for National Geographic News
Lifelong herder Namdag lives in a traditional felt tent home—or "ger"—among some half dozen cars in various states of disrepair, an informal junkyard against the towering, snow-capped mountains that surround the Mongolian capital of Ulaanbaatar (Ulan Bator).
"I miss my old life," said the 71-year-old, now a world removed from the sweeping steppes he once called home. "But life out there is too difficult."
Namdag, who like many Mongolians uses only one name, is one of the hundreds of thousands who in recent years have abandoned their nomadic herding lives for an urban existence.
The former herders crowd into sprawling townships on the periphery of Ulaanbaatar, which has doubled its population in the past two decades. (See a video of Mongolian nomads and their fading lifestyles.)
While there are many reasons for the migration, observers say climate change is increasingly a driving force behind Mongolians' move toward the cities.
Over the past 60 years the average temperature in Mongolia has risen by 3.4 degrees Fahrenheit (1.9 degrees Celsius). In contrast, the average temperature around the world has climbed only about 1 degree Fahrenheit (about 0.6 degree Celsius) in the past century.
The warmer temperatures are drying up Mongolia's grasslands, which provide food for the country's livestock.
"The Mongolian herding way of life is under threat from global warming," said Azzaya, director of the Institute of Meteorology and Hydrology in Ulaanbaatar.
With its hot summers and cold winters, Mongolia has one of the most extreme climates anywhere on Earth.
It also ranks as the world's least densely populated nation. On the vast steppes (see photo) that stretch across northern Mongolia, miles often separate individual gers, which are moved by their nomadic inhabitants up to four times a year according to the seasons.