When James Hansen testified to Congress in 1988, the world was just beginning to grapple with the reality of climate change. Yet, as early as 1988, internal ExxonMobil files reveal the company was bracing for the consequences of global warming.

Frank Sprow, a scientist at Exxon, warned his colleagues in a memo that if a consensus emerged on the need for action to mitigate greenhouse gas effects, Exxon could face significant negative impacts. This document, part of a batch of previously undisclosed files, provides a stark insight into the company’s internal deliberations from the 1980s to the 2010s.

The documents align with hundreds of other confidential files that have come to light, but they offer new details on Exxon’s internal climate strategy. While the company publicly funded climate change denial, its scientists were privately grappling with the potential impacts of their work.

These revelations are timely, coming as the Supreme Court considers whether to halt a lawsuit brought by the city and county of Boulder against Exxon and Suncor Energy. The outcome could determine whether other claims against oil companies can proceed.