Ironically, climate change could render parts of the water scheme superfluous. Chinese and U.S. models predict that northern China will become increasingly wet as average temperatures rise. That shift may begin as early as next decade, Ye says. He and others are pressing the government to reconsider plans to forge ahead with the western route, which is not a fait accompli. But “no one can stop” the eastern and central routes, says Ye. The vast experiment is well under way—and both China and the world are awaiting the consequences.