Are We Changing Planet Earth?

With so much of the natural world under threat from the impact of climate change, how much is being caused by the actions of man? In the first part of a thought-provoking, two-part documentary for the BBC's Climate Chaos season,David Attenborough considers the evidence, including drought-stricken rainforests, a decline in the number of polar bears, flooded homes and bleached coral.What can we do to influence what will happen next?