Precipitation in austral autumn and winter has declined over parts of southern and especially southwestern Australia in the past few decades1, 2, 3, 4. According to observations and climate models, at least part of this decline is associated with changes in large-scale atmospheric circulation1, 2, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, including a poleward movement of the westerly winds and increasing atmospheric surface pressure over parts of southern Australia. Here we use a high-resolution global climate model to analyse the causes of this rainfall decline. In our simulations, many aspects of the observed regional rainfall decline over southern and southwest Australia are reproduced in response to anthropogenic changes in levels of greenhouse gases and ozone in the atmosphere, whereas anthropogenic aerosols do not contribute to the simulated precipitation decline. Simulations of future climate with this model suggest amplified winter drying over most parts of southern Australia in the coming decades in response to a high-end scenario of changes in radiative forcing. The drying is most pronounced over southwest Australia, with total reductions in austral autumn and winter precipitation of approximately 40% by the late twenty-first century.
At a glance
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