Climate-linked ills threaten humanity
Pakistan is the epicenter of a global wave of climate health threats, a Post analysis finds
By Annie Gowen,
Saiyna Bashir
Annie Gowen traveled with Saiyna Bashir in Sindh province, Pakistan, to capture climate impacts on life and human health. Niko Kommenda, in London, worked with modelers and scientists to analyze how extreme heat will spread in coming decades.
Sept. 5 at 6:00 a.m.
Bagh Yusuf, Pakistan
The floods came, and then the sickness.
Muhammad Yaqoob stood on his concrete porch and watched the black, angry water swirl around the acacia trees and rush toward his village last September, the deluge making a sound that was like nothing he had ever heard. “It was like thousands of snakes sighing all at once,” he recalled.
At first, he thought villagers’ impromptu sandbags, made from rice and fertilizer sacks, had helped save their homes and escape Pakistan’s worst floods on record. But Yaqoob — whom villagers call a wadero, or chief — soon realized it was just the beginning of a health disaster. The temperatures rose to triple digits, as the water that would not recede festered in the sun.
The Human Limit
An exploration of the insidious threat that climate change poses to human health, from malaria to extreme heat.
An elderly woman died in a boat on the way to the hospital, overcome by heat and dehydration. Dark clouds of mosquitoes bit through even the toughest donkey’s hide, spreading malaria to Yaqoob and four dozen of his neighbors. People came down with itchy dermatitis from walking through the floodwaters. Farmers who could not plant in drenched fields began cutting back their simple meals of vegetables and rice from three a day to two. And then, for some, just one.
“I had no idea what miseries this flood would bring for us,” said Yaqoob, whose village is in Sindh, the hardest hit province in a disaster that left a third of the country underwater.
Pakistan is the epicenter of a new global wave of disease and death linked to climate change, according to a Washington Post analysis of climate data, leading scientific studies, interviews with experts and reporting from some of the places bearing the brunt of Earth’s heating. This examination of climate-fueled illnesses — tied to hotter temperatures, and swifter passage of pathogens and toxins — shows how countries across the globe are ill-prepared for the insidious, intensifying risks to almost every facet of human health.
To document one of the most widespread threats — extreme heat — The Post and CarbonPlan, a nonprofit that develops publicly available climate data, used new models and massive data sets to produce the most up-to-date predictions of how often people in nearly 15,500 cities would face such intense heat that they could quickly become ill — in the near-term and over the coming decades. The analysis is based on a measure called wet-bulb globe temperature (WBGT), which takes into account air temperature, humidity, radiation and wind speed, and is increasingly used by scientists to determine how heat stresses the human body.
Number of days in 2030 with highly dangerous heat In the shade
Highly dangerous heat days reach a maximum wet-bulb globe temperature of more than 89.6°F
Pakistan experiences some of the most intense heat on the planet. Cities such as Jacobabad and Hyderabad are projected to have several months each year when conditions are so extreme that even people in the shade face health risks.0/ 4
Pakistan experiences some of the most intense heat on the planet. Cities such as Jacobabad and Hyderabad are projected to have several months each year when conditions are so extreme that even people in the shade face health risks.
Other regions projected to face increasingly severe heat waves include the Middle East, India and parts of Vietnam and China.
When taking into account the force of the sun, the health risks are even higher. Over 40 million people in Pakistan would endure dangerous heat for more than half of the year unless they can find shade.
In the United States, more dangerous heat will envelop large parts of the South and Southwest.
Pakistan experiences some of the most intense heat on the planet. Cities such as Jacobabad and Hyderabad are projected to have several months each year when conditions are so extreme that even people in the shade face health risks.
The Post analysis showed that by 2030, 500 million people around the world, particularly in places such as South Asia and the Middle East, would be exposed to such extreme heat for at least a month — even if they can get out of the sun. The largest population — 270 million — was in India, followed by nearly 190 million in Pakistan, 34 million across the Arabian Peninsula and more than 1 million apiece in Mexico and Sudan.
The results show how the risk has been growing and will escalate into the future. The number of people exposed to a month of highly dangerous heat, even in the shade, will be four times higher in 2030 than at the turn of the millennium.
