The Nature Climate Change study looked at both present and projected future flood losses in the 136 largest coastal cities in the world, looking at their financial risks both in absolute terms—taking into account protections like sea walls and dikes—and as a percentage of the city’s GDP. The cities ranked as most at risk today range from Guangzhou in southern China to Mumbai in India to, yes, New York City. What those cities tend to have in common is high wealth and population levels and relatively little flooding protection. (By contrast, Dutch cities like Amsterdam or Rotterdam—which are extremely flood-prone geographically—aren’t found on the list because the Netherlands government has invested heavily in coastal protection.) Three American cities—Miami, New York and New Orleans—are responsible for 31% of the total losses across the 136 cities surveyed in 2005. When it comes to losses as a percentage of total city GDP—which gives the very richest cities like New York an advantage—Guangzhou, New Orleans and Guayaquil in Ecuador are most at risk.
What is a thousand-mile-wide storm pushing eleven feet of water toward our country’s biggest population center saying just days before the election? It is this: we are all from New Orleans now. Climate change—through the measurable rise of sea levels and a documented increase in the intensity of Atlantic storms—has made 100 million Americans virtually as vulnerable to catastrophe as the victims of Hurricane Katrina were seven years ago.
Arriving atop fantastically warm water and aided by a full foot of sea-level rise during the last century, Hurricane Sandy is just the latest example of climate change’s impact on human society. Unless we rapidly phase out our use of fossil fuels, most Americans within shouting distance of an ocean will—in coming years—live behind the sort of massive levees and floodgates that mark Louisiana today.