...According to our analysis, sea level rise due to global warming has already doubled the annual risk of extreme coastal flooding across widespread areas of the nation.
Global average sea level has risen about 8 inches since 1880. This means that warming is already contributing to the damage caused by any coastal flood today. Diverse studies bracket additional global rise likely this century between 1 and 7 feet.
In some areas, especially for Louisiana, Texas, and mid-Atlantic states, sinking land will add to the total effective rise and compound problems.
Taking such local factors into account, we made mid-range projections for sites around the lower 48 of 1-to-8 total inches increase by 2030, and 4-to-19 inches by 2050, depending upon location.
All along the Pacific, from Seattle to the Oregon coast to San Francisco to Los Angeles, the component of past and projected sea level rise from global warming more than triples the odds of “century” floods by 2030 in our analysis, as you can see from the display.
The same is true inside the Chesapeake and Delaware Bays, and many sites to the north.
These increases are likely to cause a great deal of damage. At more than half the 55 sites where we studied flood risk, storm surges on top of sea level rise have better than even chances to reach more than 4 feet above the high tide line by 2030.
Yet nearly 5 million U.S. residents live in 2.6 million homes on land below this level. Multiplied by the national average sales price of existing homes in 2010, this stock comes to more than $500 billion of residential real estate, in a rough estimate.
An enormous amount of infrastructure also lies in the same zone, from airports to wastewater treatment plants, and including nearly 300 energy facilities — as you can see in the second display, along with values for some individual states, and population figures.
The facilities shown are mainly natural gas, oil and gas, and electric facilities. More than half are in Louisiana, the vast majority there unprotected by levees.