Climate change: running rivers dry

Annual streamflow into the Murray-Darling Basin is likely to fall by 10 to 25 per cent by 2050, and by 16 to 48 per cent by 2100 according to one of Australia’s leading experts on the effects of climate change on our river systems.

“Our ongoing water security problems in southern and eastern Australia are likely to increase by 2030,” said Dr Bryson Bates, Climate Science Leader for CSIRO’s Division of Marine and Atmospheric Research.

“There are no integrated assessments of the impacts of climate change on runoff quantity and quality, biodiversity, salt interception revegetation policies, and water pricing and trading policies. Such assessments are essential if we are to adapt to climate change in an informed manner.”

Dr Bates, who spoke on May 22 at the 5th Australian Stream Management Conference on ‘Climate change and what it means for river management’ said the rivers and catchments of southwest Australia and to a lesser extent of SA and the southeast corner of the Murray-Darling Basin, were the ones most likely to be affected by climate change.

“The likely situation for northern Australia is unclear in terms of both the direction and the magnitude of change,” he said.

Dr Bates said little was known about likely impacts on groundwater resources.

“The current drought has demonstrated that we need to reconsider how we manage our water resources to better balance supply and demand and provide water for the environment,” he said.

“It is not too late, but we must act now rather than later. It is no longer an issue that we can put off for the next 20 to 70 years. Further climatic change is already locked-in; we will need to learn how to adapt to that and any additional change that might be incurred in the future.

“Past approaches to water planning have relied on the historical record. Given that we appear to be moving out of the historical ‘envelope’ we need to consider scenario-based approaches to planning wherein we explore the consequences of alternative and plausible futures, identify key decision points and develop contingency plans. This will involve the expenditure of more thought and effort on risk management and more dependence on seasonal forecasts provided the underpinning science can deliver an increase in predictive skill above the level that is currently available.