Publication: Consequences of rapid ice sheet melting on the Sahelian population vulnerability
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2017-06-20
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National Academy of Sciences
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Abstract
The acceleration of ice sheet melting has been observed over the last few decades. Recent observations and modeling studies have suggested that the ice sheet contribution to future sea level rise could have been underestimated in the latest Intergovernmental Panel on Climate Change report. The ensuing freshwater discharge coming from ice sheets could have significant impacts on global climate, and especially on the vulnerable tropical areas. During the last glacial.deglacial period, megadrought episodes were observed in the Sahel region at the time of massive iceberg surges, leading to large freshwater discharges. In the future, such episodes have the potential to induce a drastic destabilization of the Sahelian agro-ecosystem. Using a climate modeling approach, we investigate this issue by superimposing on the Representative Concentration Pathways 8.5 (RCP8.5) baseline experiment a Greenland flash melting scenario corresponding to an additional sea level rise ranging from 0.5 m to 3 m. Our model response to freshwater discharge coming from Greenland melting reveals a significant decrease of the West African monsoon rainfall, leading to changes in agricultural practices. Combined with a strong population increase, described by different demography projections, important human migration flows could be potentially induced. We estimate that, without any adaptation measures, tens to hundreds million people could be forced to leave the Sahel by the end of this century. On top of this quantification, the sea level rise impact over coastal areas has to be superimposed, implying that the Sahel population could be strongly at threat in case of rapid Greenland melting.
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We thank Michel Crucifix and an anonymous reviewer for their constructive comments and suggestions that helped improve the manuscript, as well as Serge Janicot and Juliette Mignot for fruitful discussions. We are also very grateful to Sarah Amram, Jean-Yves Peterschmitt, and Aurelien Quiquet for technical support, and to Sandra Bouneau and Sylvain David for numerous exchanges. This work was supported by the French Atomic Commission (CEA) within the framework of the Variations Abruptes du Climat: Consequences et Impacts eNergetiques project funded by the Departement des sciences de la matieres (DSM) with the DSM-Energie Program. It benefited from the high performance computing (HPC) resources made available by Grand Equipement National de Calcul Intensif, CEA, and Centre National de la Recherche Scientifique. The authors thank the Potsdam Institute for Climate Impact Research for providing the gridded data population (SSP3) based on a preliminary version of the SSP population data (the 2012-05-11 data in the IIASA database). This database has been elaborated within the Inter-Sectoral Impact Model Intercomparison Project.