National Aeronautics and Space Administration

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Construction of Three Gorges Dam over Chinas
Yangtze River May Affect Regional Climate
National Aeronautics and Space Administration Eart
h Science Enterprise
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Construction of Three Gorges Dam over Chinas
Yangtze River May Affect Regional Climate
National Aeronautics and Space Administration Eart
h Science Enterprise
A recent climate modeling study predicts that
construction of the planned Three Gorges Dam over
Chinas Yangtze River could cause changes to the
climate of that region. After the completion of
the Dam, some of the Yangtze River water, which
normally flows to the Japan Sea, will be diverted
for agricultural use. When completed, the Yangtze
River Dam will be the largest hydroelectric dam
in the world, towering about 600 feet high, and
holding a water reservoir of more than 370 miles
long. Construction is expected to be completed
around 2010. Usually, the fresh water carried
into the oceans by rivers float on top of the
salty ocean water, providing a shield which
effectively insulates the ocean from the
atmosphere above. By placing the dam on the
Yangtze River, some of the fresh water is
prevented from flowing into the Japan Sea,
thereby changing its salt content. This is
effectively equivalent to breaking of the
protective shield over the water. 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. The water cooled by the
atmosphere sinks all the way to the bottom of the
ocean to depths greater than 2000 meters. This
breakage (expected to occur within a few years
after construction) could most likely cause
warming of the atmosphere over Japan, according
to a new modeling study (partially funded by
NASAs Earth Science Enterprise) by Dr. Doron Nof
of the Florida State University, which appeared
in the April 2001 issue of the Bulletin of the
American Meteorological Society. The forecasted
warming is in addition to the much-discussed
global warming expected due to CO2 production and
other greenhouse gases. Thus, Japan could likely
suffer from both regional and global warming.
The cover shows the image of Yangtze river
acquired by Japans ASTER instrument aboard
NASAs Terra spacecraft. In this false color
image, red represents vegetated land surface and
the light blue is the Yangtze river. Green shows
exposed land surfaces. The yellow box shows the
construction site of the Three Gorges Dam.
Understanding how human-induced and natural
changes influence global and regional climate
change and the impacts on our civilization is
part of a long-term research effort supported by
NASAs Earth Science Enterprise.
Yangtze River in China.
The Japan Sea and its neighboring bodies of
water. Adopted from the article by D. Nof,
Chinas Development Could Lead to Bottom Water
Formation in the Japan/East Sea (Bulletin of the
American Meteorological Society, April 2001.
July 2001