ALTANBULAG, Mongolia — It was another harsh winter on the central Mongolian steppe, with temperatures dropping to nearly 50 below zero and thick snow covering the rolling grasslands. More than a million cattle, sheep and goats, weakened by a dry summer, died, while nomads’ precious horses froze to death on their feet. “It was very hard, and the snow was deep,” said 38-year-old herder Nyamdorj Tumursanaa, drinking milky tea in the nomads’ traditional circular tentlike home known as a ger. “Even if the animals dug through the snow, there was no grass underneath. We had to buy grass for them, but still many of our animals died.” Here on the central Asian steppe, the ancient home of Genghis Khan and his Mongol horde, the nomads are brought up tough. Yet their ancient lifestyle is under threat as never before. Global climate change, combined with local environment mismanagement, government neglect and the lure of the modern world, has created a toxic cocktail. Every year, thousands more herders abandon their way of life and head for Mongolia’s crowded capital, Ulaanbaatar, which holds half the nation’s population. The nomadic culture is the essence of what it is to be a Mongolian, but this is a country in dramatic and sudden transition: from a Soviet-style one-party state and command economy to a chaotic democracy and free-market economy, and from an entirely nomadic culture to a modern, urban lifestyle. Climate change is a major culprit, and Mongolia, landlocked and far from the moderating effects of the ocean, is suffering more than most parts of the world. At the best of times, this is a fragile climate, with little rainfall and huge variations in temperature, which is why this vast territory supports a population of only 3 million people, making it the world’s most sparsely populated country. Now, government figures show average temperatures have risen by about 2.2 degrees Celsius (4.0 degrees Fahrenheit) since systematic records began in 1940 — well above the global average rise of about 0.85 degrees Celsius (1.53 degrees Fahrenheit) since 1880. Summers, when most of the rainfall occurs, have become drier, and “extreme climate events” have become more frequent, said Purevjav Gomboluudev, head of climate research at Mongolia’s Information and Research Institute of Meteorology, Hydrology and Environment. The most dangerous event of all is a dry summer followed by severe winter, a phenomenon known as dzud. Drought leaves livestock weak and reserves of grass low, making cold weather more dangerous: Extreme cases in 1999-2001 and 2009-2010 wiped out a combined 20 million animals. On the grasslands outside the small town of Altanbulag, 47-year-old Banzragch Batbold and his wife, Altantuya, remember how streams used to run off every mountain in their youth, how horses would dive into a local pond to cool off in the summer. “Now all that water is gone,” she said. Hundreds of rivers, lakes and springs have dried up across the country, the environment ministry says. And as the water retreats, the desert advances. Roughly three-quarters of Mongolia’s land is degraded or suffering desertification, with about a quarter seriously affected, said Damdin Dagvadorj, managing director of the Climate Change and Development Academy. But Mongolia’s mismanaged twin transitions are also to blame. In the Soviet era, Mongolia, a satellite state, kept nomadism under tight control. Animals were kept under collective ownership, but their numbers were limited, while the state supplied veterinary services, winter fodder and a guaranteed market. In 1990, as the Soviet Union disintegrated, Mongolia threw off its one-party state and became a democracy. Three years later, it began privatizing the herds. What followed was a huge expansion in animal numbers as individual herders valued their worth by how much livestock they held. State support simultaneously vanished almost overnight. Today, 66 million livestock roam the Mongolian steppe, nearly three times the 23 million cap maintained in the communist era. Overgrazing is a major cause of pastureland degradation, especially by the voracious and sharp-hooved goats whose numbers have exploded to supply the valuable trade in cashmere. Rampant, uncontrolled mining also uses huge amounts of groundwater, pushing the water table ever lower. At the same time, the government has failed to extend education, health care and veterinary care to remote herding communities, said Ulambayar Tungalag of the Saruul Khuduu Environmental Research Center. “There is no incentive to stay in rural areas,” she said. And inequality is rising: Eighty percent of the livestock is controlled by the richest 20 percent of owners, among them elite city dwellers who pay others to look after their herds. More than 220,000 Mongolian families depend on herding, but more than half have fewer than 200 animals, government figures show, well below the 250-to-300 threshold considered economically sustainable. Herders may have solar panels, smartphones and televisions, but life isn’t getting any easier. Families are separated for much of the year as children head for boarding schools in the nearest towns, sometimes with mothers tagging along. In the winter, Altantuya stays, getting up at first light to dig frozen cowpats out of the snow to build a fire, with Batbold heading out to protect the animals from wolves, wind and snow. “In the winter, people get lonely,” he admitted. “You can’t go anywhere. You have TV now, but your children are in school. The women go crazy, and the men drink vodka.” The couple’s children are being educated in Ulaanbaatar. Neither child has expressed any desire to follow in their parents’ footsteps. “No one wants to be a nomad,” Batbold said. “When I’m old, and if I am not able to ride, there will be no one left to look after the steppe.” Quentin Moreau, country director for AVSF (Agronomists and Veterinarians Without Borders), a French nonprofit group supporting smallholder farming, says no investment is being made to make herders’ lives easier. Projects to promote quality over quantity — for example, by rewarding herders with higher prices for better-quality cashmere — are still too small-scale to make a difference, and government plans to promote intensive farming make no sense on the water-starved grasslands, he said. Moreau fears an acceleration of the rural exodus — to the point where the system of villages and towns serving herders is no longer sustainable. What few social services that are available could disappear entirely. Yet the lure of the capital often proves to be a mirage. A century ago, the town that is now Ulaanbaatar was little more than a trading post and a monastery. Today, it is a sprawling mess of 1.4 million people, half living in Soviet-style apartments, half in the sprawling, unplanned “ger districts” where people have pitched their homes on the hills surrounding the city. Mongolians are a people deeply connected to nature, who call their country the Land of the Eternal Blue Sky. But their capital has become the land of choking smog, as ger dwellers burn coal to ward off the cold. In winter, the capital has some of the worst air pollution in the world. Cases of respiratory infections have nearly tripled in a decade, pneumonia is a leading cause of death for infants, and children living in the center of the city have 40 percent lower lung function than those in rural areas, UNICEF says. Residents of ger districts lack access to running water, while jobs for rural migrants are few and poorly paid — a watchman, a cook, a driver perhaps. Many people lack the skills to succeed here. During festivals and important events, politicians like to don the national costume — the herders’ calf-length tunic, or deel — but are doing nothing to protect the source of that culture, Tungalag said. Meanwhile, in urban society, herders are often stigmatized, their lifestyles looked down upon. “Nobody understands that actually Mongolian identity — being a nomadic person, being close to nature — is being lost,” Tungalag said.