China's development could lead to bottom water formation in the Japan/East Sea

Abstract

Using hydrographic data and box models, it is shown that the presently discussed diversion of rivers such as the Yellow or the Yangtze for agricultural use is likely to cause the renewal of Bottom Water formation in the Japan/East Sea. Such formation was common (near the Siberian coast) in the 1930s, 1940s, and 1950s, but subsided since that time due to a warming trend (accompanied by a decreased salinity due to the melting of ice). Since a diversion of freshwater is analogous to evaporation, a (diversion induced) increase of salinity is expected and the increase is large enough to allow Bottom Water formation even at the present-day cooling rates. Even a modest diversion of "merely" 3000 m3 s-1 (which is 10% of the total freshwater flux) will probably cause Bottom Water formation at a rate of roughly 750 000 m3 s-1. This is the first study that predicts anthropogenic reversal of an existing vertical structure in a semienclosed sea.