Himalayas' melting glaciers will open floodgates to catastrophe
 

by Richard Lloyd Parry, South-East Asia Editor

DELUGE, drought, disease: if the experts are right, then the misfortune facing Asia will be like a biblical catastrophe.

It will begin with overflowing rivers, which will wash away homes and fields in China, India and South-East Asia. After a few decades will come drought, as the same rivers dwindle to a trickle. And then will come the second deluge - immense walls of water, like mountain tsunamis, which will break through thin walls of frozen earth, washing away bridges, dams and Himalayan communities.

Countless people will drown or die from the inevitable epidemics and food shortages. Many more will lose their livelihoods and be condemned to poverty in some of the most densely populated areas of the world. And, most alarming of all, it may be too late to do anything about it.

Those are the potential consequences of one of Asia's most serious environmental problems - the melting of the Himalayan glaciers, the vast moving mountains of ice that grind imperceptibly along the valleys of the Tibetan Plateau.

According to an increasing number of environmentalists and climate scientists who have studied the glaciers, there is no doubt that they are melting as a result of global warming, with incalculable consequences for countries as far apart as Pakistan and Cambodia.

In China alone, more than 700 people died and almost three million were displaced last month when rivers in the south and east of the country burst their banks. Climate scientists say that it is difficult to make a clear connection between the melting of the glaciers and these recent floods, which were also the result of heavy rain. But rising temperatures in the Himalayas are only going to make such disasters bigger and more frequent.

Hilary Cox, of the World Wide Fund for Nature, said in Beijing: "Many of China's rivers are fed by glaciers on the Tibetan Plateau. Changes on the plateau will have an effect of what's going on in the rivers."

Seventy per cent of the world's fresh water is frozen in glaciers, and the Himalayas possess the highest concentration anywhere apart from the polar ice caps. During the dry seasons, melt water from glaciers flows down the valleys and swells rivers that would otherwise dwindle dangerously low.

The Himalayan glaciers supply 8.6 million cubic metres (304 cu ft) every year to Asian rivers, including the Yangtze and Yellow rivers in China, the Ganga (Ganges) in India, the Indus in Pakistan, the Brahmaputra in Bangladesh, the Salween and Irrawaddy in Burma, and the Mekong, which flows through China, Burma, Thailand, Laos, Cambodia and Vietnam.

But the average temperature in the Himalayas has risen by 1C since the 1970s, and the glaciers are in retreat. The Khumbu Glacier in Nepal, where Sir Edmund Hillary and Tenzing Norgay began their ascent of Everest, has retreated more than three miles since they climbed the mountain in 1953. According to a report published in March by the WWF, a quarter of the world's glaciers could disappear by 2050.

Jennifer Morgan, head of the WWF's global climate change programme, said: "The rapid melting of Himalayan glaciers will first increase the volume of water in rivers, causing widespread flooding. But in a few the water level in rivers will decline, meaning massive economic and environmental problems for people in western China, Nepal and northern India."

The most dramatic danger comes from glacial lake outburst floods. Glacial lakes form when melted ice builds up around a glacier in a valley. Sometimes the lakes are held in by nothing more than a thin dam of rock and frozen earth, which can collapse without warning, releasing vast amounts of water that rush down valleys, carrying rock, trees and other debris.

Nepal and Bhutan are susceptible to such floods, and scientists have identified scores of lakes that could empty themselves over the next ten years.

A 15m-high flood from the Dig Tsho lake in Nepal in 1985 washed away 14 bridges and a hydroelectric power plant and killed dozens of people. In 2003, a glacial lake outburst flood from the Kawar lake killed five people.

(Timesonline)