Some of the World's Biggest Lakes Are Drying Up. Here's Why.

Warming climates, drought, and overuse are draining crucial water sources, threatening habitats and cultures.

This story appears in the March 2018 issue of National Geographic magazine.

Tire tracks stretched across the flat lake bed to the horizon. We followed them in a Suzuki 4x4, looking for clues about what’s happened to Poopó, once Bolivia’s second largest lake, which has vanished into the thin air of the Andean highlands.

We were driving on the lake bottom, yet we were more than 12,000 feet above sea level. The spring air was lip-chapping dry. Many of the fishing villages that have relied on Lake Poopó for thousands of years have emptied too, and we drove past clusters of abandoned adobe homes. Dust devils danced around them, spinning in warm winds. In the distance we spotted several small aluminum boats that seemed to be floating on water. As we drove closer, the mirage receded, and we found the boats sitting abandoned in the silt. I stepped out of the vehicle. My shoes cracked the salty crust that had formed jagged lumps, like ice cream in a freezer that has melted and recrystallized.

My guide, Ramiro Pillco Zolá, crunched across the salt pan to reach one of the dilapidated, half-buried boats. Boyhood memories of paddling across the lake flooded back to him from long before he left his village of San Pedro de Condo to study hydrology and eventually earn a Ph.D. in hydrology and climate change at Lund University in Sweden. “We’re not talking about a small thing,” Pillco Zolá told me. “Three decades ago this lake covered 3,000 square kilometers. It’s going to be hard to recover.”

Water that once spread across an expanse about the size of Rhode Island was gone. A pair of black rubber boots lay discarded near the boat. A fish skull bleached brilliant white flashed under the blinding sun. The wind suddenly stopped, cloaking the post-apocalyptic scene in silence. If water is life, this was the absence of both.

Round the globe, climate change is warming many lakes faster than it’s warming the oceans and the air. This heat accelerates evaporation, conspiring with human mismanagement to intensify water shortages, pollution, and loss of habitat for birds and fish. But while “the fingerprints of climate change are everywhere, they don’t look the same in every lake,” says Catherine O’Reilly, an aquatic ecologist at Illinois State University and co-leader of a worldwide lake survey by 64 scientists.

In eastern China’s Lake Tai, for example, farm runoff and sewage stimulate cyanobacterial blooms, and warm water encourages growth. The organisms threaten drinking-water supplies for two million people. East Africa’s Lake Tanganyika has warmed so much that fish catches that feed millions of poor people in four surrounding countries are at risk. The water behind Venezuela’s massive Guri hydroelectric dam has reached such critically low levels in recent years that the government has had to cancel classes for schoolchildren in an effort to ration electricity. Even the Panama Canal, with its locks recently widened and deepened to accommodate supersize cargo vessels, is troubled by El Niño–related rainfall shortages affecting man-made Gatun Lake, which supplies not only water to run the locks but also fresh drinking water for much of the country. Low water levels have also forced limits on the draft of ships so the ships don’t run aground in the lake.

Of all the challenges lakes face in a warming world, the starkest examples are in closed drainage basins where waters flow into lakes but don’t exit into rivers or a sea. These terminal, or endorheic, lakes tend to be shallow, salty, and hypersensitive to disturbance. The vanishing act of the Aral Sea in Central Asia is a disastrous example of what can happen to such inland waters. In its case the main culprits were ambitious Soviet irrigation projects that diverted its nourishing rivers.

Similar scenarios are playing out in terminal lakes on nearly every continent, a combination of overuse and worsening drought. Side-by-side satellite images reveal the shocking toll. Lake Chad in Africa has shrunk to a sliver of its former self since the 1960s, heightening shortages of fish and irrigation water. Displaced people and refugees who now depend on the lake put an additional strain on resources. Shortages as well as tensions in the hot, dry Sahel are driving conflict and mass migration. Utah’s Great Salt Lake and California’s Salton Sea and Mono Lake have undergone periods of recession too, diminishing critical breeding and nesting areas for birds as well as playgrounds for recreational boaters.

After the Caspian Sea, Iran’s Lake Urmia was once the largest saltwater lake in the Middle East. But it has shrunk by some 80 percent over the past 30 years. The flamingos that feasted on brine shrimp are mostly gone. So are the pelicans, egrets, and ducks. What remain are piers that lead nowhere, the rusting carcasses of ships settled into the silt, and white, barren salt flats. Winds that whip across the lake bed blow salt dust to farm fields, slowly rendering the soil infertile. Noxious, salt-tinged dust storms inflame the eyes, skin, and lungs of people 60 miles away in Tabriz, a city of more than 1.5 million. And in recent years Urmia’s alluring turquoise waters have been stained blood-red from bacteria and algae that flourish and change color when salinity increases and sunlight penetrates the shallows. Many of the tourists who once flocked here for therapeutic baths are staying away.

