States with the most homes at risk of coastal flooding
States with the most homes at risk of coastal flooding
While it's difficult to attribute any specific storm to climate change, scientists agree that overall, extreme weather events are increasing in frequency and intensity because of the Earth's changing climate. There have already been five category-5 hurricanes in the Atlantic Ocean in the past four hurricane seasons, and many others that were category 4 or 3 by the time they hit land in the United States.
This increase in extreme weather events has caused flooding, especially in U.S. coastal states. However, despite flooding increases, building in some states is increasing in flood-prone areas. According to a joint report conducted in July 2019 by Climate Central and Zillow, new homes are being built in Connecticut 3.5 times faster in risk zones than in safer locations. In Delaware, Mississippi, New Jersey, and Rhode Island, the rate is twice as fast as other, more safe areas. Also, Florida, New Jersey, and North Carolina combined have built more than 9,000 homes in risk zones since 2010.
The report, "Ocean at the Door: New Homes and the Rising Sea," determined which states have the most homes at risk of coastal flooding using the metric of how many homes they would build in a 10-year flood zone by 2050. A 10-year flood zone refers to an area that has a 10% chance of flooding annually. These zones were determined based on a moderate greenhouse-gas emissions scenario with a Representative Concentration Pathway of 4.5, meaning that, under this projection, emissions would peak in 2040 and then decline.
Using data from the report, Stacker has ranked 24 states impacted by America's coastlines, plus Washington D.C., and ranked them based on how many homes each will have in a 10-year flood zone by 2050. This list also includes information about which states are building the most homes in these risky areas, which are trying to curb new building, and which already have experienced unprecedented flooding.
To determine the states with the most homes at risk of coastal flooding, Stacker worked with the Climate Central and Zillow joint July 2019 report, "Ocean at the Door: New Homes and the Rising Sea." Climate Central investigated 24 states and the District of Columbia, all located on or close to America's coastlines, to determine how many homes would be located in 10-year flood zones in 2050 under the Representative Concentration Pathway of 4.5, a moderate greenhouse emissions scenario. Then, Zillow attached property values to these homes. The states are ranked here based on how many total homes will be at risk. This story also includes new homes that will be located in 10-year flood zones; new homes refers to dwellings built between 2010 and 2017 for most states, or between 2010 and 2016 in Alabama, Florida, Mississippi, and New York. Ten-year flood zones refer to areas that have a 10% chance of flooding annually.
Read on to discover which states have the most homes threatened by coastal flood risk.
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#25. District of Columbia
- Homes in 10-year flood zones by 2050: 8 (0% of all homes, $7 million in property value)
- Homes built since 2010 in flood zones by 2050: data not available
- Most threatened counties:
--- District of Columbia (8 homes threatened, 0% of all homes in the county, $7 million in property value)
Of the United States' 25 coastal states or areas, Washington D.C. has the fewest homes in danger of flooding. By 2050, it is estimated that only eight homes will be in 10-year flood zones, totaling $7 million in real estate value. That doesn't mean that the District is safe. D.C. is still vulnerable to three types of flooding: interior, which is when drainage systems can't keep up with heavy rainfall, riverine, and tidal, the latter two caused by rivers but from different directions.
#24. Alaska
- Homes in 10-year flood zones by 2050: 23 (0.01% of all homes, $16 million in property value)
- Homes built since 2010 in flood zones by 2050: data not available
- Most threatened counties:
--- Juneau City and Borough (23 homes threatened, 0.26% of all homes in the county, $16 million in property value)
In Alaska, 23 of the state's homes will be in 10-year flood zones by 2050. The most threatened area is Juneau (city and borough) where just over 32,000 people live. The 23 homes under threat make up 0.26% of Juneau's total homes. In early October 2019, Juneau experienced heavy rains, which caused mudslides and flooding.
#23. Pennsylvania
- Homes in 10-year flood zones by 2050: 1,221 (0.03% of all homes, $332 million in property value)
- Homes built since 2010 in flood zones by 2050: 0
- Most threatened counties:
--- Philadelphia County (958 homes threatened, 0.21% of all homes in the county, $288 million in property value)
--- Delaware County (146 homes threatened, 0.08% of all homes, $17 million in property value)
--- Bucks County (117 homes threatened, 0.06% of all homes, $27 million in property value)
The county most at risk in Pennsylvania is Philadelphia County, where nearly 1,000 homes will be threatened, representing $288 million in property value. Already, $90 million worth of property is destroyed each year by floods in the state, and a big storm in Philadelphia in July gave residents a preview of what could be to come.
