Arctic Live is a three-part series exploring the planet's last undiscovered wilderness.

Every autumn, polar bears gather on the shores of Hudson Bay in Canada to wait for the sea ice to form, so they can begin their winter hunt. And every year, they're waiting longer. In one of BBC Two's most ambitious live broadcasts, Gordon Buchanan, Kate Humble and Simon Reeve head north to Churchill, Canada, to follow the remarkable story of not just these bears, but the entire Arctic to see what life is really like on top of the world.

Vast and stunningly beautiful, the Arctic spans eight countries and over five million square miles of frozen ocean. As temperatures rise it has become an increasingly valuable battleground: shipping routes are opening up, and oil, gas and minerals are tantalisingly within reach.