Although climate change has intensified droughts and elevated hot summer temperatures around Urmia, speeding up evaporation, that’s only part of the story. Urmia has thousands of illegal wells and a proliferation of dams and irrigation projects that divert water from tributary rivers to grow apples, wheat, and sunflowers. Experts worry that Urmia could fall victim to the same overexploitation of water as the Aral Sea. Their voices seem to have reached Tehran. Iranian President Hassan Rouhani has pledged five billion dollars to revive Urmia by releasing more water from dams, improving the efficiency of irrigation systems, and switching to less thirsty crops. And although United States–Iran relations have been strained for decades, the two countries have permitted scientists to brainstorm about ideas to replenish both Urmia and Great Salt Lake. Neither nation wants to see its salt lake go the way of Poopó.

Bolivia's high plain, the Altiplano, unfurls like a leaf-shaped plateau wedged into an unusual place where South America’s Andes cleave into two separate ranges. The windswept landscape remains brown much of the year. Grasses and shrubs grow sturdy and low to the ground. The people who eke out a living in this inhospitable landscape are just as hardy. Toward the north end of the plateau sits Lake Titicaca, at 12,500 feet, straddling the border between Peru and Bolivia. At the southern end is blindingly white Salar de Uyuni, at 11,995 feet. Poopó rests between them, the transition zone between the world’s highest commercially navigable lake and the world’s largest salt flat.

Scientists have long suspected that Poopó would someday be choked with sediment, desiccate, and transition into another salt flat like Salar de Uyuni. Yet its demise wasn’t projected to come for at least another thousand years, says Milton Pérez Lovera, a natural sciences professor at Oruro Technical University and a member of a team monitoring bodies of water in the Bolivian highlands. A combination of factors, including climate change, drought, upstream water diversions for agriculture, and mining, have accelerated the process, he says, leaving the lake increasingly dry and barren. Pérez Lovera expects Poopó may partly refill, perhaps as soon as this year, if La Niña conditions bring more rain to the Andes. But he and other scientists are less sure the lake will regain its ecological function as a prime wintering habitat for waterfowl, including three species of flamingos, one classified as vulnerable to extinction. Nor are they certain whether or when its fertile fishing grounds—which for millennia provided food for indigenous people—might recover.

The fate of Lake Poopó is intertwined with that of the Urus, an indigenous group known as “people of the water.” The lake’s size and depth have been diminishing for years, forcing Uru fishermen to travel farther onto the lake to catch fish. In 2014 and 2015 the ever shallower lake suffered fish die-offs as water temperatures soared beyond the usual 60s and 70s Fahrenheit. Millions of carcasses floated belly-up at the surface. When Franz Ascui Zuna, assigned by Bolivia’s Ministry of Health to monitor the largest Uru village, Llapallapani, recorded a water temperature of 100.4°F, he pronounced a diagnosis: The lake was “running a fever.”

Soon the ducks, herons, flamingos, and other birds that typically inhabit the lake were starving, either dying or flying away. In a flash of evaporation in 2015, the remaining lake vanished as its overheated waters were fanned by the Altiplano’s winds. The government declared Poopó a disaster area. It sent each family in surrounding villages some pasta, rice, cooking oil, and sugar. Then rains refilled a portion of the lake, prompting federal officials, in early 2017, to celebrate and release pictures taken from a helicopter. But soon after, Bolivian President Evo Morales toured the lake and confirmed what locals already knew: The shallow layer of water was receding fast. Satellite images in October 2017 showed the lake was once again nearly dry.

Morales has sought to deflect any government culpability in the crisis, pointing to natural cycles of drying and recovery. His father once told him about bicycling across the lake bed from a nearby village where he grew up. Indeed, the lake has dried and recovered, most recently in the mid-1990s. Yet scientists point out that things have worsened since then. And now the watershed and the poor people who live here are teetering on something more tenuous.

On the road into the village of Puñaca Tinta María, we watched an old man in rubber boots and a floppy straw hat stoop over, using a short-handled hoe to stir together clay with salty water he had hauled out of a hand-dug well. Every day since the lake dried up, Féliz Mauricio has toiled in mud-splattered clothes to make adobe bricks. “We have no lake,” he says. “We have no fish. We have nothing.” Mauricio, 77, comes from a long line of indigenous fishermen. A respected elder of the Urus, he’s known for his craftsmanship in lashing together reeds into small balsa fishing boats using giant bulrushes called totora and for preparing a table of offerings in traditional ceremonies to usher in bountiful rain and fishing seasons.

