A rise of 5C would be a temperature the world has not seen for 30 to 50 million years. We've been around only 100,000 years as human beings. We don't know what that's like.

Fortunately poorer countries, such as China, are showing leadership and beginning to demonstrate to the world how to invest in low-carbon growth.

I think that once people understand the great risks that climate change poses, they will naturally want to choose products and services that cause little or no emissions of greenhouse gases, which means 'low-carbon consumption.' This will apply across the board, including electricity, heating, transport and food.

The scientific evidence is now overwhelming: climate change presents very serious global risks, and it demands an urgent global response.

Do politicians understand just how difficult it could be, just how devastating rises of 4C, 5C or 6C could be? I think, not yet

I've never really had much of a career plan, and interesting opportunities kept cropping up.

There is still time to avoid the worst impacts of climate change, if we take strong action now.