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Environment by Numbers: selected articles on Australia's Environment is a collection of articles on sustainability and the environment. Topics covered include climate change, Australia's rivers, renewable energy, forest conservation, salinity, and the impacts of transport, construction, fishing, mining, manufacturing and agriculture on the environment. The articles were written by ABS staff as well as many external authors.
The Johannesburg World Summit on Sustainable Development in 2002 marked 10 years since the first summit in Rio de Janeiro in 1992. 2003 is also the International Year of Freshwater. Given these milestones, and the importance and topicality of sustainable development and environmental issues generally, the ABS decided to make environmental issues, and particularly sustainable development, a major theme of the 2003 edition of Year Book Australia. A number of articles throughout that edition address environmental issues, as do the Environment and Energy chapters of the Year Book.
The purpose of this introductory chapter is to draw together the threads in those articles, and of related parts of the Environment and Energy chapters, and thereby present a brief statistical overview of environmental issues in Australia.
Many environmental, social and sustainable economic development issues are interrelated. The chapter addresses them in the following order:
What do we mean by sustainable development?
The World Commission on Environment and Development (1987) defined Ecologically Sustainable Development as:
development which meets the needs of the present without compromising the ability of future generations to meet their own needs.
The National Strategy for Ecologically Sustainable Development commits all Australian governments to the following three core objectives:
At the World Summit on Sustainable Development, many countries attached a high priority to improving the material wellbeing of their residents. For Australia, progress has been strong in this area. Two indicators compiled for Measuring Australia’s Progress, 2002 (1370.0) show this to be the case. Graph 1.1 shows a strong and continuous rise in real net national disposable income per head since 1992. Graph 1.2 shows, for real national net worth per head, that while there have been some fluctuations over this period, the trend has been strongly positive. The growth in both these indicators suggests that broadly the needs of the present generation are being met (through increasing levels of income) and that the needs of future generations are not being compromised (to the extent that national wealth, which underpins future national income, is increasing).
Frameworks for measuring progress and wellbeing are discussed in Chapter 2, Beyond GDP: Towards wider measures of wellbeing.
Chapter 3, Sustainable forest management and Chapter 4, Forest conservation describe the framework and processes used in Australia to manage Australia’s forest resources in a way that strikes a reasonable balance between the economic, ecological, social and cultural values of forests for current and future generations.
The Montreal Process, established in 1994, is being used as a tool to assist in monitoring and reporting on Australia’s progress toward sustainable forest management.
A number of threatening processes directly or indirectly jeopardise the health and vitality of forest ecosystems. These include clearing and fragmentation of habitats, mining, timber harvesting, the impact of invasive species, altered fire regimes, and climate change.
In recognition of the potentially adverse impacts of these threatening processes on Australia’s forests, the Commonwealth Government and the state and territory governments have moved to protect Australia’s forest ecosystems through forest conservation. About 26.8 million hectares (ha) of native forest are protected and conserved in reserves, representing 16% of Australia’s remaining native forest estate.
Establishing a conservation reserve system is one of the key objectives of the Regional Forest Agreement (RFA) process implemented through the 1990s. The RFA process added 2.9 million ha to the existing estate of forest reserves, giving RFA regions a total of 10.4 million ha of forest in conservation reserves. This increased the reserved forest area in RFA regions by about 39%. More than 8.5 million ha are within formal dedicated conservation reserves. The RFAs increased old-growth forest protection across the 10 RFA regions by about 42%, from 2.4 million ha to 3.4 million ha. As a consequence, about 68% of existing old-growth forests in RFA regions have been reserved.
Unfortunately neither the Montreal indicators nor the information publicly available from the RFAs indicate the degree to which native forest timber resources are being depleted. The best available information is in an article in the June quarter 2002 edition of Australian National Accounts: National Income, Expenditure and Product (cat. no. 5206.0). This shows that the real or volume estimates of native standing timber available for production fell by 8% between 1993 and 2001 (graph 1.3), but appear to have stabilised in recent years.
Sustainable fisheries and marine ecosystems
Chapter 5, Fishing and the environment, discusses the extent to which Australian fisheries stocks are being managed in a sustainable manner and the effects of fishing on habitat and non-target species.
It shows that fisheries production of a number of species has been declining since the late 1980s. Reasons for declines in some fisheries include overfishing, use of non-selective fishing gear, loss of habitat, pollution, natural disasters, and the complexity of Australia’s marine jurisdiction, which hinders management of fish stocks.
