16 In view of the general character of the industry, as described in Answer 17, it is also reasonable to presume—though not yet demonstrated—that during the early decades of the 20th Century, the fossil fuel industry was or should have been aware of the possibility that fossil fuel combustion might alter the global climate during this period. Building on earlier work by John Tyndall a half century earlier, Svante Arrhenius first calculated how fossil fuel combustion might affect global temperatures in 1896. He revisited the theory a few years later in a wellreceived and widely read book for popular audiences. While Arrhenius’ idea was initially regarded with skepticism, the possibility of fossil-fuel based warming was addressed in college level geology texts in the early decades of the twentieth century, in popular works by other authors, and even by local newspapers in far flung corners of the globe. After British engineer Guy Callendar correlated a decades long temperature increase with the rise in fossil fuel combustion in 1938, the potential for climatic change became a matter of recurring discussion within the scientific and technical literature. For most of this period, the potential for anthropogenic climate change was not viewed as a matter of concern. It is nonetheless reasonable to infer that researchers within fossil fuel industry were aware or should have been aware of the scientific discourse regarding potential global implications of their products. The oil industry’s active engagement in and funding of research into closely related fields, including radiocarbon dating, paleoclimates, the relationship between climate change and sea level rise, and the causes and consequences of hurricanes, made the industry uniquely equipped not only to understand this discussion but to grasp its potential social and environmental implications. More fundamentally, however, from 1957 onward there is a substantial and growing body of evidence demonstrating not just that the oil industry should have known about climate change and climate risks, but that it did know. • From 1957 onward, the oil industry was clearly and demonstrably on notice of linkages between fossil fuel combustion, atmospheric CO2 concentrations, and potential climate related risks. • From 1968 onward it was warned repeatedly and in increasingly stark terms about the mounting scientific evidence of climate change, the compelling fit between that evidence and the role of fossil fuels, and the potential for changes to the global environment on an unprecedented and potentially catastrophic scale. • By the late 1970s and early 1980s, industry scientists were acknowledging—and highlighting to executives—the growing scientific consensus about climate change and climate risks, and oil companies were taking those risks into account in their own long-term infrastructure investments. Companies were also acknowledging that they possessed technologies with the potential to slow CO2 emissions.