The 2017 Hans Oeschger Medal is awarded to Denis-Didier Rousseau in recognition of his pioneering work in continental climate reconstruction by developing new proxies and combining them with innovative climate-model simulations.
Denis-Didier Rousseau obtained his PhD in geology from the University of Dijon (France) in 1985. He is a world leader in continental palaeoclimate studies based on loess, and his research spans the fields of geology, palaeontology, palaeoecology and palaeoclimatology. His pioneering research has yielded new proxies and transfer functions resulting in quantitative reconstruction of past climate changes in continental areas. In particular he uses fossil land snails and combines this information with ecological principles to produce quantitative records of past climate of Europe, North America and China. This has lead to several important high-resolution records that provide understanding of regional patterns of climate variability and change including quantification of past changes in temperature and monsoon strength. His contributions form the basis for a deeper process-based understanding of how the climate system works from a continental perspective and how essential elements of it respond to changes in forcing and other perturbations. Rousseau has elevated the extraction of environmental information from loess deposits to a new level. He has pushed this archive from a qualitative and descriptive history of climate change to a source of quantitative information. To this end, he employs stable isotope methods to interpret palaeovegetation changes, and in combination with climate models, he is able to evaluate the interaction between abrupt climate change and dust emissions. Denis-Didier Rousseau has therefore demonstrated leadership by combining different activities in palaeoclimate science, much in the spirit of the late Hans Oeschger. Rousseau is also an excellent facilitator of science and a mentor of scientists. His service to the scientific community is numerous and widespread. He is the founding co-editor of Climate of the Past, a leading EGU journal in this field. With this contribution he brought palaeoclimate science to a much wider audience and provided the community with a unique platform for scientific exchange and progress. He served as a President of the EGU Climate Division and as a member of the Scientific Steering Committee of PAGES, the international Past Global Changes Programme of IGBP, now Future Earth. As Program Chair of the American Geophysical Union Denis-Didier Rousseau continues to service the scientific community in a significant way.