Chapter 6, Aquaculture and the environment discusses Australia’s rapidly expanding aquaculture industry (production rose by 146% in the decade to 2000-01, compared to a rise of 46% in the total gross value of fisheries production) and its environmental impacts. Aquaculture takes some pressure off wild fisheries, but it has the potential to alter coastal foreshores, estuaries, mangroves, salt marshes, and marine and other aquatic environments. The main environmental impacts of aquaculture are water pollution, pest species, the strain placed on wild fish populations for brood and feed purposes, and the culling of natural predators. The potential also exists to introduce diseases and for farmed exotic fish to escape into the wild.
Chapter 7, Coastal and marine environment discusses population and human settlement pressures on Australia’s marine and coastal area (one of the largest in the world, extending over some 16 million square kilometres), which hosts a wide variety of habitats including estuaries and mangroves, dunes and beaches, rocky and coral reefs, seagrasses, gulfs and bays, seamounts, and a huge area of continental shelf. At 30 June 1996, 83% of Australia’s population lived within 50 kilometres of the coast. All states except the Northern Territory and South Australia are experiencing higher rates of population growth and urban development within 3 kilometres of the coast than elsewhere within the state (Newton et al. 2001). The coastal strip is an ecologically sensitive zone, and urban sprawl, and pollution of rivers, lakes and seas, were described by the Resource Assessment Commission as the two most important problems faced by the coastal zone (RAC 1993).
Australia’s estuaries in particular face a number of pressures from urban and industrial development in coastal areas, and from disturbance through land use and vegetation clearance in catchments. For example, estuaries are often used for dumping, sand or water extraction, and construction of marinas, ports and canal estates, and are susceptible to changes in natural flows caused by the construction of dams and weirs. Such pressures threaten the condition of estuaries by causing excess nutrient concentrations, sedimentation, loss of habitat, weed and pest infestation, and the accumulation of pollutants.
Another focus of the chapter is coral reefs, which are among the most productive and complex ecosystems in the world. The Great Barrier Reef is the largest coral reef in the world, consisting of about 3,000 individual reefs covering an area of 345,950 square kilometres.
Australian coral reefs face a variety of pressures. These include: run-off of sediment and nutrients at a number of coastal locations, which is steadily increasing through human activities (primarily from the effects of agriculture and land use practices, as well as increasing industrial and urban development); increased recreational and commercial fishing; increasing pressure from tourism developments; threats from invasive and pest species such as the crown of thorns starfish; and coral bleaching, possibly due to global warming (SoE 2001). Chapter 8, Sustainable tourism in the Great Barrier Reef Marine Park addresses management of the impacts of tourism on the Park.
Chapter 9, Mining and the environment briefly discusses the main environmental impacts of mineral mining, such as wastes, and the rate of resource use (where the supply of minerals depends on the rate of resource use, which is affected by the economic life of mineral deposits and the rate at which new reserves are discovered). The chapter also summarises environmental management initiatives, such as the use of legislation, environmental impact assessments, environmental protection expenditure, rehabilitation and industry self-regulation.
Data from the national balance sheet of the Australian national accounts, show that the quantity of economically viable mineral reserves is increasing (as new discoveries are made and new technologies and lower production costs make existing reserves more profitable).
Sustainable land and water use, and protecting Australia’s biodiversity
Since European settlement of Australia, around 100 million ha of forest and woodland have been cleared, mostly for agricultural production (NFI 1998), and land continues to be cleared for agriculture. Today around 456 million ha, or 59% of land in Australia, are used for agriculture, making it the dominant form of land use. Agriculture is also the largest consumer of water in Australia; in 1996-97 it accounted for 15,500 gigalitres (GL) or 70% of total water use.
This publication contains a number of chapters on sustainable land and water use, and protecting Australia’s biodiversity. Chapter 10, Australia’s rivers is followed by Chapter 11, Environmental impacts of agriculture, which discusses land degradation and related issues, including results from the recently released Salinity on Australian Farms, 2002 (ABS 2002c). Chapter 12, Australia’s biodiversity discusses biodiversity, extent and clearing of native vegetation, and invasive species.
Some of the main findings from these chapters follow.
Water is essential for all living organisms. Australia is considered one of the driest inhabited continents. Compared to other continents, Australia is also characterised by variable climatic conditions and high levels of evapotranspiration. These factors result in a low proportion of rainfall converted to streamflow, making freshwater a valuable resource.
