The Air Pollution Model developed at CSIRO can assess pollution from industrial sites and individual chimneys.

Aerosols and the climate

Aerosols, both natural and human produced, can cause significant changes to the climate, including to rainfall and temperature.

• 11 December 2006 | Updated 14 October 2011

• Changing patterns
• Impact of Asian aerosols

Natural sources of aerosols include wind-blown dust, volcanoes, marine biota and vegetation.

Anthropogenic (human-made) sources are mainly the burning of fossil fuels and vegetation.

Most aerosols exert a direct cooling influence on climate by reflecting sunlight back into space and this is thought to be masking the upward trend in global temperatures. They also have an indirect effect by acting as condensation nuclei to increase cloud formation.

Changing patterns

Observations of Australian rainfall and cloudiness since 1950 show increases over much of the continent, and especially in the northwest

CSIRO scientist, Dr Leon Rotstayn, says that when anthropogenic aerosol changes were included in CSIRO’s climate model, it showed increasing rainfall and cloudiness over Australia from 1951-96. The pattern of increasing rainfall was strongest over northwestern Australia, a pattern consistent with the observed trends.

Observed summertime rainfall trends across Australia (1951-1996). Click on image for high-resolution view.

When anthropogenic aerosol changes were omitted, the model did not match observations, giving decreasing rainfall and cloudiness over Australia during 1951-96.

Impact of Asian aerosols

'The strong impact of aerosols was predominantly due to the massive Asian aerosol haze, as confirmed by a sensitivity test in which only Asian anthropogenic aerosols were included,' Dr Rotstayn says.

'The Asian haze altered the north-south temperature and pressure gradients over the tropical Indian Ocean, thereby increasing the tendency of monsoonal winds to flow towards Australia.'

'Climate model simulations responding to increased greenhouse gases have generally not reproduced the observed rainfall increase over northwestern and central Australia.'

'Our results suggest that a likely reason for this failure was the omission of modeled responses to Asian aerosols, and that inclusion of these aerosols is essential in future modeling of Australian climate change,' Dr Rotstayn says.

Discover more about CSIRO's research into Understanding Climate Change.