Tom Beer, Michael Borgas, Willem Bouma, Paul Fraser, Paul Holper and Simon Torok
CSIRO Atmospheric Research
prepared for the 2006 Australian State of the Environment Committee, 2006
For many people, the state of the atmosphere is a key measure of the health of the environment. Climate affects Australia’s animals and plants as well as the economic, social and medical wellbeing of our society. The composition of the atmosphere dictates air quality, which affects human health and aesthetic values, as well as ecological systems.
Air pollution and global warming continue to be environmental topics of great concern to Australians (Sensis 2004). Ten percent of Australians nominate air pollution as the main environmental issue, and the same percentage nominate global warming as their key environmental concern. This commentary considers four major issues related to the atmosphere, namely climate variability, climate change, stratospheric ozone, and air quality.
The environmental indicators that accompany this commentary help track changes in the atmospheric variables by selecting key measures—physical, chemical, biological or socio-economic—that represent the key elements of the relevant environmental issue. The air quality indicators used in this report address human health rather than atmospheric impacts on ecological systems. Readers should refer to other theme commentaries (such as biodiversity, land and inland waters) for discussions about that. Indoor air quality is dealt with in human settlements.
As with most environmental issues, pressures on the state of the atmosphere are closely linked to human population and activity. Australia has a unique meteorology as an island continent that is relatively isolated in the southern hemisphere. The nation suffers little from air pollution from beyond the borders. The low population and technological sophistication limit air pollution problems, although large cities and intensive industrial zones can put significant pressure on the local or regional environment.
Australia will suffer the consequences of global environmental pressures such as climate change. Australia’s per capita greenhouse gas emissions are high. Ozone depletion will continue to exacerbate health and other problems that are associated with Australia’s already high rates of ultraviolet radiation.
Indicators of the state of the atmosphere can be separated into measures of climate, driven by large-scale forces, and measures of air quality, driven by regional or local factors. A major difference between the large-scale and local forces is the lifetime of atmospheric pollutants. Those with large-scale impacts persist in the atmosphere for years to centuries. Carbon dioxide, chlorofluorocarbons (CFCs) and halons are examples. Short-lived pollutants such as sulphur dioxide cause local impacts.
Australia State of the Environment 2001 included information about Australia’s climate and assessments of global and national atmospheric environmental issues (ASEC 2001).
On the global scale, the report detailed Australia’s contributions to the enhanced greenhouse effect and to stratospheric ozone depletion, as well as the actual and likely impacts these phenomena are likely to have on Australia.
There were also details on air pollution in regional and urban Australia.
A summary of the key findings from the Atmosphere chapter of Australia State of the Environment 2001 follows (Manins et al. 2001):
Urban air quality has generally improved. Concentrations of sulphur dioxide, nitrogen dioxide and lead are not of concern in any urban area. Carbon monoxide is of concern in a few specific urban locations.
In rural and regional Australia, levels of most pollutants are well below actual or proposed standards. Sulphur dioxide emissions have decreased substantially in regional locations and are now of concern only in a few limited localities.
Accumulation of total chlorine from ozone-depleting gases in the stratosphere slowed during the early 1990s and is now declining slowly.
Public action in avoiding excessive ultraviolet radiation has increased significantly.
There has been no decline in four-hourly concentrations of ozone in urban areas, indicating that photochemical smog in those areas is still an issue.
Australians have a high per capita level of greenhouse gas emissions by world standards. Greenhouse gas emissions increased by 16.9 per cent between 1990 and 1998.
Dust and other particulates, including woodsmoke, are of concern in some regions and localities.
Australia has the highest per capita number of hay fever sufferers in the world, but monitoring is poor with the exception of Melbourne.
Since 1910, Australian average surface temperature has increased by 0.76 °C, consistent with the global temperature increase of 0.6–0.7 °C.
Ozone loss over Antarctica appears to have stabilised during the 1990s, although there is no direct evidence of long-term ozone recovery.
Many of the warmest years on record have occurred in the 1980s and 1990s.
A mean sea level rise around Australia during the last 100 years appears to be about 12 to 16 cm. This value is consistent with the Intergovernmental Panel on Climate Change (IPCC 2001) global estimates for the last century (10–20 centimetres).
The commentary below, on the indicators for the 2006 State of the Environment report, should be read with these outcomes from Australia State of the Environment 2001 in mind. In particular, we will emphasise the changes in greenhouse gas emissions between 1998 and 2003 because the estimates markedly changed in the intervening years because the method of calculation altered.