Note: Although Pennsylvania is not a coastal state, it is in danger of coastal flooding because the tidal influence of the Delaware River extends through densely populated areas, including Philadelphia. Climate Central and Zillow included it in their study as a result.
#22. Hawaii
- Homes in 10-year flood zones by 2050: 1,701 (0.41% of all homes, $1.3 billion in property value)
- Homes built since 2010 in flood zones by 2050: 16 (0.26% of all new homes, $9 million in property value)
- Most threatened counties:
--- Maui County (1,187 homes threatened, 2.21% of all homes in the county, $531 million in property value)
--- Honolulu County (359 homes threatened, 0.13% of all homes, $585 million in property value)
--- Kauai County (126 homes threatened, 0.47% of all homes, $160 million in property value)
Hawaii's most threatened counties are Maui, Honolulu, and Kauai: This can be a problem for homeowners in hurricane zones, who might find that their insurance won't fully cover their losses. "Unlike most homeowners' insurance in other states, policies in Hawaii generally exclude hurricanes from coverage," according to CNBC personal finance writer Sarah O'Brien.
#21. Oregon
- Homes in 10-year flood zones by 2050: 2,011 (0.15% of all homes, $418 million in property value)
- Homes built since 2010 in flood zones by 2050: 14 (0.08% of all new homes, $3 million in property value)
- Most threatened counties:
--- Clatsop County (1,307 homes threatened, 6.99% of all homes in the county, $266 million in property value)
--- Coos County (233 homes threatened, 1.04% of all homes, $39 million in property value)
--- Lincoln County (219 homes threatened, 0.81% of all homes, $43 million in property value)
The counties with the most homes at risk in Oregon are Clatsop, Coos, and Lincoln. Already, Coos County had to declare a state of local emergency in February after snow, along with 5 to 7 inches of rain, hit the western side of the state. Coos County will have 233 homes in a 10-year flood zone in 2050.
#20. Maine
- Homes in 10-year flood zones by 2050: 2,107 (0.54% of all homes, $1.1 billion in property value)
- Homes built since 2010 in flood zones by 2050: 72 (0.71% of all new homes, $62 million in property value)
- Most threatened counties:
--- York County (1,657 homes threatened, 2% of all homes in the county, $946 million in property value)
--- Cumberland County (144 homes threatened, 0.15% of all homes, $93 million in property value)
--- Sagadahoc County (143 homes threatened, 1.11% of all homes, $45 million in property value)
Maine will have 2,107 homes in a 10-year flood zone by 2050, 72 of which were built in the past decade. These homes represent $1.1 billion in property value. A study in January 2019 by Columbia University and the First Street Foundation showed that between 2005 and 2017, $69.9 million was lost in Maine because of flooding.
#19. Rhode Island
- Homes in 10-year flood zones by 2050: 2,209 (0.70% of all homes, $1.4 billion in property value)
- Homes built since 2010 in flood zones by 2050: 78 (1.56% of all new homes, $74 million in property value)
- Most threatened counties:
--- Washington County (1,144 homes threatened, 2.11% of all homes in the county, $844 million in property value)
--- Newport County (486 homes threatened, 1.52% of all homes, $307 million in property value)
--- Bristol County (322 homes threatened, 1.98% of all homes, $147 million in property value)
By 2050, Rhode Island's Washington County will have 1,144 homes, 2.11% of the state's total, in a 10-year flood zone, totaling $1.4 billion in property value. However, while scientists have seen the writing on the wall, the real estate industry has not. Lint Barrage, an assistant professor of economics and environmental studies at Brown University found that people with homes in federally designated flood zones underestimate their risk of being flooded. Of the aforementioned 1,144 homes, 78 were built between 2010 and 2017.
