Extreme heat is forcing farmers and fisherfolk to work overnight, an adaptation that comes with a cost todayheadline

This story was produced by Grist and co-published with The Guardian.

Every morning, for years, Josana Pinto da Costa would venture out onto the waterways lining Óbidos, Brazil, in a small fishing boat. She would glide over the murky, churning currents of the Amazon River Basin, her flat nets bringing in writhing hauls as the sun ascended into the cerulean skies above.  

Scorching temperatures in the Brazilian state of Pará have now made that routine unsafe. The heat has “been really intense” this year, said Pinto da Costa in Portuguese. It feels as if the “sun has gotten stronger,” so much so that it’s led her to shift her working hours from daytime to the dead of night.

Abandoning the practice that defined most of her days, she now sets off to the river in the pitch dark to chase what fish are also awake before dawn. It’s taken a toll on her catch, and her life. But it’s the only way she can continue her work in the face of increasingly dangerous temperatures. 

“A lot of our fishing communities have shifted to fishing in the nighttime,” said Pinto da Costa, who advocates nationally for fisherfolk communities like hers through the Movimento de Pescadores e Pescadoras Artesanais do Brasil, or the Movement of Artisanal Fishermen and Fisherwomen of Brazil. 

Moving from daytime to overnight work is often presented as the most practical solution for agricultural laborers struggling with rising temperatures as a result of climate change. But it is no longer simply a proposal: This shift is already underway among many of the communities that catch, grow, and harvest the world’s food supply, from Brazil to India to the United States. Studies show the most common means of adapting to rising temperatures in most crop-growing regions has been to start working when it’s still dark out, or even to shift to a fully overnight schedule. 

“The obvious piece of advice that you’ll see given is, ‘Work at night. Give workers head torches,’ and so on,” said Zia Mehrabi, a food security and climate researcher at the University of Colorado, Boulder. “But the reality is, that can lead to other rights violations, other negative impacts.” 

That’s been the case for Pinto da Costa and her fishing community in Brazil. Nighttime work has been an additional hardship for a community already struggling with the impacts of climate change. The region has experienced decades of severe drought conditions, causing fish to die off and physically isolating people as waterways dried up. 

Research shows that regularly working during the night is physically and mentally disruptive and can lead to long-term health complications. Nighttime fishing is also threatening social and communal routines among the fisherfolk. A daytime sleep schedule can curb quality time spent with loved ones, as well as limit when wares can be sold or traded in local markets. 

It’s also impacting their ability to support themselves and their families through a generations-old trade. “We’ve actually been working more hours with less food, with less production,” said Pinto da Costa, noting that working at night has made their work less efficient and led them to find less fish. “This is across all regions of Brazil,” she added. 

The impact of a shift to nighttime hours is an understudied piece of the puzzle of how climate change and rising temperatures threaten the world’s food supply and its workforce. But for many experts, and those on the front lines, one thing is clear: Overnight work is far from a straightforward solution.

“It’s a very scary time for us,” said Pinto da Costa.  

Outdoor workers, with their typical midday hours and limited access to shade, face some of the most perilous health risks during periods of extreme heat. A forthcoming analysis — previewed exclusively by Grist — found that, on average, the amount of time considered unsafe to work outside during a typical 9-to-5 workday will increase 8 percent by 2050, assuming greenhouse gas emissions stay on their current trajectory.

Led by Naia Ormaza Zulueta, a Ph.D. student at the University of Colorado, Boulder, and Mehrabi, the analysis measures the number of extreme heat days by geographic region, and then breaks down daily and hourly temperatures by the estimated amount of population exposed. The research reveals that an estimated 21 percent of the global population already faces dangerous levels of heat stress during typical workday hours for more than a third of the year. By 2050, without cuts to planet-warming greenhouse gas emissions (known as the “business-as-usual” scenario), that portion will jump to 39 percent. 

“The number of days that people will experience a violation of their rights to a safe climate is going to substantially increase, but then also the number of possible working hours in a season, and productivity, is going to be substantially reduced,” said Mehrabi. “It’s a massive lose-lose situation.” 

