Abrupt Indian summer monsoon shifts aligned with Heinrich events and D-O cycles since MIS 3

The tropics experienced a unique monsoon climate that drove important changes in socio-economic conditions and shaped different phases of human history during the late Quaternary across the Indian subcontinent. This study presents a new high-resolution speleothem-record of Indian summer monsoon (ISM) variability ranging from similar to 45,000 to 34,000 yr BP combined with a published record up to 5500 yr BP from the Mawmluh cave, northeastern India. We document significant changes in solar insolation and precession harmonics, implicating solar activity as one of the major forcing factors for rapid monsoonal shifts. Our new delta O-18 time series shows high-amplitude shifts in the ISM during the marine isotope stage 3 (MIS 3), similar to Dansgaard-Oeschger (D-O) oscillations recorded at high northern latitudes, which mimic the Greenland ice sheet record. The sun driven Northern Hemisphere high latitude climate anomalies played an active role in driving ISM variability and changes in the regional hydrological cycle on centennial to millennial time scales across the Indian subcontinent.

Automated summary

The study suggests that solar activity is a key driving factor for rapid changes in the Indian summer monsoon, with monsoonal shifts influenced by changes in solar insolation and precession harmonics. The new δO-18 time series indicates high-amplitude shifts in the Indian summer monsoon during marine isotope stage 3, similar to oscillations recorded in high northern latitudes.