In this episode we discuss the efforts of three scientists–Svante Arrhenius, Guy Callendar, and Charles David Keeling–to figure out exactly what fossil fuel emissions might be doing to the atmosphere and the global temperature. Surprisingly, Arrhenius and other early climate scientists didn’t necessarily think that global warming would be…such a bad thing? But by the 1970s scientists began to push for more concerted efforts to research the effects of increasing carbon dioxide concentrations in the atmosphere. We’ll pick up that part of the story in the next episode. You’ll also hear about Guy Callendar’s contributions to climate science. Guy was a fellow who held no academic degrees in science but did live through a dangerous childhood. We’ll conclude with Charles Keeling and his famous curve showing how the CO2 concentration in the atmosphere began increasing at an accelerating rate during the twentieth century.