A slow-moving heat dome is bringing record-breaking temperatures to the northern hemisphere. Climate scientists are alarmed by how bad it is – and what might follow in Australia. By Max Opray.

Welcome to the heat dome

A firefighting tanker drops retardant over the Grandview Fire in Oregon.
A firefighting tanker drops retardant over the Grandview Fire in Oregon.
Credit: Oregon Department of Forestry

Erica Fleishman and her colleagues at the Oregon Climate Change Research Institute wondered if something might have been wrong with the weather forecast. The high temperatures predicted for the north-west United States were more like Portland, New South Wales, than Portland, Oregon.

“People’s reactions were like: ‘This is very strange,’ ” Fleishman tells The Saturday Paper. “It was not until it was about a week out when we realised: ‘Wow, this is going to be major – this is not a modelling mistake.’ ”

In late June, a slow-moving “heat dome” weather system settled over vast swaths of North America, from Mexico right up to the Arctic Circle. In Canada, the temperature record was shattered by 5 degrees, with the thermometer hitting 49.6 degrees in Lytton, British Columbia. Days later, Lytton was obliterated by fires that are sweeping the western half of the continent.

Nearly 2000 firefighters are battling the Bootleg Fire in Oregon alone, one of the largest in the state’s history at more than 380,000 acres (about 155,000 hectares) – big enough to create the pyrocumulus thunderstorms seen during Australia’s Black Summer.

Further heatwaves followed in July, including another heat dome that had Death Valley in California potentially set a new, reliable global temperature record of 54.4 degrees Celsius.

Climate scientist Andrew Weaver experienced firsthand the disruption from his home on Vancouver Island.

“We simply have no analogue anywhere close to what happened at any time since humans have been recording temperatures in British Columbia,” the former leader of Canada’s Green party tells The Saturday Paper. “There was a run on airconditioners and they sold out everywhere. People were living in basements to try and keep cool … There was massive dieoff of coastal marine life.”

Weaver, who lived in Sydney in the 1980s, says Canadian cities are ill-equipped to handle the heat – just as Australian cities aren’t built for extreme cold. “We simply don’t have the systems in place to keep people cool at such temperatures,” he says, “especially when they are sustained.”

The BC Coroners Service recorded more than 800 deaths from June 25 to July 1 – four times the average number of fatalities in a week. Many of these have been linked to extreme heat.

Weaver warned that if this could happen in Canada, the global implications are ominous. “Honestly, the world hasn’t really begun to experience what we have in store,” he says. “It will get far, far worse before – and if – it gets better. The cognitive dissonance within broader society is quite unbelievable.”

With the northern hemisphere weather forecasts proving accurate, despite doubts, questions are now being asked of longer-term climate projections.

When it comes to extreme weather events, it’s not easy to unsettle Dr Sarah Perkins-Kirkpatrick. The UNSW Sydney expert on climate change-fuelled heatwaves spends her professional life studying charts of the coming decades, but the past month of record-shattering heat in North America has her rattled.

“It’s freaked me out a little if I’m honest,” she says. “I’ve just moved down to Canberra with a young family and knowing how bad it could get with just over 1 degree of warming – I didn’t think this was possible.”

Perkins-Kirkpatrick and fellow climate scientists across the world are digesting the news that even their worst-case projections may underestimate the severity of heatwaves to come.

She says that although conditions in the north don’t indicate whether Australia can expect a particularly hot summer this year, they do throw into question just how hot future heatwaves will get.

Perkins-Kirkpatrick said the northern hemisphere extremes – sweltering heatwaves have also hit Siberia and Scandinavia – lend additional uncertainty to Australian projections, suggesting that Sydney could potentially have 50-plus temperatures “in the next decade or two”.

“Most models can’t do regional heatwaves really well – we need more data, which is an age-old problem,” she says. “To create better models, we need more funding, better computer power.”

CSIRO oceans and atmosphere expert James Risbey says the heat dome was caused by an unusual combination of a high-pressure system that lingered in place accompanied by a trough offshore, preventing intrusion of maritime air to decrease temperatures.

“Part of the saving grace for that region is it is next to the ocean, which tends to moderate high temperatures but didn’t in this case,” he says.

Heat domes, marked by prolonged, still heat that lasts day and night, have also hit Australia. One settled over the continent in January 2019, when Australia registered its hottest month on record, with the mean temperature 2.9 degrees above the January average. Bourke in north-western New South Wales recorded 21 days in a row above 40 degrees.

Professor Kristie Ebi, of the Center for Health and the Global Environment at the University of Washington, says the death toll from the North American heatwave is yet to be finalised.

In Washington state alone, the number of fatalities stands at 112. Ebi expects the numbers to gain ground on the Canadian toll once death certificates are issued – a process that takes several months longer in the US.

“Heatstroke deaths actually represent a tiny fraction of all the deaths from a heatwave,” she says. “Body mechanisms try to bring down the core body temperature to a range that our cells and organs operate at most efficiently. When these mechanisms fail, you start to heat organs, to heat cells. So with heart disease, respiratory disease, diabetes, obesity, over-65s, you are at higher risk during heatwaves.”

Ebi says better infrastructure needs to be established, such as green roofs on homes, and cooling centres that allow public access to airconditioners. “Around the world, people live in all kinds of environments that are well outside the limits of where humans theoretically can survive,” she says. “We’re pretty adaptable as a species – we’ve built infrastructure to live in the Arctic, in incredibly hot areas of the Sahel.”

Ebi pointed to how, during the heatwave, cherry orchard workers in Washington state harvested the crop in the evening under floodlights.

“Ultimately, though, we need to be reducing greenhouse gas emissions – our future is in our hands regarding how hot it’s going to get,” she says.

John Boland, professor of environmental mathematics at UniSA, has been putting research under way at his workplace into practice at home.

Boland lives in the Adelaide suburb of Felixstow, where he has watched in horror as new homes are erected with little consideration for the heatwaves of today, let alone tomorrow. He is working with the climate solutions committee for the City of Campbelltown local government area, in the north-eastern suburbs of Adelaide, to advise on regulations and education campaigns at a local level.

“There are very simple things people can do, even with bad houses – but it would be helpful if things were well designed in the first place,” he says.

Boland retrofitted his 1940s weatherboard home with insulated walls, along with strategically placed vegetation to block sun and hot northerly winds.

“We have designed our retrofit to take advantage of gully breezes in summer to cool our place in the evening,” he says. “We watch the weather and see when it is a good time to open up the place and take advantage of the breezes.”

The system works so well he doesn’t need an airconditioner – just as he didn’t back in Canada, his country of origin.

When Boland saw the news about the heatwaves, he fired off an email to some old friends now living in Portland, Oregon. “They came to visit me here once,” he says. “So, I told them: ‘Oh, it’s like you’re living in Adelaide now.’ ”

Back at the Oregon Climate Change Research Institute, Fleishman says the heatwaves and fires have not triggered a great deal of local conversation around the drivers of global warming, such as fossil fuels. The focus, instead, has been on how to adapt.

“For example, Oregon is one of two states where you can’t pump your gasoline yourself – to maintain jobs someone pumps your gasoline for you,” Fleishman says. “It was so hot the governor suspended this and said you can go pump your own gas for the next three days. That’s like, ‘Whoa – that’s a big deal here.’ ”

This article was first published in the print edition of The Saturday Paper on July 24, 2021 as "Welcome to the heat dome".

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