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Why a killer US heatwave points to a stifling future for our cities

Professor Sebastian Pfautsch is an expert in urban heat.

Professor Sebastian Pfautsch is an expert in urban heat.Credit:Wayne Harley

Pimlott’s dread was shared in Australia.

Dr Sebastian Pfautsch, a specialist on urban heat at Western Sydney University, says though Australian attention has drifted from the terrible summer of 2019 and 2020, he fears for the future of residents of some suburbs in Sydney and Melbourne.

The heat is coming, he says, and we are not prepared for it.

Stephen Livesley is an associate professor in forest sciences at the University of Melbourne, and an expert on the benefits of urban forests. “It’s possible we’re going to end up with large neighbourhoods which people in 20 or 30 years’ time will simply avoid,” he says.

This concern is not misjudged, says Professor Christian Jakob, a Monash University atmospheric scientist.

His analysis of the heatwave that struck North America shows that it originated with an unremarkable rainshower on the other side of the Pacific Ocean, not far from Japan.

The shower caused an atmospheric disturbance that in turn created what scientists call a Rossby wave, which was guided towards North America by the jet stream, amplifying as it travelled before breaking upon the shores of the Pacific Northwest.

There the wave caused a high-pressure system. As Jakob explains, air heats under pressure. On the ground, temperatures soared. What caused the temperatures to reach such extremes, though, and what made the system linger long enough to cause such misery and destruction beneath it, cannot yet be explained by science says Jakob.

Until better computer models are created all we can know is that as the climate heats due to global warming such heatwaves will in some areas increase in intensity and duration.

Areas particularly prone to the phenomenon include northern Europe, North America and south-eastern Australia, he says.

Caddens in Sydney’s west is being transformed by new developments.

Caddens in Sydney’s west is being transformed by new developments.Credit:Wolter Peeters

On the day that Penrith became for a time the hottest place on earth, with temperatures hitting 48.9 degrees on January 4 last year, Keith Heggart’s air conditioner conked out by midday. The manual said it sometimes did that in extreme heat and recommended hosing it down, but due to bushfires water use was banned. Heggart and his young family closed windows against the smoke and the blinds against the sun and sheltered in the living room where a fan pushed around the hot air.

Watching the news from America these past few weeks, Heggart has fretted about the summers to come. His street in Penrith is older than others and there is some shade, some gaps between the houses, but when he looks at the new developments nearby, he despairs.

“There are no trees, there is no shade,” he says. “You could reach out your window and touch the house next door.

When he looks at new developments on the fringes of Australian cities, Pfautsch says residents have been abandoned to wholly predictable heat extremes caused by global warming but exacerbated by poor planning regulation.

Infrared images show the high temperatures generated by dark roofs in density housing.

Infrared images show the high temperatures generated by dark roofs in density housing.

Council areas such as Blacktown, Penrith and Campbelltown in Sydney and suburbs like Wollert, Mernda and Mickleham in Melbourne are compelled to absorb growing populations by state governments, but are failing to impose proper planning regulations. Strapped for cash, they have allowed property developers to shape the built environment, he says.

NSW Planning Minister Rob Stokes says combatting urban heat is a major focus, particularly in Sydney’s western suburbs.

“We are undertaking the biggest urban reforestation program in NSW history,” he says. “Since 2019 we have planted almost 600,000 more trees across Sydney as part of the NSW government’s plan to reach 1 million trees by 2022. We are also investing unprecedented funds in new parks and public spaces, with $250 million being invested with local government to provide more parks across NSW.”

Penrith Council did not respond to a request for comment.

It is not just that large houses on small blocks leave no room for trees, Pfautsch says. The little space left between them provides no room for recreation and serve to increase heat, with side-passages often home to air-conditioning systems that spew heated air across dividing fences.

But Pfautsch sees other wilful mistakes. Unshaded black roads absorb heat during the day only to radiate it at night, extending the heat of day into the evening. This contributes to the urban heat island effect.

Roofs, exterior walls and even driveways created by developers in currently fashionable dark shades serve to exacerbate the impact, he says.

But, according to Pfautsch, the problems begin even before the new suburbs are laid out, when developers clear new sites of all existing trees, ponds and watercourses to maximise space and save on construction costs.

What greenspace remains is often not connected to homes by shaded foot or bike paths.

“It is inhumane to expect people to live like this in the temperatures we anticipate,” he says. “I can’t say it more strongly than that.”

New developments in Sydney’s west are particularly vulnerable to extreme heat.

New developments in Sydney’s west are particularly vulnerable to extreme heat.Credit:Wolter Peeters

In May, the Victorian state government announced it would plant 500,000 trees in Melbourne’s west, in areas like Maribyrnong, Wyndham, Melton and Hobsons Bay.

Residents had been calling for help to green these suburbs as their populations took off without enough trees being planted to provide amenity or reduce the heat.

Trees are recognised globally as a weapon against the urban heat island effect.

