Extract from ABC News
The weather behind Canada's record-breaking fires, which have seen millions of hectares destroyed and tens of thousands evacuated from their homes, was made significantly worse by climate change, according to a rapid analysis by a leading team of climate scientists.
Key points:
- Researchers found climate change made the peak in the extreme fire weather twice as likely and 20 per cent more intense
- One of the report's authors said hot and dry conditions in Canada meant the landscape was more flammable
- Australia is also likely to see 'more frequent and more severe extreme weather events' due to global warming
Canada is experiencing its worst fire season by a long shot with more than 15 million hectares burned already this year, smashing the record previously set in 1995, when more than 7 million hectares were destroyed by fire.
The hot, dry weather over eastern Canada that has allowed the fires to spread and intensify was completely unprecedented, but is no longer rare, according to the paper which has not yet undergone peer review.
The researchers found the peak in the extreme fire weather, between May and July 2023 in the region, was made twice as likely and 20 per cent more intense by human-induced climate change.
Researchers also found throughout the entire fire season, the cumulative extreme fire weather was made seven times as likely because of climate change.
The fires continue to ravage eastern Canada, with the Canadian Interagency Forest Fire Centre this week reporting there were more than 1,000 fires burning across the country, with 659 listed as out of control.
"The word 'unprecedented' doesn't do justice to the severity of the wildfires in Canada this year," paper co-author Dr Yan Boulanger from Natural Resources Canada said in a statement.
"From a scientific perspective, the doubling of the previous burned area record is shocking."
He said the hot and dry conditions — driven by climate change — meant the landscape was more flammable.
"This means that a single spark, regardless of its source, can rapidly turn into a blazing inferno," Dr Boulanger said.
Results expected but 'nonetheless alarming', expert says
Mostly driven by the burning of coal oil and gas, the climate has warmed by about 1.1 degrees Celsius since 1900.
Climate scientists have warned we are likely to see 1.5C of warming as early as 2030.
The study was conducted by the World Weather Attribution initiative, a group focused on rapidly deciphering the role of climate change in extreme weather events.
"This is the leading group doing real time attribution," said Dr Sarah Perkins-Kirkpatrick, a climate scientist at the University of New South Wales, who does similar research.
"I am cautious that it hasn't been peer reviewed — that process is there to pick up nuances with the method that the authors didn't see themselves.
"Although peer review may highlight some issues or shortcomings, in this case I don't think it will change the results."
Dr Andrew King from the University of Melbourne also works on attributing extreme weather to climate change.
"We anticipate that climate change will see worse and larger fires. And this is consistent with that trend — but it is nonetheless alarming," he said.
Dr Perkins-Kirkpatrick said she had confidence in the results partly because they were in line with studies on other fires.
A similar study by the same group, looked at the influence of climate change on Australia's disastrous Black Summer of 2019 to 2020.
That event was driven by a range of factors, including a record hot week in December 2019. The researchers found that record heatwave was at least twice as likely now than it would have been in 1900, because of global warming.
It found the extreme fire risk index values during the fires were at least twice as likely because of climate change.
Scientists warn severe weather will get worse
Both Dr King and Dr Perkins-Kirkpatrick said finding the role of climate change in driving fire was particularly hard as it was driven by so many complicated weather phenomena including wind speed, prior rainfall and humidity.
It is complicated further by the features of the local landscape.
Dr Perkins-Kirkpatrick said lots of evidence was now converging, showing that climate change was making fires worse.
That includes studies which showed increased length of fire seasons and increased severity of fires.
She said during the Black Summer fires, Australia saw roughly the same number of fire-induced thunderstorms, known as pyrocumulonimbus, as seen in the country over several decades.
"It was just phenomenal," Dr Perkins-Kirkpatrick said.
"It's going to get worse.
"We're going to warm more and unfortunately; with that we will see more frequent and more severe extreme weather events."
Dr King said one of the worst impacts of fires like those in Canada and during the Black Summer in Australia was the widespread impact on air quality.
The Canadian fires lowered air quality in cities as far as New York and the Black Summer fires caused poor air quality in Melbourne, Sydney and Canberra.
"As these get more frequent and more severe, we have to learn to live with these effects," Dr King said.
"It's hard to adapt to — if the air we breathe isn't safe to breathe.
"It's quite an alarming effect of climate change if we get more of those days."
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