With 73 days left in the Atlantic hurricane season, communities across the Gulf Coast and Eastern Seaboard face risk of more storms like Beryl or Debby — storms that pose expanded danger thanks to a flurry of new home construction in flood-prone areas since 2001.
Between 2001 and 2019, about 850,000 new homes have been built in floodplains, a new study in the journal Earth’s Future has found.
That makes up a footprint of 2 million acres of at-risk property — about the size of Delaware — of which nearly half were in Florida.
In a sense, this is good news, the report authors argued: Only about a quarter of American communities have expanded into floodplains “more than would be expected, given the hazards they face.”
That’s because about three-quarters of local governments in some way limit new development in floodplains, and nearly 90 percent limit new housing construction.
But these adaptations lead to their own reverse consequences. A 2023 study in the Journal of the American Planning Association found that floodplain development happened at higher rates in communities that participate in Federal Emergency Management Agency (FEMA) programs aimed at reducing flood risk — a reverse outcome caused by FEMA cutting flood insurance costs for participating communities.
The Planning Association study found that more than 10 new houses in at-risk areas had been built for every one removed by buyouts, which seek to remove homes most endangered by worsening storms and rising seas.
The study comes amid a wave of new research into how America’s social and physical infrastructure is missing in action in confronting climate change.
Another study last week in the Journal of Geophysical Research found that dams placed in estuaries — structures placed to control the impacts of rising seas, salt and ultimately storm surge — often make flooding worse.
The reason why — because the bottle-like shape of estuaries, as these zones where rivers enter into the sea are called, can focus the power of storm surges and make them most dangerous inland, where they aren’t expected.
In the Charleston area, for example, the highest storm surges come 50 miles inland.
Global dam construction is also starving coastal estuaries and sandbars of the silt that would allow them to block hurricanes, a 2022 study in Science found.
These findings come in the wake of new and extreme risks from climate change.
Coastal risks are increasing. Last September, seismologists picked up a strange signal — which turned out to be a “mega-tsunami” caused in an isolated Greenland inlet, according to research published this month in Science.
With the Arctic heating four times as fast as the rest of the world, a glacier at the base of the mountain melted, undermining a pile of rock and ice the approximate volume of 10,000 Olympic-sized pools.
When it crashed into the sea, it created a tidal wave 650 feet tall that rocketed back and forth across the narrow fjord for more than a week.
A 2017 landslide elsewhere in Greenland triggered a tsunami that killed four people in what amounted to a surprise attack by the melting Arctic.
“The disaster was entirely unexpected since no previous records of large rock slope failures were known in the region,” scientists wrote in a 2020 study.
