Recurring summer and winter droughts from 4.2-3.97 thousand years ago in north India

Creators: Giesche, Alena; Hodell, David A.; Petrie, Cameron A.; Haug, Gerald H.; Adkins, Jess F.; Plessen, Birgit; Marwan, Norbert; Bradbury, Harold J.; Hartland, Adam; French, Amanda D.; Breitenbach, Sebastian F. M.

Abstract

The 4.2-kiloyear event has been described as a global megadrought that transformed multiple Bronze Age complex societies, including the Indus Civilization, located in a sensitive transition zone with a bimodal (summer and winter) rainfall regime. Here we reconstruct changes in summer and winter rainfall from trace elements and oxygen, carbon, and calcium isotopes of a speleothem from Dharamjali Cave in the Himalaya spanning 4.2–3.1 thousand years ago. We find a 230-year period of increased summer and winter drought frequency between 4.2 and 3.97 thousand years ago, with multi-decadal aridity events centered on 4.19, 4.11, and 4.02 thousand years ago. The sub-annually resolved record puts seasonal variability on a human decision-making timescale, and shows that repeated intensely dry periods spanned multiple generations. The record highlights the deficits in winter and summer rainfall during the urban phase of the Indus Civilization, which prompted adaptation through flexible, self-reliant, and drought-resistant agricultural strategies.

Additional Information

© The Author(s) 2023. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/. The authors would like to thank Dr. Giulio Lampronti for assistance with XRD measurements at the University of Cambridge. N.M. received financial support from the German Science Foundation (DFG projects MA4759/9-1 and MA4759/11-1). A.G., D.A.H., and C.A.P. received support from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (grant agreement no 648609). A.G., A.H. and S.F.M.B. received support from the European Union's Horizon 2020 program (QUEST project, grant agreement no 691037), C.A.P. received funding from the Global Challenges Research Fund's TIGR2ESS project (BB/P027970/1), and A.H. was further supported by Rutherford Discovery Fellowship (RDF-UOW1601) awarded by Royal Society Te Apārangi. Calcium isotope analyses were supported through NERC NE/R013519/1 (H.J.B.). No permissions were required for sampling, but we gratefully acknowledge the support of the local village leaders and accompanying guide. Contributions. A.G., D.A.H., C.A.P., and S.F.M.B. designed research; A.G., S.F.M.B., A.D.F., H.J.B., G.H.H., J.F.A., B.P., and N.M. performed research; A.G., A.H., D.A.H., and S.F.M.B. analyzed data; A.G. and S.F.M.B. prepared figures; A.G., D.A.H., C.A.P., H.J.B., and S.F.M.B. wrote the paper. The authors declare no competing interests.

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