Homes and businesses along the Jersey shore, the Florida coast, California and many of your favorite beach spots may all be under the same threat.

Hundreds of thousands of buildings along nearly 13,000 miles of coastline of the United States lie in the path of rising seas, a Union of Concerned Scientists (UCS) recent report says.

Prior to being permanently underwater, these coastline properties will face more frequent flooding, as the tides inch higher and reach farther inland. This flooding is expected to affect millions of Americans living in coastal communities.

As sea levels rise, persistent high tide flooding will begin to render coastal properties effectively unlivable, and could leave whole communities financially unattractive.

Jim and Maryann O'Neill's home in a back bay neighborhood of Manahawkin N.J., surrounded by water after a moderate storm on March 14, 2017. Back bay flooding is a type of recurring nuisance flooding that affects millions of Americans. (AP Photo/Wayne Parry)

However, property values in most coastal real estate markets do not currently reflect this risk. Most homeowners, communities and investors are not aware of the financial losses they may soon face as a result of sea level rise, the report reads.

“We know that sea levels are rising and that puts our coasts at risk. But this near-term threat to our coastal properties, our homes and businesses has been flying under the radar and that's dangerous,” Union of Concerned Scientists Senior Climate Scientist Dr. Kristina Dahl said.

UCS examined the risks to properties in the near term, not by the properties that will be underwater every single high tide, but what properties will experience chronic inundation.

Chronic inundation is flooding that occurs 26 times per year, or every other week on average.

The researchers looked at chronic inundation because “no property owner is going to sit around and wait until they see their property underwater every high tide to make a decision,” Dahl said.

They used property data from Zillow as well as a previous analysis they published that mapped out areas affected by chronic inundation.

UCS identifies the number of U.S. homes at risk from chronic flooding over the coming decades due to sea level rise in a recently published national analysis.

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The analysis also shows the current property value, estimated population and portion of the property tax base at risk. Information is available by state, community and zip code.

Two time frames are featured in the analysis. The first falls within the lifespan of a 30-year mortgage issued today. The second extends out to 2100, and shows that more than 2.5 million of today's homes, collectively valued at $1.07 trillion, could be at risk.

“We're starting to see signals. There are plenty of places that may not be experiencing this chronic flooding today but will be within the lifetime of the mortgage, and it’s those places in particular where we're concerned that potential home-buyers may not be aware of the risk,” Dahl said.

Property values may vary when they reflect this risk from place to place. A lot of the evidence currently is fairly anecdotal, Dahl said.

For example, homes in Norfolk, Virginia, that are flood prone are sitting on the market longer. They are not selling for high prices typically associated with waterfront real estate, according to Dahl.

The Boston area also experiences more frequent high tide in populated areas, especially this past winter. When the spring real estate season heated up, those homes that were in or close to areas of flooding were not selling as quickly, according to the Boston Globe.

“In some cases where this issue of chronic flooding is at the forefront of people's minds, we are starting to see a market signal,” Dahl said.

A rising high tide covers roads in Hampton, N.H, in October 2012. A commission that studies risks and hazards to New Hampshire's coast is releasing a report Friday March 18, 2016 on projected sea-level rise and flooding and the effect on communities. (AP Photo/Jim Cole)

Communities have different amounts of time to respond to this threat. While some communities are already facing it, other communities have a much longer time before a significant number of homes in their community could see this type of flooding.

“Every community, regardless of how much time they have, needs to be concerned about their risk and considering the options that are in front of them,” Dahl said.

As individual homeowners, there is the option to use flood-managing measures like to elevate your home or to install floodgates.

“However, it doesn't necessarily do you a whole lot of good if the road in front of your home is chronically flooded and you're unable to drive through the saltwater to get to work or to drop your kids at school,” Dahl said.

At the community level, once a community understands its risk, its options fall into three basic categories.

There is the option to defend your community with seawalls and hard structures.

There is the option to try to accommodate the rising tides, such as ensuring that waterfront property is not housing critical infrastructure. Areas at high risk would be open space, so when the tide rises, it’s flooding parks and places that don’t pose any risk to life or property.

The third option is retreat, which unfortunately may be the best option for many communities, according to Dahl.

Retreat often does not often involve physically moving homes. It would typically take the form of a buyout.

Homeowners may have the option to sell their homes to the community, the state or the federal government, and then use the money to relocate to a new home.

Without a buyout, homes affected by sea level rise will experience constant flooding and will become an unlivable place.

“It raises a lot of interesting questions,” Dahl said. ”If you have a home that is getting chronically flooded and you decide to leave it then you don't have a buyout of any kind. What happens to that land and who owns that land as it gets increasingly inundated by high tides?”

Waves roll up to and under homes perched over a sandy beach in Malibu, Calif, in December 2015. A study from March 2017 predicts that with limited human intervention, 31 percent to 67 percent of Southern California beaches could completely erode back to coastal infrastructure or sea cliffs by the year 2100, with sea-level rises of 3.3 feet to 6.5 feet. (AP Photo/John Antczak)

The Louisiana Coastal Master Plan was updated in 2017. It became the first state plan to specifically mention potential funding for buyouts in specific affected areas in Louisiana.

Louisiana ranks in the top five in terms of the number of homes at risk in the next 30 years in the UCS study, Dahl said.

Louisiana also stands out as being both highly exposed to sea-level rise and having very high poverty rates, according to Dahl.

The coastal city of Del Mar, California, considered the planned retreat option. However, the Del Mar City Council agreed on Monday, May 21, that the “planned retreat” will not be part of its long-term strategy for dealing with sea-level rise, according to the San Diego Union-Tribune.

In this case of planned retreat, also called “managed retreat,” the strategy includes removing seawalls, roads, homes and other structures gradually over the years in advance of rising sea levels.

The retreat policy would have affected about 600 low-lying Del Mar homes. Seawalls and rock revetments currently protect nearly all of the city’s shoreline.

Many of those coastal property owners are opposed to the idea of retreat. They say that even any mention of the idea in their proposed adaptation policy would slash property values for their multi-million dollar homes, according to the San Diego Union-Tribune.

As sea level rise continues to become an increasingly real and prevalent risk, coastal communities and homeowners will be forced into making tough decisions on their beloved homes.

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