This article was created in partnership with the National Geographic Society.

Golam Mostafa Sarder starts every day before dawn, rising from a thin reed mat in the shed that he shares with fifteen roommates. Each has just enough space to lie flat. He dresses in gym shorts and t-shirt by the light of a single dangling bulb.

Outside the shed’s open doorway, in the outskirts of Dhaka, the sprawling megacity capital of Bangladesh, is the brick factory where Golam and his neighbors work for fifteen hours a day, seven days a week, at least six months a year. His home in Gabura, a remote village on the country’s southwestern coast, is more than a day’s journey from the city by bus, rickshaw, and ferry.

Golam’s job is to push wheelbarrows of mud down the production line. Waist-high rows of drying bricks spiral off from a towering kiln that belches smoke over an area the size of a city block. By 6 p.m. his lanky frame is spattered in gray mud. The evening air swims with mosquitoes. He has just enough strength left to clean his bare feet and angular face, inhale a dinner of lentils and rice, and collapse back onto his mat.

View Images A teenage boy works at a brick field in Bhola, Bangladesh. Brick fields in urban areas are a common destination for coastal climate migrants, especially young men. Photograph by Mahmud Hossain Opu

Golam has never heard of global warming. But he says he knows one thing for sure: “If the river didn’t take our land, I wouldn’t need to be here.”

Bangladesh, a densely populated, riverine South Asian nation, has always survived its share of tropical storms, flooding, and other natural disasters. But today, climate change is accelerating old forces of destruction, creating new patterns of displacement, and fueling an explosion of rapid, chaotic urbanization. A report last week from the U.S. Government Accountability Office found that the State Department and other foreign aid agencies have not done enough to combat climate change-induced migration in developing countries, and highlighted Bangladesh as particularly vulnerable. And as climate change drives the migration of up to 200 million people worldwide by 2050, Dhaka offers a cautionary tale for refuge cities around the globe.

Interviews with dozens of migrant families, scientists, urban planners, human rights advocates, and government officials across Bangladesh reveal that while the country is keenly aware of its vulnerability to climate change, not enough has been done to match the pace and scale of the resultant displacement and urbanization, toppling any prospect of a humane life for one of the world’s largest populations of climate migrants.

“Right now the government’s vision is to have no vision,” says Tasneem Siddiqui, a political scientist who leads the Refugee and Migratory Movements Research Unit at the University of Dhaka. “It’s just that everything is in Dhaka, and people are all coming to Dhaka. And Dhaka is collapsing.”

Climate-driven displacement

Bangladesh holds 165 million people in an area smaller than Illinois. One-third of them live along the southern coast, a lush honeycomb of island villages, farms, and fish ponds linked by protective embankments. Most of the country’s land area is no higher above sea level than New York City, and during the rainy season more than one-fifth of the country can be flooded at once.

For tens of thousands of years, people living in the vast Ganges Delta accepted a volatile, dangerous landscape of floods and tropical storms as the cost of access to rich agricultural soil and lucrative maritime trade routes.

View Images Forida Khatun stands behind her house in Gabura, Bangladesh, in November. Two of her sons migrated to Dhaka after the family home was destroyed by storms multiple times and agricultural jobs were lost due to salinity intrusion. “Only Allah can save us," she says. "We don’t have any power to save our children.” Photograph by Tim McDonnell

“People have always coped with flooding, and they learned how to cope with death,” Siddiqui says. “But with climate change, many of the damages are permanent. So you have to adapt to a new way of life.” (Learn about Bangladesh’s floating hospital.)

Climate change is disrupting traditional rain patterns—droughts in some areas, unexpected deluges in others—and boosting silt-heavy runoff from glaciers in the Himalaya Mountains upstream, leading to an increase in flooding and riverbank erosion. Every year, an area larger than Manhattan washes away. Meanwhile, sea-level rise is pushing saltwater into coastal agricultural areas and promising to permanently submerge large swaths.

