The world's highest ice fields are melting so quickly that they are on course to disappear within 100 years, driving up sea levels, increasing floods and turning verdant mountain slopes into deserts, Chinese scientists warned on Thursday.
After the most detailed study ever undertaken of China's glaciers, which are said to account for 15 percent of the planet's ice, researchers from the Academy of Science said that urgent measures were needed to prepare for the impact of climate change at high altitude.
Their study, the Glacier Inventory, was approved for publication last week after a quarter of a century of exploration in China and Tibet. It will heighten alarm at global warming.
Until now, most research on the subject has looked at the melting of the polar ice-caps. Evidence from the inventory suggests that the impact is as bad, if not worse, on the world's highest mountain ranges -- many of which are in China.
In the past 24 years, the scientists have measured a 5.5 percent shrinkage by volume in China's 46,298 glaciers, a loss equivalent to more than 3,000km2 of ice; there has been a noticeable acceleration in recent years.
Among the most marked changes has been the 500m retreat of the glacier at the source of the Yangtze on the Tibet-Qinghai plateau.
The huge volumes of water from the glacier's melted ice, estimated at 587 billion cubic meters since the 1950s, are thought to have been a factor in flooding that has devastated many downstream areas in recent years.
Shrinkages were observed at almost every ice-field in the Karakorum range, including the Purugangri glaciers, which are said to be the world's third largest body of ice after the Arctic and Antarctica. According to Yao Tandong, who led the 50 scientists in the project, the decline of the Himalayan glaciers would be a disaster for the ecosystem of China and neighboring states.
If the climate continued to change at the current pace, he predicted that two-thirds of China's glaciers would disappear by the end of the 2050s, and almost all would have melted by 2100.
"Within 20 to 30 years, we will see the collapse of many of the smaller glaciers," Yao said. "Within 60 years, we can predict a very significant reduction in the volume of high-altitude ice fields."
In the short term, he said, the water from the ice would fill reservoirs and lead to more flooding -- as was already the case in Nepal and downstream areas of China.
In the future, he predicted, the end of the glaciers would deprive the mountain ecology of its main life source and hasten the desertification that threatens western China, particularly in Gansu and Xinjiang provinces.
Once the mountain ice was gone, rivers would start to dry up and ocean levels would rise, threatening coastal cities.
The inventory confirms earlier studies of Everest, which showed the world's tallest peak more than 1.3m shorter than in 1953, when it was first scaled by Edmund Hillary and Tenzing Norgay.