[U-03] Advanced understanding of Quaternary and Anthropocene hydroclimate changes in East Asia

[U03-P15] Contribution of Lakes in Sustaining Greening of the Sahara during the Mid-Holocene

*Yuheng LI¹、Kanon Kino¹、Alexandre CAUQUOIN²、Taikan Oki¹ (1.Department of Civil Engineering, The University of Tokyo、2.Institute of Industrial Science, The University of Tokyo)

キーワード：Green Sahara, West African Monsoon, Lake Contribution

The contribution of lake-climate feedback to sustain the Green Sahara in the mid-Holocene (MH, 6000 years ago) is debatable. To assess the lake-induced climate response over North Africa, we investigated the roles of western Sahara lakes and Megalake Chad using the isotope-enabled fifth version of the Model for Interdisciplinary Research on Climate (MIROC5-iso) based on reconstructions of MH Sahara lake maps. The western Sahara lakes pushed the West African monsoon northward and extended it eastward by expanding Megalake Chad. Such lake-climate feedback was caused by the cyclonic circulation response related to weakened African Easterly Jet and enhanced Tropical Easterly Jet. Based on Budyko’s aridity index results, the northwestern Sahara climate region shifted from hyper-arid to arid or semi-arid with lake expansion. Moreover, precipitation scarcity could reduce by up to 13% to sustain semi-humid conditions. Our findings indicate a promising method to understand the contribution of lakes in sustaining the Green Sahara.