Contribution of lakes in sustaining the Sahara greening during the mid-Holocene
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Published:2023-10-06
Issue:10
Volume:19
Page:1891-1904
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ISSN:1814-9332
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Container-title:Climate of the Past
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language:en
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Short-container-title:Clim. Past
Author:
Li YuhengORCID, Kino KanonORCID, Cauquoin AlexandreORCID, Oki TaikanORCID
Abstract
Abstract. The climate impact contribution of lakes to sustain the Green Sahara in the mid-Holocene (MH, 6000 years ago) is still under debate. To assess the lake-induced climate response over North Africa, we investigated the roles of western Sahara lakes and Megalake Chad using reconstructions of MH Sahara lake maps as surface boundary conditions for the isotope-enabled atmospheric model MIROC5-iso. Our results show that the western Sahara lakes pushed the West African monsoon northward and extended it eastward by expanding Megalake Chad. This lake–climate impact was caused by the cyclonic circulation response related to the weakened African Easterly Jet and enhanced Tropical Easterly Jet. According to the Budyko aridity index, the northwestern Sahara climate region shifted from hyper-arid to arid or semi-arid with the lake expansion. Moreover, precipitation scarcity could have been reduced by up to 13 % to sustain the semi-humid conditions. Such lake–climate impacts could alleviate Sahara aridity, relying on lake positions in the monsoon regions. Our findings are promising for understanding the contribution of lakes to sustaining the Green Sahara.
Funder
Japan Society for the Promotion of Science Environmental Restoration and Conservation Agency Ministry of Education, Culture, Sports, Science and Technology
Publisher
Copernicus GmbH
Subject
Paleontology,Stratigraphy,Global and Planetary Change
Reference66 articles.
1. Adkins, J., deMenocal, P., and Eshel, G.: The “African humid period” and
the record of marine upwelling from excess 230Th in Ocean Drilling Program Hole 658C, Paleoceanography, 21, PA4203, https://doi.org/10.1029/2005PA001200, 2006. 2. Bartlein, P. J., Harrison, S. P., Brewer, S., Connor, S., Davis, B. A. S., Gajewski, K., Guiot, J., Harrison-Prentice, T. I., Henderson, A., Peyron, O., and Prentice, I. C.: Pollen-based continental climate reconstructions at 6 and 21 ka: a global synthesis, Clim Dynam., 37, 775–802, https://doi.org/10.1007/s00382-010-0904-1, 2010. 3. Bercos-Hickey, E., Nathan, T. R., and Chen, S.-H.: On the relationship between the African Easterly Jet, Saharan Mineral Dust Aerosols, and West
African Precipitation, J. Climate, 33, 3533–3546, https://doi.org/10.1175/jcli-d-18-0661.1, 2020. 4. Berger, A.: Milankovitch theory and climate, Rev. Geophys., 26, 624–657,
https://doi.org/10.1029/RG026i004p00624, 1988. 5. Biasutti, M. and Sobel, A. H.: Delayed Sahel rainfall and global seasonal
cycle in a warmer climate, Geophys. Res. Lett., 36, L23707,
https://doi.org/10.1029/2009gl041303, 2009.
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