Heinrich events drove major intensification of the Indo-Australian monsoon over the last 150,000 years

Abstract

Abstract Nearly two thirds of the world’s population depend on monsoon rainfall. Monsoon failure and extreme precipitation have affected societies for millennia. The distribution and amount of monsoon precipitation is predicted to change as the climate warms, albeit with uncertain regional trajectories. Multiple glacial-interglacial terrestrial records of east Asian monsoon variability have been developed, but there are no terrestrial records of equivalent length of the coupled Indo-Australian monsoon at the southern monsoon limit — Australia. Here we present a continuous, absolute-dated, 150,000-year record of monsoon dynamics from a permanent lagoon in the core monsoon region of northern Australia. We show that Australian rainfall is broadly anti-phased with the East Asian monsoon. We identify periods of intense monsoon activity associated with high local insolation in Marine Isotope Stage 5 during ‘megalake’ phases in Australia’s arid interior. We also identify periods of monsoon intensification that are associated with Heinrich events and coincide with weak monsoon events in East Asia. The results suggest that strong asymmetry in inter-hemispheric monsoon rainfall might accompany the current weakening in the strength of the Atlantic meridional overturning circulation. This asymmetry will involve drying in the heavily populated regions north of the equator, and intensification of rainfall in northern Australia.