3 Atmosphere | Key findings
State of the Environment 2011 Committee. Australia state of the environment 2011.
Independent report to the Australian Government Minister for Sustainability, Environment, Water, Population and Communities.
Canberra: DSEWPaC, 2011.
Earth is warming
Since the release of the Fourth assessment report: climate change 2007 from the Intergovernmental Panel on Climate Change, observations and research outcomes have further confirmed and strengthened the position that Earth is warming and that human emissions of greenhouse gases are the primary cause. Even in 2007, mainstream science held this view with a high level of certainty, and now this certainty has increased. Internationally, there is a clear consensus among atmospheric scientists that mean global temperatures have generally risen compared with pre-industrial levels in 1750.
Large step-changes in climate may occur.
Smooth changes are the exception rather than the norm in the global climate system, which is nonlinear in nature. This means that a number of feedback mechanisms exist that can amplify or accelerate climate change and have the potential to cause large step-changes (sudden or major changes) in regional and global climate. Should such changes occur, adaptive strategies framed around incremental change are unlikely to be adequate to prevent major harmful impacts on key sectors. Instead, what the Commonwealth Scientific and Industrial Research Organisation describes as 'transformational' change will be needed and 'a major scientific and societal challenge [will be needed] to understand and decide how, where, and when this transformational change is required'.
We are already seeing changes in Australia’s variable climate.
Although Australia’s climate is naturally highly variable, evidence continues to accumulate that temperatures are increasing and rainfall distribution patterns are changing.
Major reductions in greenhouse gas emissions are urgently needed nationally and internationally.
Per person, Australia’s greenhouse gas emissions are the largest of any country in the Organisation for Economic Co-operation and Development (OECD)—26.8 tonnes in 2008, which is nearly twice the OECD average. If the world's current emissions path is projected to 2070, warming in Australia is expected to be in the range of 2.2–5.0°C, with widespread and significant risk to Australia’s natural ecosystems, water security and coastal communities. Even if national and international mitigation efforts increase dramatically over the next decade or two, leading to a rapid stabilisation of greenhouse gas emissions, temperatures will remain at elevated levels for centuries to come.
We will need both a national approach and approaches at the state and territory level to mitigate and adapt to climate change.
Australia’s Fifth national communication on climate change sets out the Australian Government's strategic approach to the challenge of climate change. Such an overarching strategy—implemented via a range of policies, plans and programs—is essential if Australia is to succeed in mitigating climate change and addressing key areas of vulnerability through adaptation. At the same time, as the communication notes, all three levels of government share responsibility for addressing climate change and are involved in planning and implementing a diverse range of climate-related programs.
Despite the success of the Montreal Protocol in controlling ozone depleting substances (ODSs), depletion of stratospheric ozone will continue for some decades.
Concentrations of chlorofluorocarbons and other ODSs in the atmosphere have been decreasing since the mid-1990s, but many of these substances are long lived and will continue to affect stratospheric ozone for some decades. Nevertheless, the prospects for recovery of the stratospheric ozone layer by around mid-century continue to be good.
Meeting our population's need for water will be a critical challenge for Australia.
Using water from our environment is fundamental to our national wellbeing and sustainability. Each year, Australian industries add about $1.2 trillion of gross value for the water we use. Demands for urban water will increase as Australia’s population grows; these demands are likely to be met without taking much more fresh water out of the environment (but potentially with other environmental costs, including increased energy use associated with desalination or wastewater recycling).
Australia has met its targets in controlling ODSs.
Australia continues to be a leading supporter of international action to control the production and use of ODSs, meeting or exceeding its phase-out obligations under the Montreal Protocol.
Ambient air quality in Australia’s major urban centres is generally good.
National health-based standards are rarely exceeded for prolonged periods, and very high levels of pollution are usually associated with short-lived extreme events such as bushfires and dust storms that generate very high levels of particulate pollution. Levels of carbon monoxide, nitrogen dioxide, sulfur dioxide and lead in urban air have decreased over the past two decades, but ozone and particle levels have not declined. Prospects for achieving reductions in levels of these two pollutants will be influenced by a number of factors, most notably vehicle technology, the extent of ongoing low-density suburban development and the availability of reliable public transport, and the impact of climate change on urban airsheds (regions sharing a common flow of air).
Despite this broadly favourable situation, the impact of urban air quality on health is still a matter of serious concern.
There is clear evidence that periods of poor urban air quality impact adversely on human health (particularly on the health of susceptible individuals). One source estimates that urban air pollution accounts for 1% of deaths and illness in Australia, with some 3000 deaths attributable to this cause in 2003—nearly twice the national road toll. Research into the health effects of particles and ozone, as well as pollutants such as sulfur dioxide, indicates there is no threshold level below which they have no health effect. This means that sensitive individuals, such as asthmatics and people with respiratory or cardiovascular disease, may be affected even when air quality standards are met.
Management of pollution affecting our air quality is generally good, but ongoing effort will be required to secure past gains and achieve further improvements.
The generally good quality of our urban air is largely due to the progressive tightening of national vehicle emission and fuel standards over the past 20 years, and the control of industrial, commercial and domestic sources of air pollution. The outlook for the next decade is that this favourable situation is likely to continue, despite the pressures associated with population and economic growth. However, this outcome is not assured, and there are sound public health, economic and social equity arguments to support ongoing efforts to reduce pollutant emissions and associated impacts on health and amenity.
Most Australians spend more than 90% of their time indoors.
The quality of indoor air is affected by many factors, notably building materials (particularly volatile materials like glues and paints), ventilation, furnishings and appliances (particularly unflued gas appliances), environmental tobacco smoke and cleaning agents. Despite the potentially significant health effects of indoor air, data on indoor air quality in Australia are limited. Australia has no specific guidelines for indoor air quality and therefore no firm basis upon which to form assessments of overall status and trend. Over the past decade, Australian governments have employed regulatory and nonregulatory approaches to improve indoor air quality, chiefly through interventions targeting environmental tobacco smoke (in commercial premises where food is prepared or consumed, shopping malls and public buildings) and unflued gas heaters (particularly in schools).