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Paleoclimatic records from the Bay of Bengal are rare. We reconstruct the sea-surface temperature (SST) 18 O sw values suggest that the monsoon was stronger and wetter resulting in a humid climate. After ~5 ka the Indian summer monsoon weakened significantly, indicating less dilution of the sea surface by the Ganges-Brahmaputra-Meghna outflow and/or less direct rainfall. We hypothesize that the prevailing late Holocene dry climate may have caused the diminishment and subsequent abandonment of the settlements of the great Indus Valley Civilizations. Our Bay of Bengal climate records are consistent with those from the Andaman Sea, corroborating broad regional changes in the Indian summer monsoon during the last 25 ka. The general pattern and timing of monsoon variability in the Bay of Bengal and Andaman Sea seems to parallel the Arabian Sea, Africa, and Asian ice cores and speleothem records suggesting that a common tropical forcing may have induced these abrupt climate changes.

[1] An additional Heinrich ice-rafting event is identified between Heinrich events 5 and 6 in eight cores from the Labrador Sea and the northwest Atlantic Ocean. It is characterized by sediment rich in detrital carbonate (40% CaCO 3 ) with high concentration of floating dropstones, high coarse-fraction (% > 150 mm) content, and has a sharp contact with the underlying but grades into the overlying hemipelagic sediment. It also shows lighter d18 O Npl values, indicating freshening due to iceberg rafting and/or meltwater discharge. This event is correlated with Dansgaard-Oeschger event 14 and interpreted as an additional Heinrich event, H5a. The thickness of H5a in the Labrador Sea reaches up to 220 cm. This additional Heinrich event has also been reported in cores PS2644 and SO82-5 from the northern North Atlantic. With the recognition of H5a the temporal spacing between Heinrich events 1 to 6 becomes more uniform ($7 ka).

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