#18. New Hampshire
- Homes in 10-year flood zones by 2050: 2,767 (0.55% of all homes, $935 million in property value)
- Homes built since 2010 in flood zones by 2050: 50 (0.38% of all new homes, $39 million in property value)
- Most threatened counties:
--- Rockingham County (2,754 homes threatened, 2.45% of all homes in the county, $929 million in property value)
--- Strafford County (13 homes threatened, 0.03% of all homes, $6 million in property value)
New Hampshire is projected to have 2,767 homes in a 10-year flood zone by 2050. This makes up 0.55% of all homes in the state and $935 million in property value. Of these, 50 have been built since 2010, representing 0.38% of all new homes built and $39 million in property value. The state is trying to raise citizen awareness about flooding dangers by creating New Hampshire Flood Safety Awareness Week, which took place in March this year. The website links to resources about flood preparation and flood insurance.
#17. Mississippi
- Homes in 10-year flood zones by 2050: 4,617 (0.54% of all homes, $877 million in property value)
- Homes built since 2010 in flood zones by 2050: 333 (1.32% of all new homes, $84 million in property value)
- Most threatened counties:
--- Hancock County (2,158 homes threatened, 11.7% of all homes in the county, $373 million in property value)
--- Jackson County (1,340 homes threatened, 2.57% of all homes, $239 million in property value)
--- Harrison County (1,119 homes threatened, 1.63% of all homes, $266 million in property value)
Of the southern states, Mississippi, with a population of nearly 3 million, will have the fewest homes in a 10-year flood zone by 2050, with 4,617 homes (0.54% of the state's total) and $877 million in property value under threat. All told, 333 of these dwellings have been built since 2010, which is 1.32% of all new homes and $84 million in property value. The state already experienced a loss in real estate values of over $260 million between 2005 and 2017, according to a First Street Foundation study.
#16. Alabama
- Homes in 10-year flood zones by 2050: 7,290 (0.46% of all homes, $2.8 billion in property value)
- Homes built since 2010 in flood zones by 2050: 167 (0.36% of all new homes, $89 million in property value)
- Most threatened counties:
--- Baldwin County (5,237 homes threatened, 5.29% of all homes in the county, $2.2 billion in property value)
--- Mobile County (2,053 homes threatened, 1.49% of all homes, $581 million in property value)
--- Clarke County (homes threatened, 0% of all homes, $ million in property value)
Alabama will have 7,290 homes, 0.46% of the state's total, in a 10-year flood zone by 2050, making up $2.8 billion in property value. Of these over 7,000 properties, 167 have been built since 2010. The two most threatened counties are Baldwin and Mobile, which in September 2019 experienced flash flooding and sewage overflows.
#15. Georgia
- Homes in 10-year flood zones by 2050: 10,345 (0.31% of all homes, $5.7 billion in property value)
- Homes built since 2010 in flood zones by 2050: 146 (0.16% of all new homes, $112 million in property value)
- Most threatened counties:
--- Glynn County (4,840 homes threatened, 14.23% of all homes in the county, $3.2 billion in property value)
--- Chatham County (3,841 homes threatened, 4.24% of all homes, $2 billion in property value)
--- Camden County (615 homes threatened, 3.46% of all homes, $175 million in property value)
In Georgia, 10,345 homes will be in a 10-year flood zone by 2050, making up $5.7 billion in property value. Of these homes, 146 were built between 2010 and 2017. Hurricane Dorian created a state of emergency in 12 counties closest to the coast, including Georgia's most at-risk counties: Glynn, Chatham, and Camden.
#14. Connecticut
- Homes in 10-year flood zones by 2050: 10,879 (1.03% of all homes, $9.3 billion in property value)
- Homes built since 2010 in flood zones by 2050: 478 (3.28% of all new homes, $880 million in property value)
- Most threatened counties:
--- Fairfield County (5,750 homes threatened, 2.11% of all homes in the county, $6.9 billion in property value)
--- New Haven County (3,196 homes threatened, 1.27% of all homes, $1.5 billion in property value)
--- Middlesex County (1,376 homes threatened, 2.27% of all homes, $589 million in property value)
Connecticut comes in as the 14th state most at risk for its properties flooding, with 10,879 homes. Connecticut is among coastal states that have been building the fastest since 2010: It is developing homes in risk zones three times more rapidly than other locations, according to the Climate Central/Zillow report. Of the most at-risk homes, 478 were built between 2010 and 2017.
