As Australia stares down the barrel of a hot summer and a rising risk of heatwaves and bushfires, politicians are going to have to get to grips with answering the obvious question. What is climate change doing to our weather extremes?
The Coalition’s shadow social services minister, Michael Sukkar, was given an early test last week and he roundly failed.
Sukkar was asked by a journalist if the climate crisis had contributed to the prospect of bushfires in the south of New South Wales or the “unseasonally hot weather” in that state and in Queensland.
“I don’t think so,” said Sukkar. “I don’t think you can say that climate change itself for any particular season, any particular event or any short period of weather can be ascribed direct to climate change.”
Dr Ailie Gallant, a climate scientist at Monash University, said Sukkar’s assertion was “patently wrong”.
“Everything that happens in the climate now is influenced by climate change in some way, and the extent of that influence gets bigger and bigger over time.
“We know El Niño tends to bring drier conditions and an increased chance of fire. However, climate change has made the impacts of El Niño worse.”
Sukkar’s response ignores almost two decades of research in a field known as climate attribution science.
For almost 20 years, scientists have been running experiments using both models and statistics to understand what increased levels of greenhouse gases in the atmosphere is doing to our extremes of weather. More than 500 individual weather events have been studied.
The studies don’t try to answer the question “did climate change cause this event” but ask what role climate change has in increasing the likelihood or severity of an event.
For example, scientists found global heating had increased the risk of the then-record hot Australian summer of 2013 by about five-fold.
Research has also found the climate crisis increased the chances of the then record hot New South Wales summer of 2016-17 at least ten-fold. The extreme ocean temperatures that caused mass bleaching of corals on the Great Barrier Reef in March 2016 were at least 175 times more likely because of the global heating.
The director of the Institute for Climate, Energy and Disaster Solutions at Australian National University, Prof Mark Howden, reviewed Sukkar’s comments and said all extreme events now have the climate crisis embedded in them.
“To not take climate change into account in how we should be preparing our systems for the forthcoming months to centuries just does not make sense,” he said.
“Instead of confusing people, we should be trying to generate clarity and understanding so people can make more informed and ethical decisions.
“It is reasonable to remind people of the primacy of climate in the fortunes of our country. Rationally, this should emphasise the importance of climate change, not downplay it.”
Hotter sunburnt country
Politicians love to quote from the Dorothea Mackellar poem My Country and those famous lines about a sunburnt country and a land of “droughts and flooding rains”.
The poem has been used countless times to undermine concerns about the climate crisis by reminding Australians that the country has always experienced extremes.
Sukkar referenced the poem too, saying the country had “always been a land of fires and flooding rains” as it had since “time immemorial”.
Mackellar first wrote the poem in 1908, two years before Australia’s long-term temperature record starts. That record shows this land “of droughts and flooding rains” has warmed by about 1.47C.
Australia has just been through its warmest winter on record. The latest State of the Climate report from the Bureau of Meteorology and CSIRO shows every decade since the 1950s has been warmer than the one before.
“Increasing trends in extreme heat are observed at locations across all of Australia,” the report says, with an at least five-fold increase in months with very high maximum daytime and night-time temperatures.
Howden said: “Harking back to the climate risk profile we had over 120 years ago misdirects the audience. Our climate risk profile has changed since then. The averages have changed and the variability has changed. So we need to update the risk profile.”
“This is basic risk management. If we did not do this sort of update in any other arena we would be rightly criticised and held to account.”
Fire weather increasing
So what about changes in the risk of fires?
Over the past four decades, the number of days in Australia where the fire risk is considered extreme has gone up by more than 50%, according to one study.
Dr Grant Williamson, a bushfire and climate scientist at the University of Tasmania, said since 2000 fire seasons have been getting longer.
He pointed to one study on the Black Summer bushfires that concluded global heating had increased the risk of that fire season happening by between 30% and 80% compared with a century ago.
In the country’s south-east, Williamson said times when the fire danger was high were extending earlier in the spring and this was cutting the time available for firefighters to carry out controlled burns.
“Going forward, climate models project that there will continue to be increasing fire risk and fire season length in south-eastern Australia, as well as increasing potential for extreme fire behaviour,” Williamson said.
Advertising denial
Climate scientists last week said Rupert Murdoch had done more than almost any other person in sowing doubt and confusion about the climate crisis through his outlets.
Over the years climate science deniers mostly haven’t needed to pay to run their screeds in Murdoch’s the Australian newspaper – they just get commissioned to write in the op-ed pages instead.
But on the same day Australia heard Murdoch was stepping down as the chairman of Fox and News Corp, the Australian ran a half-page advertisement of very old-school climate science denial.
The ad was the work of “The Climate Study Group” – a group of men with links to mining, finance and agriculture that includes two former directors of the Institute of Public Affairs. The group has been running occasional ads in the Australian for almost a decade.
The advert, titled “The Carbon Dioxide Climate Myth”, claimed the threat of a climate catastrophe from rising levels of CO2 was “a myth” and dismissed the role CO2 has played in warming the planet and pushing up sea levels. News Corp was approached for comment.
Prof Steve Sherwood, a climate scientist at the University of New South Wales, described the ad as “a delusional regurgitation of false tropes that have been around for at least 30 years and have been debunked over and over”.
The ad claimed that as CO2 rises in concentration in the atmosphere, its warming effect declines and this was why “climate models predictions with higher CO2 has failed compared with actual temperature observations”.
A chart in the ad showed that as CO2 increases in concentration in the atmosphere, its effect on warming the planet is reduced.
But the chart starts by plotting atmospheric CO2 at levels well below 200 parts per million – a level so low it’s almost never seen in at least 400 million years on Earth.
The chart shows that changing the atmospheric concentration of CO2 from 200 parts per million to 600ppm (humans have caused almost all the rise from about 280 ppm just before the industrial revolution to about 417 ppm now) gives an extra 5 watts per square metre of energy at the Earth’s surface.
Gallant said that equates to about 3C of global warming, “so their graph is not showing what they think it’s showing”.
“Their argument is a complete red herring and a misinterpretation of what energy surplus means. Even an extra 1 or 2 watts per square metre would lead to another degree or so of global warming.
“Healthy scepticism is part of science, but these arguments have been continually refuted for more than 20 years. They don’t stack up. It’s mind-boggling to me that people still make them.”
Another chart in the ad claims to show a large discrepancy between observations of global temperatures by satellites and weather balloons and those forecast by models.
The chart is a simplified version of one that has been in circulation since at least 2016, and has faced heavy criticism from scientists.
Gallant said one reason it is misleading is that it averages temperatures for the whole of the lower part of the atmosphere. She said global heating is greatest near the surface where CO2 is most efficient at trapping heat.
Dr Zeke Hausfather, a climate scientist at Berkeley Earth, said the chart compared model results of temperatures in the lower troposphere (about 3.2 km or 2 miles up) with observations there.
“There is a much bigger model disagreement in that region of the atmosphere than on the surface where we all live, where models agree quite well with observations.”
