business venture, or for any other reason, these patents demonstrate that at least one company (now ExxonMobil) was not just aware of but developing technology for vehicles with fuel cells. It is extremely difficult to assess how the path of development, electrification, and carbonization might have changed had the petroleum industry been forthright about the risks of climate change. It is not clear the degree to which we would have demanded low-carbon energy and transportation had we been properly warned. It is not clear how much damage would have been avoided if the petroleum industry continued developing carbon capture and fuel cell technology, or if they released the patents and allowed others to attempt to do the same. It is clear, though, that in addition to promoting the combustion of fossil fuels and the accumulation of carbon in the atmosphere, the petroleum industry – or at least several members of it – were keenly aware of low-carbon alternatives. Summary of Industry Knowledge of and Action on Climate Change The following essential facts can be drawn from the foregoing synthesis. The theory that accumulating carbon dioxide could cause global warming and large-scale climatic changes dates back to the nineteenth century. The fact that fossil fuel combustion releases tremendous amounts of carbon dioxide waste to the atmosphere has been undisputed for more than a century. In 1938, at least one scientist claimed to have measured a noticeable impact both on atmospheric carbon dioxide and global temperatures. From no later than the 1940s, and continuing thereafter, the oil industry was actively engaged in pioneering research in an array of areas relevant to climate change and climate impacts. This included, inter alia, research into long-term changes in the earth’s temperature; the relationship between global temperatures and sea level rise; changes in the concentration of CO2 in the atmosphere; the nature, causes and history of hurricanes; and techniques, technologies, and consequences of intentional weather modification. In 1957, Roger Revelle and Hans Suess published research demonstrating that the world’s oceans would not rapidly absorb this CO2, and suggested carbon dioxide levels in the atmosphere were likely to increase significantly. Scientists working at Humble Oil (now ExxonMobil) were aware of this research at the time of its publication and published their own research in early 1958, in which they recognized the increase in atmospheric CO2, acknowledged the connection between fossil fuel combustion and that increase, acknowledged the link between atmospheric CO2 and potential temperature increases, and acknowledged Revelle’s criticisms of their own conclusions on ocean absorption of CO2. By no later than 1957, therefore, at least one major oil company was clearly on notice that the most important waste product from oil and other fossil fuels might be accumulating in the earth’s atmosphere with the potential to affect the climate on a planetary scale. By 1958, the oil industry as a whole, through the American Petroleum Institute’s Smoke and Fumes Committee, was funding collective research into the accumulation of fossil carbon in the atmosphere. By no later than 1958, therefore, the oil industry collectively was on notice that the most important waste product from oil and other fossil fuels might be accumulating in the earth’s atmosphere, and was funding research into this question as part of an industry-wide air pollution program. Industry records, oral histories from persons involved, and analyses of its activities by independent researchers strongly indicate that the core mission of the Smoke and Fumes Committee was to combine 17