Dag Retsö is an economic historian and currently associate professor at the Dept. of Economic History and International Relations of the Stockholm University, Sweden. He is currently specialized in medieval North European history, but has also a past in Latin American studies. His main research interests are the climatic variability of Sweden in the Middle Ages and the early modern period, and its impacts on agricultural production and society in general. He has published a number of articles on the historical climatology of pre-modern Sweden, including papers on droughts, hydrological extremes and winter severity.