By world standards Australia is a dry continent with few freshwater resources. Australian rivers are characterised by relatively low and variable flows.
In much of the intensive land use zone of Australia, catchment land use has significantly modified the physical and chemical nature of the rivers. These now carry higher than natural levels of sediment and nutrient. In some regions, the biological condition of the rivers, wetlands and groundwater dependent ecosystems has been severely impacted by the extraction of large volumes of water for agricultural, urban and industrial use.
The consumption of Australia’s freshwater resources from lakes, rivers and underground aquifers has increased strongly in the last two decades. Between 1983-84 and 1996-97 national water consumption increased from 14,600 GL to 23,300 GL annually (NLWRA 2001c).
Across Australia, catchment land use and diverting water are considered the most serious threats to the ecological condition of Australia’s rivers, wetlands and groundwater dependent ecosystems.
Based on state assessments of sustainable yield, the 2001 National Land and Water Resources Audit determined that 34 (11%) of Australia’s 325 surface water basins are overused, with a further 50 (15%) highly developed. On the other hand, 60% of Australia’s river basins have less than 30% of the nominated sustainable flow regime diverted (NLWRA 2001c). Almost all of the basins with a high volume of unused sustainable yield are in the northern parts of Australia.
Land use in the catchment, combined with how well this use is managed, is a major driver of river condition. In the non-urban regions, most of the elevated nutrient and sediment loads to rivers are a consequence of using land for agricultural production. High fertiliser application rates, and other agricultural practices, have resulted in some landscapes leaking more nutrients into the waterways than they did before the adoption of European agricultural production systems (NLWRA 2001a).
Environmental impacts of agriculture
The chapter of this name looks at the impact of agricultural activities on the Australian environment. In particular it examines land and water use, salinity and the adoption of various land management practices.
The combined impacts of land and water use for agricultural production have been substantial. For example:
Salinity, sodicity and acidity are all naturally occurring conditions of Australian soils, but these have been exacerbated by agricultural activities.
In recent years salinity has gained prominence as a national environmental issue. Results from the 2002 Land Management and Salinity Survey show that around 20,000 farms and two million ha have land showing signs of salinity (ABS 2002c).
The impacts of salinity extend beyond the agriculture sector. Roads, houses and water supply infrastructure can all be degraded by it. Over four states (New South Wales, Victoria, South Australia and Western Australia) the roads, buildings and/or water supply infrastructure of 68 towns are at risk of damage from salinity. Biodiversity is also at risk through the loss and degradation of native vegetation. Across Australia around 630,000 ha of native vegetation and 80 wetlands, including wetlands of international importance, are at risk (NLWRA 2001b).
One factor contributing to salinity is the rise in water tables due to increased amounts of water entering underground water bodies from irrigated land. This ultimately results in increased salt loads entering river systems. Reduced river flows, brought about by the construction of dams, weirs and water diversions, compound the problem as the flow is insufficient to dilute saline groundwater inflows (ABS 1996).
Between 1990 and 2000 the area of irrigated land increased by more than half a million ha (30%). The growth in irrigated area was greatest in Queensland, where an additional 236,000 ha (or 76%) were irrigated in 2000, compared to the area irrigated in 1990. Irrigation can also cause a decline in soil structure and water quality, while the method of irrigation used influences the efficiency of water use and impacts on the environment (Smith 1998). Impacts on water quality result from the high levels of fertiliser use in conjunction with some irrigation methods. Continued awareness of the need for greater efficiency and technological advances can be expected to improve land management practices and reduce the decline in the health of land and water assets. For example, there has been a growth in the use of irrigation methods that are more efficient in terms of water delivery. In 2000 around 30% of irrigators reported using spray, micro spray or drip irrigation methods compared to 23% in 1990.
The increasing use of more efficient irrigation methods, the implementation of salinity management activities and adoption of other land use practices are an indication that farmers are more aware of the environmental impact of their activities than in the past. Much of the impact on the environment is the result of historical land management decisions, and has taken decades to manifest. The impact of agriculture on the environment can be reduced, and there are a number of community groups and government programs dedicated to achieving this. However, it is likely that the damage already done will take decades to abate and repair.
Australia is identified as one of 17 megadiverse countries. The loss of biodiversity is considered one of the most serious environmental problems in Australia.
