The fate of the world's coasts rests on a knife edge as global warming melts ice sheets and glaciers from the Alps to the Andes. The choices we make now will determine whether oceans rise by a coast-swamping one metre by 2100 or whether we can save our coastal communities. Can you move an entire population to another country? This is no longer a theoretical question, it is one that we must answer as entire islands, towns and countries are set to be lost to the seas. From the glaciers of Antartica and the high Andes, to the small island states of the Pacific and the coastal cities of Miami, New York, Venice and Rotterdam - Alister Doyle tracks the thaw that threatens life as we know it. The Great Melt is a wake-up call for action on climate change. It will bring the thaw to life by focusing on the most vulnerable people at the shoreline who are already moving inland, on the scientists puzzling about what is going on, and on the ideas about how to limit the damage.