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Australia has no inland glaciers, so it is dependent on rainfall alone. Australia receives very low rainfall and has very high evaporation of available surface water. Further, a notable feature is Australia's high year-to-year rainfall variability; where it falls and how it falls can be quite different from one year to the next. Over the last twelve years, Melbourne has experienced below-average rainfall, dropping from 655 to 575mm per year.
How does climate change affect water availability?
As the climate changes, water will become more scarce. Global warming impacts on water availability in two ways:
1. Glacial ice-melt. Glaciers feed and annually refresh many of the rivers, lakes and deltas of the world. As the planet warms, less ice forms each winter and more of it melts in the warmer months. The initial result is more water in spring and less in summer and autumn when it is most needed. This affects most current cropping patterns and causes seasonal water scarcity. The long-term effect is the rapid melting and possible disappearance of glacial ice. The Intergovernmental Panel on Climate Change (IPCC) estimates that at the current rate of melt, 75 to 80% of the world's glacial ice may completely disappear by 2050. The Himalayan glaciers alone are a life source to over 750 million people in Asia.
2. Increased rainfall variability. In many parts of the world, rainfall patterns have been relatively steady for most of the last 10,000 years. Global warming has an impact on where, when and how much rain falls. This means a higher likelihood of not getting rain where you expect it and in the amount you expect. The long-term effects include reduced rainfall in catchments, reduced flows in waterways and increased desertification.
How will climate change affect water availability in Australia?
The anticipated effects of climate change on Australia's water availability and supply mean that over the next 50 years, Australia will continue to experience decreasing rainfall and flows (in rivers and catchments) in regions like south-east Australia. This can lead to declining water quality, the collapse of inland freshwater systems, increasing desertification and salinity, increased risk of bushfires and drought.
In short, climate change will ‘exaggerate' our existing patterns of low water availability and variability; Australia will become much drier and experience even greater year-to-year rainfall variability.
Flow-on effects of reduced water availability
Primary flow-on effects include the rising costs of water and food, as well as detrimental effects to other industries reliant on water, such as mining and some forms of manufacturing.
To find out more about climate change, visit the Climate Change page.