November 17, 2010
One of the scarier predictions about global warming is the suggestion that melting glaciers and ice caps could cause sea levels to rise as much as 15 to 20 feet over the next century. Set aside the fact that the best research we have - from the United Nations climate panel - says that global sea levels are not likely to rise more than about 20 inches by 2100. Rather, let's imagine that over the next 80 or 90 years, a giant port city - say, Tokyo - found itself engulfed by a sea-level rise of about 15 feet. Millions of inhabitants would be imperiled, along with trillions of dollars' worth of infrastructure. Without a vast global effort, could we cope with such a terrifying catastrophe?
Well, we already have. In fact, we're doing it right now.
Since 1930, excessive groundwater withdrawal has caused Tokyo to subside by as much as 15 feet. Similar subsidence has occurred over the past century in numerous cities, including Tianjin, Shanghai, Osaka, Bangkok and Jakarta. And in each case, the city has managed to protect itself from such large relative sea-level rises without much difficulty.