Following the oil money as it’s pumped to contrarian scientists and think tanks. As millions of dollars flow from oil companies to researchers looking into ‘solar variation’ or picking holes in the temperature record, we reveal that ten years previously, oil company researchers had dismissed these very arguments. An internal American Petroleum Institute document from 1995 said ‘hypothesis about the role of solar variability and Michaels’ questions about temperature record are not convincing arguments against any conclusion that we are currently experiencing warming as a result of greenhouse gas emissions’. So why were they funding people who made these arguments years later? From climate change to smoking and cancer, this is the story of how doubt has been manufactured. This 10 part series explores how powerful interests and sharp PR managers engineered doubt about the connection between smoking and cancer and how similar tactics were later used by some to make us doubt climate change. With the help of once-secret internal memos, we take you behind boardroom doors where such strategies were drawn up and explore how the narrative changed on one of the most important stories of our time - and how the marketing of doubt has undermined our willingness to believe almost everything. Clip used from 'The Hunt' series from 2015 by David Attenborough and Hunter Films Ltd. Presenter: Peter Pomerantsev Producer: Phoebe Keane