The problem with water, though, is that the shortfalls don't show up until the very end. You can go on pumping unsustainably until the day you run out. Then all you have is the recharge flow, which comes from precipitation. This is not decades away, this is years away. We're already seeing huge shortages in China, where the Yellow River runs dry for part of each year. The Yellow River is the cradle of Chinese civilization. It first failed to reach the sea in 1972, and since 1985 it's run dry for part of each year. For 1997 it was dry for 226 days.