RECONSTRUCTING PAST TEMPERATURE FROM LAKE SEDIMENTS IN DARWIN CRATER, TASMANIA, AUSTRALIA USING THE BRGDGT BIOMARKER PROXY

Reconstruction of past temperature and other paleoenvironmental conditions has increasingly become important to improve our understanding of the climate system and to prepare for future climate because past conditions, especially intervals warmer than today, are useful analogs for future climate under ongoing global warming. In this project, we reconstructed past temperature from samples collected from a lake sediment core from Darwin Crater, western Tasmania, Australia using the brGDGT biomarker paleotemperature proxy. The Darwin Crater sediment record is a powerful archive for paleoclimatic reconstructions as it spans approximately the last 800,000 years, consisting of multiple glacial-interglacial cycles. In this work, we focused on a recent glacial-interglacial cycle to explore the efficacy of the brGDGT biomarker proxy and the collection of Darwin Crater’s lake sediment samples for reconstructing regional paleoclimate in western Tasmania. Through this project, we aimed 1) to advance our understanding of regional paleoclimate and paleoenvironment in Tasmania, Australia over long timescales, and 2) to contribute to the scientific community’s understanding of the brGDGT (branched glycerol dialkyl glycerol tetraether) biomarker as a relatively new paleotemperature proxy. Our results suggest that the brGDGT biomarker is capturing temperature variability that likely relates to a shift from glacial to interglacial conditions at the site, though this signal may be influenced by local changes in the depositional environment. Our study illustrates both the usefulness of this biomarker as a paleotemperature proxy, as well as some potential limitations.