EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Speleothems of South American and Asian Monsoons Influenced by a Green Sahara

Clay Tabor1, Bette Otto-Bliesner2, and Zhengyu Liu3
Clay Tabor et al.
  • 1University of Connecticut, Geosciences, Storrs, United States of America (
  • 2National Center for Atmospheric Research, Boulder, United States of America (
  • 3Department of Geography, The Ohio State University, Columbus, United States of America (

Compared to preindustrial, the mid-Holocene (6 ka) had significantly greater Northern Hemisphere summer insolation, slightly warmer global surface temperature, and slightly lower CO2 concentration. Vegetation was also different during the mid-Holocene. Possibly most prominent was the growth of temperate vegetation in the now barren Sahara. This Saharan vegetation response was related to intensification of the African Monsoon associated with the mid-Holocene orbital configuration. Hydroclimate of the Asian Monsoon and South American Monsoon also responded to mid-Holocene forcings, with general wetting and drying, respectively.

The mid-Holocene is frequently used for model-proxy comparison studies. However, climate models often struggle to replicate the proxy signals of this period. Here, we attempt to reduce these model-proxy discrepancies by exploring the significance of a vegetated Sahara during the mid-Holocene. Using the water isotopologue tracer enabled version of the Community Earth System Model (iCESM1), we perform mid-Holocene simulations that include and exclude temperate vegetation in the Sahara. We compare our model results with δ18O values from mid-Holocene speleothem records in the Asian and South American Monsoon regions.

We find that inclusion of vegetated Sahara during the mid-Holocene leads to global warming, alters the hemispheric distribution of energy, and generally amplifies the δ18O of precipitation responses in the South American and Asian Monsoon regions; these feedbacks improve the δ18O agreement between model outputs and speleothem records of the mid-Holocene. Our results highlight the importance of regional vegetation alteration for accurate simulation of past climate, even when the region of study is far from the source of vegetation change.

How to cite: Tabor, C., Otto-Bliesner, B., and Liu, Z.: Speleothems of South American and Asian Monsoons Influenced by a Green Sahara, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13896,, 2021.

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