When Australia was ravaged by wildfires that killed over 200 people earlier this month, the acts of arson that police suspect were behind at least some of the blazes were made even worse by the decade-long dry spell the country has been enduring.
Though this heavily eroded and sparsely populated continent has experienced two other major droughts over the last century, both the intensity and duration of the current lack of rainfall has scientists worried that the country’s environment may be permanently shifting to a drier regime.
The Murray-Darling Basin—a river system in the southeast that drains one-seventh of Australia’s land mass—has been particularly hard hit, with official figures showing that, from 2006 until 2007, the amount of water flow into the basin was just 1,000 gigaliters. Normal inflows into the basin previously measured about 10,000 gigaliters a year. From 2007 until 2008 it improved marginally to a still-meager 3,000 gigaliters. The region had record low inflows of water between 2006 and 2008, with the inflows for 2006-2007 less than 60 percent of the previous minimum—a figure based on 117 years of records. Helping to irrigate such states such as Victoria, the site of the worst wildfires, as well as New South Wales and Queensland, the basin was once wet enough to irrigate crops that produced 1.2 million metric tons of rice. Last year, the rice harvest fell to 18,000 metric tons.
Across southern Australia, scientists have also witnessed an intensification of the subtropical ridge phenomenon, a swath of high pressure characterized by a reduction in the amount of rainfall in autumn and late winter. The expansion of the ridge has been closely linked to global warming.