#13. Delaware
- Homes in 10-year flood zones by 2050: 12,597 (3.63% of all homes, $7.2 billion in property value)
- Homes built since 2010 in flood zones by 2050: 1,268 (5.61% of all new homes, $863 million in property value)
- Most threatened counties:
--- Sussex County (10,662 homes threatened, 10.32% of all homes in the county, $6.7 billion in property value)
--- New Castle County (1,259 homes threatened, 0.69% of all homes, $391 million in property value)
--- Kent County (676 homes threatened, 1.12% of all homes, $116 million in property value)
In Delaware, 12,597 homes will be in 10-year flood zones by 2050, totaling $7.2 billion in property value. Of these, 1,268 homes were built between 2010 and 2017; 5.61% of all new homes built in the state. Delaware is the lowest-lying state in the nation and already a number of roads in the state flood regularly.
#12. Washington
- Homes in 10-year flood zones by 2050: 14,386 (0.63% of all homes, $6.8 billion in property value)
- Homes built since 2010 in flood zones by 2050: 136 (0.34% of all new homes, $121 million in property value)
- Most threatened counties:
--- Grays Harbor County (5,865 homes threatened, 19.96% of all homes in the county, $603 million in property value)
--- King County (2,124 homes threatened, 0.35% of all homes, $2.5 billion in property value)
--- Island County (1,209 homes threatened, 3.38% of all homes, $1 billion in property value)
On the West Coast, Washington is facing the threat of 14,386 homes in a 10-year flood zone by 2050, totaling $6.8 billion in property value. The Quinault Indian Nation town of Taholah, in Grays Harbor, is being relocated to keep it above sea level and protect it from tsunamis, according to the Kirkland Reporter. Even landlocked counties, such as Lewis, have experienced flooding from rivers.
#11. Massachusetts
- Homes in 10-year flood zones by 2050: 20,846 (1.06% of all homes, $15.8 billion in property value)
- Homes built since 2010 in flood zones by 2050: 188 (0.59% of all new homes, $369 million in property value)
- Most threatened counties:
--- Suffolk County (7,825 homes threatened, 5.62% of all homes in the county, $6.9 billion in property value)
--- Plymouth County (3,720 homes threatened, 2.25% of all homes, $1.8 billion in property value)
--- Essex County (3,234 homes threatened, 1.5% of all homes, $1.7 billion in property value)
In Massachusetts, 20,846 homes will be in 10-year flood zones by 2050. These homes add up to a property value of nearly $16 billion. The counties most at risk are Suffolk, Plymouth, and Essex. Suffolk, where Boston is located, will have 7,825 homes in a 10-year flood zone and $6.9 billion in property value under threat. The city has developed a comprehensive and science-driven initiative called Climate Ready Boston to be ready for the coming storm surges and rising seas.
#10. Texas
- Homes in 10-year flood zones by 2050: 27,339 (0.34% of all homes, $8 billion in property value)
- Homes built since 2010 in flood zones by 2050: 1,637 (0.28% of all new homes, $606 million in property value)
- Most threatened counties:
--- Galveston County (14,249 homes threatened, 11.95% of all homes in the county, $4.6 billion in property value)
--- Brazoria County (2,990 homes threatened, 2.7% of all homes, $547 million in property value)
--- Nueces County (2,296 homes threatened, 2.11% of all homes, $829 million in property value)
Rounding out the top 10 coastal states with the most homes at risk for flooding is Texas. This state, with the largest land mass in the lower 48, will have 27,339 homes in 10-year flood zones by 2050, making up $8 billion in property value. The three most threatened counties are Galveston, Brazoria, and Nueces. Given the homes that will be in danger, along with the damage from Hurricane Harvey, a new law will require homeowners to disclose to potential buyers whether their properties lie in a flood-prone area or if they have previously flooded.
