Australian hydroclimate during Marine Isotope Stage 3: a synthesis and review

Abstract

Improved reconstructions of Australia's climate during Marine Isotope Stage 3 (MIS 3) are important for understanding the environmental context of widespread human settlement of the continent and the extinction of a wide range of megafauna by 45 ± 5 thousand years ago (ka). To better understand spatial and temporal climate trends during this period, we present a synthesis of hydroclimate data from 40 Australian MIS 3 records. Hydroclimate records were evaluated and weighted by a scoring system developed to evaluate dating and proxy quality and resolution before inclusion into the synthesis. Our analysis reveals that Australia experienced spatially variable climates from ∼57 to 49 ka before becoming predominantly wet from ∼49 to 40 ka. After ∼40 ka increasingly dry climates dominated MIS 3. Records from monsoon-influenced regions indicate a rapid drying from ∼48 ka to the end of MIS 3, while there was a wetter period from ∼50 to 40 ka in south westerly wind-influenced records. The implications of our findings are discussed in relation to other proxy records, with there being a significant relationship with regional fire history, but little correlation to atmospheric CO₂ concentration or global sea level.