Clearing of native vegetation is a significant threat to terrestrial biodiversity. Other threats include invasive species (i.e. pests and weeds), dryland salinity, pollution, nutrient loading and sedimentation of waterways and coastal areas, altered hydrological and fire regimes, and climate change. These processes constitute major threats to sustainable management of our ecosystems and the environment, as well as to the social and economic values of biodiversity.
Native vegetation is a key element contributing to Australia’s biodiversity. In 2000, there were 5,251 protected areas in Australia, occupying 61.4 million ha and accounting for 8% of the total land area.
Energy, greenhouse gases and climate change
Using Australia’s energy resources prudently and efficiently, and minimising energy-related contributions to greenhouse gas emissions and global warming are important environmental issues. The sorts of questions which are relevant include the extent to which Australia is energy sufficient, the extent of depletion of our reserves, and whether and how we are managing to reduce the links between economic growth on the one hand and energy use and greenhouse gas emissions on the other.
Australia has an abundance of fossil fuel and mineral energy resources which are not being depleted to any great extent by current patterns of use. The rate of energy use and the extent of greenhouse gas emissions appear no longer to be directly linked to gross domestic product (GDP). The factors underlying this favourable trend include: the continued growth in the dominance of service industries (relatively low users of energy and generators of greenhouse gases) in the economy, the increasing share of natural gas in overall energy use (natural gas produces less greenhouse gases per unit of energy), and continuing, albeit small, gains in how efficiently energy is used by industry and households.
The energy intensive export industries, such as heavy manufacturing and natural gas liquefaction, have a major impact on Australia’s energy use and greenhouse gas emissions. In 1994-95, goods and services produced for export accounted for 29% of energy use, either directly or indirectly.
Chapter 13, Energy resources, production, trade and use shows that Australia has an abundance of energy resources, and our trends of energy production and use are a reflection of this abundance. Australia’s per capita energy consumption is one of the highest in the world, with a heavy reliance on fossil fuels.
Between 1990-91 and 1998-99 Australia’s total energy consumption increased by 23%. Over the same period, population increased by just under 10%, and real GDP by over 34%. The aggregate energy intensity (energy consumed per unit of output) of the economy declined by around 9% from 1990-91 to 1998-99, partly due to improved energy efficiency, but mainly due to a change in the structure of the economy towards less energy intensive service industries.
Australia is far more dependent on coal for the production of electricity than most Organisation for Economic Co-operation and Development (OECD) countries. Chapter 14, Renewable energy in 2003, shows that 94% of domestic energy use comes from fossil fuels. In 1999, of the 6% share of total primary energy coming from renewable energy, the major contributors were biomass in the form of bagasse (39%) which was used to generate electricity and steam, wood (39%) which was used primarily for home heating, hydro-electricity (21%) and solar (1%). Renewable energy contributed 11% to electricity generation; most electricity was generated from large-scale hydro-electric schemes (ABARE 1999).
Use of natural gas constituted the fastest growing primary energy use over the 20 years 1978-79 to 1998-99. The growth of coal (black and brown) use was also above the overall trend, due primarily to the strong growth in electricity generation over the period. The consumption of crude oil has also grown significantly, reflecting the heavy use of petroleum products in the transport sector. The annual growth in consumption of renewable energy sources has declined over the years (ANZMEC 2001).
Although depletion of fossil fuels is not an important issue for Australia for the foreseeable future, many environmental benefits are to be gained from renewable energy development. Renewable energy, energy efficiency and use of cleaner fossil fuel technologies are key tools in a strategy for sustainable energy use and reductions in greenhouse gas emissions. As well as being perpetually available, renewable energy sources are low pollutants and produce very little or no net greenhouse gas emissions when operating. In Australia, government, industry and community support are driving renewable energy growth, particularly for electricity generation and transport use.
Greenhouse gas emissions and climate change
Chapter 15, Energy and the environment discusses the production of energy-related greenhouse gases by industries, and energy-related emissions in the production and consumption of goods and services for the final use categories: consumption by households; comsumption by general government; exports; and gross fixed capital formation. Chapter 16, Greenhouse gas emissions describes the history behind and targets associated with the Kyoto Protocol (an international treaty under which developed countries have agreed to limit net greenhouse gas emissions).
Developed countries are committed to reducing their greenhouse gas emissions by at least 5% from 1990 levels by the period 2008-12. In recognition of the fact that developed countries have different economic circumstances and differing capacities to make emissions reductions, each developed country has a specific, differentiated target (AGO 2002). Australia has signed (but not ratified) the treaty, which has a target increase for Australia of 8% above 1990 levels by this time. This target includes a one-off benefit from land clearing, where reduced emissions compensate for large increases in transport and power generation.
