'The last forests of Antarctica'

Scientists have called for more research into the last time when atmospheric carbon dioxide levels were the same as today. The Pliocene Epoch - 2.6-5.2 million years ago - was some 2-3 degrees warmer globally than it is now. The Antarctic Ice Sheet was also likely greatly reduced, so much so that conditions permitted plant growth just 500km from the pole itself. Prof Jane Francis, director of the British Antarctic Survey, spoke with our science correspondent Jonathan Amos.