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THE MELTING OF THE WORLD'S ICE.

In the past century, much of the world's polar and mountain ice has melted, and in the past few decades the melting has accelerated. Ice is essential to global climatic and ecological stability, and as the ice turns to water, several major kinds of effects have been seen. First, as land-based ice on Greenland and Antarctic melts and drains into the oceans, sea-levels are rising--although the larger cause of sea-level rise is the expansion of water as it warms. Higher water combined with storm surges will likely inundate many coastal cities and ecosystems. Second, as glaciers and snow in the mountains melt and increase runoff, human settlements in major river valleys downstream from the mountains (such as the Gauges and Jiang [Pearl] river basins below the Himalayas) will become increasingly vulnerable to floods. Within decades, hundreds of millions of people could be displaced by floods or altered coastlines. As a result, coastal and riverine ecosystems all over the world are likely to be disrupted. Climate m odels also suggest that melting could cause major alterations in ocean currents, including a possible reversal of the warm Gulf Stream that now provides Europe with its mild climate. Ironically, some scientists believe a warming of the world's climate overall could bring a new ice age to Europe.
VULNERABLE RIVER BASINS
Many of the world's cities are in watersheds down-stream from mountains
where accelerated melting of glaciers or snow could contribute to
severe flooding, especially if the basins have been heavily deforested.
All of these basins have lost more than 50 percent of their original
forest cover.
 Mountains Number of Large Cities
Basin Upstream (over 100,000) in Basin
Ganges Himalayas 85
Rhine Alps 68
Danube Alps 62
Yangtze Himalayas 56
Parana Andes 54
Indus Hindu Kush 34
Huang Tibetan Plateau 27
Jiang Himalayas 18
Magdalena Andes 17
Missouri/Miss. Rockies 15
Brahmaputra Himalayas 14
Po Alps 12
Rhone Alps 12
Source: Janet Abramovitz, et al., Watersheds of the World (Washington,
DC: World Resources Institute and Worldwatch Institute, 1998].


Alaska's Columbia Glacier has retreated 13 kilometers since 1982 and all 14 other glaciers in the area are retreating.

100 of the 150 glaciers of Montana's Glacier National Park have completely melted since 1850 and the rest are projected to be gone in 30 years.

Upsala Glacier in Argentina has retreated 60 meters a year For the past 60 years, and the rate is accelerating.

South Patagonian Ice Field in Argentina and Chile has decreased by more than 500 square kilometers in the past 50 years.

Duosuogang Peak glaciers in the Ulan Ula Mountains of China have shrunk by 60 percent since the early 1970s.

Pindari Glacier in the Indian Himalayas is retreating at an average of 135 meters a year.

Tien Shan Mountain glaciers of Central Asia have last 22 percent of their volume in the last 40 years.

About 2,000 of the glaciers in the eastern Himalayas have disappeared in the post century.

Arctic sea ice has thinned by 40 percent in less than 30 years.

Three glaciers in Irian Jaya have increased rate of retreat from 30 meters a year in the 1920s to more than 45 meters a year.

Tasman Glacier in New Zealand has thinned by about 200 meters on average since the 1970s.
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Title Annotation:effects of polar and mountain ice melting
Publication:World Watch
Article Type:Brief Article
Date:Nov 1, 2000
Words:545
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