Productivity collapses in the Arabian Sea during glacial cold phases
Article first published online: 3 AUG 2011
Copyright 2011 by the American Geophysical Union.
Volume 26, Issue 3, September 2011
How to Cite
2011), Productivity collapses in the Arabian Sea during glacial cold phases, Paleoceanography, 26, PA3210, doi:10.1029/2009PA001923., , , , , and (
- Issue published online: 3 AUG 2011
- Article first published online: 3 AUG 2011
- Manuscript Accepted: 5 MAY 2011
- Manuscript Revised: 15 APR 2011
- Manuscript Received: 29 DEC 2009
- Arabian Sea;
- millennial-scale monsoon change
 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.