China's Yangtse River Basin Could Lead to Regional Climate Change

Jeffery Seay, FSU Media Relations Office, (850) 644-4030

By Stephanie Kenitzer, (425) 432-2192, [email protected]

April 3, 2001

MAJOR DEVELOPMENTS ALONG CHINA'S YANGTSE RIVER BASIN COULD LEAD TO REGIONAL CLIMATE CHANGE

TALLAHASSEE, Fla.-Major development and construction planned for China's Yangtze and Yellow Rivers, especially the Three Gorges Dam, could dramatically alter the salt content of the Sea of Japan and thereby change the climate in regions near these ocean waters, according to a paper appearing in the April 2001 issue of the Bulletin of the American Meteorological Society.

In the paper "China's Development Could Lead to Bottom Water Formation in the Japan/East Sea," Florida State University oceanography Professor Doron Nof says that rain and fresh water carried into the oceans by rivers float on top of the salty oceanic water, providing a shield which effectively insulates the ocean from the atmosphere above. When the shield is broken, the lack of an insulating layer allows heat from the surface of the ocean to move into the atmosphere above. Without the protective shield, the water cooled by the atmosphere sinks all the way to the bottom of the ocean cooling the deep ocean, which is normally insulated from the atmosphere.

The construction of the Three Gorges Dam threatens to break the fresh water shield by obstructing the flow of river water into the ocean, thereby altering the salt distribution in the Sea of Japan or Japan/East Sea.

"The construction of the Three Gorges Dam on the Yangtze River - the largest dam to be constructed on earth - will divert some of the fresh Yangtze River water, which normally finds its way to the Japan/East Sea, for agricultural use," Nof said. "The lack of fresh and rain water in the Sea of Japan could break the protective barrier these waters normally provide. The breakage will most likely cause warming of the atmosphere over Japan."

At present, the insulating shield of ocean water is broken only in a very few locations including the Labrador Sea situated between Greenland and Canada, the Norwegian Seas, and the Weddel Sea near Antarctica, which constitute less than 1% of the entire area of the world's oceans. In these regions, the atmosphere is warmer than it would have been in the presence of a shield, according to Nof.

Presently, the shield in the semi-enclosed Japan/East Sea is not broken, according to Nof. However, the construction of the Three Gorges Dam on the Yangtze River threatens to break it within a few years after construction is completed in 2010. The resulting warming is in addition to the much-discussed greenhouse effect and Japan may face not only global warming but also regional warming, added Nof.

Nof used a simple mathematical model that takes into account the existing situation, the salinity budget in the Japan/East Sea, the mass budget and the heat budget, as well as the dynamical properties of the Japan/East Sea to derive his conclusions.

Founded in 1919, the AMS is the nation's leading professional society for scientists in the atmospheric and related sciences. The Society publishes well-respected scientific journals, sponsors scientific conferences, and supports public education programs across the country. Additional information is available on the Internet at http://www.ametsoc.org/ams

The research-oriented FSU department of oceanography offers both doctor of philosophy and master of science degrees. The faculty, who guide students' research while conducting their own, offer specialized graduate courses in physical, chemical and biological oceanography and more general undergraduate courses in oceanography.

###

Note: Nof's paper is available online at http://www.ametsoc.org/ams.