National Aeronautics and Space Administration Earth Science Enterprise

1. Construction of Three Gorges Dam over China’s Yangtze River May Affect Regional Climate National Aeronautics and Space Administration Earth Science Enterprise

2. Construction of Three Gorges Dam over China’s Yangtze River May Affect Regional Climate National Aeronautics and Space Administration Earth Science Enterprise A recent climate modeling study predicts that construction of the planned Three Gorges Dam over China’s 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 NASA’s 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 Japan’s ASTER instrument aboard NASA’s 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 NASA’s Earth Science Enterprise. Yangtze River in China. The Japan Sea and its neighboring bodies of water. Adopted from the article by D. Nof, “China’s Development Could Lead to Bottom Water Formation in the Japan/East Sea” (Bulletin of the American Meteorological Society, April 2001. July 2001