Productivity collapses in the Arabian Sea during glacial cold phases

Productivity in the Arabian Sea is one of the highest in the world. It is controlled by seasonally reversing monsoonal wind‐driven upwelling of nutrient‐rich deeper waters which fuel phytoplankton growth. The detailed history of upwelling‐induced productivity in the eastern Arabian Sea is unknown. H...

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Bibliographic Details
Published in:Paleoceanography 2011-09, Vol.26 (3), p.n/a
Main Authors: Singh, Arun Deo, Jung, Simon J. A., Darling, Kate, Ganeshram, Raja, Ivanochko, Tara, Kroon, Dick
Format: Article
Language:English
Subjects:
Arabian Sea
Climate change
Holocene
Marine
millennial-scale monsoon change
Monsoons
Oceanography
Organic carbon
Paleoclimate science
Phytoplankton
Productivity
Relative abundance
Upwelling
Water column
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Summary:Productivity in the Arabian Sea is one of the highest in the world. It is controlled by seasonally reversing monsoonal wind‐driven upwelling of nutrient‐rich deeper waters which fuel phytoplankton growth. The detailed history of upwelling‐induced productivity in the eastern Arabian Sea is unknown. Here we present paleoproductivity records from a composite sediment core at the millennial scale during the last 80 kyr B.P. These records are based on relative abundance counts of planktonic foraminifera and organic carbon contents, which are shown to mainly vary in concert. The eastern Arabian Sea upwelling‐induced productivity was higher in the glacial period than in the Holocene, but it fell repeatedly on millennial timescales. These productivity declines occurred during cold events in the North Atlantic region, with the most pronounced changes prevailing during the Heinrich events. Hence, seasonal monsoon winds that drive upwelling‐induced productivity in the east were weak when the North Atlantic was cold. These weak winds resulted in stratification of the water column, comparable to today's Arabian Sea stratification in the intermonsoonal period. Combining the new eastern with published western Arabian Sea results shows that the entire biological factory was severely diminished during the North Atlantic Heinrich events, and the seasonal productivity change in the Arabian Sea monsoon system was reduced with year‐round low productivity. Key Points Synchronous millennial‐scale productivity change in the Arabian Sea Glacial‐interglacial productivity change
ISSN:0883-8305
2572-4517
1944-9186
2572-4525
DOI:10.1029/2009PA001923