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Big dam project in China may warm Japan.



The link between widespread industrial activity and global warming has long been on the world's list of worries, but now there's concern that a single construction project--the Three Gorges Dam Three Gorges Dam, 607 ft (185 m) high and 7,575 ft (2,309 m) long, on the Chang (Yangtze) River, central Hubei prov., China, 30 mi (48 km) W of Yichang. The largest concrete structure in the world, the dam was constructed from 1994 to 2006.  in China--could cause regional warming hundreds of miles away in Japan.

The 610-foot-high dam, scheduled for completion later this decade, would stretch more than 1.3 miles across the Yangtze River and create a reservoir the length of North America's Lake Superior. Although primarily built to generate hydroelectric power, to extend navigation upstream, and to provide flood control downstream, the project would impound impound v. 1) to collect funds, in addition to installment payments, from a person who owes a debt secured by property, and place them in a special account to pay property taxes and insurance when due.  more than 10 trillion gallons of water that could be used for irrigation irrigation, in agriculture, artificial watering of the land. Although used chiefly in regions with annual rainfall of less than 20 in. (51 cm), it is also used in wetter areas to grow certain crops, e.g., rice. .

If such agricultural use significantly diminishes the Yangtze River's flow,

it could instigate convection in the Japan Sea, argues Doron Nof, an oceanographer at Florida State University Florida State University, at Tallahassee; coeducational; chartered 1851, opened 1857. Present name was adopted in 1947. Special research facilities include those in nuclear science and oceanography.  in Tallahassee. That process could bring relatively warm water to the sea's surface and raise temperatures over Japan. Nor presents his analysis in the April BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY Bulletin of the American Meteorological Society is a publication of the American Meteorological Society. The official organ of the society, devoted to editorials, topical reports to members, articles, professional and membership news, conference announcements, programs and .

China's Yangtze River, the third longest river in the world, currently dumps up to 8 million gallons of fresh water into the Yellow Sea each second. This fresh water, along with flow from the Yellow River, mixes with ocean currents and sweeps northward into the Japan Sea. There, the low-salinity water flows along the surface and forms an insulating blanket that impedes heat transfer to the atmosphere from the warmer, saltier waters trapped below, says Nof.

Even in the coldest part of the winter, when Siberian winds chill the surface water, the Japan Sea's top layer doesn't become dense enough to sink, says Nof. The last bout of large-scale convection in the Japan Sea occurred more than a half-century ago. Since then, warming farther north in the Sea of Okhotsk Noun 1. Sea of Okhotsk - an arm of the Pacific to the east of Asia
Pacific, Pacific Ocean - the largest ocean in the world
 has melted ice there and sent additional fresh water southward.

Nof contends that if China diverts as little as 10 percent of the Yangtze's flow, the Japan Sea's surface layer at times would become salty enough to sink. Warmer water coming to the surface would cause the temperature of the overlying overlying

suffocation of piglets by the sow. The piglets may be weak from illness or malnutrition, the sow may be clumsy or ill, the pen may be inadequate in size or poorly designed so that piglets cannot escape.
 air to rise. Such convection elsewhere in the world raises regional air temperature several degrees Celsius, he adds.

Alberto D. Scotti, an oceanographer at the University of North Carolina at Chapel Hill The University of North Carolina at Chapel Hill is a public, coeducational, research university located in Chapel Hill, North Carolina, United States. Also known as The University of North Carolina, Carolina, North Carolina, or simply UNC , says it's "definitely plausible" that increased salinity in the upper layers of the Japan Sea could restart the convection there, especially during cold winter conditions. Despite the argument's simplicity and elegance, at this point it's only speculation, Scotti says. "Without more detailed analysis, the only way to know [if the argument is valid] is to see what happens when the dam is completed," he notes.
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Author:Perkins, S.
Publication:Science News
Geographic Code:9JAPA
Date:Apr 21, 2001
Words:442
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