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Their analysis finds that outdoor agricultural workers will encounter the largest health-related risks, with laborers in some areas being hit harder than others. 

India, in particular, is projected to be one of the countries whose workforce will be most exposed to heat stress under the business-as-usual climate scenario. There are roughly 260 million agricultural workers in India. By 2050, 94 percent of the country’s population could face more than 100 days in a year when at least one daytime working hour exceeds a wet-bulb temperature of 28 degrees Celsius, or 82.4 degrees Fahrenheit — a conservative threshold of what is considered safe for acclimatized workers experiencing moderate rates of work. (Unacclimatized workers, or those unaccustomed to working in such environments, will face greater levels of heat risk at the same temperature and amount of work.) 

In Brazil, another of the world’s top agricultural suppliers, heat risk is not as dire, but still poses a substantial risk for outdoor workers, including Pinto da Costa’s community of fisherfolk. By 2050, roughly 41 percent of the country’s population could experience more than 100 days a year when wet-bulb temperatures exceed the recommended threshold for at least one hour a day, according to the Boulder team’s analysis. 

Mary Jo Dudley, the director of Cornell University’s Farmworker Program and the chair of the U.S. National Advisory Council of Migrant Health, said that the analysis is significant for what it reveals about the human health consequences of extreme heat, particularly as it relates to the world’s agricultural laborers. She’s seeing more and more outdoor agricultural workers in the U.S. adopt overnight schedules, which is only adding to the burdens and inequities the wider workforce already suffers from. This is poised to get worse. Zulueta and Mehrabi found that 35 percent of the total U.S. population will experience more than 100 days of wet-bulb temperatures exceeding 28 degrees C, or 82.4 degrees F, for at least one hour a day every year by 2050.

“This transition to a nighttime schedule pushes an extremely vulnerable population into more difficult work conditions that have significant mental and physical health impacts,” said Dudley.  

Rebuking the human body’s circadian rhythms — that 24-hour internal clock that regulates when you sleep and wake — ramps up a person’s risk of health complications, such as cardiovascular disease and types of cancer, and diminishes their body’s ability to handle injury and stress. Working untraditional hours also can reduce a person’s ability to socialize or participate in cultural, communal activities, which are associated with positive impacts on brain and body health. 

Women are particularly vulnerable to the social and economic impacts of transitioning to nighttime schedules. Despite making up nearly 45 percent of artisanal fishers in Brazil, women receive lower pay than their male counterparts. That means that when harvests decline with nighttime fishing, their margins are even smaller.

In the Brazilian state of Bahia, tens of thousands of women fishers work to collect shellfish en masse, while in Maranhão, women fisherfolk herd shrimp to the shore using small nets. Clam harvesting in Brazil’s northeast is also dominated by women. Because these jobs traditionally happened during the day and close to home, they allowed women to balance cultural or gendered family roles, including managing the household and being the caregiver to children. Shifting to evening hours to avoid extreme heat “poses a fundamental challenge,” said Mehrabi. “When you talk about changing working hours, you talk about disrupting families.”  

Overnight work comes with other risks too. In many areas of Brazil, nighttime work is “either impossible” or “very complicated” because there are procedures and regulations as to when fisherfolk in different regions can fish, said Pinto da Costa. Nighttime fishing is regulated in some parts of Brazil — measures that have been shown to disproportionately impact artisanal fishers.

Even so, says Pinto da Costa, many are braving the risks “just to reduce the amount of exposure to the sun.”

“Honestly, when I saw that this was accepted in the literature, that people were giving this advice of changing their working shifts to the night, I was shocked,” said Zulueta, the author of the Boulder study, citing a paper published earlier this year where overnight work is recommended as an adaptation tool to reduce agricultural productivity losses to heat exposure. Under a policy of “avoiding unsafe working hours,” shifting those hours to the nighttime “is not a universally applicable solution,” she said.  