By 2050, the number of people suffering from a month of inescapable heat could further grow to a staggering 1.3 billion. At this point, vast swaths of the Indian subcontinent will swelter under extreme humid heat, as will parts of Bangladesh and Vietnam. Only those who can find cooling will find respite.
To reach these estimates, The Post and CarbonPlan combined one of the most detailed sets of historic heat data with the latest climate projections produced by NASA supercomputers, offering one of the most detailed estimates of current and future heat stress at a local level ever produced. The projections assume countries make steady progress toward cutting planet-warming emissions, as they have committed to do.
The Post defined its dangerous heat threshold as more than 89.6 degrees Fahrenheit wet-bulb globe temperature, equal to a temperature of 120 degrees on a dry day, or mid-90s temperature on a very humid day. Spending more than 15 or so minutes beyond that limit, many researchers say, exacts a harsh toll on even a healthy adult; many deaths have occurred at much lower levels.
Moderate and extreme heat days are on the rise
Annual distribution of wet-bulb globe temperatures, 1985-2015 vs. 2030
Jacobabad, Pakistan
Dubai, U.A.E.
Kolkata, India
Phoenix
Extreme heat, which causes heat stroke and damages the heart and kidneys, is just one of the ways that climate change threatens to cause illness or kill.
So far this year, more than 235,000 Peruvians have come down with dengue fever and at least 399 died, according to Peru’s national center for disease control, the most in that nation’s history. Smoke from record-breaking Canadian wildfires billowed across the United States, triggering asthma attacks that forced hundreds to seek hospital care. And East Africa’s worst drought in at least 40 years, which has spurred widespread risk of famine, is 100 times more likely to have happened because of human-caused warming, researchers say.
The number of heat-related deaths of people over 65 increased by 68 percent from 2017 and 2021 compared with between 2000 and 2004, according to a peer-reviewed report from the Lancet last year, while the months of favorable conditions for malaria in the Americas’ highlands rose by 31 percent between 2012 and 2021 compared with 60 years earlier.
“We can say now that people are dying from climate change, and that’s a different kind of statement than we would have made before,” said Kristie L. Ebi, a professor in the Center for Health and the Global Environment at the University of Washington who co-authored the 2022 Lancet Countdown report. “Climate change is not a distant threat to health, it’s a current threat to health.”
Many of the most affected countries have contributed the least to the climate crisis, and are ill-prepared to manage the rapidly multiplying threats.
Last year in Pakistan, dangers piled one atop the other. First, the country suffered a record-breaking heat wave beginning in March. Fires rampaged through its forests. Record high temperatures melted glaciers faster than normal, triggering flash floods. And then heavy monsoon rains caused unprecedented floods, which left 1,700 dead, swept away 2 million homes and destroyed 13 percent of the country’s health-care system.
“Pakistan’s crisis was almost prophetic,” said Sherry Rehman, Pakistan’soutgoing climate minister, in a phone interview. “Look at this summer.”
As the world shatters temperature records — this year is now likely to be the warmest in recorded history — she said, “countries like us, the hot spots, are going to feel the burn immediately.”
Inside the ward
On a recent 109-degree day, babies wailed and adults vomited into buckets in the crowded heat stroke ward of Syed Abdullah Shah Institute of Medical Sciences, a 350-bed government medical center in central Sindh. With just seven beds for heat stroke victims, patients’ parents and relatives crowded together on the mattresses. Nurses in green scrubs attached bags of intravenous hydration fluids to the arms of even the tiniest patients as fans whirled and two air conditioners dripped and chugged.
The number of heat stroke patients coming to the hospital in summer has increased around 20 percent a year in the last five years, according to M. Moinuddin Siddiqui, the hospital’s medical director, at a time when Pakistan experienced three of its five hottest years on record.
The changing climate has affected people in painful ways, Siddiqui said, including high-grade fevers, vomiting, diarrhea and related diseases such as gastroenteritis. “I have been a doctor here for two decades and such climate changes I have not seen before. It’s disheartening,” he said.