The chapter shows that the stationary energy sector (emissions from fuel combustion in energy industries such as the electricity industry) is the biggest contributor of greenhouse gases (graph 1.4), accounting for 49% of net emissions in 2000, with electricity generation accounting for the majority of this sector’s contributions (264 megatonnes of carbon dioxide equivalents (CO2-e)). Large reductions in emissions have taken place in the forest and land use sector.
Chapter 17, Climate change discusses natural versus human induced climate change and whether, for example, the recent systematic drying of the south-west corner of Australia is due to some natural long-term fluctuation in (say) the southern ocean or whether it is a manifestation of large-scale geographically-anchored circulation changes forced by enhanced greenhouse warming. It makes the point that, with the current state of knowledge, it will be very difficult to provide temperature and climate projections which will be sufficiently reliable to support planning for adaptation over a lengthy timescale (a century).
Through their behaviour, industries and households have direct and indirect impacts on whether natural resources are used prudently and efficiently, and on the extent of waste and pollution. A number of chapters address environmental issues associated with the manufacturing, construction and transport industries and the behaviour of households.
Chapter 18, Manufacturing and the environment observes that, after agriculture and mining, manufacturing has the next largest environmental impact. This industry:
Chapter 19, Construction and the environment discusses the significant impact on the environment of the construction of residential buildings, commercial buildings and other infrastructure. Direct impacts include use of land, materials and energy, which in turn leads to greenhouse gas emissions and the production of other wastes. Indirect impacts include the energy consumed in providing building materials and in operating the completed buildings.
The chapter shows that Australians currently send approximately one tonne of construction and demolition waste per person per year to landfill. This can make up to 40% of landfill and represents a potentially valuable natural resource being wasted. Materials include metals, concrete and bricks, glass, fittings and fixtures from demolished or refurbished buildings, wood and wall panelling.
Chapter 20, The WasteWise Construction Program shows that, since its beginnings in 1995, the Program has, with the cooperation of five major Australian construction companies, pioneered best practice in waste reduction and recycling. The participating organisations have successfully decreased the amount of their waste going to landfill, in some cases by more than 90%.
Chapter 21, The use of forest products explores past and projected trends in the consumption of structural wood (mainly for building and construction), and its production, import and export. It observes that forest plantations have provided progressively more of Australia’s structural wood resources in recent years. Some recent revisions to projected wood supplies from both forest plantations and native forest, however, suggest that this process is occurring more quickly than previously expected. It is now possible that forest plantations could be providing 75% of domestic industrial wood supplies by 2010, compared with expectations of only around 62% several years ago.
Chapter 22, Attitudes of residential builders to energy issues and usage shows that most builders are also sympathetic to the concept of the ‘clean, green’ home. In 2001-02 the majority of builders surveyed were installing dual flush toilets (99%), ceiling insulation (71%), wall insulation (63%), gas hot water systems (60%) and hot water temperature control (56%).
Chapter 23, Environmental impacts of Australia’s transport system discusses the use of energy and greenhouse gases by the transport system, the increasing size of the transport task, increases in fuel efficiency, and the impact of transport on wildlife, biodiversity and aquatic environments. A number of indirect impacts of transport are also discussed, such as air pollution and related illnesses, the livability of urban environments and the environmental impacts of the materials used by the transport system.
Chapter 24, Environmental issues and behaviour has sections dealing with households’ views and practices regarding water supply, quality and conservation, and household waste management.
The first of these shows that:
As shown in Chapter 15, Energy and the environment, a majority (about 56%) of Australia’s energy-related greenhouse gases were emitted in the production and consumption of goods and services for the purpose of household final consumption. The consumption of electricity by households indirectly produced the greatest amount of energy-related greenhouse gas emissions (17%). This was followed by direct emissions by households (14%), most of which were due to the consumption of motor vehicle fuels.
This publication concludes with Chapter 25, Accounting for the environment in the national accounts, which returns to the theme of measurement taken up in Chapter 2, and on this the work being done by the ABS to extend the core national accounts into what could be called a satellite account for the environment.
ABARE (Australian Bureau of Agricultural and Resource Economics) 1999, Australian Energy Markets and Projections to 2014-15, Canberra.
