Sea level rise will most affect the property lines of Florida's coastal counties, a new report says

WUSF | By Jessica Meszaros

Published September 9, 2022 at 7:06 AM EDT

A new analysis released Thursday highlights how sea level rise will change private property boundaries along coastal areas.

Using the latest climate models and current emissions data, researchers with Climate Central, a nonprofit news organization that analyzes and reports on climate science, have determined that private property owners across the U.S. will lose an area the size of New Jersey by the year 2050.

“By mid-century, more than 648,000 individual tax parcels, totaling as many as 4.4 million acres, are projected to be at least partly below the relevant tidal boundary level," according to the report. "Of those, more than 48,000 properties may be entirely below the relevant boundary level. Florida, Louisiana, and Texas have the largest number of affected parcels.”

Don Bain, an engineer and senior advisor for Climate Central, said Florida has the most properties that will be impacted — more than 140,000 by 2050.

His team generated more than 250 individual county reports to identify any potential movements of public-private property boundaries. He said the losses will result in less property tax revenue.

Click here to find analysis results in your county

“It's very situational dependent upon the county, how much they're dependent upon property tax revenues and the potential impact to those revenues as a result of the loss of the current tax land tax base,” Bain said.

“It's not only a question of losing the revenue associated with property tax, but very often it comes at the same time you're having to spend money on flooding, interventions clean up, and etc. So, while revenues are going down, quite often, expenses are going up.”

Monroe and Miami-Dade counties will be most affected in Florida, according to Bain.

In Monroe, the study finds that 46,324 land parcels, or 52% of the 89,009 total, with a current taxable land value of $3.47 billion are projected to be in the annual flood risk zone by 2050.

And for Miami-Dade, 14,135 land parcels, or 2.4% of the 580,031 total, worth $3.81 billion for tax purposes will be in the annual flood risk zone by mid-century.

Within the greater Tampa Bay region, Pinellas County has the costliest tax revenue loss at $2.19 billion — 24,345 land parcels projected to be in the annual flood risk zone, or 5.6% of the 435,565 total by 2050.

By that time in Hillsborough County, the parcel loss will be less than half of that in Pinellas at 10,186, or 2% of the 507,147 total, with a current taxable land value of $492.96 million.

It’s not just coastal counties that will be affected with the shifting tidal boundaries, Bain said.

"Below the ground, there's also a boundary. It's a boundary between saltwater and freshwater. And that boundary extends significantly inland. And that boundary moves as the boundary on the surface moves, as well,” Bain said.

“So, it's moving inland. The consequence of that is you have you find saltwater intrusion in the freshwater wells."

But Bain called himself an optimist and said there are some ways to create resilience at the community level, like preventing growth in high-risk areas, and participating in the National Flood Insurance Program.

“We encourage people to use science-based analysis like we've done here to inform their investments — in these investments and adaptation include things like improving the stormwater system, potentially implementing intervention trends like levees and storm walls or sea walls where they're possible,” Bain said.

“Lastly, we encourage citizens to get educated and to participate in the planning … so they can be part of designing a better future for these cities as we're forced to move and adapt.”