The proliferation of climate ills has taxed this regional hospital center at the same time it has taken in patients from 12 nearby clinics and medical dispensaries swept away in the flood, he said.
The hospital has taken a variety of “special measures” to support the heat patients, including creating the small stroke unit, where patients are treated before either being admitted or sent home with electrolyte powder packets for rehydration. They also added air conditioners in every ward, but sometimes even those don’t cool enough to make patients comfortable.
Despite such preparations, he said, last year’s heat wave shocked the whole system. The air conditioning shut down under intense use and a huge crowd amassed inside the hospital, creating a “panic-like situation” for both the patients as well as health-care providers.
Farm laborers are routinely brought in unconscious with high fevers and may even end up on a ventilator, the doctor said. Outdoor workers are at increasing risk of heat-related illness, but their low-wage jobs are a lifeline. About half of Sindh’s population lives in rural areas, according to a World Bank report, and 37 percent of that population lives below the poverty line.
Siddiqui finds it difficult to tell them to avoid working in the oppressive heat when they earn the equivalent of just a few dollars a day.
“If they take rest in the house they go hungry!” he said.
Around Sindh, women and child specialists and nurses say that they are seeing a rise in miscarriages, low birth weight babies and decreased production of breast milk — that they blame on the stress from the floods, along with rising summer temperatures.
“Miscarriages have been increasing because of the intense heat,” said Zainab Hingoro, a local health-care worker. When she once would have 3 out of 10 pregnant patients miscarry, she now has 5 to 6 out of 10. The number of low-birth-weight babies is “drastically increasing,” she added.
Sughra Bibi, 38, who was about to deliver her sixth child, said she suffered frequent kidney pain and gastrointestinal upset from drinking unsafe water.
“I am not well,” she said, adding that her husband, a laborer, struggled to get enough food to sustain her pregnancy. The couple still lives in a temporary tent nearly a year after the floods, and she wept as she showed photos of her children, ages 9 and 6, who died in the floods’ chaotic aftermath.
Insect-borne diseases are also on the rise. Siddiqui said his hospital saw a “very unusual” influx of malaria patients during February through June, a time not generally considered peak malaria season.
After the floods, Pakistan grappled with over 3 million suspected malaria cases, up from 2.6 million in 2021, according to the World Health Organization. The outbreak was spurred on by standing water and other circumstances making it easier for mosquitoes to breed, reversing decades of progress of reducing cases.
Malaria kills more than 600,000 people a year around the world, and studies show that climate change is driving the once tropical disease to higher altitudes and new areas. A study last year by Pakistan’s Global Climate-Change Impact Studies Center showed that dengue — another mosquito-borne illness — will begin appearing in far higher altitudes by the end of this decade.
Yaqoob, 62, the chief of Bagh Yusuf village, has made two trips to the hospital’s malaria ward in the past year.
Yaqoob, a retired primary schoolteacher, moves around Bagh Yusuf’s rocky lanes on crutches, after he lost a leg a decade ago when bandits shot him while trying to steal his scooter.
The village of concrete and thatched roof dwellings sits up on a dune, so people there can catch cooling breezes in the summer. On hot nights, they sleep outside on string cots, called charpoys, covered in the colorful quilts the region is known for. Still, the heat can be brutal. Villagers drink a combination of jaggery — sugar cane — and black pepper water they say wards off heat stroke.
When the floodwaters lapped at their doorsteps last fall, villagers kept them at bay and Yaqoob held out his crutch to help save several people from drowning.
But three months of living surrounded by contaminated water that smelled like the corpses of dead animals took its toll. First, one of his neighbors sparked a fever, then another. Getting sick in Bagh Yusuf was never easy, even before the flood. Villagers go to a small dispensary if they fall ill: A private doctor costs too much and a trip to the hospital is a last resort.
After 15 days, it was Yaqoob’s turn.
He was overcome with a fever stronger than he had ever experienced and began bleeding from his nose. Relatives had to take him out by boat to the hospital.
Once there, he remained unconscious most of the time. “I hallucinated that the water had reached my house and I had to keep my family members safe. Another time, I thought my siblings were in bad condition and living in a roadside shelter,” he said.