ABS (Australian Bureau of Statistics) 1996, Australian Agriculture and the Environment, cat. no. 4606.0, ABS, Canberra.
ABS 2001a, Australia’s Environment: Issues and Trends, cat. no. 4613.0, ABS, Canberra.
ABS 2001b, Australian System of National Accounts, 2000-01, cat. no. 5204.0, ABS, Canberra.
ABS 2002a, Australian National Accounts: National Income, Expenditure and Product, June Quarter 2002, cat. no. 5206.0, ABS, Canberra.
ABS 2002b, Measuring Australia’s Progress, 2002, cat. no. 1370.0, ABS, Canberra.
ABS 2002c, Salinity on Australian Farms, 2002, cat. no. 4615.0, ABS, Canberra.
AGO (Australian Greenhouse Office) 2002, National Carbon Accounting System - factsheet1.doc, last viewed August 2002, http://www.greenhouse.gov.au/ncas/.
ANZMEC (Australian and New Zealand Minerals and Energy Council) 2001, Energy Trends: An Analysis of Energy Supply and Use in the National Energy Market - 2000.
Newton PW, Baum S, Bhatia K, Brown SK, Cameron AS, Foran B, Grant T, Mak SL, Memmott PC, Mitchell VG, Neate KL, Pears A, Smith N, Stimson RJ, Tucker SN & Yencken D 2001, ‘Human Settlements’, in Australia State of the Environment Report 2001 (Theme Report), CSIRO Publishing on behalf of the Department of the Environment and Heritage, Canberra.
NFI (National Forest Inventory) 1998, Australia’s State of the Forests Report, National Forest Inventory, Bureau of Rural Sciences, Canberra.
NLWRA (National Land and Water Resources Audit) 2001a, Australian Agricultural Assessment, National Land and Water Resources Audit, Canberra.
NLWRA 2001b, Australian Dryland Salinity Assessment 2000, NLWRA, Canberra.
NLWRA 2001c, Australian Water Resources Assessment 2000, Surface water and groundwater - availability and quality, National Land and Water
Resources Audit, Canberra.
NLWRA 2002, Australians and Natural Resources Management, National Land and Water Resources Audit, Canberra.
RAC (Resource Assessment Commission) 1993, Coastal Zone Inquiry - Final Report, AGPS, Canberra.
Smith DI 1998, Water in Australia, Resources and Management, Oxford University Press, Melbourne.
SoE (State of the Environment) 2001, Australia State of the Environment Report 2001, CSIRO Publishing on behalf of the Department of the Environment and Heritage, Canberra.
World Commission on Environment and Development (Brundtland Commission) 1987, Our Common Future, Oxford University Press, Oxford.
This short article is largely based on Chapter 10: Australia's Rivers. It also includes information from Chapter 11: Environmental impacts of agriculture.
In recognition of the central importance of water resources to the planet's future, the United Nations General Assembly proclaimed the year 2003 as the International Year of Freshwater. Freshwater is the single most precious element for life on earth. It is essential for satisfying basic human needs, health, food production, energy and maintenance of regional and global ecosystems.
Environment by Numbers: Selected articles on Australia's Environment includes a major article, Australia's Rivers, contributed by John Whittington and Peter Liston of the Cooperative Research Centre for Freshwater Ecology. The authors state that catchment land use has significantly modified the physical and chemical nature of rivers in much of Australia’s intensive land use zone.
The National Land and Water Resources Audit (NLWRA) describes river condition using an environmental index that combines the effects of catchment disturbance, habitat condition, hydrological disturbance, and nutrient and suspended sediment loads. The environmental index shows that within the intensive land use zone of Australia, which represents approximately 40% (3 million square kilometres) of the continent, over 85% of the rivers have been degraded to some extent by human activity.
The Audit also reported that nutrient and suspended sediment loads were significantly above natural levels for 92% of river length. Total phosphorus loads in rivers averaged 2.8 times higher than estimates for pre-European settlement levels and total nitrogen loads are 2.1 times higher. Exceedence of national guidelines for nutrient concentrations is a major concern in 61% of river basins.
The National River Health Program used aquatic plants and animals as indicators of river condition. The majority of rivers (69%) across Australia were found to be in good condition. The remaining 31% were suffering from some degree of impairment, ranging from mild impairment where some of the animals normally occurring in a river were missing, to major damage where most animals were missing.