By his reckoning, Mauricio, his wife, and their daughter are one of the few families left in adobe and thatch-roofed homes on the banks of what was once Lake Poopó. One son moved away to herd sheep and cattle; another took a low-skilled construction job in the city of Cochabamba. His neighbors in Puñaca Tinta María and other villages have scattered too, like chaff in the wind. Some have gone to work in textile and garment factories in Chile and Argentina; others have moved to cities and taken jobs as day laborers or work underground as miners extracting tin, lead, silver, and other metals. A few dozen have headed off to what may be the future of their beloved Poopó—working in the salt mines of Salar de Uyuni.

In the global scheme of things, the fate of the Urus may seem trivial. An estimated 5,000 Urus remain today, and fewer than a thousand lived around Poopó before it went dry. Yet those who are forced to relocate join a procession of people around the world who have been uprooted from their homes by climate-related environmental disruptions. The United Nations warned a decade ago that indigenous people would be among the first to be ravaged by climate change because so many rely on nature’s bounty as subsistence hunters and fishermen. An estimated 23.5 million people fled their homes in 2016 because of storms, floods, wildfires, extreme temperatures, and other weather-related disasters, according to the Norwegian Refugee Council’s Internal Displacement Monitoring Centre. That exceeded the 6.9 million newly displaced by conflict and violence that year.

In sheer numbers those fleeing “natural” calamities have outnumbered those fleeing war and conflict for decades. Still, these figures do not include people forced to abandon their homelands because of drought or gradual environmental degradation; almost two and a half billion people live in areas where human demand for water exceeds the supply. Globally the likelihood of being uprooted from one’s home has increased 60 percent compared with 40 years ago because of the combination of rapid climate change and growing populations moving into more vulnerable areas.

Most of these displaced people stay within their home countries. If they cross a border, they do not qualify for UN protections as refugees because they cannot claim they are fleeing violence or persecution. “We live in an era of the most forced migration since the Second World War,” says William Lacy Swing, director general of the United Nations’ International Organization for Migration. “This time, though, in addition to war, climate is looming as a major driver. We are going to need to support those who are ravaged by climate change so they can migrate with dignity.”

“Stop!” Pillco Zolá yelled inside our wind-buffeted SUV. “Go back.” We were racing across a flat, sandy expanse of highlands above Poopó. Without realizing it, we had crossed a small bridge over an irrigation canal. The canal was empty, as was the adjoining Desaguadero River, with the exception of a small pool we found as we walked around the bend. More than 65 percent of Poopó’s water comes from the Desaguadero River, which meanders 185 miles through the Bolivian highlands from its primary source, Lake Titicaca. Hundreds of irrigation canals and other water-diversion schemes have been built along the river for mining and for growing crops. Farms and cities also siphon water out of the Mauri River, a major tributary in Bolivia and Peru.

Another 22 smaller, seasonal streams and rivers also flow into Poopó from surrounding mountains. Virtually all of them are tapped for agriculture or mining operations, such as a state-owned tin mine in the dirt-poor town of Huanuni. When I visited, a chute emerging from the hillside mill was plopping ash gray tailings directly into the river in a conical mound as big as a house. Such tailings contribute to the lead, cadmium, arsenic, and other heavy metals that pollute the lake and fill it with sediment.

An hour’s drive away, a dam built in 1961 on the Tacahua River holds a thick layer of sediment with only a veneer of water. “We’ve got five dams like this one,” Pillco Zolá told me as we walked across the dry spillway, looking at the reservoir bed far below. “It doesn’t make sense to build dams in a semiarid area. We are just stopping water upstream, causing it to evaporate.”

In an average year the Lake Poopó region collects about 15 inches of rain from November to March, followed by seven dry months. Yet the rainy season keeps shrinking, when it comes at all. The Altiplano has suffered repeated El Niño–related droughts, which scientists project will come more often in a warmer climate. The 2015-16 El Niño brought the most dramatic drought and the hottest temperatures ever recorded in the Bolivian highlands, Pérez Lovera says. The Altiplano tends to trap heat between the mountain ranges, he said, and mean temperatures increased 1.6 degrees Fahrenheit over a single decade, accelerating water loss due to evaporation.

Rising atmospheric temperatures in the Andes over the past 40 years also have triggered the rapid retreat of its glaciers, melting half the ice that rings the Titicaca-Poopó basin.