He recovered after about a week, but relapsed in July, spending two more days in the hospital before doctors said he was strong enough to go home.
‘Hotter and hotter’
One June afternoon, a bread maker in Jacobabad, Pakistan — which has temperature highs in the summer months so extreme it’s often called “the hottest place on Earth” — sat outside when it was 111 degrees, flipping rounds of dough into the air and toasting them over hot coals.
The air around his workspace outside a downtown restaurant is always several degrees hotter than the normal air temperature, Dil Murad said, which can often be overwhelming. He said he feels trapped in his job as the summer heat intensifies, and tries to keep as cool as he can by drinking large amounts of water every hour.
“It’s difficult because this scorching heat has become unbearable,” said Murad, 25. “I don’t have any other source of income, and I have to feed my kids. It’s the only craft I know.”
During a devastating heat wave last year that lasted weeks and vented misery across Pakistan and India, the temperature in Jacobabad soared to a world high of 123.8 degrees on May 14. Human-caused climate change made this record-breaking heat wave at least 30 times more likely, according to modelers at the World Weather Attribution initiative. About 50 people died in Jacobabad alone, according to one estimate.
When temperatures soar life slows to a near halt in this city of 170,000, where the streets are crowded with men wearing loose white cotton clothes and women in headscarves who jostle for space with farmers driving donkey carts. Residents who can’t afford air conditioning try to not move and stay indoors or search for a patch of shade. Sometimes their only respite is a slow-moving fan run by a single solar panel — which only works during the day.
Sweaty rickshaw drivers and construction workers crowd around volunteers passing out cooling herbal drinks made of the bluish-red falsa berries, and residents buy blocks of ice from the area’s busy ice factories to keep themselves — and their food — cool.
In villages outside the city, farmworkers still venture into the rice, wheat and fodder fields, but try to rest during the hottest part of the day, from noon until about 3 p.m. Even then, some become dizzy and collapse. Cows and buffalo — their ribs visible — take refuge in ponds.
The number of days when Jacobabad’s temperature surpassed 113 degrees rose from 12 between 2011 and 2015 to 32 between 2016 to 2020, according to an analysis by Aga Khan University.
“It has gotten hotter and hotter,” said Muhammad Yousif Shaikh, the deputy commissioner for the Jacobabad District. “For some vulnerable communities, the weather has become simply unbearable.”
Shaikh said the district is working to put in place long-term solutions to rising temperatures, such as shoring up the community’s shaky water infrastructure and planting shade trees lost to unplanned development.
But residents have said that they have done little to help them during the hottest days. The district had no permanent heat stroke center until the height of the heat wave last May, when a local NGO, the Community Development Foundation, helped establish one in a local hospital. It has only eight beds.
“During last year’s heat the government did not do anything for us, not even water, nothing,” said Mukhtiar Bhatti, the head of Pir Bux Bhatti, a village about 11 miles north of Jacobabad.
Researchers who have formed a group dubbed the Climate Impact Lab found in a recent study that heat-related mortality will expand dramatically in the coming decades and in the world’s poorest and hottest places, exacerbating inequality.
They projected that higher temperatures will lead to a staggering 150,000 added deaths per year in Pakistan by 2040 — unless the country can grow substantially more wealthy and better adapt to frequent bouts of extreme heat. The rising death rate, 50 per 100,000, is higher than that of nearly all other countries, barring some of the least developed parts of Africa and the Middle East. It is more than twice the number estimated for neighboring India, which has more financial resources to shield its population from the worst climate impacts.
“The way the rich countries are going to respond is by spending more to protect ourselves, and in many parts of the world those opportunities don’t exist,” said Michael Greenstone, a University of Chicago economist and the study’s co-author.
In many cases, improving odds of survival means one thing — access to air conditioning. A study led by scientists at the University of California at Berkeley projects that less than 1 in 10 Pakistani households will have air conditioning in 2030, compared with 25 percent of Indian homes. In the United States, 92 percent of residents had air-conditioned homes as of 2021.
