Too big to flood? Megacities face a future of major storm risks

Bruce Stutz in the Guardian Environment Network (via Yale Environment 360): By the middle of the century, the scores of billions it cost to compensate the greater New York City area for being unprepared for superstorm Sandy may seem like a bargain. Without major adaptation measures to increase the level of storm protection beyond a 1-in-100-year event, the value of the city's buildings, transportation, and utilities utility infrastructures currently at risk from storm surges and flooding — an estimated $320 billion — will be worth $2 trillion by 2070, according to continuing studies by the Organization for Economic Cooperation and Development (OECD).

...Some of those cities with the most at-risk assets now — Tokyo, New Orleans, Amsterdam, Rotterdam, and Nagoya — will, over the next 50 years, be surpassed by Calcutta, Shanghai, Mumbai, Tianjin, Bangkok, Ningbo, and Ho Chi Minh City, booming Asian coastal metropolitan areas where trillions of dollars in economic assets will be vulnerable. So will many millions of these cities' residents, most of them poor and living in low-lying areas.

Just as banks grew "too big to fail," over the next half-century these coastal megacities may grow "too big to flood." But flood they will unless they dramatically revise their growth strategies and undertake major infrastructure projects designed to protect them from the dual threat of rising sea levels and intensifying storms, experts say.

Based on the conservative assumption that sea levels will rise by only 18 inches by 2070, the OECD finds that total assets vulnerable to flooding and storm surges of just 10 of these cities could account for some 9 percent of the world's GDP. But many climate scientists and coastal experts note that sea level rise forecasts by groups such as the Intergovernmental Panel on Climate Change did not factor in the melting of the Greenland and Antarctic ice sheets. When they are taken into account, these experts say that global sea levels could well rise 3 to 6 feet this century, leaving scores of cities and massive amounts of economic infrastructure dangerously exposed....

Employees from MTA New York City Transit worked to restore the South Ferry subway station after it was flooded by seawater during Hurricane Sandy. Photo: Metropolitan Transportation Authority / Patrick Cashin. Wikimedia Commons via Flickr, under the Creative Commons Attribution 2.0 Generic license