3647. Climate Change: Increasing Human Mortality from Heatwaves

 

By David Wallace-Wells, The New York Times, July 10, 2024

In April 2020, when New York City was the “Covid capital of the world,” 815 New Yorkers died from the disease on the city’s deadliest day. A potter’s field burial site on Hart Island was receiving 24 bodies each day, as many as the city typically used to bury there in a week.

Last month in Karachi, Pakistan, temperatures approached 120 degrees Fahrenheit and hospitals reportedly treated thousands for heatstroke. A nonprofit operating four mortuaries registered 128 deaths in a single day, mostly of people on the margins of society. The next day it registered 135. There are no reliable citywide death totals, but over a five-day period the Edhi Foundation, which handles about 40 daily deaths in more normal times, says it took in 568 bodies.

Last weekend, the heat came home for Americans. In June, more than one-third of the country’s population was under extreme heat advisories, but immediately after Independence Day things intensified. In Palm Springs, Calif., temperatures reached a record 124 degrees, Las Vegas broke its own previous record by three degrees and in Death Valley, Calif., temperatures reached 129, within one degree of the all-time, anywhere-in-the-world modern record. Across the West, temperatures routinely registered 15 to 30 degrees above average, and in California, at the beginning of a “historic” heat wave made five times more likely by climate change, scientists predicted a statewide death toll of about 100 each day.

In his vivid book “The Heat Will Kill You First,” Jeff Goodell describes one worst-case scenario as “the Hurricane Katrina of extreme heat,” echoing the words of the researcher Mikhail Chester: a dayslong blackout in metropolitan Phoenix coinciding with a now-routine heat wave and half of the city requiring medical attention. This is, admittedly, an unlikely set of circumstances — the whole city going fully dark for a few days, then taking a few more to get power up and running again. But suspected heat deaths in Phoenix have nearly doubled since last year, when temperatures reached 110 or more for 31 straight days and the city’s burn centers were filling up with people who had fainted or fallen and been scalded by asphalt. Fourteen people died from those contact burns; this year, so far, four have.

It has been a remarkable year globally, with 12 straight months now registering global average temperatures more than 1.5 degrees above the preindustrial average. More than 60 percent of the global population — almost five billion people — faced extreme heat between June 16 and June 24, according to analysis by Climate Central, including about 600 million each in both China and India.

In Delhi, India, June highs averaged 107 degrees and May highs averaged over 106. By the middle of June, the city recorded its hottest night in over five decades, and the Safdarjung hospital there reported nearly 10 times as many deaths as had been observed earlier in the month, when temperatures were already extremely high, as Anumeha Yadav reported for the The Migration Story in a harrowing dispatch from the hospital’s “heat ward.” One of the patients, a young migrant in his 20s who worked the pizza oven for a delivery service, arrived with a temperature over 105 degrees and a heart rate of 170 beats per minute. He was registered with only a first name. “A tall security guard, in a black and red uniform, stepped out of the hospital’s new emergency block and called out,” Yadav wrote. “Who is with Rohit? Who is with Rohit?” There was no response.

In Japan, one city’s all-time heat record was broken by 11 degrees Celsius a month before the country’s hottest time of year. In Greece last month, so many tourists died or went missing, got disoriented and then collapsed, that the country issued a special advisory warning visitors of the dangers — then did it again this month, when another heat wave drove “insane” temperatures. Earlier in the spring, a heat wave made 35 times more likely by climate change killed more than 100 people in Mexico — though the true count is almost certainly higher — and a heat wave that would have been impossible without climate change swept across Mali, in Africa’s Sahel region, where the Gabriel Touré hospital in Bamako registered almost as many deaths over four days as it typically sees in a month.