Pakistan is lacking the means to adapt to dangerous heat by 2030
Note: Circles are sized by population. Gross domestic product, air conditioning access and age statistics are modeled for 2030. Data on the rate of physicians is from 2019-2021. GDP per capita is based on purchasing power parity.
Jacobabad has always had high temperatures in the summer but climate change is fueling heat waves that arrive earlier and last longer than ever before, which may eventually make the area uninhabitable for even healthy humans, experts say. In Jacobabad, a wet-bulb globe temperature of at least 90 degrees will prevail for a third of the year by 2030, The Post analysis found.
Scientists say the higher the wet-bulb globe temperature climbs, the more difficult it becomes to keep cool and the heart and the kidneys can fail as they work overtime to maintain blood pressure and the flow of fluid in the body.
“As the temperature begins to rise, in order to lose enough heat, you have to sweat,” said Zac Schlader, an associate professor at Indiana University at Bloomington who studies the physiological impact of extreme heat. “And that evaporation of that sweat is dependent on the amount of water vapor that’s in the air.”
If the air is too moist to absorb sweat, a person’s internal body temperature will continue to rise. The heart pumps faster and blood vessels expand to move more blood closer to the skin, in order cool off. At the same time, the brain sends a signal to send less blood to the kidneys to stop losing liquid through urine, which deprives the kidneys of oxygen.
The wet-bulb globe temperature combines the regular air temperature (“dry-bulb”), the humidity-adjusted temperature (“wet-bulb”) and the radiant heat from the sun and hot surfaces (“globe temperature”) to capture heat stress.
While every human body is different, many experts and institutions cite just under 90 degrees as the wet bulb globe temperature beyond which the risks of heat illness become very severe. The U.S. Marine Corps cancels all physical training at 90 degrees. The National Weather Service says that in much of the United States, that threshold represents an “extreme threat” to health and it will stress the body after working in direct sunlight for just 15 minutes. A study in Taiwan found that on days reaching a wet-bulb globe temperature of at least 89.6 Fahrenheit (32 Celsius), heat-related emergency hospital visits increased by about 50 percent compared to other warm season days.
Even lower temperatures pose “a very real risk to human health,” Schlader said, especially for vulnerable people.
Temperatures had reached 122 degrees one day in Pir Bux Bhatti during last year’s heat wave when Fazeela Mumtaz Bhatti, age 46, rose to prepare breakfast for her husband, Mumtaz Ali, 50, and their 11 children.
Bhatti — who was otherwise healthy — had made a bit of potato and charred bread, working in a poorly ventilated brick room on an open fire fueled by dung patties. Around 1 p.m., she began to complain she wasn’t feeling well, her daughter Naheed, 18, recalled.
Bhatti left the house to walk a few dozen yards and collapsed, face first, in the dust. In a panic, Naheed ran to help, cradling her mother’s head in her arms and trying to ply her with water combined with sugar and salt to help her rehydrate.Other women in the village rushed to assist, moving the woman back into the small house and onto a string cot, where they doused her body with water from a nearby pump and tried to keep her calm.
“She was fire to the touch,” Naheed recalled. “She just kept saying, ‘Don’t you worry about anything, I’ll be okay. Just make sure your father and siblings are fed.’”
But Bhatti’s condition worsened, and her husband raced to borrow a car to take her to the hospital in the city, some distance away. By the time they reached the hospital, she was already dead.
Naheed mourns the loss of her mother, who often spoke of finding Naheed a good man to marry, and used to tease her eldest daughter by saying, “You are only a guest here, you only have so much time to live in your father’s house.” In quieter moments, she would tell Naheed, “You have to find courage within yourself because life is difficult.”
Now, Naheed is left to manage the housework and care for the large family on her own.
“We just couldn’t keep her safe and alive,” she said quietly. “It’s difficult for me, but I have to take care of my brothers and sisters. I just try and cope with it.”
‘People have forgotten us’
In Bagh Yusuf, life has returned to some semblance of normalcy after the floods, but several aftershocks remain. All but about six of the families who had fled returned. The residents were able to clear the cemetery and have their annual religious festival, where they pray to their ancestors and celebrate with a mutton feast. The farmers who live in their village revved up their gaily decorated red tractors and begin planting again.
