Protracted Indian monsoon droughts of the past millennium and their societal impacts

Severe and long-lasting droughts represent one of the greatest potential threats to human societies in the Indian subcontinent. While historical documentary sources from the region provide vivid accounts of catastrophic drought-related famines and mass mortality events, these accounts are fragmentary, and their veracity cannot always be confirmed. In this study, we have used the oxygen isotopes in speleothems from northeast India to reconstruct a history of Indian summer monsoon droughts over the past millennium with an unprecedented dating accuracy comparable in precision to historical records. Our reconstructed summer monsoon drought history is in striking synchrony with the historical evidence and provides important context against which the key geopolitical and societal changes and their links to climate can be assessed.