Preprints
https://doi.org/10.5194/cp-2023-11
https://doi.org/10.5194/cp-2023-11
20 Mar 2023
 | 20 Mar 2023
Status: a revised version of this preprint was accepted for the journal CP and is expected to appear here in due course.

Contribution of Lakes in Sustaining Greening of the Sahara during the Mid-Holocene

Yuheng Li, Kanon Kino, Alexandre Cauquoin, and Taikan Oki

Abstract. The contribution of lake-climate feedback 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. Such lake-climate feedback was caused by the cyclonic circulation response related to weakened African Easterly Jet and enhanced Tropical Easterly Jet. According to Budyko aridity index, the northwestern Sahara climate region shifted from hyper-arid to arid or semi-arid with lake expansion. Moreover, precipitation scarcity could be reduced by up to 13 % to sustain semi-humid conditions. Such lake-climate feedback alleviates the Sahara aridity but relies on lake positions in the monsoon regions. Our findings are promising for understanding the contribution of lakes to sustaining the Green Sahara.

Yuheng Li et al.

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on cp-2023-11', Anonymous Referee #1, 21 Apr 2023
  • RC2: 'Comment on cp-2023-11', Anonymous Referee #2, 26 Apr 2023
  • EC1: 'Comment on cp-2023-11, reviews and response', Martin Claussen, 12 Jun 2023

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on cp-2023-11', Anonymous Referee #1, 21 Apr 2023
  • RC2: 'Comment on cp-2023-11', Anonymous Referee #2, 26 Apr 2023
  • EC1: 'Comment on cp-2023-11, reviews and response', Martin Claussen, 12 Jun 2023

Yuheng Li et al.

Yuheng Li et al.

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Short summary
Our study using the isotope-enabled climate model MIROC5-iso model shows that lakes may have contributed to the Green Sahara during the mid-Holocene period (6000 years ago). The lakes induced cyclonic circulation response, enhancing the near-surface monsoon westerly flow and potentially humidifying the northwestern Sahara with the enhanced West African Monsoon moving northward. Our findings provide valuable insights into understanding the presence of the Green Sahara during this period.