what they preach?