The rivers with biota in good condition tended to be in national parks, mountainous regions or remote regions. Rivers showing impact tended to be close to major cities or in highly developed agricultural areas. Also impacted were rivers in mountainous regions affected by river regulation.
In some regions the extraction of large volumes of water for agricultural, urban and industrial use has had a severe impact. Consumption of Australia’s freshwater resources from lakes, rivers and underground has increased dramatically in the last two decades. Between 1983-84 and 1996-97 national water consumption increased from 14,600 GL to 23,300 GL annually.
Irrigated agriculture is by far the biggest consumer of Australia’s freshwater resources. Of the water diverted in 1996-97, approximately 75% was used for irrigated agriculture (17,356 GL), 5% (1,238 GL) for other rural purposes such as stock and domestic uses, with the remaining 20% (4,673 GL) for urban and industrial purposes.
The Murray-Darling Basin is one of the worst affected basins, with 20% of river length accumulating more than 0.3 metres of sediment. Land management that targets erosion control could provide a significant benefit to managing supply sediment loads and nutrient loads to many rivers.
Based on state assessments of sustainable yield the Audit determined that 34 of Australia’s 325 surface water basins are overused, with a further 50 highly developed. Almost all of the basins with a high volume of unused sustainable yield are in the northern parts of Australia. Undoubtedly, these regions will be heavily targeted for water resource development in the future, and long-term planning for this needs to be undertaken so as to avoid the mistakes made in many of the southern water basins.
Trends over the last century
In his article Climate Change,Professor Zillman, the Director of Meteorology, demonstrates that there has been a warming trend during the 20th century in Australia. Most years of the past two decades have been above the 1961-90 normal and approximately half a degree warmer than the average for the first half of the century. The general warming trend over the 20th century is evident in both summer and winter temperatures as well as in daily maxima and minima.
The warming trend in Australia is of the same general magnitude as the observed globally-averaged warming described in the Third Assessment Report of the IPCC. However, this warming trend is not uniform across Australia. While parts of Queensland have warmed by more than 1oC over the past 50 years, parts of New South Wales and Victoria and large areas of north west Australia have experienced only minimal warming, or have actually cooled, over the period.
The pattern of changing rainfall is also highly variable from region to region. Most of central and north-west Australia has got wetter over the past 50 years while south-west Western Australia , Victoria and much of New South Wales and Queensland have got drier. Overall, there has been a very slight increase in rainfall for Australia as a whole.
Cause of climate change
At the global level, the IPCC has concluded that 'there is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities'. There appears to be good reason to believe that the overall warming trend over Australia over the past half century is also largely a result of enhanced greenhouse warming.
Impacts of climate change
It is clear from the experience of the past century that the challenge of living with climate change in Australia is mainly that of planning and managing for the large natural year-to-year and decade-to-decade variability of rainfall and other characteristics of Australian climate. The lessons learnt from this experience will be critical to the 21st century challenge of living with whatever human-induced long-term change is superimposed on the continuing natural variability.
Scenarios and projections for the future
Zillman presents the scenarios and projections published in the IPCC Emission Scenarios as a method for gaining an understanding of the sensitivity of the global climate system to increasing (or decreasing) emissions. The scenarios are based on models where a range of emission scenarios are used to produce concentration scenarios which are then used to produce corresponding projections of how the enhanced greenhouse effect would be expected to modify the real climate. Both sea level and temperature are projected to rise under all scenarios. Temperatures are projected to rise between 1oC and 6oC and sea levels are projected to rise between 0.1m and 0.9m.
State of knowledge
Despite criticisms of the emissions scenarios, the conclusions of the Third Assessment Report remain the most up-to-date and most reliable summary of the state of knowledge of the science of climate change. These conclusions include:
Future climate change over Australia
The most confident statement that can be made about the next decade and the next century is that Australia must expect to continue to experience the major El Niño- and La Niña-associated multi-year fluctuations of temperature and rainfall which have earned it its reputation for climate extremes and its image as a land of ‘droughts and flooding rains’.
The next most confident thing that we can say about future climate change in Australia is that there seems likely to be a general warming trend, as a result of the inevitable continued build-up of greenhouse gases in the atmosphere, of up to perhaps a few degrees over the century, superimposed on whatever temporal and spatial change (including short-term variability) occurs as a result of natural processes.
Environment by Numbers can be downloaded from the website (payment with a credit card). It is also available for purchase in hardcopy from ABS Bookshops.
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