Unbearably hot temperatures are already testing the limits of human survival and will continue to rise, challenging our bodies’ ability to cope and making parts of the world increasingly uninhabitable.
Scientists say urgent measures are needed for humans to adapt to extreme heat, including rethinking the way we live, work and blow up air conditioning.
“Extreme heat is going to get more problematic going forward, period,” said Professor Blair Feltmate, head of the Intact Center on Climate Adaptation at the University of Waterloo in Ontario.
India and Pakistan have recently seen temperatures soar to 50°C, killing at least 90 people and devastating agricultural crops. South Asia, along with Africa, Australia and the US Gulf States, now face potentially fatal combinations of heat and humidity – conditions scientists had not predicted until the end of this century.
Canada is also feeling the effects of extreme heat: in British Columbia last summer, 595 people died from the heat. The village of Lytton, BC, set a new Canadian heat record (49.6 C) on June 29, before being razed by a wildfire the next day. The same “heat dome” left the ground parched, contributing to catastrophic flooding in BC months later.
Feltmate is one of the authors of a recent report warning of a “potentially lethal future” for Canadians in terms of heat, especially those living in the southern interior of BC, along the US border in the prairies and in southern Ontario and Quebec. .
“We’re going to see extreme heat events that will make what we saw in British Columbia last year during the heat summit look relatively mild,” Feltmate said.
How heat affects our bodies
When you’re exposed to prolonged heat, you can feel sluggish because your organs are working harder to keep you cool — and alive.
Your heart beats harder to push blood to your skin, where it can cool down. Sweating is also essential for cooling the body, but it gets harder as the humidity increases.
In extreme cases of heat stroke, your body essentially starts to cook, breaking down cells and causing organ damage.
“It’s a lot like cooking an egg,” said Professor Stephen Cheung, an environmental stress expert in human physiology at Brock University in St. Catharines, Ont.
“The reason it goes from a liquid mass to a solid white mass is because the proteins have changed… If your body keeps heating up and you can’t control your temperature, eventually your proteins will do the same thing in your cells.”
Sitting in the shade and drinking water is not enough when you are already suffering from heat stroke. “It is essential to cool [an overheating person] down as quickly as possible, ideally by dipping them into as cold water as possible,” said Cheung.
Getting too hot at bedtime also makes it harder to sleep, which can lead to poor decision-making and injury, as well as having a negative impact on people’s mental health, says Michael Brauer, a professor at the University of British Columbia’s School of Population. . and public health.
“Night temperatures matter a lot. It’s really trying to keep your room cool enough, cool your body down enough so you can sleep.”
Beating the heat
For anyone who assumes they can train their body to handle the increased heat, Cheung — who helped Canadian athletes prepare for the heat and humidity at last year’s Tokyo Olympics — says it’s possible to some extent. Our bodies’ core temperatures can adjust to the higher heat over a period of about two weeks of gradual and continuous exposure.
But “in terms of global warming, it’s a Band-Aid solution.”
“The biggest advantage, in a sense, that humans have over other animals is our behavior — that we can develop things like housing, air conditioning, better clothes, etc,” Cheung said. “But that comes at a cost, whether it’s keeping us indoors or increasing air conditioning energy use.”
Many people are unable to stay indoors and keep cool, including those whose jobs involve physical exertion outdoors, such as farmers and manual laborers.
In the future, says Feltmate, the workday will have to change so that these workers can avoid the hottest part of the day — for example, starting work at 5:30 am and finishing at 1 pm.
Cities themselves need to be cooled, and that involves designing and renovating buildings with heat in mind, planting more trees, and painting roofs white to reflect light instead of absorbing it, says Feltmate.
He also says it’s critical that residential buildings have a backup power supply to ensure air conditioning and fans keep running if there’s a heat-induced blackout.
the lack of urgency
As simple as these measures may seem, Feltmate says Canadian cities and governments aren’t moving fast enough, despite warnings about the potential for devastating loss of life from extreme heat.
“What’s missing from the equation, more than anything, is a lack of a sense of appreciation for the need to act urgently to implement adaptation measures.”
Adapting also means creating a plan for when places actually become too hot for human habitability, as is expected to be the case in parts of the Persian Gulf, South Asia, Central America and West Africa before the end of the century.
“There are true limits that our bodies can reach even when you’re acclimatized, and the Gulf region is starting to exceed those limits more regularly,” said Cascade Tuholske, a researcher at the University’s Center for the International Earth Science Information Network. from Columbia, whose research focuses on exposure to deadly urban heat.
Poorer countries, where people rely on subsistence agriculture, could see mass migration to cities, which are ill-equipped to cope with the increased heat.
That’s why global solutions to climate change are so important, Tuholske said.
“I really question the habitability of many of the most populated places on the planet due to extreme heat without adaptation. The future really depends on the present and how much we mitigate the heat now.”