We’ve all encountered those who passionately deny climate change is real. But given the overwhelming consensus of the scientific community, where does this doubt come from? Naomi Oreskes, historian of science and author of Merchants of Doubt, explains the story of the secretive climate denial machine and who some of the key players who have been sowing doubt, and blocking action on the greatest threat facing our society, and what they learned from Big Tobacco. Recorded August 2015, for The Elephant podcast For more interviews on the stories of climate change, head to www.elephantpodcast.org