Abrupt changes in Indian summer monsoon strength during 33,800 to 5500years B.P.

Speleothem proxy records from northeastern (NE) India reflect seasonal changes in Indian summer monsoon strength as well as moisture source and transport paths. We have analyzed a new speleothem record from Mawmluh Cave, Meghalaya, India, in order to better understand these processes. The data show a strong wet phase 33,500-32,500years B.P. followed by a weak/dry phase from 26,000 to 23,500years B.P. and a very weak phase from 17,000 to 15,000years B.P. The record suggests abrupt increase in strength during the Bølling-Allerød and early Holocene periods and pronounced weakening during the Heinrich and Younger Dryas cold events. We infer that these changes in monsoon strength are driven by changes in temperature gradients which drive changes in winds and moisture transport into northeast India. Key Points Longest record of summer precipitation from speleothem from India Abrupt changes in summer monsoon precipitation Less precipitation during Younger Dryas and Heinrich events.