Last Glacial Maximum cooling induced positive moisture balance and maintained stable human populations in Australia

Long-standing interpretations of the Last Glacial Maximum (21,000 ± 2000 years ago) in Australia suggest that the period was extremely cold and arid, during which the Indo-Australian summer monsoon system collapsed, and human populations declined and retreated to ecological refuges to survive. Here, we use transient iTRACE simulations, combined with palaeoclimate proxy records and archaeological data to re-interpret the late Last Glacial Maximum and terminal Pleistocene (21,000 – 11,000 years) in Australia. The model suggests climates during the peak Last Glacial Maximum were cooler than present (−4 to −11 °C), but there is no evidence of monsoon collapse or substantial decreases in moisture balance across Australia. Kernel Density Estimates of archaeological ages show relatively stable and persistent human activity across most regions throughout the late Last Glacial Maximum and terminal Pleistocene, consistent with genetic evidence. Spatial coverage of archaeological sites steadily increased across the terminal Pleistocene; however, substantial population change is not evident.