This story includes details on the impacts of climate change that may be difficult for some readers. If you are feeling overwhelmed by this crisis situation here is a list of resources on how to cope with fears and feelings about the scope and pace of the climate crisis.
As the northern hemisphere grapples with relentless heat, experts warn that high temperatures are hard on the mind and body alike, while raising alarm over a new climate threat: a deadly fungus that thrives in the heat, and within the human body.
The Earth just had its hottest July in 174 years, with vast stretches of the northern hemisphere baked by “record shattering” temperatures, reported the U.S. National Oceanic and Atmospheric Administration. On July 16, the heat index at an airport on Iran’s southwest coast hit 66.7°C. That same day, the town of Sanbao in northwest China saw the mercury rise to 52.2°C, “setting a record for a country that was battling -50°C weather just six months ago,” Reuters wrote at the time.
Three days later, Sardinia hit 46°C during what the Italian media dubbed “settimana infernale”—or “week of hell.” And days later in North Africa, Tunis seared at 50°C, five degrees beyond the city’s usual maximum temperature.
Meanwhile in North America, July saw Phoenix, Arizona, endure a full month “in hell” with temperatures reaching 43.3°C, wrote the New York Times. At last report, the state capital was under another heat warning, with similar alerts issued for Washington state and Oregon, and only slightly cooler temperatures of 35°C to 42°C predicted for the Okanagan in southern British Columbia.
Extreme Heat Harms the Human Body
More than 100 people have died from heat-related causes in Mexico this year, along with dozens in the United States, including people in Arizona who died from third-degree burns acquired when they fell on the scorching pavement, reported CBC News.
In Arizona, the temperature of asphalt, sidewalks, and concrete on a warm summer afternoon can sometimes reach 82.2°C, Dr. Kevin Foster, director of the Arizona Burn Center, told CNN.
“It’s just a little below boiling, so it’s really something,” Foster said, adding that it can take a fraction of a second to get a “pretty deep burn.”
And on a hot day, the odds of falling are high, warns CBC, since extreme heat is known to cause a drop in cognitive function.
Humans can become more, sometimes fatally, befuddled as temperatures rise, when our brains become starved of blood as our bodies try to shed excess heat by pumping blood to the skin. This temporary rerouting of blood flow, together with sweating, are the two main ways the human body can control rising temperatures, said Penn State University physiology professor Larry Kenney.
The ability to sweat is critical, but can fail in conditions of high humidity when the cooling effect of moisture evaporating off the skin is negated by high levels of moisture in the ambient air.
“Scientists call the concept the wet-bulb temperature, the point where water stops evaporating from a wet thermometer bulb,” writes CBC. “At 35°C, humans can no longer cool themselves.”
The danger of heat stroke lies beyond this point. In the absence of cooling sweat, our internal temperature continues to rise, to more than 40°C in 10 to 15 minutes—“which can lead to permanent disability or death.”
Like the brain, the heart also suffers from the emergency rerouting of blood supply to the skin. “What happens is that it places greater strain on your heart because now it has less blood coming back, and it has to work harder to pump that blood out to the rest of the body,” said Brock University senior research fellow Stephen Cheung. The strain can be compounded by high levels of air pollution, for instance in a big city, or in a community enduring smoke from wildfires.
A just-published study by a team of Chinese epidemiologists “suggested the particular combination of extreme heat and air pollution hiked the risk of having a deadly heart attack, particularly among older individuals, by as much as nearly 75% during a four-day heat wave,” CBC reported.
The lungs are likewise vulnerable to extreme heat, with a 2018 editorial in the renowned medical journal The Lancet warning that “exacerbations of chronic conditions such as chronic obstructive pulmonary disease and asthma increase drastically in line with high temperatures, often aggravated by increased air pollution in cities, as well as seasonal allergies.”
Growing evidence of the increased risk of heart and respiratory disease, especially among the elderly, and particularly among older women, will be critical in a case currently before the European Court of Human Rights. Filed by the KlimaSeniorinnen Schweiz, a group of some 2,400 Swiss women aged 64 and over, the suit alleges that Switzerland has violated the plaintiffs’ rights to life and autonomy by failing to curb emissions.
Responsible for filtering blood, the kidneys can also be profoundly harmed by extreme heat, when dehydration from sweating or insufficient fluid intake leads to stress on the organ. Extreme heat has been correlated to a “30% increase in kidney disease morbidity,” reported CBC, citing a 2019 meta-analysis of previous studies. Studies also show that those who labour outdoors with insufficient hydration and rest during their work day are at significant risk of developing chronic kidney disease.
Heat Plays Havoc with Mental Health
The threat of extreme heat doesn’t stop at our bodies, but can also “singe the mind,” writes the Times, especially when it is unrelenting across multiple days and nights. The effects can be benign, leading to feelings of sadness or irritability, but can also be very dangerous, worsening existing mental health conditions and interfering with drug regimes.
The body of evidence linking the climate crisis—high temperatures in particular—with impaired mental health remains relatively small, since the research field is so young, said Dr. Joshua Wortzel, chair of the American Psychiatric Association’s committee on climate change and mental health.
“It’s really only been over the past five years that there’s been a real recognition of the impact,” he said.
But what is known confirms a devastating pattern, with multiple studies finding high temperatures to be “strongly associated with an increase in suicides” and with violent crime, especially interpersonal violence. Heat has also been linked to an increase in hospitalization rates for people suffering schizophrenia, dementia, psychosis, and substance abuse. Those coping with the last three on that list become 5% more likely to die with every 1°C increase in temperature, the Times reported.
The inability to get restorative sleep as temperatures remain above 20°C at night—a burden felt by the unhoused and those unable to afford air conditioning or to improve insulation in their homes—is also being flagged as an important link between heat stress and mental distress.
Those with pre-existing conditions requiring drug treatment may also be a greater risk, with many common drugs including antibiotics, beta blockers, and some antidepressants and antihistamines now understood to “affect the body’s ability to sense and regulate body temperature.”
Widely used to treat bipolar disorder, depression, and schizophrenia, lithium is particularly dangerous, as it can actually accelerate sweating and leave the body dehydrated and exposed to toxic levels of the element.
Heat Helps Spread Valley Fever
The CBC revealed yet another heat-related nightmare in a recent feature story. Valley Fever is the manifestation of fungal spores called coccidioides that are inhaled into the lungs and go on to spread and multiply, “causing symptoms ranging from a cough to exhaustion to dangerous swelling around the brain.”
Valley Fever is already a familiar presence in arid places like Arizona. Now, encouraged by rising temperatures, the “potent and hardy” fever spores are on the move, and projected to hit the Canadian border by the end of the century.
The illness can be restrained by antifungals. But if you catch it, you’ll have it for life, absent some kind of medical breakthrough.
Among vulnerable populations, it kills one in 10.