Overall, Melbourne lost 0.3 per cent of its canopy between 2014 and 2018. Almost 2000 hectares of trees were cut from the east and south-east, mostly at residential properties.

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And the distribution is patchy. The western region of Melbourne had about 5 per cent canopy cover in 2018, compared to 17 per cent in the inner south-east and 25 per cent in the east. Before it was earmarked for development, the city’s west was a basalt plain covered in critically-endangered native grasslands, not an area of thick bushland.

Even these remnant grasslands are dwindling: the Auditor General found Victoria had failed to protect its critically-endangered grasslands despite an agreement with the Commonwealth that was supposed to ensure their survival.

Now, much of these grasslands are gone and new homes in growth-area housing estates are often built almost to the edge of the plot, without room for a garden.

A spokesperson from the Victorian government said that in 2017 it mandated that a minimum garden area must be kept, as a percentage of a housing lot or subdivision, to protect the character and green space within Melbourne’s suburbs. The Victorian Planning Authority’s draft guidelines for new precinct plans propose a 30 percent tree canopy target for Melbourne’s new growth areas. These are expected to be released by the end of the year.

The outer parts of Australian cities are submitting to urban sprawl.

Stephen Livesley says the heat island effect is a challenge that will only get worse as the climate becomes warmer and dryer.

Livesley often takes his students on field trips to the Melbourne outer suburbs of Tarneit and Point Cook to show them what poor urban planning in the field, like public parks where developers have done initial plantings but not continued to water them, meaning that after a year or two the trees are stunted or die, and weeds take over.

“We’re ending up with dark-roofed, back-to-back, nose-to-front, housing suburbs on the outskirts of Melbourne. And if you add dark, asphalt and concrete surfaces you’re going to get really hot suburbs,” he says. “When you have high-temperature events intersecting with urban heat islands, you have really, really high temperatures.”

According to Pfautsch, even a concerted effort to increase tree coverage in the suburbs most prone to the heat-island effect will only have limited impact in the years to come.

We are pushing some of the most vulnerable people in our society into these low-tree, low-services environments.

Stephen Livesley

But more significantly, he notes that while photosynthesis in trees causes a cooling effect when temperatures are in the 20s and low 30s, in extreme cases, many species simply shut down, some even dump their leaves to preserve what moisture they have retained.

In the heat spikes to come, he says, trees will only be able to help us so much.

All this raises thorny questions of environmental and climate justice, Livesley says, as the suburbs most affected are often the most affordable.

“We are pushing some of the most vulnerable people in our society into these low tree, low services environments, with poor public transport infrastructure.”

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He agrees with Pfautsch that planning regulations and incentives need to be changed. One simple fix would be to encourage lighter-coloured roofs to reflect solar radiation. And using recycled water to ensure public parks and nature strips are kept moist would add a green buffer during heatwaves: “They may only cool the surrounds by a degree but that could be the difference between someone going to hospital or dying”.

In Mildura, a town near the border in north-west Victoria, temperatures have increased in line with worldwide heating trends. Between 1998-99 and 2018-19 the number of days each year where the temperature went above 35 degrees increased by about 20 days, and the number of heatwaves rose from six to nine.

For residents living in public housing – who faced huge bureaucratic hurdles to having air conditioners installed – recent summers have been a nightmare, prompting local service provider Mallee Family Care to lobby the state government.

With the University of Sydney School of Public health, the service undertook research to find out what the effects of extreme heat were on these public housing tenants.

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All residents agreed there was little respite, with nowhere to escape from the heat even at night, when many were forced to drag their mattresses outside.

It was hotter inside non-air-conditioned houses than outside, but many felt compelled to stay indoors to reduce the risk of sunburn. Some recorded temperatures inside their homes in the 40s and 50s.

They reported headaches, sweating, heat exhaustion and heatstroke. One pregnant resident told researchers: “I thought I was going to die. Honestly, I wanted to die because it was just so hot. I didn’t want to leave the house, I just isolated myself, lying in the hallway.”

Mental health conditions were exacerbated and some worried about the future, with one woman saying: “I’m 65 now, what happens in my 70s? I think about 70 without an air conditioner. Life might be very hard.”

Mallee Family Care chief executive Teresa Jayet says there was evidence substance abuse and family violence worsened. School students were exhausted and unable to undertake their school work. Some were sent to the sick bay to catch up on sleep.

In November, the state government announced $122 million in funding to seal windows and doors, upgrade heating, cooling, and hot water in 35,000 social housing properties.

Ms Jayet welcomed the funding but said the work needed to happen quickly. “If we don’t invest now, the trajectory will be too late for people, it will be too hard to come back to try and rectify this issue,” Ms Jayet says.

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As the heatwave caused havoc in America, Pfautsch thought of the central Australian desert, he says. There each summer the air is superheated above the red dirt and fed to the east and south.

“There is nothing we can do about that, there is nothing we can put between us and hundreds of cubic kilometres of hot air,” he says.

“Planting trees is not enough.”

Instead, he says, not only should we be tackling climate change, we should be totally re-imagining how we build our suburbs.

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