The Younger Dryas: Relevant in the Australian region?

摘要

An assessment of Australian climate during the Younger Dryas Chronozone (YDC) is presented. This review focuses on securely dated records from sites of continuous deposition, placing greatest emphasis on temperature reconstructions, with records of effective precipitation (i.e. the combined effect of precipitation minus evapotranspiration) also considered. While there is a paucity of Australian records covering the last glacial interglacial transition, particularly those which directly infer temperature, sufficient data exist to examine YDC climate from southern and eastern Australia. Temperature reconstructions from Tasmania, based on both chironomid and pollen data, show no evidence for Younger Dryas cooling. By contrast there is evidence for cooling associated with the Antarctic Cold Reversal, from Tullabardine Dam pollen data and the sediment organic content from Eagle and Platypus Tarns in Tasmania. Records from a number of eastern Australian mainland sites provide no evidence of effective precipitation shifts concurrent with the Younger Dryas Chronozone. Similarly, reconstructions of discharge from the Murray-Darling Basin, which covers a large proportion (14%) of the Australian continent, and dust transport from a larger portion of the continent also show no evidence of climate shifts concomitant with the Younger Dryas. Of research published in the past decade, only one study, located in the Great Australian Bight, claims evidence of a YDC cooling (Andres et al., 2003). By contrast, this review suggests that there is no conclusive evidence for cooling, or indeed any distinctive climate patterning, during the Younger Dryas Chronozone in Australia.