Flash flooding to grow under climate change

Flash flooding is emerging as a growing natural disaster threat for Australia as the recent State of the Climate report warns Australia’s weather is becoming more chaotic and heavy rainfall bursts will continue to intensify, driven by rising temperatures.

The report, authored by CSIRO and the Bureau of Meteorology, found climate change would cause “an increase in the risk of natural disasters from extreme weather”.

Australia’s average temperature has risen 1.47 degrees in the past century, which means cloudbursts of increasing intense rainfall are more likely as warming continues, since the air can hold 7 per cent more moisture for every degree increase in temperature.

Risk Frontiers climate scientist Stuart Browning said floods create the most financial damage of any natural disaster, but it was extremely difficult to predict where flash floods would occur.

“Climate systems warming, and air mass as a whole holds more moisture, so when it rains, we’re going to get more rain, but pinpointing exactly where that’s going to happen is really, really hard,” he said.

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“Oftentimes, even the Bureau of Meteorology weather forecasts, right, up until a day or so before an event, are still fairly vague about where we’re going to get the most intense rainfall.”

The State of the Environment report said atmospheric warming was driving “more intense short-duration heavy rainfall events, even in regions where the average rainfall decreases or stays the same”.

“This will lead to a complex mix of effects on streamflow [rivers], and associated flood and erosion risks, including increased risk of small-scale flash flooding.”