High-resolution reconstruction of Indian summer monsoon during the Bølling-Allerød from a central Indian stalagmite

Although the Indian monsoon during the last deglaciation has been reconstructed from marine sediments from the Indian Ocean, a detailed high resolution (decadal or less) reconstruction from terrestrial records such as speleothems has been lacking from the core monsoon zone of India. Such reconstructions can help determine whether the monsoon is controlled by insolation alone or also other feedbacks within the Earth system. We present here a new data set of high resolution record based on 1186 measurements of δ18O from a 43-cm long speleothem from the Kailash Cave, Central India that record Indian Summer Monsoon (ISM) rainfall changes encompassing the Bølling-Allerød interstadial (14.8 to 12.6 ka). The growth rates varied from 0.6 to 37.1 mm/year, with the monsoon strength. This is also confirmed by the δ18O record, with a rapid increase in the rainfall during 14.8 to 14.5 ka, stabilizing subsequently, and exhibiting centennial and multi-decadal oscillations. Our results corroborate an earlier observation that although the boundary conditions during the last several millennia and the Bølling-Allerød were very different, multi-decadal and centennial climate dynamics may have been similar. In addition to solar insolation, our results show a relation of ISM shifts to coupled ocean-atmospheric processes. Strong link of Indian Summer Monsoon (ISM) variability to proxy records from the southern hemisphere is also noted in this work.