School of Geography - Theses
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ItemData synthesis and modern cave process studies in southeastern Australia: towards improving regional palaeoclimate records for the Common Era( 2019)Hydroclimate variability has profound socioeconomic and environmental impacts in Australia. Therefore, it is of vital importance to understand the influences and range of variability through time. The past 2,000 years is advocated as an appropriate period for establishing a baseline of recent natural climate variability. My research examines climate variability in southeast Australia during the last 2000 years through two objectives: (i.) The collation and systematic review of existing Australasian non-annually resolved palaeoclimate records and application of suitable records to reconstructing hydroclimate in southeast Australia during the Common Era, and (ii.) the construction of an informed palaeoclimate record for the purpose of expanding knowledge of the climate of the last 2000 years in southeast Australia. The findings of the first objective suggest that although there are few records that are ideal for examining climate during the Common Era, a small subset of quality controlled records is effective for examining hydroclimate variability in southeast Australia. Two regional modes of climate variability demonstrate an increase in effective moisture between 900CE and 1750CE and suggest that seasonality of rainfall and the influence of Southern Hemisphere circulation patterns affect effective moisture on multi-decadal time scales. Outcomes of the second objective indicate that oxygen isotopes in Kangaroo Island precipitation reflect rainfall amount on daily to monthly time scales, but moisture source controls seasonal amount-weighted averages. Changes in rainfall seasonality may distort the rainfall amount signature in amount-weighted annual mean isotopic values. Speleothems (i.e. cave formations) from Kelly Hill Cave on Kangaroo Island predominantly reflect rainfall chemistry, which is influenced by both the rainfall amount and temperature-controlled effective moisture. Overall, the two palaeoclimate reconstructions presented in this thesis furthers our understanding of hydroclimate variability in southern Australia during the last two millennia, and highlights the importance of the temperature component in determining regional and local effective moisture.