This week, we look back at a previous episode about how climate change is altering the face of the planet, and affecting the lives of the people who live here. Desiree Schell speaks to science writer and naturalist Christoper White, about his book "The Melting World: A Journey Across America's Vanishing Glaciers." And she's joined by sociology researcher Stephen Castles, to discuss the factors driving human migration, and how it could be affected by the shifting climate. Download "Foresight: Migration and Global Environmental Change" (2011) Final Project Report from the UK Government Office for Science, London. Download Stephen Castles' "concluding remarks...