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Abstract Proxy reconstructions from the mid‐Holocene (MH: 6,000 years ago) indicate an intensification of the West African Monsoon and a weakening of the South American Monsoon, primarily resulting from orbitally‐driven insolation changes. However, model studies that account for MH orbital configurations and greenhouse gas concentrations can only partially reproduce these changes. Most model studies do not account for the remarkable vegetation changes that occurred during the MH, in particular over the Sahara, precluding realistic simulations of the period. Here, we study precipitation changes over northern Africa and South America using four fully coupled global climate models by accounting for the Saharan greening. Incorporating the Green Sahara amplifies orbitally‐driven changes over both regions, and leads to an improvement in proxy‐model agreement. Our work highlights the local and remote impacts of vegetation and the importance of considering vegetation changes in the Sahara when studying and modeling global climate.
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Speleothems of South American and Asian Monsoons Influenced by a Green Sahara
Abstract 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 δ18O 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 δ18O 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.
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- Award ID(s):
- 1804747
- PAR ID:
- 10362118
- Publisher / Repository:
- DOI PREFIX: 10.1029
- Date Published:
- Journal Name:
- Geophysical Research Letters
- Volume:
- 47
- Issue:
- 22
- ISSN:
- 0094-8276
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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