A perfect storm of factors created devastating flood conditions in Queensland and NSW this year and global warming could have made them worse, the Bureau of Meteorology says.
Key points:
- BOM relates flooding to a trend of high-intensity rainfall events due to climate change
- He says more than 50 sites in Queensland and NSW recorded more than a meter of rain in a week
- The floods were caused by a series of stagnant weather systems over the regions
An office report on disasters released today confirms that many centennial records fell when a series of deep low-pressure systems powered by La Niña repeatedly poured heavy rain over a soaked landscape.
The office said that while climate change did not cause disasters, it linked flooding to a trend towards more intense and short-lived rainfall events, especially in northern Australia.
Months of heavy rains hit the east coast as Australia experienced its first consecutive La Niña weather systems in a decade. Scientists say that next summer there is the possibility of a rare La Niña of “triple immersion”.
Today’s report comes as the office issued unwanted news for those parts of the country where dams remain full and flood recovery continues, with signs of more heavy rainfall in the coming months.
In its update to the climate controller, the office expects a negative dipole in the Indian Ocean (a measure of sea surface temperature) to develop, which increases the chances of above-average rainfall in the Indian Ocean. winter and spring in much of Australia.
At the same time, signs of La Niña’s release have slowed and “the expected sea surface temperature pattern in the tropical Pacific still favors average and above-average winter rains in eastern Australia.” .
Properties fall on Gympie on February 26th. (ABC News: Matt Bouveng)
Today’s office report says more than 50 locations in south-east Queensland and north-east New South Wales recorded more than a meter of rain in the last week of February.
“These systems have just been parked in southeast Queensland. And when those systems do, that’s when really big floods happen,” said Karl Braganza, the office’s national climate services manager.
“The catchments were already saturated. And then (after the rain) you started to have an incredible runoff.”
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The Mary River in Gympie, Queensland, which has flood records dating back to 1870, surpassed all previously recorded flood peaks except the Great Flood of February 1893. The Lower Logan River, south of Brisbane, it experienced its worst flooding since 1974.
In some parts of northern New South Wales, floodwaters easily hit previous record highs, some dating back more than 100 years.
Devastating floods occurred in Lismore (Wilsons River) and other nearby cities, such as Coraki and Woodburn (Richmond River) and Murwillumbah and Tumbulgum (Tweed River).
In the Heart (2021) sculpture by Holly Ahern and Eden Crawford-Harriman following the 2022 floods in Lismore. (Photo: Brendan Beirne)
The report said a warmer atmosphere could contain more moisture, resulting in heavier rains.
“The same climate models have long projected an intensification of the hydrological cycle, which is essentially droughts that become potentially longer, warmer and more frequent, but also, when the conditions are right and the weather is right, that the rains be more abundant than they were in the past.
The Girl facts:
- Three-year-old girls are rare and most recently produced between 1973–76 and 1998–2001.
- While La Niña brings a humid climate to Australia, it brings a dry and hot climate to places such as South America and East Africa.
- It is difficult to predict when and how strong the wet weather may be, but if a third La Niña is installed, it is unlikely to be strong.
Northern Australia is getting wetter and the south is drier, says Dr Andrew King of the University of Melbourne’s ARC Center of Excellence for Extreme Climate Change.
But he says that in south-east Queensland and east in New South Wales, rainfall is so variable that it’s hard to spot any trends.
“We don’t know how the rains will change in this region in the future. The weather projections are very uncertain, and that’s a big problem,” he said.
“We need to understand how especially extreme rain events in this region will change because of the huge impacts they can have,” he said.
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Braganza said there were so many factors contributing to storm events that predicting them was a challenge.
“We’re going to have to see amazing things that we couldn’t necessarily predict because of the complexity of the climate system,” he said.
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Posted 3 hours, 3 hours ago, Wednesday, May 25, 2022 at 1:09 AM, updated 7 minutes ago, 7 minutes ago, Wednesday, May 25, 2022 at 4:46 AM