Darwin. Broome. Port Headland. These significant Australian economic centres risk being uninhabitable within 70 years, a new report warns.
Government inaction and corporate disinformation have the world on track for an average temperature increase of 2.7C by 2100, the Intergovernmental Panel on Climate Change (IPCC) warned in March.
Now a new study published by the science journal Nature Sustainability has defined what this means.
Two billion people worldwide will have to live with dangerous heat.
Human beings, like smartphones, have a temperature performance range. Optimal performance is generally between 13C and 27C.
But an unexpected surge in northern hemisphere heatwaves this year has rammed home the message that this “human climate niche” (or Goldilocks Zone) is retreating.
And Australia’s not insulated from this “heat bubble”.
Northwestern regions such as Darwin, Broome and Port Headland join large swathes of Southeast Asia, India, the Middle East, Africa and South America that are at risk of becoming uninhabitable.
And the IPCC warns that only a concerted effort to reverse the amount of carbon dioxide in the atmosphere can cap temperature rises at 1.5C and keep these regions safe.
University of Melbourne global health experts Professor Kathryn Bowen and research fellow Annabelle Workman have assessed the implications of the new data. And they warn fatal “wet bulb” events – where a combination of raw heat and humidity overwhelm the human body’s ability to cool itself – will force populations to flee to cooler climates.
“Let’s be clear. [Even] a 1.5 world will result in injury and death,” the Melbourne University experts warn.
Why you’ll be hearing about ‘wet bulbs’
The Australian Academy of Science warns Darwin could have to contend with 265 days every year above 35C.
Average dry temperatures of 29C and above quickly become intolerable. And events over 40C shut down almost all human activity.
Prolonged heat causes heat stroke and dehydration. But it also affects mental health. And that’s before you consider the fallout on food production, water availability and air quality.
But add humidity and things can become fatal for even the most healthy.
“The wet-bulb temperature reflects humidity and is a method used to measure heat stress,” the Australian researchers write in The Conversation. “That’s because it’s the point at which sweating is no longer effective as a means of cooling.”
That’s why wet-bulb temperatures of 35C can kill.
The Nature study found that any further increase in the 1.2C global warming already being felt by the planet will significantly increase the number of humans exposed to temperature extremes.
Last week, the World Meteorological Organisation predicted the very high probability that a warming of 1.5C will be exceeded within the next five years.
“This spells trouble for human health,” the University of Melbourne experts warn. “Even incremental warming increases exposure to health hazards including potentially deadly heatwaves, infectious diseases and diet-related health issues.”
And that includes Australia.
“For example, a 2019 study found heat-related health issues in Australia have been grossly underestimated,” they write. “It found more than 36,000 deaths between 2006 and 2017 were attributable to heat.”
Now analysts warn that the projected 2.7C outcome of current global efforts to restrict warming will threaten a third of the world’s population.
“The costs of global warming are often expressed in financial terms, but our study highlights the phenomenal human cost of failing to tackle the climate emergency,” study author Timothy Lenton writes. “For every 0.1C of warming above present levels, about 140 million more people will be exposed to dangerous heat.”
People’s health then affects economics.
“Historically, health has rarely been included in these economic assessments, much less ethical considerations,” the University of Melbourne academics add. “Emissions reduction policies need to consider health and equity issues, and in doing so can provide governments with a strategic rationale to act.”
And the economic cost of ignoring this fallout could be astronomical.
“There are physiological limits to adaptation, particularly to heat,” they add. “These limits can have negative consequences for labour productivity, especially for outdoor workers, and for health service demand, leading to increased hospital admissions, emergency department visits, and ambulance calls.”
It’s also a national security risk.
The University of New South Wales recently ‘war-gamed’ extended extreme heat scenarios with a group of Australian and South-East Asian diplomats and military leaders. It resulted in riots, mass migration, mass deaths, martial law – and eventually a collapse of international order.
The new Nature study found the nations at greatest risk from current temperature trends include India (with an estimated 600 million people affected), Nigeria (300 million) and Indonesia (100 million).
“That’s a profound reshaping of the habitability of the surface of the planet, and could lead potentially to the large-scale reorganisation of where people live,” said lead author Professor Tim Lenton, director of the Global Systems Institute at the University of Exeter.
Adapting to change
“The findings are sobering and a stark reminder as to why we fight tooth and nail to keep global warming to the lowest levels possible,” University of Oxford environmental economics expert Dr Laurence Wainwright told a Science Media Centre briefing.
“Technically, adaptation is almost always possible,” International Climate Risk and Adaptation analyst Dr Richard Klein added. “People can spend most of their lives in airconditioned buildings and import their food from elsewhere, provided they have the means to do so.”
But this needs economic investment in infrastructure and resilient power supplies.
“For many of the people and countries affected, however, this is not an option,” Dr Klein says. “The question then is what these people will do. Move to cooler places? Which places are they, and what opportunities will they have there? Might it lead to conflicts over scarce resources?”
The ability for people to pay for cooling also concerns climate physicist Dr Christian Franzke.
“For example, not everyone can afford airconditioning. In developed countries – like Germany – most work takes place in buildings that can be cooled.” But many industries and economies are reliant on outdoor activities – such as agriculture and mining. “There, you could change working hours and introduce a siesta at noon, like in Spain, but that probably won’t maintain all labour productivity,” he says.
Jamie Seidel is a freelance writer | @JamieSeidel