Tom Harris: October, 2016 - Leonardo DiCaprio is releasing a new climate change movie. "Before the Flood" will debut on the National Geographic Channel. It will also be available for free on YouTube. Before the Flood is based on the highly debatable hypothesis that carbon dioxide (CO2) emissions from human activities are causing catastrophic climate change. Coal, oil, and natural gas, the world’s least expensive and most abundant energy sources, must therefore be turned off as soon as possible, DiCaprio says.