But hunger remains a problem.
Muhammad Ishaq, 42, lost his cotton crop during the flood, along with the $81 he’d invested in seed and insecticide. After the floods, the debt made farming impossible, so he began laboring as a stone crusher for about $3 a day. In April, he was able to sow his cotton crop, he said, but water is scarce.
“We hardly eat two times a day,” he said. They generally eat bread, okra or potatoes for breakfast, lentils for lunch and goat milk and bread for dinner. The younger of his five children often whimper and cry from hunger, he said.
His oldest son, Tariq, 17, has been working in construction which has allowed them to buy more food. But it also put him more at risk, because he’ll be laboring outdoors.
Pakistan — a fast-growing country of 241 million — had myriad challenges even before the floods, with a high percentage of poverty, low literacy rate, vanishing water supply, rising inflation and ongoing political turmoil after last year’s ouster of former prime minister Imran Khan, now jailed, with elections set for the coming months.
Officials in Pakistan say that the scale of the flood disaster was so epic — “biblical” in the words of Rehman — that it was beyond their ability to respond, with total damage to the economy estimated at $30 billion. They say they now need $13 billion in additional international support — on top of $16 billion already pledged — to prepare their country for future disasters.
Pakistan wants to use the additional money to expand its network of hospitals in rural areas, move residents out of flood plains and bolster its water supply. The government of Sindh is already working with the World Bank to replace lost mud brick dwellings with 350,000 homes that will have rainwater harvesting systems and latrines.
Ali Tauqeer Sheikh, a climate change specialist based in Islamabad, said the country needs to upgrade construction standards to withstand more extreme weather, shore up its reserves of emergency food and water for the next crisis and develop heat action plans for its cities and provinces. The only city with a significant plan to address a heat wave emergency is Karachi, with one he helped write after a deadly heat wave there killed more than 1,200 in 2015.
Muhammad Jaohar Khan, a health specialist with UNICEF in Islamabad, said that the floods — which submerged more than 2,000 health-care facilities — ratcheted up pressure on a system that was already burdened and failing to reach the poor in rural provinces like Sindh. Even before the floods, poor nutrition had stunted the growth of 40 percent of the children under 5 in Pakistan.
“These districts were already deprived, and had been hit several times by floods and droughts,” he said. “They went from the bad to worse category.”
Samuel S. Myers, a principal research scientist at the Harvard T.H. Chan School of Public Health, says that one of the biggest threats South Asia faces is malnutrition, as climate change harms crops. The global rate is rising again after years of declines, with more than 8oo million people at risk for malnutrition in 2022.
Children are among the most vulnerable to rising temperatures, which affect pregnant women and disrupt food production.
At the Jacobabad Institute of Medical Sciences, Kamala Bakht, a doctor in the infant nutrition center, said that the number of low birth weight babies entering the feeding program had been steadily increasing since 2018 — from about 40 to 55 a month.
She says more intense heat — which exacerbates dehydration, putting mothers at risk for miscarriages — has played a role, as well as the floods, which had a “great impact” on her patients and their ability to properly nourish themselves and their newborns.
Inside one of the feeding rooms, a woman named Pathani cradled her tiny son, Allah Dino. She had worked for three of her earlier pregnancies, she said, harvesting rice in the heat, and had miscarried each time. With this latest pregnancy, she had stayed indoors, but then came down with typhoid and delivered the baby prematurely — at eight months. When she first arrived at the feeding center, Allah Dino weighed 2.4 pounds, she said. Ten days later, his weight was 2.6 pounds.
If Pathani’s son lives to be 27 years old, at that point Pakistan will experience more than two months of highly dangerous heat each year, even in the shade.
After years of resistance by richer nations, Pakistan and other developing nations also pushed through a breakthrough “loss and damage” fund at global climate talks last year, where richer countries like the United States — which have contributed the bulk of the world’s greenhouse gas emissions — will give money to poorer nations bearing the brunt of the impacts.
