Climate change

Glaciers shrinking fast, warns scientist

PUBLISHED : Wednesday, 26 December, 2007, 12:00am
UPDATED : Wednesday, 26 December, 2007, 12:00am


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Chinese glaciers are melting at almost twice the rate previously estimated, the latest national glacial survey has found.

In about half a century, more than 7.4 per cent of the 60,000 square kilometres of glaciers from southern Yunnan to northern Xinjiang that supply water to a third of the mainland's population have disappeared.

The annual shrinkage was roughly equivalent to the size of Hong Kong Island, Liu Shiyin, the survey's chief scientist warned yesterday.

The rate of decline is double the estimate released in the last national survey, in 2000.

'The situation is gloomy. The meltdown is accelerating and the impact will be severe if not devastating,' Professor Liu said.

Glaciers are critical in China because their seasonal melt feeds most rivers in western China.

'What we are sure of is that hundreds of inland rivers will be turned into deserts, grassland into Gobi and cities to dust ... once the ice is gone. But we are uncertain how soon and where the first, severest hit will be - whether it is decades away. It is difficult to predict,' Professor Liu said.

But history may provide some important clues.

Comparisons of a glacier's present state with historical records allow researchers to generate a model for making predictions.

By collecting data from thousands of glaciers, scientists could establish a model for the entire west, Professor Liu said.

He said the work was extremely labour intensive and the first survey, which started with manual calculation and analysis, took more than two decades.

But thanks to China's rapidly improving satellite remote sensing technology, more powerful computers and increasing funding and staff, mainland researchers could now obtain more precise and dependable results in one day than they would have been able to produce in months, if not years in the past.

The five-year study, which began this year, found the worst glacial shrinkage on Qilian Mountain where the Yanglonghe No1 glacier has retreated 260 metres in about two decades.

The thickness of the mountain's glaciers has also declined, with many shedding 20 to 50 metres.

But the glaciers in China's west have not shrunk uniformly. In central Tibet , glacial formations have undergone comparatively mild changes in the past few decades.

To understand better the nature of the glaciers, scientists will set up China's first permanent glacier observation station on Qilian Mountain, home to one of the longest ice ranges in China.

Professor Liu said Beijing had agreed to fund the project.

With the station and world-class monitoring equipment, scientists will be able to closely study the birth, life or death of a glacier.

'It is important because - ironically - we still know little about the process. We still know little about the ice-heat-water cycle that shapes a glacier. We still can tell little about their daily changes because they are as tiny as a hair's growth,' Professor Liu said.

'But the fate of millions may depend on such knowledge.'