New York Times columnist Tom Friedman investigates the increasing population of climate refugees — migrants forced to leave their homes due to climate change-induced sea-level rise, natural disasters and destroyed livelihoods. He travels from the COP21 climate conference in Paris to the Sahel region of a parched and war-torn Africa, where he hears from refugees themselves. He explores this new wave and what the future may bring. Actor Don Cheadle is on the ground in California, where the worst drought in 1,200 years is devastating the nation’s most populous state and the world’s seventh-largest economy. He investigates how Gov. Jerry Brown’s administration is fighting the drought while also fighting climate change. Along the way, Cheadle meets a scientist who warns of a global water and food crisis as well as a family of farmers whose lives may never be the same as they struggle to find water in the parched Central Valley.