When glaciers first begin to melt, they provide an extra flush of water, explains Dirk Hoffmann, a German researcher based in La Paz who co-authored the book Bolivia in a 4-Degree Warmer World. “But we’ve probably reached peak water in most glacial watersheds,” he says, meaning that meltwater from glaciers will now diminish in the region until it is gone.

Meanwhile, demand for water has surged along with Bolivia’s population, which has grown by 42 percent since the mid-1990s. Last year the government dug a canal in one branch of the sediment-laden Desaguadero River to speed water to Poopó. It also provided wheelbarrows, pickaxes, and some food to support desperate Uru workers as they built a one-and-a-half-foot-high earthen berm on the lake bed in hopes of concentrating water in one small section so it might last longer. To hydrologists like Pillco Zolá, such efforts seem all but futile. More realistic solutions would mean tearing down dams, switching to more efficient irrigation, and reducing the volumes of water diverted from the rivers. Yet there’s little political will to cut off upstream farmers and even less funding for water projects in Bolivia, one of the poorest nations in Latin America.

A Peruvian-Bolivian commission that co-governs Titicaca has built floodgates designed to release more water into the Desaguadero River during dry years. But as demand for water increases upstream in Peru, these floodgates may be rendered useless in the not too distant future. Mark Bush, a paleoecologist at the Florida Institute of Technology, notes that it doesn’t take much of a drop in the water level at Lake Titicaca for the river to stop flowing altogether. That has happened three times before, tucked in the deep recesses of time.

“The Altiplano is exquisitely sensitive to evaporation,” Bush says. Although he cautions that climate models don’t capture the Andes particularly well, he predicts that the region soon may reach a tipping point. “The prognosis for cities like La Paz and villages around Lake Poopó is really dire, given what we think is going to happen in the future,” Bush says. “By mid-century we might see at least two degrees [Fahrenheit] of warming, and we would be flirting with the threshold that would cause Lake Titicaca to evaporate away or greatly reduce its volume.”

South of Poopó, in the highlands, the lakeshore gives way to an even more arid landscape, with wind-sculpted rocks and herds of llamas, alpacas, sheep, and a few wild vicuñas—often clustered near no-hunting signs posted on the highway. In early spring much of the land remains bare, with soil left exposed after the harvest of quinoa that feeds an insatiable appetite for the high-protein grain in Europe and the U.S.

The timing is unfortunate. Before the year’s crops are planted, the winds off the Atacama Desert in Chile scour the empty fields, carrying twice as many tons of sediment into the lake as they did before native grasses and shrubs were cleared for quinoa production. The result: The lake, which used to be 12 feet deep, is filling with sand and dust faster than had been projected.

Beyond the highlands the surface of Salar de Uyuni—crusted with polygons the size of card tables—is broken only by roads and mounds of salt chipped out of the ground to be shipped to nearby salt factories.

Is this the future of Poopó? Paulino Flores, a former Uru community leader, hopes not—but he’s preparing, just in case. Flores, 57, and his family moved to the neighboring town of Colchani to work in the salt factories. Flores says he has mastered every aspect of production: chipping the salt out of the hard ground with a pickax and shovel, hauling it to the factory, removing impurities, grinding it, bagging it. He rubs his callused, salt-stained hands as he talks, squinting into the sun under his knitted Andean chullo hat.

Flores has considered establishing a salt factory on the shores of Poopó, working with the nongovernmental group Center of Ecology and the Andean People. The group’s executive director, Gilberto Pauwels, says his colleagues are exploring every angle to help the Urus develop other livelihoods, preserve their communities, and keep their culture alive. Puñaca Tinta María is just one of the half-deserted villages on one desiccated lake that has left subsistence fishermen and hunters scrambling to figure out how to feed their families. It’s a pattern that’s being repeated around the world.

Flores dreams about the lake’s recovery, the return of its fish and fowl. He talks wistfully about his former life, growing up hunting and fishing with his father and relatives—a life that revolved around Lake Poopó. The Urus believe they are descendants of people who first settled on the Altiplano 3,700 years ago. A 2013 genetic study suggests they may be right, revealing distinctive ancestry likely derived from ancient Andean lineages. These self-reliant people, who once lived on floating reed islands, outlasted the Inca Empire and survived the brutal conquest by the Spaniards. But now the Urus around Poopó face a diaspora with the disappearance of their cherished lake. “If there is no lake, there is no Uru people,” Flores says. “It gives us food and gives us a future.”

Kenneth R. Weiss, a freelance writer based in Carpinteria, California, earned a degree in folklore from the University of California, Berkeley and was awarded a Pulitzer Prize for explanatory reporting in 2007.

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