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Clemens, Steven C.; Yamamoto, Masanobu; Thirumalai, Kaustubh; Giosan, Liviu; Richey, Julie N.; Nilsson-Kerr, Katrina; Rosenthal, Yair; Anand, Pallavi and McGrath, Sarah M.
(2021).
DOI: https://doi.org/10.1126/sciadv.abg3848
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 CO2 changes at Earth-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 CO2 levels is fully consistent with dynamics of the past 0.9 million years.