Atmospheric aerosols are small particles which can scatter or absorb sunlight as it passes through the atmosphere. These effects are important for climate, satellite observations and also for air quality and human health. The purpose of the Aerosol Workshop, held at UNSW from March 30 - April 1, 2005, was to bring together the rather diverse community of Australian scientists working on various aspects of aerosol science and impacts in order to share information about the range of activities being undertaken and to investigate ways of working together better in the future. The 60 people who attended came from a range of different organisations including Universities, CSIRO, Bureau of Meteorology, State and Federal government departments, ANSTO and a number of private companies.

Funding from the ARC Network for Earth System Science allowed us to bring Dr Stephen Schwartz from Brookhaven National Laboratory in New York to Australia as a keynote speaker. It also allowed us to subsidise travel for several postgraduate students to attend. Further support was obtained from a number of private companies.

The Workshop began with a talk by Stephen Schwartz, titled “Aerosols Down Under: A Yank looks at the Cleanhouse”, which reviewed some of the work on aerosols in both Northern and Southern Hemispheres. His conclusion was that “Down Under is a wonderful testbed for examining aerosol chemistry, microphysics and life cycle”. Presentations over the next two days reflected the wide range of work currently being done in Australia and the breadth of expertise available. Topics included laboratory experiments, field measurements, satellite observations and modelling. The final session canvassed options for future cooperation and a second meeting will be held at QUT in mid-2006.

A highlight of the Workshop was Stephen Schwartz’s Public Lecture at UNSW on the evening of 31st March. This lecture, “Radiative Forcing of Climate Change by Aerosols: Why This is so Important and How Well it Needs to be Known”, attracted a large and interested audience, who enjoyed a stimulating talk. The talk gave an overview of how aerosols influence climate and the reasons why aerosol forcings are uncertain. The uncertainties in aerosol forcings need to be reduced significantly to meaningfully inform policy on greenhouse gas emissions. The figure from the IPCC Report illustrates this. Currently the Earth is being warmed by greenhouse gases and cooled by anthropogenic aerosols. We know the Earth is warming slowly, but is this the difference between two small effects or two large effects? If it is the latter, then the threat of climate change is much greater.

Gail Box and Michael Box