Over the last decade, nearly 700,000 Bangladeshis were displaced on average each year by natural disasters, according to the Internal Displacement Monitoring Centre. That number spikes in years with catastrophic cyclones, like 2009’s Aila, which displaced millions of people and killed more than 200. But even in relatively calm years, there is a rising drumbeat of displacement as sea-level rise, erosion, salinity intrusion, crop failures, and repeat inundation make life along the coast untenable.

Overall, the number of Bangladeshis displaced by the varied impacts of climate change could reach 13.3 million by 2050, making it the country’s number-one driver of internal migration, according to a March 2018 World Bank report.

“On the coast, we can predict with great certainty that many people living there now will simply not be able to continue there, because their livelihoods will be lost,” says Saleemul Huq, director of the Dhaka-based International Centre for Climate Change and Development and one of the country’s leading climate scientists.

As people flee vulnerable coastal areas, most are arriving in urban slums—particularly in Dhaka, one of the world’s fastest-growing and most densely populated megacities. The city is perceived as the country’s bastion of economic opportunity, but it is also fraught with extreme poverty, public health hazards, human trafficking, and other risks, including its own vulnerability to floods. Already, up to 400,000 low-income migrants arrive in Dhaka every year.

“Dhaka is filled with people who fled their village because it was swallowed by the sea or the rivers,” Huq says. “The coming millions will be impossible to absorb.”

How migration happens

Today, city planners, policymakers, scientists, and farmers are reinforcing embankments, innovating home design, rebuilding communities, building shelters, and cultivating salt-tolerant rice seeds, among other actions. But they’re moving too slowly to help many people like Golam, who survived a series of catastrophic storms only to find that migration was the only viable path remaining.

Golam was a child the first time his family’s house was destroyed. He was too young to remember the wind ripping out his father’s fruit trees, floodwaters carrying off tea and rice from the family’s small shop, the mud walls crumbling, him taking shelter with his mother in a neighbor’s house and then, when that too washed away, falling into an empty grave as they ran from the raging riverbank in the dark.

A second storm several years later took their next house. And a third, after that: Cyclone Aila washed away not only the latest house and everything in it, but also the land on which it stood, the family’s last piece of property.

After Aila, Golam’s family was homeless, landless, with almost no possessions, and awash in high-salinity water that would silently sabotage fishing and agriculture for the next decade. For a young man with a third-grade education, the brick factory and its promise of hard cash became the only way to feed his family.

“In my childhood, no one used to come out here for work,” he says. “But now, from my village, nearly every family sends at least one person.”

Golam’s family sent two: A couple years ago, his younger brother joined him. Each earns just shy of $1,500 in six months, his total income for the year.

Their only time off is when it rains. On those days, they take a bus to the international airport and stand outside the perimeter fence to watch planes fly in and out, and imagine where they might be going.

“I hope God will look at me kindly,” Golam says, “and change my luck.” (Learn about Bangladesh’s shipbreakers.)

View Images Young men relax on a flood gate in the booming port town of Mongla, Bangladesh. The city aims to recreate itself as a magnet for climate migrants, with investments in sea walls and other adaptive infrastructure, factories and other job opportunities, as well as public services like affordable housing, schools, and hospitals. Photograph by Mahmud Hossain Opu

A city of climate change slums

For climate migrants who arrive in Dhaka, life is seldom easy. Men and boys work in brick factories, drive rickshaws, and build skyscrapers. Women and girls clean houses, stitch Western fashions, and raise families—often fending off sexual violence at multiple steps along the way. Education is a luxury; rent is preposterous. Eviction can come as suddenly as a collapsing riverbank. Home feels very far away.

Sahela Begum, 34, lost her husband to a heart attack in February. She managed to support their four daughters off his life savings for a few months in a town called Naria, on the banks of the Padma River. Then she lost their house. On a sticky evening in August, the riverbank it was on crumbled, sending it downstream along with a dozen of her neighbors’ houses.

“When my house was going in the water, I felt like I was having a stroke and might die,” she says. “When we lost the house, we ran out of options.”

