ALEXANDER VON HUMBOLDT'S CLIMATOLOGICAL WRITINGS

Humboldt is often credited with being the forerunner of modern ecology and environmentalism and the founder of modern comparative climatology - without having written a single book on climate. His contributions can be found in the 800 articles and essays that he published in scientific journals. New bibliographic and editorial research on these writings allows this article to present the forgotten climatological contributions for the first time, with the main intention of providing an overview over the extensive material. Humboldt published articles on the distribution of heat on the globe as well as about the chemistry of the subterranean atmosphere in mines. He invented the infographic concept of isothermal lines and wrote on sound propagation in the atmosphere. His mountaineering accomplishments promoted alpine climate studies. In his articles he compared the snow heights of the Andes, the Himalayas and the Alps. He wrote on the temperature of the Atlantic Ocean and the Baltic Sea, about the climate of Spain and that of Central Asia. In South America he was the first to describe the cold-water current of the west coast ('Humboldt current'). He also described and analysed anthropogenic climate change. These diverse contributions provide a new perspective on Humboldt's climatological research. What was the relevance of Humboldt's climatological writings in their time and what is it today?