#9. South Carolina
- Homes in 10-year flood zones by 2050: 29,418 (1.53% of all homes, $19.1 billion in property value)
- Homes built since 2010 in flood zones by 2050: 1,216 (1.52% of all new homes, $1.3 billion in property value)
- Most threatened counties:
--- Charleston County (13,824 homes threatened, 9.64% of all homes in the county, $11.5 billion in property value)
--- Beaufort County (6,449 homes threatened, 8.17% of all homes, $4.3 billion in property value)
--- Horry County (4,667 homes threatened, 2.67% of all homes, $1.3 billion in property value)
By 2050, South Carolina will have nearly 30,000 homes in a 10-year flood zone, adding up to $19.1 billion in property value. However, the Climate Central and Zillow report found that this has not stopped building in the state, as South Carolina is one of eight states where building in flood zones has increased more than in safer parts of the states. Between 2010 and 2017, 1,216 new homes were built in flood zones, representing 1.52% of the state's new homes and $1.3 billion in property value.
#8. Maryland
- Homes in 10-year flood zones by 2050: 29,854 (1.56% of all homes, $10.2 billion in property value)
- Homes built since 2010 in flood zones by 2050: 682 (0.97% of all new homes, $345 million in property value)
- Most threatened counties:
--- Worcester County (14,145 homes threatened, 27.13% of all homes in the county, $4.7 billion in property value)
--- Somerset County (3,950 homes threatened, 43.85% of all homes, $465 million in property value)
--- Dorchester County (2,744 homes threatened, 19.81% of all homes, $778 million in property value)
In Maryland, 29,854 homes will be in 10-year flood zones by 2050, making up 1.56% of all homes in the state and over $10 billion in property value. Nearly half of those homes are in Worcester County, where 14,145 homes representing $4.7 billion in property value will be in these flood zones by 2050. To help combat some effects of climate change in the county, the Maryland Board of Public Works recently approved a Resiliency through Restoration initiative in Worcester County, which will be one of four in the state. The goal of the project is to strengthen community resilience in the face of the impacts of climate change, including flooding and extreme weather.
#7. Virginia
- Homes in 10-year flood zones by 2050: 33,667 (1.24% of all homes, $11.2 billion in property value)
- Homes built since 2010 in flood zones by 2050: 882 (0.96% of all new homes, $420 million in property value)
- Most threatened counties:
--- Accomack County (5,215 homes threatened, 29.23% of all homes in the county, $1.1 billion in property value)
--- Virginia Beach city (5,179 homes threatened, 3.62% of all homes, $2.5 billion in property value)
--- Norfolk city (4,674 homes threatened, 8.09% of all homes, $1.5 billion in property value)
Virginia has 33,667 homes that will be in 10-year flood zones by 2050, representing 1.24% of homes in the state and $11.2 billion in property value. At most risk are Accomack County, and the cities of Virginia Beach and Norfolk. Virginia Beach wants to discourage people from living in threatened areas by possibly implementing a program that would offer buy-out money to residents who want to leave homes that either have flooded or are at risk of flooding. The houses then would be demolished, and the city would restrict development on the land.
#6. California
- Homes in 10-year flood zones by 2050: 42,648 (0.45% of all homes, $58.9 billion in property value)
- Homes built since 2010 in flood zones by 2050: 367 (0.18% of all new homes, $798 million in property value)
- Most threatened counties:
--- San Mateo County (19,723 homes threatened, 10.23% of all homes in the county, $29.8 billion in property value)
--- Marin County (4,827 homes threatened, 6.03% of all homes, $6.5 billion in property value)
--- San Joaquin County (4,680 homes threatened, 2.48% of all homes, $1.8 billion in property value)
California, the most populous state in the country, will have 42,648 homes in 10-year flood zones by 2050, totaling nearly $60 billion in property value. Of those homes, only 367 were built between 2010 and 2017. San Mateo County has by far the most homes at risk, with 19,723 homes and almost $30 billion in property under threat. The county is now proposing expanding the existing flood control district to address these threats.
#5. North Carolina
- Homes in 10-year flood zones by 2050: 50,477 (1.41% of all homes, $18 billion in property value)
- Homes built since 2010 in flood zones by 2050: 1,910 (1.07% of all new homes, $840 million in property value)
- Most threatened counties:
--- Dare County (11,689 homes threatened, 36.22% of all homes in the county, $4.8 billion in property value)
--- Carteret County (5,369 homes threatened, 12.91% of all homes, $1.9 billion in property value)
--- Brunswick County (5,298 homes threatened, 6.95% of all homes, $2.6 billion in property value)
By 2050, North Carolina will have over 50,000 homes in the 10-year flood zone, making up 1.41% of all homes in the state. The three counties most at risk are Dare, Carteret, and Brunswick. Dare and Carteret are part of the Outer Banks, which experienced severe flooding and damage during Hurricane Dorian this past summer.
