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

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

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.

As an undergraduate, I did maths and physics. That doesn't make me a scientist. So I try to read and understand and talk to scientists.

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

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.