Svante Arrhenius first published his theory linking atmospheric carbon dioxide to global warming in 1896. His paper, titled “On the Influence of Carbonic Acid in the Air upon the Temperature of the Ground,” appeared in the Proceedings of the Royal Swedish Academy of Sciences.
Arrhenius was investigating whether changes in atmospheric carbon dioxide could help explain the alternation between ice ages and warmer interglacial periods. Using physical-chemistry principles and infrared observations, he estimated how changes in carbon dioxide would affect Earth's surface temperature. He concluded that increasing carbon dioxide could produce substantial warming.
His calculations were much simpler and less accurate than modern climate models. He used “carbonic acid” as an older term for atmospheric carbon dioxide and omitted important processes such as cloud feedbacks and convection. Even so, his central insight—that additional carbon dioxide changes Earth's heat balance—became foundational to climate science.
Arrhenius was building on earlier work by Joseph Fourier, John Tyndall, and Eunice Newton Foote. He later published related discussions in 1901 and in his 1908 popular book Worlds in the Making, but 1896 is the year of his first major publication on the subject.