Once-In-A-Generation Heatwaves Could Be A Yearly Event, New Research Finds

news.com.au - Benedict Brook

The sun rises on another hot day in Sydney.

IT’S been a sticky old week across southern Australia with the mercury topping 41C in the west of Sydney and severe heatwaves in parts of New South Wales and northern Western Australia.
But far from being an unusual occurrence, climate scientists are predicting heatwaves globally are on the rise with extreme heat events, which previously only occurred “once in a generation”, could happen every year.
And that means more than just some extra days at the beach, with predictions of more bushfires, stretched emergency services and severe impacts to farmers and food production.
In a paper published in the journal Climatic Change, researchers found heatwaves only experienced once in every 20 years could, in years to come, happen every year in some places. By 2075, 60 per cent of the Earth’s land mass could see these extreme heat events annually or even more frequently.
By 2050, heatwaves could be three degrees warmer across half the world and across 10 per cent of the Earth’s surface a scorching five degrees hotter.

The Bureau of Meteorology predicts Australia will almost certainly have above average temperatures during March. Source: BoM.

Fifth warmest year
The study’s co-author, Claudia Tebaldi, from the US National Centre for Atmospheric Research said “Mitigation is crucial. We have a lot to gain from limiting greenhouse gas emissions, and [those] benefits will be felt fairly soon,” reported Climate Control.
Although the northern hemisphere is more likely to be in the firing line, there’s little respite for us in Australia with a marked increase in heatwaves and their intensity, climate researchers have said.
On Thursday, the Bureau of Meteorology (BoM) warned daytime temperatures during Autumn were likely to be warmer than average, particularly in March.
According to the BoM’s annual climate statement, 2015 was Australia’s fifth warmest year on record with temperatures 0.83C above average and exceptionally warm spells including heatwaves across north and central Australia in March and south and south eastern Australia in the latter part of the year.
Heatwave conditions in Australia are defined by three days of unusually hot minimum and maximum temperatures for any given area.

Beachgoers walk into the sea at Coogee on Thursday in Sydney as temperatures peaked at 41C in the city’s west. Photo: Mark Metcalfe/Getty Images.

Longer and more extreme
Speaking earlier this month, Dr Sarah Perkins-Kirkpatrick, of the University of NSW’s Climate Research Centre, said the trend was for longer and more extreme heatwaves.
“We’re seeing heat and hot weather we’ve never seen before that [is] breaking lots of records.
“We’re not expecting to see heatwaves last all summer but those really rare heatwaves we might only have seen every 20 years we could now see every two years, which may not have happened if climate change hadn’t occurred.”
However, the pattern of heatwaves wasn’t uniform, said Dr Perkins-Kirkpatrick. Sydney had seen its heatwave season kicking in three weeks earlier, as had Melbourne — although the latter hadn’t seen an overall increase in the number of days experiencing extreme heat.
In Canberra, they really can’t bear it, with a doubling in the number of heatwave days although the intensity had remained stable.
The new research said if nations cut emissions, 95 per cent of land areas could see a reduction in worst-case temperatures on extreme heat days by 1C while half the earth’s land mass could see a 2C cut. Areas severely affected by heatwaves might drop to between 10 and 25 per cent rather than the 60 per cent predicted.
More than 100 countries have pledged to work towards keeping temperature rises to below 2C by the end of the century.

The only way to cool down. Photo: Mark Metcalfe/Getty Images

Cooking the planet
Activist group GetUp!’s Climate Change Campaigns Director, Sam Regester, said it was not surprising that the globe was seeing a rise in heatwaves and nations needed to do more to prevent climate-induced catastrophes.
“More extreme weather events mean more bushfires and natural disasters and emergency services are just not equipped to deal with once in a generation heatwaves every few years.
“It also puts a huge stress on farmers. In some heatwaves we see entire seasons of crops destroyed and unless we address climate change, food security becomes a real and urgent problem and we won’t be able to take abundant fresh food for granted.”
While 2015 was one of Australia’s hottest years on record, overall temperatures have been reducing, coming off a record peak in 2013. Aren’t things going in the right direction already?
“You just have to take a step back and look at the long term trends of 30 years in a row of above average temperatures,” said Mr Regester. “There’s no question — the world’s getting hotter and getting hotter at a dangerous rate.
“We need to transition urgently away from fossil fuels that are literally cooking the planet and move to 100 per cent renewable as fast as possible.”
While Australia’s south-east corner is in for cooler temperatures this weekend, with Sydney topping 28C on Sunday and Melbourne only reaching 23C, there are still spots of punishing heat elsewhere. Brisbane will reach 35C on Sunday with Perth sweltering with a whopping 38C the same day.
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