Lake Chad hydrological cycle under current climate change

• Main Authors: Sylvestre, Florence, Crétaux, Jean-François, Berge-Nguyen, Muriel, Pham Duc, Binh, Mahamat Nour, Abdallah, Bouchez, Camille, Frappart, Frédéric, Papa, Fabrice
• Other Authors: Centre Européen de Recherche et d'Enseignement des Géosciences de l'Environnement (CEREGE), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), University of N'Djamena, Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France-Centre National de la Recherche Scientifique (CNRS), Hanoi University of Science and Technology (HUST), Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), European Geosciences Union
• Format: Conference Object
• Language: English
• Published: HAL CCSD 2021
• Subjects: [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology; North Atlantic
• Online Access: https://insu.hal.science/insu-03226322; https://doi.org/10.5194/egusphere-egu21-12738

International audience In a near future, the Sahara and Sahelian regions could experience more rainfall than today as aresult of climate change. Wetter conditions in the hottest and driest place of the planet today raisethe question of whether the near future might hold in store environmental transformations,particularly in view of the growing human-induced climate, land-use and land-cover changes.Reflecting an enhancement of the global hydrological cycle under warmer conditions, someexperiments provide support for the notion of a strengthening of the monsoon in the future andmore rainfall in central Sahel and Sahara. However, some remote forcing could counterbalancethe decadal trend. Modeling experiments suggest that the freshwater discharge coming fromGreenland melting could significantly impact the sea surface temperature of North Atlantic andinduce a decrease in Sahel rainfall for the next decades, remaining left open the question howSahara will be in a warmer climate?By chance, Lake Chad, located at the southern edge of the Sahara, is recognized for being the bestsite in Africa for deciphering hydrological and climate change. After being ranked at the world’ssixth largest inland water body with an open water area of 25,000 km2 in the 1960s, it shrunkdramatically at the beginning of the 1970s and reached less than 2000 km2 during the 1980s,decreasing by more 90% in area. Because it provides food and water to 50 millions of people, itbecomes crucial to observe precisely its hydrological cycle during the last 20 years.Here by using a new multi-satellite approach combined with ground-based observations, we showthat Lake Chad extent has remained stable during the last two decades, slightly increasing at14,000 km2. We extend further this reconstruction by adding new data from the hydrological year2019-2020, which is considered at an extreme in precipitation recorded over the Sahel. Moreover,since the 2000s, groundwater which contributes to 70% of Lake Chad’s annual water storage, isincreasing due to water ...