The Hindu Kush Himalaya Assessment touches on the phenomenon of elevation-dependent warming. Though it is well known that temperature changes due to increased levels of greenhouse gases are amplified at higher latitudes, like in the Arctic, there is growing evidence that warming rates are also greater at higher elevations.

“Mountain people are really getting hit hard,” said David Molden, the director general of the International Center for Integrated Mountain Development, the research center near Kathmandu, Nepal’s capital, that led the study. “We have to do something now.”

Around South Asia, the impact of climate change has already intensified. Brutal heat waves are becoming unbearable, making people sicker and poorer, and diminishing the living standards of 800 million people.

Access to water is also a concern. Last spring, shortages were so severe in the Indian city of Shimla, in the Himalayas, that some residents asked tourists to stop visiting so that they would have enough water for themselves.

A government report released last year found that India was experiencing the worst water crisis in its history. About half of India’s population, around 600 million people, faced extreme water scarcities, the report found, with 200,000 people dying each year from inadequate access to safe water.

By 2030, the country’s demand for water is likely to be twice the available supply.

In neighboring Nepal, rising temperatures have already uprooted people. Snow cover is shrinking in mountain villages, and rain patterns are less predictable. Fertile land once used for growing vegetables has become barren.

“Water sources have dried up,” said Pasang Tshering Gurung, a farmer from the village of Samjong, which is about 13,000 feet above sea level.