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An international team(1) has reconstructed a paleoprecipitation map which occurred in the tropical Andes 15 500 years ago, allowing to understand atmospheric processes which produced abrupt changes in the water cycle in tropical South America.In the Southern part of the tropical Andes, today's climate is extremely dry in the largest salted desert of the world: the Salar Uyuni. However, 15 500 years ago, this region was covered by the huge Tauca lake, with a size comparable to the Michigan lake.Present day landscapes of Salar Uyuni (3660 m) (© P.-H. Blard).15 500 years ago, the Tunapa volcano was an isolated island in the former lake Tauca.In this study, researchers from CRPG and their colleagues used the glacial deposits on the Altiplano, together with a new methodology. A lake and a glacier have different sensitivities to precipitations and temperatures because more energy is needed to evaporate a lake than to melt a glacier. By reconstructing the simultaneous extents of Tauca lake and neighbouring glaciers, they quantified the temperature and precipitation conditions prevailing 15 500 years ago. They produced the first regional map of paleoprecipitations at the Altiplano scale.Sources:Institut National des Sciences de l’Univers, CNRSLake Tauca highstand (Heinrich Stadial 1a) driven by a southward shift of the Bolivian High, L.C.P. Martin, P.-H. Blard, J. Lavé, T. Condom, M. Premaillon, V. Jomelli, D. Brunstein, M. Lupker, J. Charreau, V. Mariotti, B. Tibari, ASTER Team, E. Davy, Science Advances, 2018;4: eaar2514.&#160;(1) Centre de recherches pétrographiques et géochimiques (CRPG, CNRS / Université de Lorraine), Institut des géosciences de l'environnement (IGE/OSUG, CNRS / IRD / UGA / Grenoble INP), Laboratoire de géographie physique : environnements quaternaires et actuels (LGP, CNRS / Université Panthéon-Sorbonne / Université Paris-Est Créteil Val-de-Marne / INRAP), Centre européen de recherche et d'enseignement en géosciences de l'environnement (CEREGE/PYTHÉAS, CNRS / Aix-Marseille Université / IRD / Collège de France / INRA), Oslo University and Université Libre de Bruxelles