The Drought Debate Down Under
Well before the agricultural revolution changed the world, a people known as the Gwion walked the earth in Northwest Australia. Until they didn’t.
Researchers believe that around 7,000 years ago, after millennia of inhabiting the continent’s Kimberley region, the Gwion either left the area or died off. The evidence comes from the sudden disappearance of a certain type of rock artwork that had been prevalent throughout the area for the preceding 10,000 years.
At the same time, the area quickly changed from a vibrant, green landscape to a barren environment, says a report co-authored by climatologist Hamish McGowan of the University of Queensland. Pollen samples found in the sediment indicate that seasonal rains stopped and the people were no longer able to survive in the region.
“Our research shows that the likely reason for the demise of the Gwion artists was a mega-drought spanning approximately 1,500 years, brought on by changing climate conditions that caused the collapse of the Australian summer monsoon,” said McGowan in a statement.
Given a recent spike in temperature on the continent, some fear that modern Australians could face a similar fate. The region started the year blanketed by a heat wave that set records. Temperatures in the first two weeks of 2013 routinely exceeded 115 degrees Fahrenheit across the continent. Australia is known for its hot summers, but a heat wave that long and so widespread is rare. On January 7, the national maximum temperature average hit 104.3 degrees, which beat a record-setting day from 1972. The following day was cooler—but just barely. January 8 became the third-hottest day ever recorded.
The popular belief is that this trend, on top of the persistent pressures of climate change, will lead to another prolonged drought. Australia has been struggling to adapt to this reality for years, making public investments in resilience such as the recently completed $450 million expansion of a seawater desalination plant in western Australia. “This does basically drought-proof Perth,” Colin Barnett, the premier of Western Australia, said in a statement.
While such projects seem vital for a water-challenged nation, a new study from Princeton University and the Australian National University casts doubt on whether or not rising temperatures will lead to more drought, both in Australia and elsewhere.
“The overall view has been that as temperature increases, drought is going to increase,” said Justin Sheffield, a research scholar at Princeton. “But it is not that simple.”
The researchers claim that shortcomings in the Palmer Drought Severity Index, a model that has been widely used to assess drought in the past, in part due to its simplicity, may be the cause of this over-generalization. This index is tied to temperature to predict drought, and while that has some predictive qualities, it leaves out many other important variables, including humidity, wind and even solar radiation.
On the contrary, Sheffield’s model, the African Drought Monitor, takes such factors into account and can thus offer better results. And now, with widely available satellite information and other data sets, it makes a lot more sense to use a more nuanced means of assessing how dry the future might be. As such, the International Panel on Climate Change has adjusted its outlook, now backtracking from earlier pronouncements and stating that there is more uncertainty around whether rising temperatures will directly lead to more drought in the future.
Still, the new outlook doesn’t change everything, and scientific consensus continues to be that higher mercury readings will mean more drought. “It certainly does not mean that things are not going to be bad in the future,” said Sheffield. “It does not negate the idea that we are having an impact on the atmosphere, and that this will have an impact on drought.”