Global warming aggravates Australia drought - study
Author: Michael Christie
The report, by the environmental group World Wide Fund for Nature Australia and two meteorologists, said record day-time temperatures last year led to unprecedented rates of water evaporation.
It said to some extent the El Nino weather event, produced by a periodic warming of Pacific waters, could be blamed for the heat and dryness, but natural climate variations alone failed to account for all of the temperature anomalies of 2002.
"Most of this warming is likely due to the increase in greenhouse gases in the atmosphere from human activity such as burning fossil fuels for electricity and transport and from land clearing," said a co-author of the WWF study, former Monash University meteorology professor David Karoly.
"This is the first drought in Australia where the impact of human-induced global warming can be clearly seen," he said in a statement released with the report.
The drought, which began in March and is continuing, has savaged Australia's winter wheat crop and cut its sheep flock to numbers not seen since the 1920s. It will slash at least 0.75 percentage points off fiscal 2003 economic growth.
The WWF report could be embarrassing for Prime Minister John Howard, whose government has thrown money at farmers to help a bastion of its support survive the "Big Dry", but which joined the United States in rejecting the Kyoto accord to cut pollution.
The 1997 treaty, drawn up in the Japanese city of Kyoto, is recognised as insufficient to halt climate change but is the world's first attempt to tackle greenhouse gases such as carbon dioxide.
The WWF study said higher day-time temperatures in 2002, which exceeded the long-term average by 1.6 degrees Celsius (34 F), led to record evaporation levels in the Murray-Darling Basin, where 40 percent of Australia's agricultural goods are produced.
Whereas estimated evaporation rates in three previous droughts - in 1994, 1982 and 1965 - amounted to 136 mm, 120 mm and 131 mm per month in the basin town of Griffith, in 2002 the evaporation rate there reached 152 mm per month, it said.
The WWF report won the independent endorsement of experts at the government-funded Commonwealth Scientific and Industrial Research Organisation (CSIRO), who said it highlighted concerns about the sustainability of Australia's massive farming industry.
Kevin Hennessy, a senior research scientist at CSIRO's Atmospheric Research department, said the agency predicted the Murray-Darling Basin would get between half a degree Celsius and two degrees Celsius warmer by 2030, and 10 percent drier.
"The challenge is, are we growing the right crops in the right areas and if we want to continue growing those crops under dry conditions, we need to choose or breed crops that are more drought tolerant, more heat tolerant and perhaps even more disease tolerant. Or move," Hennessy told Reuters.
The WWF said its findings underscored the need for Australia to ratify the Kyoto agreement.
"Global warming is a reality that is affecting the livelihoods of rural Australians and Prime Minister Howard must act to prevent further economic and environmental devastation," said Anna Reynolds, WWF Australia's climate-change campaigner.