The Chinese South-to-North Water Diversion Project is a landscape-altering megaproject to bring water from the Yangtze River, the fourth largest river in the world, to the aid of the country’s arid north. The project has long been surrounded by debates over its social, economic, and environmental consequences. In the News of the Week story “Pollution slows China’s canal project” (28 September 2007, p. 1846), H. Xin reported that the first phase of the eastern route of the massive project has been delayed at least 3 years because of the low quality of the water to be diverted northward. The article then quoted Qian Ye from the U.S. National Center for Atmospheric Research in Boulder, Colorado [the same source as quoted by the earlier News Focus article “Going against the flow” (R. Stone and H. Jia, 25 August 2006, p. 1034)], who suggested that global warming “could make China’s north wetter and allow authorities to scale back the controversial project.” However, the perception of a wetter northern China is contrary to the common wisdom about the impact of global warming in this region. Meteorological records show that northern China has experienced a coupled warming and drying trend over the past several decades (1, 2). Both the Intergovernmental Panel on Climate Change (3) and the National Climate Change Program of China (4) foresee a drier condition in the coming decades for this part of China.
There is no shortage of reasons to reconsider the Chinese water canal project. But in the context of global warming, the quantity—and quality—of the water that the Yangtze could offer in the future is worthy of careful consideration. The river is fed by the glaciers and permafrost on the Tibetan plateau. The glacier area in northwestern China shrunk by 21% and the permafrost in the Plateau thinned dramatically in the past 50 years due to global warming (4). If its source continues to shrink, the Yangtze River might run out of water as well.
Shaopeng Huang
Department of Geological Sciences, University of Michigan, Ann Arbor, MI 48109–1005, USA and Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, China.
References
1. X. Zou, P. Zhai, Q. Zhang, Geophys. Res. Lett. 32, L04707, 10.1029/2004GL021853 (2005).
2. Z. Ma, X. Ren, Ad. Clim. Change Res. 3, 195 (2007).
3. R. T. Watson et al., “IPCC Special Report on The Regional Impacts of Climate Change An Assessment of Vulnerability,” (IPCC, 1997); www.grida.no/climate/ipcc/regional/261.htm.
4. China's National Climate Change Program, http://english.gov.cn/2007- 06/04/content_636052.htm.
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