Growing up a pastoralist in Ahmedabad, India, Bhavana Rabari has spent much of her life helping tend to her family’s herd of buffalo. Although she now spends her days advocating for pastoralists across the Indian state of Gujarat, the routine of her childhood is still ingrained in her: Wake up, feed and milk the herd, and then tend to the fields that surround their home. 

But extreme heat threatens to change that, as well as the preservation of her community. When temperatures soar past 90 degrees F in Ahmedabad — now a regular occurrence — Rabari worries about her mom, who hand-collects feed for their buffalo to graze on. Other pastoralists are nomadic, walking at least 10 miles a day herding cattle from region to region in the hunt for pastureland. 

“If we lose our livestock, we lose our culture, our dignity,” said Rabari. “If we continue our occupations, then we are dignified. We live with the dignity of our work.” 

But rapidly rising temperatures are making it hard to hold on to that dignity of work. “The heat affects every life, every thing,” said Rabari. 

Working overnight is a tactic Rabari has heard of other agricultural workers trying. But the idea of tending to the herd in the dark isn’t something she sees as safe or accessible for either her family or other pastoralists in her community. It’s less efficient and more dangerous to work outdoors with animals in the dark, and it would require them to overhaul daily lives and traditions. 

“We are not working at night,” said Rabari. But what the family is already doing is waking up at 5 a.m. to beat the heat, collecting milk from their buffalo and preparing products to sell in the market during the dusky hours of the morning. 

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Rabari’s family and other pastoralists across Gujarat are increasingly in an untenable position. Hotter temperatures have already caused pastureland to wither, meaning animals are grazing less and producing less milk. More unsafe working hours means lost work time on top of that, which, in turn, changes how much income pastoralist families are able to take home.

The result has been not adaptation, but an exodus. Most pastoralists Rabari knows, particularly younger generations, are leaving the trade, seeking employment instead as drivers or cleaners in Ahmedabad. Rabari, who organizes for women pastoralists through the Maldhari Mahila Sangathan, or the Pastoral Women Alliance, says women are most often the ones left behind to tend to the herds. 

They “have to take care of their children, they have to take care of the food, and they have to take care of the water,” she said. “They face the heat, they face the floods, or the excess rain.”

Halfway across the world, April Hemmes is facing off against unrelenting bouts of heat amid verdant fields of soybeans and corn in Hampton, north-central Iowa. A fourth-generation small Midwestern farmer, Hemmes works more than 900 acres entirely on her own — year in and year out. 

The Midwest is the largest agricultural area in the United States, as well as one of the leading agricultural producers in the world. It’s also an area that has been battered by human-caused climate change. In fact, scientists just recently declared an end to the drought that had devastated the region for a whopping 203 weeks. The conditions impacted crop yields, livestock, the transportation of goods, and the larger supply chain. 

Hemmes has the luxury of not having to face the same degree of heat stress that Rabari and Pinto da Costa are confronting elsewhere in the world, per the Boulder analysis. When compared to India and Brazil, the U.S. is on the lowest end of the worker health impact scale for extreme heat. And yet, heat is also already the deadliest extreme weather event in the U.S., responsible for more deaths every year than hurricanes, floods, and tornadoes combined. 

A few years back, while building a fence on her farmland, Hemmes suffered her first bout of on-the-job heat exhaustion. Suddenly, her heart started to race and her body felt as if it began to boil from within, forcing her to abandon her task and head indoors, away from the menacing heat. It was a wake-up call: Ever since, she’s been hyper-cautious with how she feels when tending to her fields.

This past summer, the heat index repeatedly soared past 100 degrees in Hemmes’ corner of Iowa. She found herself needing to be extra careful, not only pacing herself while working and taking more frequent breaks, but also making sure to get the bulk of the day’s work done in the morning. She even began starting her day in the fields an hour or so earlier to avoid searing temperatures compounding with brutal humidity throughout the afternoon. 