Within a week, she left with her daughters for Dhaka, several hours upstream. They managed to find a room in a slum called Kamrangirchar, near the city center, in a dead-end alleyway behind a cacophonous fabric market built over an old trash dump. She pays around $40 a month, seventy percent of the salary she earns doing domestic work every day, for a darkened, ten-by-ten-foot concrete room under a stairway. Her oldest daughter, 13, also does domestic work, while the 11-year-old stays home to care for the 6- and 9-year-olds. They share three toilets and one four-burner stove with twelve other families living in the alley.

Forty percent of the city’s residents live in slums like this, hundreds of which are spread across the city. According to the International Organization for Migration, up to seventy percent of the slums’ residents moved there due to environmental challenges.

Slums emerge unplanned and unsanctioned in the backyards of glassy skyscrapers, straddling railroad tracks, on stilts above water-logged floodplains, on the fringes of construction sites. Single beds are frequently shared by five or more family members. Sewage runs freely. Structure fires spread easily. Most electricity, when it’s working at all, is tapped illegally from the grid. Insect infestations are inescapable. Skin and gastrointestinal diseases transmitted by dirty water are routine, and the infant mortality rate is twice that of rural areas. Rent money flows into a real estate black market controlled by corrupt local officials and businessmen.

“It’s very hard to get a living here,” Begum says. “But my life is my childrens’ life. If I can make a good future for them, that’s the best thing I can hope for.” (Read about Bangladesh's Rohingya refugee crisis, which also has roots in environmental degradation.)

Cities for climate migrants

When Bangladesh gained independence in 1971, the population was 91 percent rural. But as the country began to pivot from an agricultural economy to one diversified into manufacturing and other urban industries, Dhaka exploded. Today, nearly one-third of the population lives in cities, and Dhaka’s population is nearly triple that of the country’s next three biggest cities combined. The city holds 47,500 people per square kilometer, nearly twice the population density of Manhattan.

Throughout that process of growth, “low-income people were totally left out of the development framework of the city,” says A.Q.M. Mahbub, an urban studies researcher at the University of Dhaka. Affordable housing, and public transit connecting the city center to suburbs as is common in megacities in India and China, were never priorities.

Local officials still tend to view slum dwellers as illegal squatters, rather than residents with a right to basic services. Tariq bin Yousuf, a senior official at the Dhaka City Corporation, a government agency that manages the city’s infrastructure, says that while the city has plans to build more affordable housing, it prefers to leave slum residents reliant on aid from local and international non-governmental organizations.

“If we invest money directly in slum areas, or give them an electricity supply, they will start to think, ‘O.K., we have these facilities, so we have the ownership of this land,’” he says. “Once we give them improved services, they become permanent.”

Many of the country’s leading public policy experts think that attitude—that climate migrants are a regrettable burden—is short-sighted.

View Images Mohammed Kabir Hossain, who drives a rickshaw, is one of many climate migrants who were attracted to Mongla as an alternative to Dhaka. “Because of salinity and flooding, there’s not much opportunity in my village. But here, I can make good money,” he says. Photograph by Mahmud Hossain Opu

“Climate change and migration you cannot stop,” the University of Dhaka’s Siddiqui says. “But you can turn them into an opportunity for development.”

Mongla, a booming port town on the country’s south-central coast, is testing that theory by embarking on an urban overhaul that aims to turn it into a magnet for climate migrants. It’s one of several emerging “secondary cities,” models of climate-savvy urban planning where investments in sea walls and other adaptive infrastructure are being paired with factories and other blue-collar job opportunities, as well as public services like affordable housing, schools, and hospitals.

“There’s no way to stop people coming to Dhaka unless we can attract them to other places,” Huq says. “The next ten million could go to these secondary towns. The girls and boys of today, the next generation of citizens.”

Mongla has the right ingredients, planners hope. It has a well-established deepwater port, surrounded by a sprawling industrial area with cement factories, diesel fuel mass storage facilities, and two dozen factories with jobs for 4,300 workers producing everything from luggage and electronics to packaged snacks and mannequins. Located in the center of the country’s coastal belt, it’s big enough to offer opportunities but small enough that there’s room to grow.

