|Page tools: Print Page Print All|
Progress in Australia: The headline dimensions
The natural landscape - biodiversity, land, and inland waters
No single indicator can hope to encapsulate biodiversity, and so we focus on two aspects: the numbers of extinct and threatened Australian birds and mammals; and the clearing of native vegetation.
Although the numbers of threatened birds and mammals are only a small part of the overall biological diversity, a decline in these groups of species threatens ecological processes and can point to a wider decline in biodiversity. The list should not be construed as a census of threatened species as they can be added to or removed from the list as their status changes or due to improved knowledge (Endnote 7). However, it is as accurate an account of the status of these species as can be currently compiled.
Between 1995 and 2005 the number of terrestrial bird and mammal species assessed as extinct, endangered or vulnerable rose by 41% from 120 to 169 (of which 67 were birds and 102 were mammals). In June 2005 just under half of these species were vulnerable, one-third were more seriously threatened (endangered) and the remaining fifth were presumed extinct. There were increases in the numbers of both endangered and vulnerable species, but the rise in species assessed as vulnerable was much higher (86%) than those assessed as endangered (26%).
Land clearing destroys plants and local ecosystems and removes the food and habitat on which other native species rely. Clearing helps weeds and invasive animals to spread, affects greenhouse gas emissions and can lead to soil degradation, such as erosion and salinity, which in turn can harm water quality. Native bushland has cultural, aesthetic and recreational importance to many Australians. The land clearing estimates include information about forest conversion (land cleared for the first time) and reclearing, both of which have environmental impacts.
The estimated 283,000 ha of Australian land cleared in 2003 is 38% less than the 457,000 ha cleared in 1993. Of the land cleared in 2003, less than half (128,000 ha) was ‘converted’ (cleared for the first time), which is less than half the area converted in 1993 (279,000 ha).
Australia's soils are old and shallow, and are susceptible to degradation by agricultural activities. Salinity occurs when the water table rises, bringing natural salts to the surface (in sufficient quantity, these salts are toxic to most plants). When trees or other deep-rooted vegetation are replaced with vegetation that uses less water, the water table may rise to cause dryland salinity. Dryland salinity threatens biodiversity, through loss of habitat on land and in water, and also impacts on water resources, pipelines, houses and roads. Areas near water are often worst affected because they occupy the lowest parts of the landscape where saline groundwater first reaches the surface.
In 2000, about 46,500 sq kms (4.6 million hectares) of agricultural land were already affected with a high salinity hazard or in an area at high risk from shallow watertables. The cost to agricultural productivity was estimated at $187 million in 2000, which was less than the cost of other forms of soil degradation, such as over $1 billion due to acidity in the same year.
However, the costs of salinity go further as it can impact on structures, as well as flora and fauna. The salt contained in rising groundwater levels can damage bitumen and concrete and so affect roads, footpaths, housing, pipelines and other assets. In 2000, about 11,800 kms of streams and lake edges, as well as 1,600 kms of rail and 19,900 kms of roads were affected or at risk (Endnote 9).
Water is fundamental to the survival of people and other organisms. Apart from drinking water, much of our economy (agriculture in particular) relies on water. The condition of freshwater ecosystems has a critical impact on the wider environment.
In 2000, about 11% of Australia’s surface water management areas were overdeveloped. Another 15% were approaching sustainable extraction limits (i.e. highly developed). Therefore, in 2000 about one-quarter of Australia's surface water management areas were classed as highly used or overused. This proportion was greater for groundwater management units, where 11% were overdeveloped, and a further 19% were highly developed (Endnote 10). Detailed national time series data are not available, but a variety of partial evidence points to a decline in the quality of some of Australia's waterways.
The air and atmosphere - urban air quality and net greenhouse gas emissions
Urban air quality
Poor air quality has a range of negative impacts: it can cause health problems, damage infrastructure, reduce crop yields and harm flora and fauna. Air pollution occurs both naturally and as a result of human activities. Australians consistently rank air pollution as a major environmental concern. The headline indicator considers the concentration of fine particles in the atmosphere, a measure of the form of air pollution about which many health experts in Australia are most concerned.
The common air pollutants are found at higher levels in urban and industrial areas than in rural Australia. It is important to note that daily changes in air quality depend on ambient conditions, like wind direction and the monitoring station’s proximity to pollution sources. Further, high concentrations of fine particles from irregular events, such as forest fires, can obscure the longer trend in levels produced by regular sources, like car emissions.
Overall, air quality in Australia is relatively good and has generally improved during the 1990s. Fine particle health standards (Endnote 11) were exceeded in the selected urban areas on average between one and two days each year between 1997 and 2001. There was a rise in 2002 and 2003, mainly due to severe forest fires and dust storms around the Sydney and Melbourne areas which caused the National Environment Protection Measure (NEPM) to be exceed on 13 days in Sydney in 2002 and 10 days in Melbourne in 2003. The was also exceeded on seven days in Brisbane in 2002. Sydney and Brisbane recorded one and two day’s exceedences, respectively, in 2004.