[W]hen we look at the graphs of rising ocean temperatures, rising carbon dioxide in the atmosphere and so on, we know that they are climbing far more steeply than can be accounted for by the natural oscillation of the weather ... What people (must) do is to change their behavior and their attitudes ... If we do care about our grandchildren then we have to do something, and we have to demand that our governments do something.

Until humanity manages to sort itself out and get a co-ordinated view about the planet, it's going to get worse and worse.

Many individuals are doing what they can. But real success can only come if there is a change in our societies and in our economics and in our politics.

I'm no longer sceptical. I no longer have any doubt at all. I think climate change is the major challenge facing the world.

I don't approve of sunbathing, and it's bad for you.

I would be absolutely astounded if population growth and industrialisation and all the stuff we are pumping into the atmosphere hadn't changed the climatic balance. Of course it has. There is no valid argument for denial.

I had a huge advantage when I started 50 years ago - my job was secure. I didn't have to promote myself. These days there's far more pressure to make a mark, so the temptation is to make adventure television or personality shows. I hope the more didactic approach won't be lost.