The report, Encroaching Tides, analyzes 52 coastal communities along America’s coast, from Freeport, Texas all the way up to Portland, Maine. Most of the communities surveyed have experienced more floods over the last 40 years, particularly during the extreme tides that happen twice each month (during the new and full moons). Sea level rise is the primary reason behind the increasing frequency and duration of these floods, though each state is affected to a varying extent.
The East Coast has seen the most significant increases in sea level. Boston’s, for instance, has grown 10 inches since 1921. New York City has measured almost a foot and a half since 1856.
By 2030, UCS estimates that more than half of its surveyed communities will experience 24 tidal floods per year. Twenty of the communities will see a threefold increase in floods. Based on moderate projections, outliers such as Annapolis, Maryland and Washington, D.C. will experience 150 tidal floods per year.
In the next 30 years, without progressive changes in city infrastructure, all 52 of the communities will see at least a foot of sea level rise, with floods penetrating deeper into cities and remaining longer, destroying property and disrupting daily life. Five mid-Atlantic communities could be inundated 10 percent of the year, the authors write.
The report outlines measures that can be taken to prevent flooding, but it is also frank about some of these cities’ future prospects:
“There is a hard truth about adaptation, however. It has fundamental limits — whether physical, economic, or social — and it can only fend off the impacts of sea level rise to a point. […] As sea level rises higher, even our best protection efforts will not suffice in some areas in the face of rising tides, waves, and storm surges.”
Some communities have already begun preparations. Four counties in south Florida, despite a governor that refuses to make up his mind about man-made climate change, are working together to adapt their cities for the coming flood.