‘Big Dry’ worst drought since European settlement

Image source: Tim Keegan

The severe drought that afflicted South Eastern Australia from 1997–2009 ‘Big Dry’ is likely to have been the worst since first European settlement according to a new study by climate scientists at the University of Melbourne.

The researchers used data derived from tree rings and coral records to determine that there is a 97% chance that 1998–2008 was the driest decade since 1788.  This conclusion was derived from a 206-year rainfall reconstruction, which has been accepted for publication in the US journal Climatic Change.

“This study is an example of the importance of understanding of pre-industrial climate variations unavailable from modern meteorological observations” said lead author Dr Joelle Gergis. “Our study shows that while rainfall has varied naturally over time, the recent drought may have been exacerbated by the 1oC increase in maximum temperatures observed in the south-eastern Australian region over the past 50 years’.

The rainfall reconstruction also indicates that relatively wet conditions prevailed during the first 45 years of European settlement, with a pronounced wet period centered on the 1820s – a period of rapid agricultural expansion. Evidence for this wet period was also found in historical descriptions of water level fluctuations in Lake George in the ACT, which is known to rise and fall in response to variations in rainfall.

The study is part of the South Eastern Australian Recent Climate History (SEARCH) project, run by experts in the fields of paelaoclimatology, meteorology and history. The SEARCH team is working to extend the climate record for South Eastern Australia that will help our understanding of the drivers of Australian climate and how they have changed over past centuries.