SMOKE AND FUMES 1 Executive Summary C limate change poses a fundamental threat to ecosystems, nations, human rights, and human lives. It is caused by the emission and accumulation of greenhouse gases in the atmosphere, primarily due to the combustion of fossil fuels—oil, gas, and coal. This report was written to answer the questions: What did the fossil fuel companies know? When did they know it? What did they do about it? For what can we hold them legally and morally responsible? Whether companies can be held legally liable for these impacts depends on whether they had the ability to foresee climate harms and the ability and opportunity to avoid or reduce those harms. Through company documents, scientific studies, and other evidence, this report © Skitterphoto/Pixabay Recent years have seen dramatic advances in the science of climate attribution, allowing researchers, investigators, and litigators alike to identify both climate harms and potential defendants with ever greater precision. Researchers have identified ninety major carbon producers, including fifty-one investor-owned companies, that are responsible for nearly two-thirds of historical carbon and methane emissions. At the same time, new techniques are enabling ever more precise calculations of the relationship between CO2 emissions, global temperature and sea level increases, and climate impacts. For the first time, scientists and plaintiffs can trace the contributions of individual companies to specific climate impacts and climaterelated disasters. These techniques, and the ability of affected communities to draw on them, are evolving and rapidly improving. Yet throughout the 1990s and 2000s, and despite company documents supporting the scientific consensus on climate change, the petroleum industry engaged in a massive public relations campaign against public understanding of climate science. shows that fossil fuel companies have been aware of the risks of climate change, and their products’ role in exacerbating those risks, for at least six decades. At least one major oil company was on notice of evolving climate science as early as 1957. By 1958, the industry as a whole was studying carbon dioxide in the atmosphere through its industry organization the American Petroleum Institute. From 1968 onward, the industry was repeatedly warned of the climate risks of its products, including by its own scientists, and often in dire terms. From the 1960s onward, the oil industry was actively patenting technologies that might have been deployed to reduce greenhouse gas emissions or accelerate the shift to clean energy. Industry leaders argued against public research into cleaner technologies—or absorbed public research dollars for themselves—even as they argued internally that deploying new technologies would reduce their own profits. By no later than the 1980s and perhaps far earlier, major oil companies were incorporating climate risks into their operational planning for major projects, and taking steps to protect their own assets from long-term climate impacts. As this report demonstrates, a robust and growing body of documentary evidence indicates that the major oil and gas companies whose products are substantially responsible for global greenhouse emissions and the resulting climate crisis had early and repeated notice of climate risks, and numerous opportunities to avoid or reduce those risks. Abundant evidence of industry support for climate denial suggests they chose a different path. Evaluated under the laws of tort, the law of noncontractual responsibility in civil jurisdictions, and international human rights law, there are ample grounds to hold companies responsible for those choices. While the present report focuses on USbased oil and gas companies, the relevant inquiry does not end there. Other industries, including the coal industry have well-documented histories of climate denial. And clear, if currently limited, evidence demonstrates that climate denial was a transnational phenomenon, involving corporate activities—and active deception campaigns—in multiple countries. One thing is already clear: For major carbon producers around the world and the communities harmed by their decades of action and inaction on climate change, the investigations into what Exxon knew are the beginning of this story, but they are by no means the end.