Local and Regional Indian Summer Monsoon Precipitation Dynamics During Termination II and the Last Interglacial

Matthias Magiera, Franziska A. Lechleitner, Andrea M. Erhardt, Adam Hartland, Ola Kwiecien, Hai Cheng, Harold J. Bradbury, Alexandra V. Turchyn, Sylvia Riechelmann, Lawrence Edwards, Sebastian F.M. Breitenbach

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

To date Indian summer monsoon (ISM) dynamics have been assessed by changes in stalagmite δ18O. However, stalagmite δ18O is influenced by multiple environmental factors (e.g., atmospheric moisture transport, rainfall amount at the study site, and ISM seasonality), precluding simple and clear reconstructions of rainfall amount or variability. This study aims to disentangle these environmental factors by combining δ18O, δ44Ca, and elemental data from a stalagmite covering Termination II and the last interglacial from Mawmluh Cave, NE India, to produce a semiquantitative reconstruction of past ISM rainfall. We interpret δ18O as a mixed signal of rainfall source dynamics and rainfall amount and coupled δ44Ca and X/Ca ratios as indicators of local infiltration rate and prior calcite precipitation in the karst zone. The wettest conditions in our studied interval (135 and 100 kyrs BP; BP = before present, with the present being 1950 CE) occurred during Marine Isotope Stage 5e. Our multiproxy data set suggests a likely change in seasonal distribution of Marine Isotope Stage 5e rainfall compared to the Holocene; the wet season was longer with higher-than-modern dry season rainfall. Using the last interglacial as an analogue for future anthropogenic warming, our data suggest a more erratic ISM behavior in a warmer world.

Original languageEnglish (US)
Pages (from-to)12454-12463
Number of pages10
JournalGeophysical Research Letters
Volume46
Issue number21
DOIs
StatePublished - Nov 16 2019

Bibliographical note

Funding Information:
This study received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska‐Curie grant 691037 (to SFMB, OK, AH). Calcium isotope analyses were supported through ERC StG 307582 CARBONSINK (to AVT) and NERC NE/R013519/1 (to HJB). Financial support came from the National Natural Science Foundation of China (NSFC‐41731174, to HC and LE), an award from the palaeoclimate program by the National Science Foundation (NSF‐1702816, to HC and LE), and a Rutherford Discovery Fellowship award (RDF‐UOW1601, to AH). Gregory Diengdoh (Shillong) is thanked for helping during sampling and Ingrid Lindeman (University of Waikato) for assistance in measuring trace elements. We thank Beate Gehnen for assisting with stable isotope analysis. We thank Daniel E. Ibarra and an anonymous reviewer for their critical feedback on earlier versions of this manuscript and the editorial team of GRL for handling our submission All data will be archived on the NOAA website ( https://www.ncdc.noaa.gov/paleo/study/27990 ).

Funding Information:
This study received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sk?odowska-Curie grant 691037 (to SFMB, OK, AH). Calcium isotope analyses were supported through ERC StG 307582 CARBONSINK (to AVT) and NERC NE/R013519/1 (to HJB). Financial support came from the National Natural Science Foundation of China (NSFC-41731174, to HC and LE), an award from the palaeoclimate program by the National Science Foundation (NSF-1702816, to HC and LE), and a Rutherford Discovery Fellowship award (RDF-UOW1601, to AH). Gregory Diengdoh (Shillong) is thanked for helping during sampling and Ingrid Lindeman (University of Waikato) for assistance in measuring trace elements. We thank Beate Gehnen for assisting with stable isotope analysis. We thank Daniel E. Ibarra and an anonymous reviewer for their critical feedback on earlier versions of this manuscript and the editorial team of GRL for handling our submission All data will be archived on the NOAA website (https://www.ncdc.noaa.gov/paleo/study/27990).

Keywords

  • Indian summer monsoon
  • Marine Isotope Stage 5e
  • Termination II
  • dry season rainfall
  • seasonality
  • speleothem

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