At 35°C and 100 per cent humidity, a healthy young person can survive just 6 hours outside before their body loses control of its inner thermostat and becomes an oven, cooking itself alive.
The limit of what the human body can withstand was tested and confirmed by a study published this year in Nature, but it’s a limit that Australians are becoming more aware of as the mercury ticks up every year.
“We spent a big chunk of time at home in late 2019 and early 2020 while I was writing, and would only go out for walks late at night after it cooled down,” says Martin Ankor, an expat Adelaidean who escaped for Hobart during the pandemic.
“We would probably have moved regardless of the climate crisis, but being aware of some of the changes in climate and weather that have occurred, and are likely to increase in the future, made it a very simple decision.”
Ankor and his partner Karen are outdoorsy types in their 40s who enjoy hiking, nature and landscape photography. Ankor is a surveyor – a job he says is “not particularly enjoyable” in an Adelaide summer.
But unlike many COVID-19 refugees, they had already set their hearts on a Tasmanian cool-change before the pandemic began.
Fast forward to 2023 and Australia has experienced its warmest winter since records began in 1910 and facing the possibility of a scorching El Niño summer. The impact of heat on where people live in this country is moving out of the theoretical and into the realms of practicality.
No matter how hot it is in Australia, Tasmania will always be the coldest place.Professor Lesley Hughes
But that worst-case scenario of death is not what is driving domestic climate migrants – yet.
The earliest signs of heat-related migration are for lifestyle reasons and, unsurprisingly, Tasmania is the prime location for Aussies seeking a bigger chill.
“I have some climate science colleagues who are planning to, or have already moved to Tasmania because no matter how hot it is in Australia, Tasmania will always be the coldest place,” says climate change researcher Professor Lesley Hughes, director of the not-for-profit Climate Council and lead author in the IPCC’s 4th and 5th Assessment Report.
“I wish I’d bought real estate in Hobart a long time ago.”
It’s hot (really hot)
Down under, parodied by fantasy writer the late Terry Pratchett as the land of the 1000-year drought, can be a hell of a place to live.
In Darwin, the upper temperature is 35°C but the maximum humidity, or the amount of water vapour in the air, can tick up over 80 per cent during the wet season.
The north of Western Australia has the hottest mean temperatures, up to 35°C, but over the last five years the west, centre and south of the country have set records above 50°C.
Come 2,100, the northwest of Australia can expect dangerous heat days almost all year round.
Already, heat is pushing the wealthy into a heat-related migration south, says Cairns-based sociologist, Associate Professor Nick Obaldiston.
“They will consistently be upper middle-income types, probably nearing retirement or have the ability to semi-retire or have a job where they can be a bit nomadic,” he tells Cosmos.
“In a place like Australia, for at least for the foreseeable future, it will be upper-middle-income folks who are seeking out that better way of life.”
Experiences on the mainland prior to moving were influenced heavily by rising temperatures and heat stress.Nick Obaldiston
Obaldiston published his work last year that surveyed 329 Tasmanian migrants on why they left the mainland. Climate was the top reason.
“Many of the participants in this study suggest that their experiences on the mainland prior to moving were influenced heavily by rising temperatures and heat stress,” he wrote.
“In our conversations, words like ‘hotter’, ‘more humidity’, ‘disgusting’, ‘unhealthy’, ‘isolating’, ‘worsening’, ‘dangerous’ and ‘dread’ are used to describe life on the mainland prior to shifting.”
The underlying fear isn’t due to a faint heart: heat is a silent killer.
In the week before the Black Saturday bushfires in 2009, in which 179 people were killed, roughly double that number died from heat-related conditions in south-east Australia, Hughes says.
World-renowned environmental, energy and health economist Dr Thomas Longden shone a spotlight on heatwave deaths in Australia between 2006 and 2017, finding that about 2 per cent of all deaths in that period were caused by heat, or 36,765 in total.
Until recent years, the intention to move has not often been backed by an actual move, given packing up and moving is a finite, and extreme, reaction to hotter temperatures.
A study in 2020 which questioned 1,344 Australians about how rising temperatures made them feel, found 73% were “stressed” by heat but only 11% intended to move.
However, the authors of that paper expect more people to act on those intentions as Australia heats up further – the BOM says the country is already almost 1.5°C above baselines from 1910 – and this information will be critical for government planning and policy decisions.
Martin and Karen Ankor are likely emblematic of the type of person who can move: child-free, and they made their migration decision after Martin had finished his PhD. In effect, they were free to do as they liked.
Furthermore, he doesn’t see them having to move again due to a changing climate.
“The geographical location of Hobart in a rain shadow should protect us to some degree from intense weather systems. A predicted increase in temperatures of 2-3ºC in Hobart will still be very manageable. Tasmania is also a state of microclimates, so in the event of high temperatures we can always go up the mountains or to a coastal area,” he says.
To date, Tasmania is the only state or territory that is explicitly mentioning a changing population due to climate change in its adaptation planning. Other governments in Australia are looking specifically at how adaptation and mitigation measures can keep people in their homes.
Without a disaster to catch government attention, heat is likely to be one of those climate-related issues the rich can escape and the poor must endure in place.
“We also have to think more seriously about the people living in Alice Springs, how are they going to cope? The people living in the Top End, people in indigenous communities where it’s already really hot and disadvantaged and where it’s already difficult to find fresh food,” Hughes says.
The old migration story
If migration due to heat increases as expected over the coming decades, the impact will be as much on the communities they join – as newcomers place extra demands on resources such as healthcare – as those they leave.
Obaldiston says migrants to Tasmania are shocked by the state of the healthcare resources there, and while they are more likely to roll up their sleeves and get involved with their new community, difficulties also emerge when outsider attitudes don’t gel with local mores.
Ankor says the discovery of community Facebook groups means they are more looped in with their new community than they were in Adelaide.
But for those left behind in places where working and playing outside becomes intolerable, or impossible, the effects will be felt disproportionately by rural communities similar to Peterborough, in South Australia.
On the northern, desertified side of Goyder’s line, Peterborough is struggling to hold on to people – it added just 10 rateable properties in the decade to July 2020, according to the town’s 2020-22 Strategic Plan – and its forward-looking budget relies heavily on grants and assumes its population will either not grow, or diminish in the coming decade.
If migration due to heat increases as expected over the coming decades, the impact will be as much on the communities they join.
Tasmania on the other hand, is looking forward to a population boost.
Hughes says heat will change where “liveable” is in Australia: in some places people simply won’t be available to work outdoors while leisure activities – an important glue for communities – are also at risk.
“Things like growing food. If we don’t get enough workers that can harvest things in the summertime… there are certain industries that absolutely rely on casual labour that is seasonal and for anything growing in the summertime, why would you go and physically risk your life, certainly risk your health, by working outside?” she told Cosmos.
“It’s also things like sports. We did a report on climate change and sport, noting all the summer sports like cricket, in particular, and how the tennis at the Australian Open have to be suspended because it is just too hot.”
Already heat is changing how long people can safely work outside, found a study jointly written by Dr Matt Brearley, one of the country’s leading occupational heat stress scientists.
Hotter and more humid days and nights mean the hours people can work outdoors in Port Macquarie and Griffith should be cut by 50 per cent, and by 20–50 per cent across northern Australia, before the body’s inner thermostat reaches 38°C for too long.
The evidence suggests Australia is looking at a wave of well-heeled migrants escaping dangerous, unliveable heat. But left behind will be those who can’t, or don’t wish to, leave the furnace that inner Australia is predicted to become.
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