The drying trend observed in southern Australia over the past few decades is partially the result of human-induced changes in the concentrations of greenhouse gases and ozone in the atmosphere, concludes an article published online in Nature Geoscience. Future projections suggest that autumn and winter rainfall in these regions may continue to decline towards the end of the twenty-first century, and may drop by up to 40%.

Thomas Delworth and Fanrong Zeng simulated past Australian rainfall with a high-resolution global climate model. They found that simulations that included human-induced variations in atmospheric greenhouse gases and ozone levels reproduced many aspects of the observed patterns of rainfall decline. A significant influence of human-made aerosols was not detected. Future projections with the same model yielded particularly strong drying trends in southwest Australia.

David Karoly notes in an accompanying News and Views that “The success of the model […] gives greater confidence in model projections that show continuing future reductions in winter rainfall across southern Australia, a prospect that poses increasing risks to sustainable water resources”.