One thing that being a scientist has taught me is that you can never be certain about anything. You never know the truth. You can only approach it and hope to get a bit nearer to it each time. You iterate towards the truth. You don't know it.

Sadly, it's much easier to create a desert than a forest.

By 2040, the Sahara will be moving into Europe and Berlin will be as hot as Baghdad. Atlanta will end up a kudzu jungle. Phoenix will become uninhabitable, as will parts of Beijing (desert), Miami (rising seas) and London (floods). Food shortages will drive millions of people north, raising political tensions.

A billion could live off the earth; 6 billion living as we do is far too many, and you run out of planet in no time.

The oil companies regard nuclear power as their rival, who will reduce their profits, so they put out a lot of disinformation about nuclear power.

Geological change usually takes thousands of years to happen but we are seeing the climate changing not just in our lifetimes but also year by year.

You never know with politicians what they are really saying. And I don't say that in a negative way-they have an appalling job.