Australia's worst drought linked to global warming

Posted: 14 January 2003

A new scientific report released by WWF and leading meteorologists shows that human-induced global warming was a key factor in the severity of the 2002 drought in Australia.

The report, Global Warming Contributes to Australia's Worst Drought, compares the 2002 drought with the four other major droughts in the country since 1950 and has found higher temperatures caused a marked increase in evaporation rates from soil, watercourses and vegetation. The report warns that higher temperatures and drier conditions have created greater bushfire danger than previous droughts. Drought severity also has increased in the Murray Darling Basin, which produces 40 per cent of Australia's agricultural produce.

The report states that in 2002 Australia recorded its highest-ever average March-November daytime maximum temperature, with the temperature across Australia 1.6°C higher than the long term average and 0.8°C higher than the previous record. The Murray Darling Basin experienced average maximum temperatures more than 1.2°C higher than in any previous drought since 1950.

"The higher temperatures experienced throughout Australia last year are part of a national warming trend over the past 50 years which cannot be explained by natural climate variability alone," said Professor David Karoly, formerly Professor of Meteorology at Monash University, who co-authored the report with Dr James Risbey from Monash University's School of Mathematical Sciences, and Anna Reynolds, WWF Australia's Climate Change Campaign manager. "Most of this warming is likely due to the increase in greenhouse gases in the atmosphere from human acitivity such as burning fossil fuels for electricity and transport and from landclearing."

According to Professor Karoly, the actual trend in Australian temperature since 1950 is now matching the climate model studies of how temperatures respond to increased greenhouse gases in the atmosphere. He believes that this is the first drought in Australia where the impact of human-induced global warming can be clearly observed.

Dr James Risbey said that although the 2002 drought was related to natural climate variations associated with El Niño, the higher temperatures could not be attributed solely to this factor: "While higher temperatures are expected during El Niño triggered droughts, the 2002 drought temperatures are extraordinary when compared to the four major droughts since 1950, with average maximum temperatures more than 1°C higher than these other droughts."

The report contains new data on evaporation rates and says low rainfall and higher evaporation has adversely impacted on agricultural productivity with lower crop production leading to lower export earnings for farmers. According to Anna Reynold, global warming is a reality that is affecting the livelihoods of rural Australians. WWF is urging Prime Minister Howard to act to prevent further economic and environmental devastation. "We can slow global warming, keep temperature increases to the lower end of the scale and reduce the severity of future droughts. The Kyoto Protocol is the first international agreement with targets for reducing greenhouse gas emissions and slowing global warming - it is in our national interest to ratify the treaty," she said.

The report can be downloaded from www.wwf.org.au and print quality graphs can be accessed at www.maths.monash.edu.au/~ris/drought.shtml