GLOBAL COMPARISONS OF SOUTHERN-HEMISPHERE CLIMATES DURING THE LAST GLACIAL MAXIMUM - ELEMENTS CONCERNING AUSTRALIA ACCORDING TO BIOGEOGRAPHIC AND GEOMORPHOLOGICAL DATA

For more than 20 000 years before about 35 000 - 30 000 BP most Austra lian environments were cool and moist. The period 35 000 - 25 000 BP b roadly represents the hemicycle of Last Glacial (LG) climatic developm ent. Due to imprecise 14C dating of this time-range, and different thr esholds that induced pollen assemblage changes, lake drying, dune buil ding and glacier formation, the data are not strictly comparable betwe en regions. Consequently no date marks the commencement Australia-wide of this phase of inferred cooling and drying climate. The period 25 0 00 - 15 000 BP represents the peak of the LG cycle when dune building was extensive in central Australia, and glaciers formed in New Guinea, the Snowy Mountains and Tasmania. The climate was cold and dry. and m aximum ice advance occurred about 19 000 BP. Cool, relatively dry cond itions persisted until about 12 000 BP when temperatures increased. Ma ximal moisture conditions occurred between 10 000 - 5 000 BP in most r egions with optimal forest development. Cooler, drier conditions succe eded after about 5 000 BP. Increased continentality during the LGM enh anced the Sub Tropical Anticyclone which more strongly influenced peri pheral Australia than today. This reduced incursions of moist easterly air, and meridional intrusions of monsoonal and westerly air. While t he northerly monsoon, and easterly Walker Circulation and trade wind f lows were weaker, the zonal westerlies south of the continent were str onger than today.