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Antarctic ice reveals insights into history of Australian rainfall

New research into Antarctic ice cores has revealed that the past 115 years’ worth of instrumental rainfall records in eastern Australia do not represent the full range of drought events possible — both now and in the future.

Published in the Journal of Hydrology: Regional Studies, the study focused on the Lockyer catchment in South-East Queensland, which shares an atmospheric link with Antarctica that influences rainfall in the region.

Led by Matthew Armstrong and Dr Anthony Kiem from the University of Newcastle, and involving Dr Tessa Vance from the Australian Antarctic Program Partnership, the study compared past rainfall records from rain gauges and ice cores, and future rainfall projections from global climate models.

“The ice cores, from Law Dome in East Antarctica, contain a history of natural climate variability over the past 1000 years, which can be used to infer east Australian rainfall over that time,” Vance said.

“This allows us to better understand the natural variability in rainfall in the region, including prolonged droughts, before instrumental records began.”

The comparison revealed that instrumental records do not encompass the full range of hydroclimatic conditions that could be possible from now until 2100.

The study observed significantly drier periods in the palaeoclimate record than are projected by the "worst case scenario" in climate models.

Armstrong said the results indicate that natural resource managers, including water utilities, use three forms of rainfall information to develop water management plans, including instrumental data collected from rain gauges with palaeoclimate data — ice cores — and climate models.

“[The results indicate] water management strategies developed using only instrumental data underestimate current and future hydroclimatic risk,” Armstrong said.

“Our study recommends that water managers evaluate the performance of existing water supply systems using a combination of instrumental, palaeoclimate and projected model data.”