In the coming months, as countries gather for the U.N. Climate Change Conference in Dubai, delegates will push wealthy nations to spell out how the loss and damage fund will work.
But Rehman says that with so many countries now facing their own climate emergencies, they will be less likely to want to help.
“Already I hear ministers saying we need to spend money in our country now,” she said. “People have forgotten us.”
Shaiq Hussain in Islamabad and Yasin Junejo in Jacobabad contributed to this report.
About this story
Design and development by Hailey Haymond and Emily Sabens. Additional development by Yutao Chen. Editing by Juliet Eilperin, Monica Ulmanu, Amanda Voisard, Joe Moore, Gaby Morera Di Núbila, Wayne Lockwood and Jay Wang.
Sources
Population projections for 2030 are from the Global Human Settlement Layer, and projections for 2050 are from Xinyu Wang et al., 2022.
The total number of people exposed to different levels of heat includes urban populations from GHS Urban Centres and a list of smaller U.S. cities, as well as the rest of the world’s population grouped into “climate impact regions”, a set of subnational regions shared by the Climate Impact Lab. The most sparsely populated parts of the world are excluded when calculating average wet-bulb globe temperatures in these regions.
Projections for gross domestic product were sourced from the International Monetary Fund and extrapolated to 2030 using a geometric average of 2023-2027 growth rates. GDP numbers are given in purchasing power parities.
Projections of AC access are from Davis et al., 2021. The ratio of physicians to total population was sourced from WHO.
How we are estimating wet-bulb globe temperature in 2030
The Washington Post and CarbonPlan calculated an approximate form of the wet-bulb globe temperature (WBGT) from future climate projections. This heat metric captures the human body’s response to dangerous combinations of temperature, humidity, the force of the sun and wind. (CarbonPlan provides a detailed technical discussion of the methodology on its website.)
Direct measurements of WBGT require specialized equipment, but approximations can be derived from climate model data. This data comes from NASA’s NEX-GDDP-CMIP6, a set of climate projections based on the latest generation of climate models known as CMIP6. The analysis is based on a “middle-of-the-road” scenario for climate policy in which countries make steady progress toward cutting greenhouse gas emissions.
Numbers given for the year 2030 refer to the average across the 20-year period from 2020 to 2039, as the weather can vary from year to year. Numbers given for the year 2050 refer to the average for 2040 to 2059.
The projections were further refined using a historic data set of extreme heat called UHE-Daily, which captures temperature variations between urban areas and less built-up regions.
The projections give only an approximate sense of the maximum wet-bulb globe temperature that is reached on any day, as the factors contributing to heat stress vary from hour to hour.
The Post presents two sets of projections — one which assumes that a person is protected from the impact of the sun and the wind, and one which assumes that a person is exposed to these elements. The impacts of sun and wind were derived from Kong and Huber (2022).
CarbonPlan’s work was led by Oriana Chegwidden with support from Jeremy Freeman. Carbon Plan is making the data available to the public here.
Climate scientists Drew Shindell (Duke University), Luke Parsons (the Nature Conservancy), Matthew Huber (Purdue University), Zeke Hausfather (Stripe) and Robert Rohde (Berkeley Earth), Jared Rennie (National Oceanic and Atmospheric Administration), Shruti Nath (Climate Analytics), Tord Kjellstrom (Health and Environment International Trust), Shouro Dasgupta (Euro-Mediterranean Center on Climate Change), Benjamin Zaitchik (Johns Hopkins University) and Joe Hamman (Earthmover) provided informal review and feedback on the methodology used to approximate wet-bulb globe temperatures. Cascade Tuholske (Montana State University) and Pete Peterson (University of California at Santa Barbara) provided access to the UHE-Daily gridded fields from Tuholske et al. (2021).
Experts consulted on the strengths and limitations of the WBGT metric and the physiological impacts of different levels of heat include Zac Schlader (Indiana University at Bloomington), W. Larry Kenney and Daniel Vecellio (Pennsylvania State University), Jonathan Patz (University of Wisconsin at Madison), George Havenith (Loughborough University, U.K.) and Jason Lee (National University of Singapore)
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