Is Your Hometown on This List of Cities Expected to Flood 200 Days a Year?
Flooded roads, piles of sandbags, and rubber boots will become the norm for more than two dozen East Coast and Gulf communities in the United States, according to a study released Wednesday.
Researchers said massive increases in tidal flooding are expected over the next three decades. That means Miami; Atlantic City, N.J.; Annapolis, Md.; and Chesapeake Bay could see more than 200 days of tidal flooding annually by 2045, affecting infrastructure, homes, roads, and more.
The report, released by the Union of Concerned Scientists, was supposed to focus on storm surges and hurricane effects, but after looking at the startling data behind projected tidal flooding levels, the researchers shifted gears.
“We found the tides themselves so compelling, we focused on them,” said Melanie Fitzpatrick, a climate scientist and the study’s lead author. “We’re talking about two-thirds of the communities we looked at seeing a tripling in flooding from high tides over the next 15 years. We didn’t expect to see that such effects could happen so quickly.”
What do coastal towns look like 30 years in the future? More like New York’s Jamaica Bay, where flooding occurs so regularly now that officials send out a calendar alerting residents of high tides and when to avoid parking on streets.
“They have days where rowboats are the mode of transportation down some roads,” Fitzpatrick said. “That’s something that could become the norm elsewhere.”
Fitzpatrick and her colleagues took historical tidal flood data from 52 of the National Oceanic and Atmospheric Administration’s gauge points along the Eastern Seaboard for a baseline and added projected sea level rise over the next 30 years to the data.
“We’re looking at sea level rise in a 30-year span—the typical lifetime of a mortgage—of around 11 inches,” she said. “That leaves about half the towns we looked at facing more than 100 floods a year.”
The scientists relied on projections from the 2014 National Climate Assessment, which calculates sea level rise based on land ice from Greenland and Antarctica melting into the oceans.
UCS researchers then selected sea level rise projections that accounted for “intermediate high” levels of sea level rise—basically the middle ground of what scientists think could occur.
Researchers looked at the baseline of tidal flooding, often called “nuisance” floods. While usually labeled “minor,” tidal flooding can escalate when accompanied by heavy rains or offshore storm surges.
“I look at it like a basketball game,” Fitzpatrick said. “A slam dunk is a flood. Right now, you have a few slam dunks a game, but now imagine the floor is raised 11 inches. You’d have a lot more slam dunks.”
If the tidal flood baseline moves up nearly 11 inches, the damage from a storm surge or heavy rains would be exponentially greater.
That’s led communities already dealing with flooding to look at infrastructure upgrades to combat flooding. Miami Beach is considering $400 million in improvements to storm-water sewer systems to prevent seawater from backing up into pipes.
Norfolk, Va.—a city built on sinking ground—faces a $1 billion bill for infrastructure fixes and plans to return some coastal parks to wetlands. The U.S. Naval Academy in Annapolis is installing “door dams” to protect building entrances from flooding.