Environmental Economic Issues of Australia

Greenhouse gases are gaseous components of the atmosphere that contribute to the greenhouse effect, which is an environmental issue that deals with the potential for global climate change due to increased levels of these gases. The major greenhouse gases are water vapour, which causes about 36-70% of the greenhouse effect on Earth; carbon dioxide, which causes between 9-26%; ozone, which causes between 3-7%; along with methane, nitrogen oxides, and some engineered chemicals such as chlorofluorocarbons (CFCs). Certain gases in the atmosphere serve to regulate the amount of heat that is kept close to the Earth's surface, and thus an increase in these greenhouse gases would trap more heat in the lower atmosphere, translating into increased temperatures, which could result in many disastrous environmental effects.

The concentrations of several greenhouse gases have increased over time due to human activities, such as the burning of fossil fuels and deforestation leading to higher carbon dioxide concentrations. As well, cattle and paddy rice farming, land use and wetland changes, pipeline losses, and landfill emissions leading to higher methane concentrations. The harmful emissions has also increased due to the use of CFCs in refrigeration systems, the use of CFCs and other halogens in fire suppression systems and various manufacturing processes.

Greenhouse gases from industry and agriculture, mostly carbon dioxide, are mainly to blame for recent global warming. Coal-burning power plants, automobile exhausts, factory smokestacks, and other waste vents of the human environment releases 22 billion tonnes of carbon dioxide increased by 31% above pre-industrial levels since 1750.

Australia is a relatively small producer of greenhouse gases, accounting for approximately 1.4% of global emissions. However, its emissions per capita rank third amongst industrialised countries. This is due to particular circumstances including an abundance of fossil fuel resources, a dispersed population with a consequent heavy dependence on fossil fuel based transport, and a relatively rapid rate of population growth. Australia is the world's second-largest emitter per capita of greenhouse gases, after the U.S. sing global climate model simulations, the CSIRO has projected future likely climatic changes in Australia due to increased greenhouse gas concentrations in the atmosphere, which include an increase in average annual temperature of 1-6°C by 2070 over most of Australia. An increase in the average number of extreme hot days and decrease in the average number of extreme cold days: could lead to the increased incidence of wildfire, causing loss of life and major property damage and having substantial effects on the ecosystem by favouring some species that are adapted to fire at the expense of others. It also predicts a decrease in annual average rainfall in the south-west and in parts of the south-east and in Queensland. In addition, CSIRO has also projected an overall drying trend for Australia due to increased temperatures and evaporation and changes in rainfall, an increase in maximum wind speed of tropical cyclones of 5-10% by 2100 and increase in precipitation rates by 20-30%.

In its CSIRO reports it has highlighted a rise in sea levels by 0.8 to 8.0cm per decade, which could cause coastal erosion and inundation as material on sandy shorelines is eroded from the upper beach and deposited on the near-shore ocean bottom, resulting in a coastal recession of sandy beaches of 4.5 to 88 metres by 2100. a substantial reduction in the duration of winter snow cover in the Australian Alps in the south east of the continent and parts of Tasmania, where the snow usually lasts a few weeks at elevations of 1200-1400m and for periods of up to several months higher in the mountains, which can have severe effects on the sensitive alpine plant and animal communities, and on the tourism and downstream irrigation industries in the alpine regions.

The CSIRO also projects damage to coastal environments: coral reefs stressed by changes in ocean temperatures, nutrients and stream flow could undergo bleaching, and higher carbon dioxide levels may lead to reduced coral growth rates, along with possible increasing cyclone intensity (stronger peak winds and higher precipitation rates) causing further damage. In Australia due to climate change 20 million people at risk of coastal flooding. negative impacts on agriculture, future wheat yields, which has both the positive effect of increased carbon dioxide levels and the generally negative impacts of projected climate change, as wheat is planted in autumn and winter and grows through spring, so any projected reductions in winter and spring rainfall would increase moisture stress and hence reduce yield,

In the Murray Darling Basin, where irrigated agriculture accounts for around 70% of all water used, climate change could impose costs to agriculture in the order of $0.8-$1.2 billion in net present value terms; climate change is also likely to lead to increases in river salinity, leading to higher production losses.