As coastal communities face more frequent, severe disruptions, costly choices loom

Billions of dollars of property at risk
The analysis finds that:

· More than 300,000 of today’s coastal homes, with a collective market value of about $117.5 billion today, are at risk of chronic inundation in 2045—a timeframe that falls within the lifespan of a 30-year mortgage issued today. Approximately 14,000 coastal commercial properties, currently assessed at a value of roughly $18.5 billion, are also at risk during that timeframe.

· By the end of the century, homes and commercial properties currently worth more than $1 trillion could be at risk. This includes as many as 2.4 million homes—the rough equivalent of all the homes in Los Angeles and Houston combined—that are collectively valued today at approximately $912 billion.    

· The properties at risk by 2045 currently house 550,000 people and contribute nearly $1.5 billion toward today’s property tax base. Those numbers jump to about 4.7 million people and $12 billion by 2100.  

· States with the most homes at risk by the end of the century are Florida, with about 1 million homes (more than 10 percent of the state’s current residential properties); New Jersey, with 250,000 homes; and New York with 143,000 homes. 

These results reflect a high sea level rise scenario—an appropriately conservative projection to use when estimating risk to homes, which are often the owner’s single biggest asset. Even with a more moderate (intermediate) rate of sea level rise, nearly 140,000 homes are still at risk of chronic inundation by 2035 and more than 1.2 million by 2100. (See below for more information about the sea level rise scenarios used in this analysis.) 

It is also important to note that these results do not include future development or new homes, nor do they include critical infrastructure such as roads, bridges, power plants, airports, ports, public buildings, and military bases. When all of these are taken together, the effects of chronic flooding could have staggering economic impacts.

The growing risks to homeowners, communities, and the economy
The challenges and choices that come with rising seas are profound and have significant implications for coastal residents, communities, and the broader economy. 

Homeowners and commercial property owners are at risk of steep financial losses if their properties flood regularly. Declining property values could erode the tax base for communities, jeopardizing funding for vital local services and infrastructure, such as roads, schools, and police and fire departments. 

Mortgages on homes that could become chronically flooded during the term of the loan are inherently riskier. As flooding becomes more frequent, the value of flooded homes will decline and many homeowners could find themselves with mortgages that exceed the value of their homes, or with homes that are increasingly difficult to insure or have even deteriorated to the point of being unlivable. With no obvious option for reversing that trend, some might choose to abandon their homes and allow banks to foreclose on their mortgages. Banks holding these risky mortgages on devalued properties could then find their financial position adversely affected.  

Mortgage-backed securities and bonds tied into these riskier coastal real estate mortgages will be at risk of losing value. Real estate developers and investors as well are at risk of losing money invested in properties that become chronically flooded. 

Once market risk perceptions catch up with reality, the potential drop in coastal property values could have broad reverberations—affecting banks, insurers, investors, developers, and taxpayers—and potentially trigger regional housing market crises as well as affect the broader national economy.

A national imperative for action
UCS says that given the enormity of the risks from sea level rise, communities, states, businesses, and the federal government all need to take action to prepare. 

A crucial first step is for communities, policymakers, and the financial sector to know the risks and amount of time they have available for a robust response. 

The nation must also implement policies that reduce the carbon emissions that cause global warming, including investments in clean energy solutions; re-orient policy and market incentives to better reflect the risks of sea level rise and build coastal resilience while also ensuring that resources are targeted to low-income and otherwise disadvantaged communities; and adopt bold, transformative policies that foster new frontiers of opportunity on safer ground for those who may have to retreat from high-risk areas. 

The risks of rising seas are profound. Many of the challenges they bring are inevitable. And our time to act is running out. There is no simple solution—but we do still have opportunities to limit the harms. Whether we react to this threat by implementing science-based, coordinated, and equitable solu­tions—or walk, eyes open, toward a crisis—is up to us right now.

About the analysis
To determine the number of coastal properties at risk from this level of chronic flooding, the analysis uses property data from the online real estate company Zillow combined with the findings of the 2017 analysis, When Rising Seas Hit Home: Hard Choices Ahead for Hundreds of US Coastal Communities, which uses a peer-reviewed methodology to assess areas at risk of chronic inundation.

Three sea level rise scenarios, developed by the National Oceanic and Atmospheric Administration (NOAA) and localized for this analysis, are included:

· A high scenario that assumes a continued rise in global carbon emissions and an increasing loss of land ice; global average sea level is projected to rise about 2 feet by 2045 and about 6.5 feet by 2100.

· An intermediate scenario that assumes global carbon emissions rise through the middle of the century then begin to decline, and ice sheets melt at rates in line with historical observations; global average sea level is projected to rise about 1 foot by 2035 and about 4 feet by 2100.

· A low scenario that assumes nations successfully limit global warming to less than 2 degrees Celsius (the goal set by the Paris Climate Agreement) and ice loss is limited; global average sea level is projected to rise about 1.6 feet by 2100.

— Read more in Underwater: Rising Seas, Chronic Floods, and the Implications for US Coastal Real Estate (Union of Concerned Scientists, June 2018); Technical backgrounder; Insights from market experts; Complete data by state; Complete data by community; Complete data by ZIP Code