“We have a master plan for making the city more functional and beautiful,” says Mohammed Alauddin, Mongla’s deputy mayor. “People used to have to leave Mongla to find work. Now they’re coming to work in industry, and staying because of the good living conditions.”

So far, local officials have invested in two flood-control gates; a freshwater treatment and distribution system that Alauddin says has increased the number of houses with running water from one-third of the city’s total to one-half; eleven kilometers of pedestrian-friendly riverside brick pathways; two dozen closed-circuit security cameras; a citywide loudspeaker system that can announce inclement weather and broadcast motivational pop music; and four thousand shade trees. Several new apartment towers are under construction, as well as a watchtower from which tourists can peer into the nearby Sundarban mangrove forest.

The investments appear to be paying off. In the last five years, the population has jumped nearly sixty percent to 110,000, and the price of land has skyrocketed. The industrial area is across a river from the town center, and every evening at rush hour the river is jammed with ferries on which passengers stand shoulder to shoulder. And the town’s reputation is spreading.

“Because of salinity and flooding, there’s not much opportunity in my village. But here, I can make good money,” says Mohammed Kabir Hossain, who drives a rickshaw from the industrial area to the ferry station. He came to Mongla a few years ago from Koyra on the southwestern coast. “A lot of people are coming here from across southern Bangladesh, especially those who are unwilling to go to Dhaka.”

‘Only Allah can save us’

At Golam’s family home in Gabura, two low wooden buildings frame a courtyard that opens onto a constellation of rectangular shrimp ponds stretching to the horizon. Immediately behind it is a crumbling ten-foot embankment, no more than three feet across, paved with the same gray bricks that Golam and men from every family here labor far from home to produce. Behind the embankment, a river divides civilization from the uninhabitable Sundarbans, the world’s largest mangrove forest. The family lives in fear that their house—on a tiny wedge rented from the village—will again wash away.

Forida Khatun, Golam’s mother, shares her son’s angular face. She crouches against the exterior wall of the house wrapped in a purple sari with yellow flowers, her arms shimmering in silvery bracelets, shooing away a nosy chicken. In a high, thin voice she recalls how Golam was an energetic, devious child, always in trouble. He loved boats, and once took a canoe out into the mangroves for so long that he was too exhausted to row himself home. That time, Khatun was able to dispatch a few older boys from the neighborhood to rescue him. Now, she worries that he’s slipped away from her for good.

“If we had the land still, if the salinity was less, our sons could have managed to stay,” she says. “Only Allah can save us. We don’t have any power to save our children.”

Here, land is wealth, and the family has none left. At the same time, salinity has poisoned the job market as much as it has the water and soil: Many wealthier farmers have converted their rice paddies—a reliable opportunity for paid labor—into salt-tolerant shrimp ponds, which essentially care for themselves.

The corrosive effect of salinity on local agricultural economies could displace up to 200,000 people from coastal Bangladesh, a November study from the International Food Policy Research Institute found. That exodus is already well underway in Gabura.

“Because of climate change, the job opportunities are reducing,” says Isharat Jahan Mintu, the chairman of the village government. “And the huge risk of natural disasters makes people want to go to safer areas.”

Mintu estimates that the high tide is rising by one foot per year on average, and that one-third of the village’s farmable acres have been rendered useless by salinity. Farmers are reluctant to bring more than a fraction of their useable acres into cultivation, for fear of seeing their entire nest egg washed away at once and local banks, seeing the same risk, are stingy with loans. As a result, up to two-thirds of the village’s men, including Golam, have left to find work in Dhaka and other cities either temporarily or for good.

As a generation of young people loses faith in what was once one of the most richly productive regions of South Asia, those who remain worry that the village’s social fabric will be irreparably damaged. Families are fragmented, children grow up without fathers, and lifelong neighbors turn against one another over land. Parts of the embankment resemble ghost towns, lined with boarded-up shops. No one wants to leave, but many see no way to stay.

“Migration is very emotional,” Mintu says. “It makes an emptiness in the heart of the village.”