Biomarker-based Holocene wildfire history of eastern Kangaroo Island

Since the Silurian, fire has played a pivotal role in the shaping of global landscapes. This is particularly evident for Australia’s environment with biological and biogeochemical processes reliant on a consistent bushfire regime. Throughout the late Holocene, there has been dramatic changes in both the anthropogenic and climatic influence on Australia’s bushfire regime, as a result of colonisation, loss of Indigenous landscape management and global warming. This project focused on reconstructing the wildfire history of eastern Kangaroo Island over the late Holocene, since ~6500 ka. Kangaroo Island was devastated by the 2019-20 summer bushfires, therefore the normality of wildfire events was called into question. By using a multi-proxy approach, coupling pyrogenic polyaromatic hydrocarbons, the anhydrosugar levoglucosan and traditional charcoal data, this allowed for a distinguishment to be made between low intensity bushfires and high intensity wildfire events. It was shown that since ~4000 cal yr there has been a gradual increase in the frequency of burn events, however in the last 1200 ka, the intensity of bushfires has surged. This project demonstrates that the uninhabitance of Kangaroo Island by Indigenous Australians, along with changes in the influence of ENSO may have contributed to the new fire regime we see today.