Speleothems of South American and Asian Monsoons influenced by a green Sahara

The mid-Holocene is frequently used for climate model-proxy comparison studies, yet models often struggle to replicate the proxy signals from this period. Here, we use an Earth system model that tracks water isotopologies to determine the importance of a vegetated Sahara in the simulation of mid-Holocene climate, with a focus on delta O-18 values recorded in speleothems from the South American and Asian monsoon regions. We find that inclusion of a vegetated Sahara during the mid-Holocene leads to global warming and generally amplifies the changes in the delta O-18 values of the precipitation in the South American and Asian monsoon regions relative to preindustrial; both feedbacks improve model-proxy agreement. 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.