The Channel 4 documentary, ‘The Great Global Warming Swindle’, put forward the idea that carbon dioxide did not in fact cause global warming, but instead was a product of global warming. It also suggested that the Earth frequently enters cold and warm periods of climate, and that the current warming was simply a natural phenomenon. We put these arguments to Stephan Harrison, an Associate Professor in Quarternary Science at Exeter University and a Senior Research Associate at Oxford University…