A fine-resolution reconstruction of climatic variability in southeastern Australia over the last 1500 years

Barr, C; Tibby, J; Gell, PA; Jacobsen, GE; Zawadzki, A

A fine-resolution reconstruction of climatic variability in southeastern Australia over the last 1500 years

Date

2011-07-21

Authors

Publisher

18th INQUA Congress

Abstract

High-resolution palaeoclimate records extend knowledge of long- and short-term climatic variability beyond the limit of instrumental data. However, to date, no millennial-length, sub-decadal resolution climate records have been produced from mainland Australia. In part, this is due to the absence of suitable archives of proxies amenable to high-resolution analysis. Here, we present a study of two crater lakes in western Victoria, southeastern Australia. A diatom-conductivity transfer function was developed specifically for application to oligosaline and mesosaline lakes, such as the two study sites; Lake Elingamite and Lake Surprise. A sub-decadal resolution sampling regime was undertaken and results demonstrate that over the past 1500 years, both lakes responded to a common regional-scale climate signal. Reconstructed conductivity, a proxy for moisture balance, indicates distinct periods of contrasting climates. Both lakes record evidence of a severe, and prolonged, dry phase centered around AD 700, which was more extreme than any subsequent drought. Between ca. AD 900 and 1500, the climate was highly variable, with substantial fluctuations in effective moisture. Thereafter, a period of positive moisture balance is evident from ca. AD 1500-1850, with a marked reduction in the amplitude of variability. Correlations with studies from further afield suggest that ENSO, and possibly the Indian Ocean Dipole, are the key drivers of the observed shifts in moisture balance. These records constitute the first high-resolution evidence of centennial- and decadal-scale climatic variability over the last 1500 years from mainland Australia. This enables a recent major drought to be viewed in an historical context for the first time and provides insight into past climate regimes across southeastern Australia in general, and western Victoria in particular.Copyright (c) 2011 INQUA 18

Keywords

Australia, Victoria, Climatic change, Indian Ocean, Correlations, Lakes

Citation

Barr, C., Tibby, J., Gell, P., Jacobsen, G., Zawaszki, A. (2011). A fine-resolution reconstruction of climatic variability in southeastern Australia over the last 1500 years. Abstract presented to the 18th International Union for Quaternary Research Congress, 21th-27th July 2011, Berne Switzerland.