A new report exposes the many ways that Big Oil has been working to deceive the public on climate change over the past several decades. The media has fallen for many of its tactics, effectively allowing the industry to change the debate on climate science and hide the industry backing behind its front groups and campaigns. For nearly three decades, top executives at ExxonMobil have known that fossil fuel emissions harm the climate, according to a document uncovered by the Union of Concerned Scientists (UCS).