Remote and local drivers of Pleistocene South Asian summer monsoon precipitation: A test for future predictions

Steven C Clemens; Masanobu Yamamoto; Kaustubh Thirumalai; Liviu Giosan; Julie N Richey; Katrina Nilsson-Kerr; Yair Rosenthal; Pallavi Anand; Sarah M McGrath

doi:10.1126/sciadv.abg3848

Remote and local drivers of Pleistocene South Asian summer monsoon precipitation: A test for future predictions

Sci Adv. 2021 Jun 4;7(23):eabg3848. doi: 10.1126/sciadv.abg3848. Print 2021 Jun.

Authors

Steven C Clemens¹, Masanobu Yamamoto², Kaustubh Thirumalai³, Liviu Giosan⁴, Julie N Richey⁵, Katrina Nilsson-Kerr⁶, Yair Rosenthal⁷, Pallavi Anand⁶, Sarah M McGrath⁸

Affiliations

¹ Earth, Planetary, and Environmental Sciences, Brown University, Providence, RI, USA. steven_clemens@brown.edu.
² Faculty of Environmental Earth Science, Hokkaido University, Sapporo, Japan.
³ Department of Geosciences, University of Arizona, Tucson, AZ, USA.
⁴ Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA, USA.
⁵ U.S. Geological Survey, St. Petersburg, FL, USA.
⁶ School of Environment, Earth and Ecosystem Sciences, The Open University, Milton Keynes, UK.
⁷ Institute for Marine and Coastal Sciences and Department of Geology, Rutgers, State University of New Jersey, New Brunswick, NJ, USA.
⁸ Earth, Planetary, and Environmental Sciences, Brown University, Providence, RI, USA.

Abstract

South Asian precipitation amount and extreme variability are predicted to increase due to thermodynamic effects of increased 21st-century greenhouse gases, accompanied by an increased supply of moisture from the southern hemisphere Indian Ocean. We reconstructed South Asian summer monsoon precipitation and runoff into the Bay of Bengal to assess the extent to which these factors also operated in the Pleistocene, a time of large-scale natural changes in carbon dioxide and ice volume. South Asian precipitation and runoff are strongly coherent with, and lag, atmospheric carbon dioxide changes at Earth's orbital eccentricity, obliquity, and precession bands and are closely tied to cross-equatorial wind strength at the precession band. We find that the projected monsoon response to ongoing, rapid high-latitude ice melt and rising carbon dioxide levels is fully consistent with dynamics of the past 0.9 million years.

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