The climate of the Last Glacial Maximum in south-eastern Australia

Abstract:

The Last Glaciation Maximum (c. 25-18 kyr) in south-eastern Australia has traditionally been regarded as both significantly colder than the present and much more arid. This was based on a variety of evidence including the dramatic reduction in tree pollen and dune activity in currently humid areas such as the Blue Mountains of NSW. Maintaining arid conditions under significantly lower temperatures is quite challenging and not all lines of evidence supported strong aridity. Over the last four years an ARC project has worked to develop new lines of evidence to test these inferences. Outcomes from the project indicate that winter temperatures were significantly colder than at present (an 8-11 C decrease) while summer temperatures were cooler but not as extreme (4-6.5 C). Moisture balances appear to have been more positive than present along the eastern highlands, while areas to the west were comparatively drier. The humid zone along the divide maintained at least seasonally stronger flows in the major rivers, meaning that water was more available in western districts than under modern climates. I will summarise the evidence for this new pattern and highlight the climatological patterns that would be consistent with the reconstruction. I will conclude by speculating on the implications for both human landscape use and what happened to the vegetation.