Edmund Hillary and Sherpa Tenzing Norgay today attempted to climb Everest, they would save 5 kilometers of ascent on the treacherous Khumbu glacier, which fell especially since their feat of 1953. Nicknamed the "Water Tower of Asia", the massive Himalayan glaciers melt seen, as a result of warming. The World Wide Fund for Nature (WWF), which brought together three studies involving India, Nepal and China, in alarm, in a report released in March 15.
The Himalayan glaciers, which cover 33 000 km2, feed seven major rivers of Asia: the Ganges, Indus, Brahmaputra, Salween, Mekong, the Yangtze (Blue River) and Huang He (River Yellow). The 8,6 million cubic meters flowing annual summits provide fresh water to millions of people. The accelerated melting of glaciers could mean for them more flooding in first few decades before a shortage ensues.
Hydroelectric power, agriculture, certain industries depend directly on the input of freshwater: the economic impact will be substantial, worries the WWF, calling on the topic of regional cooperation.
Projections show a century for India a contrasting situation in time and space: in the Upper Indus, the flow will increase 14 90% to% in the first decades, before decreasing in the same proportion of by 2100. In the Ganges, the upstream part will experience the same type of variation, while in the most downstream area, where the water supply is primarily due to monsoon rains, the impact of deglaciation will be practically negligible.
These differences are that glacial meltwater is only 5% of the flow of Indian rivers, but it contributes greatly to their regulation, particularly during the dry season. Thus, to the Ganges, loss of glacial meltwater would reduce the rate of two-thirds from July to September, which would mean a shortage of water for millions of people and 500 37% of Indian affect irrigated crops, provides report.
WWF also highlights the increased risk of sudden emptying of glacial lakes. Overfed because of melting ice, they are in fact more likely to break the natural dams that contain them. And cause catastrophic floods below, sometimes tens of kilometers. 229 on glaciers identified in the Arun basin, Tibet, 24 "potentially dangerous," the report notes.
In China, the basins of the Yangtze and Yellow rivers experiencing a decrease in wetland and lake surfaces. Desertification progresses. The Yellow River could reach the sea during 226 1997 days, a record year.
"All observations are consistent," says Yves Arnaud (IRD Glaciology Laboratory in Grenoble). Topographic and satellite data he analyzed himself show a decrease in the thickness ranging from Himalayan glaciers to 0,2 1 m meter fifty years ...