“This [farm] has been in my family for over 125 years,” she said. “I do everything from banking to planting to spraying, everything. So it’s all on me, and it’s my family farm. I’m very proud of that.” In 1993, her dad and grandfather both retired, and she took over operations. She’s been more or less “a one-woman show” since. Keeping her farm well-managed is a responsibility she doesn’t take lightly. “You do what’s best for the soil. Because that’s the inheritance of future generations,” she said. 

When Hemmes looks at how to prepare for a future with hotter working conditions, she knows one thing: Nighttime work is out of the question. 

Not only are summertime mosquitoes in Iowa “terrible after dark,” but Hemmes says some of the chemicals she uses are regulated, restricting her from spraying them during the nighttime. In addition, she would need to get lights installed throughout the fields to alleviate the risk of injury when she uses equipment, and she would be even more fearful of that equipment breaking down. 

“It would take more energy to work at night,” said Hemmes. “I think it would be far more dangerous … to work after the daylight was gone.” 

Like Pinto da Costa and Rabari, Hemmes is involved in advocacy for her community. With the United Soybean Board, Hemmes advocates for women in agriculture. With more resources at her disposal than Pinto da Costa and Rabari, Hemmes is focused on how to ensure solo-farming operations like hers have access to the technology they need to overcome heat spells — and never have to seriously consider an overnight harvest schedule.

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On her own farm, she’s invested in “expensive” autonomous agriculture technology that allows her to take breaks when she needs to from the blistering sun. And she would like to see more precision technology and autonomous agriculture tools readily applied and accessible for farmers. She currently uses a tractor with an automatic steering system that improves planting and plowing efficiency and requires much less work, which she credits as one of the pivotal reasons she’s able to successfully manage her hundreds of acres of fields on her own. 

She also hopes to see farmers tapping into their inherent flexibility. “What farmers are is adaptable,” she said. “I don’t have an orchard on my farm, but if I did, and I saw this thing [climate change] coming, you know, maybe you look at tearing the trees out and starting to plant what I can in those fields. Maybe the Corn Belt will move up to North Dakota. Who knows, if this keeps progressing?” 

In Gujarat, Rabari and the Maldhari Mahila Sangathan are working to secure better representation for pastoralists in policymakers’ decisions about land use. The hope is for these communities to inform policies that would allow pastoralists job security and financial safety nets as climbing temperatures make it difficult to work and turn a profit.

Women pastoralists in particular are entirely left out of these policy spaces, said Rabari, which isn’t just an issue of exclusion but means their unique ecological knowledge is lost, too. “We have a traditional knowledge of which grass is good for our animals, which grass they need to eat so we get the most meals, how [they] can be used for medical treatment,” she said.

Pinto da Costa and the Movimento de Pescadores e Pescadoras Artesanais do Brasil are also advocating for monetary relief from the Brazilian government to offset the losses her fisherfolk community has faced from climate change and shifting work hours. In addition, she is looking for technical support to improve fisherfolk’s resources and equipment.

“I have maintained my energy and motivation to continue to fight for our rights,” said Pinto da Costa.

For all, it’s a race against time. Eventually, even working at night may not be enough to keep outdoor agricultural work viable. The Boulder researchers found that an overnight working schedule will not significantly alleviate dangerous heat stress exposure risk in key agricultural regions of the world — particularly across India. After all, heat waves don’t only happen during the day, but also take place at night, with overnight minimum temperatures rising even more rapidly than daytime highs. 

Zachary Zobel, a scientist at the Woodwell Climate Research Center who has separately researched the impact of overnight work adaptations on global agricultural productivity levels, said the Boulder team’s analysis has a “novel” result, and lines up with what his team has found.

“Warming past 2 degrees C, which we will experience over the next 30 years, would mean that even overnight shifts wouldn’t recover productivity,” said Zobel. 

“How do you solve a problem like that?” Mehrabi said. “The reality is that the workers most at risk are the people contributing least to the climate change problem. That’s not to say that we can’t have better policies around hydration, shading, health. But it’s just kind of trying to put a BandAid on a problem. It doesn’t actually deal with the problem at its root cause, which comes down to this trajectory of fossil fuel consumption and emissions.”