Sea level rise caused Hurricane Florence’s storm surge to be much worse, new data analysis by non-profit First Street Foundation has found. And the economic impact is expected to be in the billions.

More than 51,000 homes were hit by the storm surge that came with Hurricane Florence, which hit the Carolinas as a Category 1 storm. But as researchers found, 1 in 5 of these homes — which saw water cover more than a quarter of their property — were damaged due to sea level rise.

Comparing today’s sea level to 1970 data, researchers concluded that some 11,000 homes hit by Florence would not have been impacted had sea levels remained stable. But since 1970, seas have risen by about 6 inches — meaning that the damage experienced by 20 percent of homes can be linked to this increase.

And with climate change, according to the Army Corps of Engineers’ projection, if seas rise by a further 15 inches (more than a foot) by 2050, the same storm surge as experienced with Florence would have double the impact, putting an estimated 102,000 homes at risk.

Climate change is making hurricanes stronger and wetter. Storm surges are made worse with higher sea levels because it means the surge is beginning from a higher starting point — there is more water available for the hurricane to push onto the land. Plus, with all this water comes less friction which would otherwise slow down the surge. Instead, more water rushes farther inland.


More damaged homes also means higher costs. New figures released on Tuesday reveal just how expensive Florence will be. According to risk modeling firm RMS, the storm is expected to rack up a bill of anywhere between $800 million to $1.2 billion in losses for the National Flood Insurance Program.

And the losses linked specifically to storm surge and inland flood damage are expected to reach between $700 million and $1.2 billion. In total, Florence will see between $2.8 and $5 billion in insured losses.

However, as RMS analysis shows, an estimated 70 percent of homes hit by Florence were uninsured.

One recent analysis by McClatchy found that the number of homes in North and South Carolina with flood insurance dropped significantly only a couple miles inland from the Atlantic coast. Part of this is likely due to the fact that many FEMA flood zone maps are out of date and so people may not know they’re living in a risky area.


And it’s not just storm surges fueled by sea level rise that are making homes more vulnerable — it’s also a matter of where homes are being built. As the analysis by First Street Foundation notes, changes in housing development are also a “significant” factor in why so many homes were hit by Florence.

Over the past several decades, wetlands and farmland in the Carolinas have been developed for urban use. Researchers compared housing development patterns in 1970 and today and found that as a result, more than half of the homes hit by Florence can be linked to increased development.

According to one estimate by The News & Observer, roughly 610,000 homes were built within 50 miles of North Carolina’s coastline over the past 30 years. Add to this the fact that FEMA disaster aid often results in homes being re-built or repaired in the exact same vulnerable areas, and it’s no surprise that the number of people at risk isn’t declining.

“With sea levels and coastal development on the rise, the impacts of hurricane storm surges will only get worse,” Matthew Eby, executive director of First Street Foundation, said in a statement. “The time to rethink America’s sea level rise and adaptation strategy is now.”