How rising sea levels could create zombie towns around U.S.

Americans are flocking to the coasts faster than ever before. And with much of the nation's priciest properties already concentrated near shorelines, this puts more people and buildings at risk from the kind of extreme storms and flooding linked to climate change.

But for many communities across the U.S. the toll is likely to go far beyond physical damage. Rising sea levels could have a knock-on effect, making certain areas unlivable long before they're uninhabitable, effectively creating zombie towns, according to a new analysis from nonprofit environmental group Climate Central that looks at the financial impact of sea-level rise over the coming century.

"Two New Jerseys"

As the water rises, up to 650,000 properties over a land area "equivalent of two New Jerseys" will likely be at least partly underwater in 30 years' time, Don Bain, senior adviser to Climate Central, told reporters in a presentation this week. About 30 counties across the nation are projected to lose more than one-tenth of their usable land, he said, while about 100 counties will lose at least 2%.

That will make some places uninhabitable and others financially undesirable by lowering property values and reducing their tax base. 

That's a huge problem for communities: property values and the attendant taxes are a critical source of revenue for schools, fire protection and other key municipal services. When real estate falls in value, that could lead to "lower tax revenues and reduced public services — a potential downward spiral of disinvestment and population decline, reduced tax base and public services, and so on," Climate Central said in its report. 

Louisiana is the nation's most vulnerable state, and is projected to lose more than 8% of its landmass by mid-century, according to the group. It's followed by Florida, which is set to lose 1.8% of its landmass; North Carolina (1.3%) and Texas (0.2%). While Climate Central looked only at sea levels, other research has found that inland areas and those close to rivers also face greater flood risk in coming decades.

East Coast most at risk

By 2050, the National Oceanic and Atmospheric Administration predicts that sea levels will rise by an average of nearly a foot — as much as they have risen over previous 100 years. Climate change is the main driver, as the warming temperatures melt landlocked glaciers at a record pace and the waters spread.

That rise won't be evenly spread across the nation. The East Coast, and in particular the Southeast, is likely to be hardest hit, Bain said. The Gulf Coast will see a double whammy from rising water levels and sinking ground due to the constant influx of sediment from the Mississippi river and the hollowing out of many areas for oil and gas pipelines.

Coastal parts of southern Alabama, Florida, Louisiana and the Carolinas already see regular flooding during high tide, even with no storms. 

"In Mobile Bay, Alabama, we have properties that are now underwater as a result of coastal erosion — and property owners who are still receiving property tax bills associated with these properties that they can no longer use," Bain said. 

Meanwhile, property insurers are bailing out of Florida, where frequent storms and floods are pushing the market to a "breaking point," according to trade publication Daily Business Review.

Sinking infrastructure

Smaller towns could be in even more jeopardy, having smaller budgets, fewer resources and generally less capacity to change their economy than larger cities, making them much more susceptible to climate risks.

"What's going to happen to the tax base for a lot of these local communities? Clearly, what the data suggests is it's being washed away," Mark Rupp, director of the adaptation program at the Georgetown Climate Center, told reporters.

Adapting to climate change, whether elevating infrastructure, building seawalls or relocating communities, costs money. And municipalities stand to lose a great deal of their main funding stream — property taxes — as more and more land disappears under water. 

It's worth noting that Climate Central's analysis is incomplete, since not all counties around the country make data on property values available — notably, researchers couldn't get information for New Orleans and New York City. But the numbers the group was able to crunch are striking. 

In Florida, for example, tax assessments worth $7 billion are predicted to be lost by mid-century to rising water in the coastal areas the group analyzed. In Texas, projected losses amount to nearly $5 billion. In North Carolina, $4.5 billion. 

2050 seems like a long time in the future; it's within the time frame of a 30-year mortgage taken out today, researchers note. But they urge politicians to start planning for adaptation and even relocation now, before they are compelled by market forces to do so.

"How many mortgage lenders want to be lending for mortgages in flood-prone areas if they don't think they're going to be paid back?" Rupp said.

"For as much as people may not want to talk about what's going on, climate change impacts are real — they are happening now."