Is air pollution in Asia influencing climate change? Scientists at the Australian Nuclear Science and Technology Organisation (ANSTO) are at the forefront of an international effort to find out, as part of a program known as the Aerosol Characterisation Experiment or (ACE).
Like greenhouse gases, aerosols are believed to influence climate. Atmospheric aerosols are very fine particles suspended in air that can come from the dispersal of material at the earth's surface or by reaction of gases in the atmosphere. They include sulphates and nitrates from the burning of fossil fuels, organic materials from the oxidation of volatile organic compounds, soot from fires, and mineral dust blown in the wind. Natural aerosols include sea salt and volcanic dust.
It is known that increased burning of coal and other biomass raises the concentrations of sulfate and soot particles in the air. These particles are thought to scatter more sunlight back into space, influence cloud formations, and alter the amount of atmospheric material deposited into the Pacific Ocean.
Scientists have theorised that these factors could cause localised cooling, affect the amount of rainfall and associated agriculture, as well as marine biota and fisheries. Environmental scientists such as Dr Wlodek Zahorowski from ANSTO are playing a key role in the ACE Asia project.
"The International Global Atmospheric Chemistry Project, IGAC, has recognised that a major limitation in our ability to predict climate change is our lack of understanding of direct and indirect forcing by aerosols," Dr Zahorowki said.
"Aerosol effects on the thermal and optical properties of the atmosphere are a large source of uncertainty in predicting future climate. Consequently, IGAC has been coordinating the Aerosol Characterisation Experiment (ACE), a multinational effort including ANSTO."
ANSTO scientists are currently collecting samples from filters at five sites strategically selected to observe the outflow of air pollution from the Asian continent. These are situated at Hong Kong, Manila (the Phillipines), Hanoi (Vietnam), Sado Island (Japan), and Cheju Island (South Korea).
Using facilities at Lucas Heights, south of Sydney, accelerator-based nuclear techniques of analysis are being applied to obtain over 25 different elemental and chemical species from hydrogen to lead, including the key components of elemental carbon, sulphate and soil important for the ACE Asia experiment.
The project, which is funded by numerous organisations in eight countries, is not due to finish until 2004. However, ANSTO measurements have already gone part of the way to answering some of the major questions that have to be answered, such as the composition and distribution of air pollution across the sites in Asia.