Friday, February 13, 2009

Aerosols may have a big impact on Australian rainfall, climate change

Science Daily: Aerosols may have a greater impact on patterns of Australian rainfall and future climate change than previously thought, according to leading atmospheric scientist, CSIRO’s Dr Leon Rotstayn. “We have identified that the extensive pollution haze emanating from Asia may be re-shaping rainfall patterns in northern Australia but we wonder what impact natural and human-generated aerosols are having across the rest of the country,” Dr Rotstayn said.

Aerosols are fine particles suspended in the atmosphere. Sources of human-generated aerosols include industry, motor vehicles and vegetation burning. Natural sources include volcanoes, dust storms and ocean plankton. Human-generated aerosols have long been known to exert a cooling effect on climate. This has partly masked the warming effect of increasing greenhouse gases. As aerosol pollution is predicted to decrease over the next few decades, unmasking of the greenhouse effect may lead to accelerated global warming.

However, in an address February 13 to the International Conference on Southern Hemisphere Meteorology and Oceanography in Melbourne, Dr Rotstayn said aerosols are much more than a 'negative greenhouse gas' because they can actively force changes in winds and ocean currents by altering the distribution of solar heating at the earth’s surface.

“Recent climate modelling at CSIRO shows that there may be important effects on Australian climate due to aerosol pollution from the Northern Hemisphere. These include an increase of rainfall in north-western Australia, and an increase of air pressure over southern Australia, which may have contributed to less rainfall there…..

Rain drops on a window, shot by Frank Vincentz, Wikimedia Commons, under the terms of the GNU Free Documentation License, Version 1.2

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