Inter-hemispheric Dynamics of the Indian Summer Monsoon across the Penultimate Deglaciation
Abstract
The Indian Summer Monsoon (ISM) represents one of Earth's most dynamic interactions of ocean-atmosphere-terrestrial interactions yet is underrepresented in paleoclimate records due to the existence of spatial and temporal gaps. Our understanding of the paleoclimate ISM beyond the last glacial period has mainly been shaped by orbital scale ISM records that capture wind driven upwelling from the Arabian Sea and southern Bay of Bengal.
Here we present geochemical records at a sub-millennial scale ( 250 to 500 years) capturing oxygen isotope composition of seawater (coupled oxygen isotopes and Mg/Ca) in response to ISM induced river runoff and terrigenous input (Nd/Ca, U/Ca and Mn/Ca) from surface ocean dwelling foraminifera (Globigerinoides ruber sensu-stricto) across the penultimate deglaciation (127 to 139 thousand years ago). We combine these foraminifera geochemical records with discrete bulk sediment elemental composition obtained on the same sample to further constrain terrigenous inputs during periods of increased river runoff. Our study site location in the northern Bay of Bengal is proximal to river runoff derived from both the Mahanadi and Ganges-Brahmaputra river systems, we infer that a primary ISM signal is captured in the proxy records. We discuss how our findings provide new constraints on ISM dynamics across a glacial-interglacial transition, insights into the role of the tropics on the global climate stage and challenge previous assumptions about the Asian Monsoon system.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMPP22C..06N
- Keywords:
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- 9340 Indian Ocean;
- GEOGRAPHIC LOCATIONDE: 1615 Biogeochemical cycles;
- processes;
- and modeling;
- GLOBAL CHANGEDE: 1807 Climate impacts;
- HYDROLOGYDE: 4904 Atmospheric transport and circulation;
- PALEOCEANOGRAPHY