The "roof of the world" is getting warmer, and people on the Qinghai-Tibet plateau region clearly feel the changes.

"The past few winters have been quite unusual," says Hou Fusheng, 83. "It's getting warmer every year."

Hou has lived all his life in Xining, capital of northwest China's Qinghai Province. In his younger days, he remembers, winters were bitter and even the thickest heavy coat did little to keep out the chill.

"Nowadays young urban women wear elegant overcoats without looking padded up. Even people my age don't need heavy coats most of the time," says Hou.

The past winter was the 15th warmer-than-average winter in Qinghai since 1986, and the average temperature from December to February was minus 7.4 degrees Celsius, almost 2 degrees Celsius higher than the average of the past decade, according to the provincial climate center.

Meanwhile, the average temperature in the Tibet Autonomous Region was 5.9 degrees Celsius last year, 1.5 degrees higher than normal and the highest in almost four decades, according to the regional climate center.

ASIA'S WATER TOWER IN DANGER

Ngawang Lhundrup, a lama at a centennial monastery at the foot of Qomolangma, is getting used to the increasing number of mountaineers, hikers, scientists and environmentalists who flock to the plateau.

But he loathes those who drive to the Qomolangma Base Camp. He believes the exhaust fumes will accelerate glacial melting on the plateau.

"Nobody has ever told him about the greenhouse gas emissions and global warming. He simply figured it out by himself," says Zhong Yu, who has participated in four Greenpeace expeditions to the Tibet plateau in a decade.

"He complains the winters are getting warmer, and the glaciers are shrinking," says Zhong.

While urbanites talk about disaster films like 2012 and worry about the future of humanity, Ngawang Lhundrup cares only for the future of Qomolangma, she said.

Zhong's expeditions took her to Qomolangma and the origin of China's three major rivers -- the Yangtze, the Yellow and the Lancang (which becomes the Mekong outside China) -- an area known as the Three-River headwaters and a "water tower" for Asia.

During an expedition to Qomolangma last year, Zhong says, a sand dune she saw in 1999 had grown from 2 to at least 10 meters high.

"The annual precipitation has decreased by 13.99 millimeters every 10 years," says Liu Jiyuan, research fellow of Institute of Geographic Sciences and Natural Resources Research of the Chinese Academy of Sciences.

Except for its westernmost section, the headwaters area has been generally getting warmer and drier in recent decades, one of the main causes of the ecological deterioration.

MELTING GLACIERS

Tibetan tour guide Lhashi says half of Mt. Galadando was covered by snow when she visited the mountain, in Nagqu Prefecture of Tibet Autonomous Region, in 1997. "This year, little snow was visible on its peak."

The average temperature at Mt. Galadando, the tallest mountain in the Tanggula Mountain Range of the Tibet plateau and the source of the Yangtze River, China's longest waterway, has risen by almost 1 degree Celsius.

The Himalayas have the world's third largest glacier reserve of 1 trillion cubic meters in an area of 11,000 square kilometers.

Yet 82 percent of glacial surfaces on the plateau have retreated, and the glacier area has decreased by 4.5 percent in the past 20 years, according to China Meteorological Administration.

"Along my way to the mountain tops, I've seen many landslides caused by melting glaciers," says Zhong Yu.

According to a report released by Intergovernmental Panel on Climate Change, a United Nations body studying global warming, 80 percent of the glaciers on the Himalayas could vanish within three decades at present warming rates.

ECO PRESERVATION

Human activities do not always damage nature, says Dai Sheng, a senior researcher at Qinghai provincial meteorological administration.

As an example, he cites artificial precipitation that produced 8.8 billion cubic meters of rainfall in the Three-River headwaters area last year alone.

"Artificial rain and enhanced environmental protection efforts will hopefully save the water tower," Dai says.

China launched an ambitious project in 2005 to preserve the ecological systems of the Three-River headwaters by relocating millions of herders from the area and curbing excessive grazing and other exploitation.

Meanwhile, Tibet also announced a 450-million-yuan (66 million U.S. dollars) environment protection project last year, following the central government's approval of a 20-billion-yuan investment in building an ecological belt on the Qinghai-Tibet Plateau.

The money will be spent on protecting pastureland from desertification, planting trees, safeguarding drinking water sources, and promoting clean energy on the plateau.

"But sadly, the plateau will continue to get warmer, unless global warming is curbed," says Dai.