Rainfall decline in south-west Australia linked to climate change

From ABC News in Science, 14 July 2014:

Declines in rainfall over south-west Australia over the last 40 years are linked to greenhouse gases and ozone depletion, new climate models show.

And the trend is likely to continue according to research, published today in Nature Geoscience , that predicts a 40 per cent reduction in autumn and winter rains by the end of this century.

The finding has implications for maintaining reliable water resources in the area, which has already seen declines in the annual stream flow into dams that supply Perth over the last century.

Using a new, high-resolution climate model that can forecast down to an area just 50 kilometres wide, US researchers from the Geophysical Fluid Dynamics Laboratory examined the impact of variation in both human and natural influences on climate.

Natural influences on climate include volcanic activity and solar irradiance, while human factors include increasing levels of greenhouse gases such as carbon dioxide, decreasing ozone levels, aerosols and land use change.

The model shows both greenhouse gas emissions and stratospheric ozone depletion contribute roughly the same amount to the drying. Anthropogenic aerosols, however, were not linked with drying.

The results show the impact of human factors will be felt much more strongly in south-western Australia than elsewhere in Australia, says lead author Dr Tom Delworth, also a lecturer at Princeton University. Read more.