But the most harrowing event of the summer so far took place during the annual hajj to Mecca, in Saudi Arabia, where temperatures hit 125 degrees Fahrenheit and at least 1,300 performing the pilgrimage died in the heat. That official count may well be far less than the real death toll, says Fahad Saeed, a Pakistani climate scientist who has studied the risks of extreme heat for the pilgrimage. On each of the five days of the hajj, he said, the combination of temperature and humidity in Mecca crossed into what he calls the “fatal zone.”

This has all been predicted; indeed, the harsh future of the hajj could be called its own little climate-science subdiscipline. But as with nearly all climate projections, it is an open question whether those warnings did more to inspire adaptive response or to anesthetize us to the punishing impacts once they came. In a 2021 paper, Saeed and his colleagues projected that at 1.5 degrees of warming, the risk of heat stroke on the hajj would increase five times compared to a world without warming. At two degrees of warming the risk would double — ten times higher.

In a few years the shifting lunar calendar will move the hajj into Saudi Arabia’s winter, but by the late 2040s it will return to September, the calendar’s most punishing month. By then, current rates of warming suggest the world may reach the two-degree-Celsius threshold, increasing the probability of fatal risks 13-fold compared to present levels, according to estimates by Saeed and his colleagues. At current rates of warming, the world may hit that threshold in that same decade. “And adaptation options have limits,” Saeed says. “There were big claims from the Saudi government about all they would do to protect people. But we saw before our eyes that those options failed.”

This year 1.8 million Muslims performed the hajj, almost half of them over the age of 55 — many of them having spent decades saving money for a once-in-a-lifetime trip, and now dramatically more vulnerable to heat stress than they might have been a few decades earlier. By 2030 Saudi Arabia, which makes tens of billions of dollars each year from pilgrimages and roughly $100 billion to $150 billion each year in oil profits, is hoping to increase the number of pilgrims to five million.

Since the 2020 publication of Kim Stanley Robinson’s “The Ministry for the Future,” that novel’s opening has offered perhaps the most talked-about depiction of the risks of extreme heat — 20 million Indians dying suddenly from exposure to extreme temperatures. Many experts have cautioned that this apocalyptic vision is vanishingly unlikely, at least anytime soon, with others emphasizing that conventional algorithms for determining the survivability of heat, on which many future projections for “inhabitability” are built, suffer from several simplifications and shortcomings: that the thresholds were calculated in experiments conducted in cooler countries, with participants unacclimated to extreme heat; that adaptations from cooling centers to widespread air-conditioning and shifting social practices from clothing to diet to daily schedules can significantly mitigate the risks; that simple knowledge of those risks, particularly when clearly communicated, can meaningfully lessen harms; and that though many people are likely to die, over time those in northern latitudes may become more resilient in the face of extreme temperatures.

But sometimes in dismissing apocalyptic scenarios — or even just in establishing context for them — we seem to diminish subapocalyptic ones, as well. Among the most remarkable things about this newsletter is that I could’ve written it, or some close approximation of it, in any of the last few years. In 2021, a lethal one-in-10,000-year heat wave hit the Pacific Northwest. In 2022, approximately 62,000 deaths in Europe were attributed to summertime temperatures there. Last year, at least 240 people died on the hajj. We may be nowhere near a 20-million-scale event, and deaths from cold may remain the larger public health problem, but 500,000 excess global deaths are already attributed annually to extreme heat. It is only 2024, and there are many decades of warming to come.

Further Reading

“No one knows exactly how many people are dying from extreme heat”: Bloomberg’s Zahra Hirji and Preeti Soni on the epistemological challenge of heat death.

“These results indicate that a significant portion of the world’s population will experience — for the first time in human history — prolonged exposures to uncompensable extreme moist heat”: a comprehensive survey of the risk of future temperatures on human health published last year in Proceedings of the National Academy of Sciences.

“Can we air condition our way out of extreme heat?” asks Andrew Dessler at the Climate Brink. (And previous posts by Dessler about how heat kills and comparing deaths from extreme cold to those from extreme heat.)

Jeff Goodell on “the heat wave scenario that keeps climate scientists up at night.”