Worrying trend for Queensland and big cyclones

CYCLONES are heading further south and increasing in strength, which could have implications for cities like Townsville, a leading climate scientist has discovered.

The phenomenon is called the "poleward shift" which describes the trend of cyclones forming further south towards the Earth's poles.

The paper "Recent poleward shift of tropical cyclone formation linked to Hadley cell expansion" published in Nature Climate Change, was based on an analysis of where cyclones form.

 

Tropical cyclones are among the most catastrophic of high-impact weather events. Pictured is Cyclone Iris when it was a Category 1 system at 10.30am Thursday, April 5, 2018. Picture: Bureau of Meteorology
Tropical cyclones are among the most catastrophic of high-impact weather events. Pictured is Cyclone Iris when it was a Category 1 system at 10.30am Thursday, April 5, 2018. Picture: Bureau of Meteorology

 

Co-author Kevin Walsh, a Professor of Meteorology at the University of Melbourne, said the results showed more cyclones were forming in regions further from the equator.

He said the evidence was consistent with predictions about the impacts of climate change which suggested an expansion of the tropics in the future.

Mr Walsh said other studies indicated the intensity of cyclones was likely to increase because of climate change.

He said further research was needed into the southward trend of cyclones. How it will impact cities in the Coral Sea like Townsville is not yet clear.

"We need to do some more in depth statistical analysis to find out the implications," Mr Walsh said.

The findings could mean more cyclones would affect people living on the edges of the tropics, the research found. More people tend to live along the southeast coastline of Australia and they could be in the firing line if the cyclone trend continues.

Mr Walsh said trends in the data were consistent with big circulation changes in the atmosphere which could imply an expansion of the tropics in the future.

"We haven't said this trend is definitely due to climate change," he said. He's expecting to focus his research into that area next," he said.

In a previous paper Mr Walsh said climate change was likely to lead to fewer tropical cyclones around the world because warm air formed at the ocean surface would not rise as fast. But those that do form will have increased power.

Tropical cyclones are among the most catastrophic of high-impact weather events and led to deaths and huge economic damage over populated tropical coastal regions in recent decades.

The poleward shift of the tropics could also lead to Townsville changing from one of the driest city in North Queensland to the wettest place in the state.

Professor Ray Wills, a commentator and adviser on sustainability and technology, said climate change was moving the "climate belt" - areas with distinct climates - south.


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