The gulf between Exxon’s internal and external approach to climate change from the 1980s through the early 2000s was evident in a review of hundreds of internal documents, decades of peer-reviewed published material and dozens of interviews conducted by Columbia University’s Energy & Environmental Reporting Project and the Los Angeles Times...“We considered climate change in a number of operational and planning issues,” said Brian Flannery, who was Exxon’s in-house climate science advisor from 1980 to 2011. In a recent interview, he described the company’s internal effort to study the effects of global warming as a competitive necessity: “If you don’t do it, and your competitors do, you’re at a loss.”...Since the late 1970s and into the 1980s, Exxon had been at the forefront of climate change research, funding its own internal science as well as research from outside experts at Columbia University and MIT...Exxon Mobil declined to respond to requests for comment on what steps it took as a result of its scientists’ warnings. According to Flannery, the company’s in-house climate expert, much of the work of shoring up support for the infrastructure was done as routine maintenance...