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Climate Change in Australia
In 2007 the Intergovernmental Panel on Climate Change (IPCC) released their fourth assessment report, concluding that:

* Warming of the climate system is unequivocal
* Humans are very likely to be causing most of the warming that has been experienced since 1950
* It is very likely that changes in the global climate system will continue well into the future, and that they will be larger than those seen in the recent past.

These changes have the potential to have a major impact on human and natural systems throughout the world including Australia.

The IPCC reports provide limited detail on Australian climate change, particularly when it comes to regional climate change projections. For this reason the Australian Greenhouse Office, through the Australian Climate Change Science Programme, engaged CSIRO and the Bureau of Meteorology to develop climate change projections for Australia.

Climate change in Australia is based upon international climate change research including conclusions from the IPCC's fourth assessment report. It also builds on a large body of climate research that has been undertaken for the Australian region in recent years.

Climate change in Australia provides essential tools for government, industry and the community to understand the likely magnitude of climate change in Australia and the possible impacts.

Visit this site to see future climate predictions for this region


Observed Changes

Temperature

Australian average temperatures have increased 0.9°C since 1950, with significant regional variations. The frequency of hot days and nights has increased and the frequency of cold days and nights has declined.

Rainfall

Since 1950, most of eastern and south-western Australia has experienced substantial rainfall declines. Across New South Wales and Queensland these rainfall trends partly reflect a very wet period around the 1950s, though recent years have been unusually dry. In contrast, north-west Australia has become wetter over this period, mostly during summer.

From 1950 to 2005, extreme daily rainfall intensity and frequency has increased in north-western and central Australia and over the western tablelands of New South Wales, but decreased in the south-east and south-west and along the central east coast. Despite forecasts for decreased rainfall in many areas of Australia, research by CSIRO (2004) predicts that by 2040, climate patterns for the eastern coast of Australia are likely to bring about more intense and more frequent extreme rainfall events. The most vulnerable regions for extreme rainfall include Coffs Harbour, Coolangatta, north of Brisbane, and over mountainous terrain (CSIRO 2004).

New South Wales (NSW)

Overall, climate change projections for NSW highlight increases in the occurrence of extreme rainfall events for many parts of the state. These events are most likely to occur in summer and autumn months, with the most vulnerable regions being eastern coastal regions, and central and south-east NSW (CSIRO 2004). Specifically, areas within these regions that will experience the most intense rainfall events occur over mountainous terrain, inland from Coffs Harbour (CSIRO 2004).

State rainfall projections under climate change include the following:

* Rainfall is expected to increase in summer and autumn months and decrease in winter and spring months, especially in the south-central and south-west regions of NSW;
* Extremely wet summers are expected to occur up to three times more then present in the south-west;
* Frequency of extremely wet autumns is expected to double in the north-central and south-central regions, and triple in the north-west region; and
* The number of extremely wet days in the north-west is expected to double.

Climate change projections for the year 2030 indicate that the frequency of drought in NSW is expected to increase by 70% under the worst case scenario (decreased rainfall) and decrease by 35% under the best case scenario (increased rainfall) (Hennessy et al 2004). By the year 2070 the range of uncertain is further exacerbated with an increased frequency of drought by more than 200% or decrease by up to 70% respectively (Hennessy et al 2004).

Visit Climate Action Network Australia for more information about how climate changes will effect water in Australia.

Oceans

Global sea levels rose by about 17 cm during the 20th century, and by around 10 cm from 1920-2000 at the Australian coastal sites monitored. Substantial warming has also occurred in the three oceans surrounding Australia, particularly off the south-east coast and in the Indian Ocean.


Key Climatic Events

A range of climatic events will play instrumental roles in shaping the changing nature of Australia's water systems under human-induced climate change. These include:

The combined impact of increasing sea level rise and extreme weather events are likely to result in an increasing occurrence and severity of flood surges (CSIRO 2003). Research shows that with a 20cm sea level rise, water levels would likely double with a 40 cm rise, and damage costs associated with flooding would increase by up to 50% (CSIRO 2003). Overall, it is now widely agreed that sea level rise will rise by 10-40cm by 2040 (CSIRO 2003).

Image: Greenpeace/Swansborough

DROUGHT
Increases in the occurrence and severity of drought events is expected across eastern and southern Australia, with the most severe events occurring in northeastern and southeastern Australia. Trends in increased drought are already being experienced in southern parts of Australia, whereby the 2002 drought was recognised as being the most severe drought since 1950 (Karoly et al 2003). The 2002 drought is the first drought in Australia where the impact of human-induced climate change can be clearly observed (Karoly et al 2003).

EVAPORATION
With hotter temperatures exacerbating evaporation rates, all parts of Australia are predicted to experience a decrease in moisture availability. Research suggests that increased evaporation rates will occur throughout all seasons, with a 0 - 10% increase by 2030 and a 0 - 32% by 2070. The most vulnerable regions include the eastern highlands and Tasmania (Passey 2003). Adding to the impacts of reduced rainfall in many parts, higher evaporation rates will further diminish river flows, leading to greater reductions in water availability.

CYCLONES
With the cyclone region expected to move further south, the progression of climate change is predicted to bring about an increase in the maximum intensity of tropical cyclones. Heavy rainfall, which is characteristic to cyclones, will also be intensified.

FIRE
A new report released by CSIRO will help south-east Australian communities prepare for possible increased risk of fire which may result from climate change

The combined frequencies of days with very high and extreme Forest Fire Danger Index ratings are likely to increase by 15 - 70 per cent by 2050

In Canberra, the annual average of very high or extreme fire danger days is likely to increase from the currrent 23.1 days to an annual average of 27.9 - 38.3 days by 2050

The increase in fire-weather risk is generally largest inland