Concerns about irreversible and unfavorable climate change are not new, nor are discussions about its possible causes and consequences. Since the late 18th century when science-based knowledge began to replace the mystic and religious views about climate change that had prevailed for centuries, there have been more or less permanent debates on climate change and climate variability. The discourse was not only carried out among experts, but repeatedly—in varying contexts—in the public as well.

By the end of the 19th century the debates about climate change culminated in a vivid discussion of the causes of the ice ages, the nature of historical climate variability, the possible human influence on future climate, and the impact on the evolving economies and societies. These issues were discussed by prominent scientists including Svante Arrhenius, Eduard Brückner, and Julius Hann. Moreover, these topics became politically relevant. As an example, a number of scientists speculated that extensive deforestation, or also reforestation, might potentially cause a large-scale anthropogenic climate change.