#4. Louisiana
- Homes in 10-year flood zones by 2050: 63,636 (4.19% of all homes, $9.5 billion in property value)
- Homes built since 2010 in flood zones by 2050: 612 (3.07% of all new homes, $141 million in property value)
- Most threatened counties:
--- Terrebonne Parish (16,695 homes threatened, 46.56% of all homes in the county, $2 billion in property value)
--- St. Tammany Parish (7,432 homes threatened, 8.03% of all homes, $1.9 billion in property value)
--- St. Mary Parish (5,939 homes threatened, 23.03% of all homes, $472 million in property value)
Louisiana will have 63,636 homes in 10-year flood zones by 2050, representing over 4% of homes in the state and $9.5 billion in property value. The three parishes most at risk are Terrebonne, St. Tammany, and St. Mary. To mitigate these flood risks, Louisiana plans to spend $1.2 billion in several ways, according to one blueprint, though the plans may change before being submitted to the federal government for approval.
#3. New York
- Homes in 10-year flood zones by 2050: 67,315 (1.40% of all homes, $45.5 billion in property value)
- Homes built since 2010 in flood zones by 2050: 393 (0.86% of all new homes, $751 million in property value)
- Most threatened counties:
--- Nassau County (24,441 homes threatened, 6.66% of all homes in the county, $14.1 billion in property value)
--- Suffolk County (16,055 homes threatened, 3.44% of all homes, $12.1 billion in property value)
--- Queens County (12,249 homes threatened, 2.72% of all homes, $7.1 billion in property value)
By 2050, the State of New York will have over 67,000 homes in a 10-year flood zone, totaling $45.5 billion in property value. The counties most at risk are all in the southern part of the state, with Nassau and Suffolk on Long Island having a combined over 40,000 homes under threat. Queens, a borough of New York City, will have 12,249 homes threatened. As the Federal Emergency Management Agency (FEMA) changes its structure for premiums for flood insurance, many people living on Long Island may see their rates go up.
#2. New Jersey
- Homes in 10-year flood zones by 2050: 133,758 (5.16% of all homes, $77.9 billion in property value)
- Homes built since 2010 in flood zones by 2050: 4,524 (11.25% of all new homes, $4.6 billion in property value)
- Most threatened counties:
--- Ocean County (46,684 homes threatened, 18.75% of all homes in the county, $27.6 billion in property value)
--- Cape May County (33,548 homes threatened, 37.69% of all homes, $25.2 billion in property value)
--- Atlantic County (19,280 homes threatened, 18.54% of all homes, $6.3 billion in property value)
New Jersey will have nearly 134,000 homes in a 10-year flood zone by 2050, which is 5.16% of all homes in the state and $77.9 billion in property value. The most-threatened counties are Ocean, Cape May, and Atlantic, all on the Atlantic coast. On the Jersey Shore, which is located across all three of these counties, the town of Ocean City alone has lost over $530 million in property value from 2005 to 2017 because of flooding, according to a study by First Street Foundation and Columbia University.
#1. Florida
- Homes in 10-year flood zones by 2050: 158,859 (2.12% of all homes, $88.6 billion in property value)
- Homes built since 2010 in flood zones by 2050: 2,645 (1.18% of all new homes, $3.4 billion in property value)
- Most threatened counties:
--- Miami-Dade County (30,171 homes threatened, 3.93% of all homes in the county, $19 billion in property value)
--- Pinellas County (23,233 homes threatened, 6.28% of all homes, $12.1 billion in property value)
--- Broward County (11,761 homes threatened, 1.81% of all homes, $5.4 billion in property value)
The state that will have the most homes in a 10-year flood zone by 2050 is Florida, with nearly 160,000 homes and $88.6 billion in property value under threat. The three counties with the most homes at risk are Miami-Dade, Pinellas, and Broward. However, these three counties alone represent less than half of the homes in Florida that will be in flood zones by 2050, making flooding a statewide issue. In North Miami, the local government in the past has bought out flood-prone properties. Now other parts of the state, like the Keys, are looking to do the same thing but on a larger scale.
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