In an epic three-part documentary series, FRONTLINE investigates the decades-long failure to confront the threat of climate change and the role of the fossil fuel industry. Part, One charts the fossil fuel industry’s early research on climate change and investigates industry efforts to sow seeds of doubt about the science. Part Two explores the industry’s efforts to stall climate policy, even as evidence about climate change grew more certain in the new millennium. And as leading climate scientists issue new warnings about climate change, Part Three examines how the fossil fuel industry worked to delay the transition to renewable energy sources — including by promoting natural gas as a cleaner alternative.