Extreme rainfall events intensifying more rapidly than first predicted

By Angel Heathcote 31 July 2018
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The link between global warming and increased rainfall events is well known, but scientists say our infrastructure may not cope at this rate.

AUSTRALIAN SCIENTISTS are concerned that extreme rainfall events are intensifying at a rate almost three times faster than was initially predicted.

Based on the new landmark study, which included analysis of 50 years of rainfall records from the Bureau of Meteorology, infrastructure may not be able to cope with the increase of heavy rainfall and flash floods.

“There’s been predictions for a while that climate change will lead to more extreme rainfall events, but our study showed stronger increases than was expected. This caused us a bit of concern, and is why we tried to publish it fairly quickly,” author of the paper Seth Westra told Australian Geographic.

“The rate of increase that we’ve seen is at least double and in some areas triple the rate that we first expected and so we really need to start understanding why this is the case, what’s driving this and whether it’s likely to continue.”

According to Seth, in the northern parts of Australia, rain is increasing by 20 per cent per degree change in temperature.

“Maybe that doesn’t sound like much, but when we think about what might happen over the 21st century, where there’s a very likely chance that we won’t meet our Paris Targets, and we may see a 3-4 degree temperature increase, we start to create a whole different rainfall regime that our cities and infrastructure needs to cope with,” Seth said.

Australia, a land of extremes

Seth acknowledged that, while Australia has always been a land of extremes, weather events have never been this severe.

“Australia has always been ‘a land of droughts and flooding rains’ as the poem says. But we know one of the challenges of climate change is that we’re seeing both ends of the spectrum increase in severity. The droughts seem to be more severe and the floods are becoming more severe as well.”

He said that it’s quite common for people to talk about “averages” when it comes to climate change. “Like the globe will warm by 2-3 degrees for example, but the real impacts of climate change are felt are in the extremes, and that’s the floods, heat waves and large storm events.”

Future planning

Better predictions models to help government and infrastructure should be a priority, said Seth. “Keep in mind that this isn’t some theoretical study, we’re already seeing these changes now. We’re making decisions now about infrastructure that will impact us 50 to 100 years in the future.

“Local governments zone regions according to their flood risk, so you can’t build in certain areas and that’s all well and good if the risk profiles don’t change but what happens when people have made all these decisions, the risk profiles change and someone who didn’t build in a flood zone is now in a flood zone, what happens to their house and insurance, who takes responsibility?”

Seth said that, if we don’t acknowledge that these changes are happening and include them in the planning of infrastructure, we’re committing future generations to a high level of risk.