Life on the coast has always carried a certain allure—sunsets over the ocean, bustling harbors, and a vibrant mix of communities who thrive on proximity to the water. Yet for millions of Americans, the same waters that provide beauty and economic vitality are becoming a growing source of risk. A 2024 study published in Nature highlights what scientists, insurers, and coastal residents have increasingly come to understand: U.S. cities are sinking, seas are rising, and the collision of those forces is creating unprecedented flood exposure.

By 2050, sea levels along U.S. coasts are expected to rise by roughly one foot. On its own, that figure might seem manageable. However, when paired with land subsidence—the gradual sinking of the ground itself—the stakes escalate dramatically. The study estimates that without effective defenses in place, nearly 500,000 people, 288,000 properties, and $109 billion in home value could be directly exposed to flood risk by mid-century.

This issue is not confined to far-off projections. Each year, coastal conditions worsen through more powerful storm surges, creeping saltwater intrusion, and erosion of natural barriers. Flood risk is no longer theoretical; it is reshaping infrastructure, insurance markets, and daily life. For businesses, homeowners, and policymakers, the question is no longer if but how communities can adapt.

The Nature study provides one of the broadest assessments to date of how sea-level rise and subsidence will combine to affect coastal communities. Looking at 32 U.S. cities across the Atlantic, Gulf, and Pacific coasts, the researchers concluded that while all coasts are vulnerable, the Atlantic and Gulf regions face the most immediate danger. This is largely due to soil composition, lower elevation, and a history of rapid urban development in fragile coastal zones.

Key Takeaways From the Study

• 25 million people live across the evaluated cities.
• 10 million properties worth an estimated $12 trillion are in harm’s way.
• Subsidence is a critical factor—ignored in many local flood projections.
• Without adaptation, by 2050 one in 50 residents and one in 35 properties in these cities will face significant flood exposure.

The report also stresses that these figures are conservative. They do not account for flood defenses currently in place—nor do they fully consider future adaptation projects. That means cities that have already invested in levees, seawalls, or natural restoration may see reduced impacts. Conversely, those without adequate protections may face even higher risks than projected.

From Boston to Miami, Atlantic cities face a mix of rising seas, storm surge, and subsidence. New York City, already tested by Hurricane Sandy, has begun billion-dollar projects to build seawalls and restore wetlands. Charleston and Savannah contend with frequent nuisance flooding that strains historic infrastructure. Miami—built on porous limestone—faces unique challenges, as water seeps underground even when walls are built along the shoreline.

The Gulf is perhaps the most vulnerable region. New Orleans, Biloxi, Galveston, and Mobile not only sit at low elevations but are also experiencing some of the fastest rates of land subsidence in the nation. In some places, the land is sinking faster than the ocean is rising. That combination creates a perfect storm for risk. Even modest sea-level rise, paired with hurricanes, could overwhelm existing defenses.

While the Pacific has fewer sinking cities, areas like the San Francisco Bay, Long Beach, and San Diego are not immune. Here, elevation and topography provide some buffer, but dense urbanization, tectonic factors, and reliance on waterfront infrastructure (such as ports) create their own exposures. The Pacific also faces the added complication of seismic risks that can compound flood vulnerabilities.

When discussing flood risk, much of the public conversation focuses on rising seas. But the ground beneath our feet is often shifting, too. Subsidence—the gradual sinking of land—occurs for both natural and human reasons.

Natural Causes

• Compaction of soil layers.
• Geological shifts.
• Natural drainage of wetlands.

Human Causes

• Groundwater extraction.
• Oil and gas drilling.
• Large-scale construction that alters soil stability.

The Gulf Coast offers a dramatic case study. In parts of Louisiana and Texas, subsidence outpaces sea-level rise. In other words, even if global warming magically stopped tomorrow, some coastal communities would still sink beneath the water line.

Ignoring subsidence in flood planning is like building a house on sand without checking the foundation. Cities that rely solely on projections of sea-level rise without accounting for land loss are grossly underestimating their risks.

Flood risk is not just about water levels—it’s about how climate change amplifies every coastal hazard.

• Storm Surges: Warmer oceans fuel stronger hurricanes, which push walls of water into coastal areas.
• Saltwater Intrusion: As seas rise, saltwater infiltrates freshwater aquifers, threatening drinking water supplies and agriculture.
• Erosion: Rising tides strip away natural defenses like beaches and wetlands.
• Infrastructure Strain: Roads, power systems, and sewer networks were often built with outdated assumptions about water levels.

For many communities, these hazards overlap. A city may simultaneously battle stronger storms, eroding coastlines, and failing infrastructure—all while trying to house and insure residents in increasingly risky zones.

The numbers are staggering. Across the 32 cities studied:

• $12 trillion in property value is potentially exposed.
• Housing markets may destabilize as buyers and lenders grow wary.
• Insurance premiums are already rising in high-risk areas, making coverage less affordable.
• Municipal budgets face mounting strain from emergency repairs, adaptation projects, and disaster recovery.

The ripple effects extend beyond the coast. National mortgage markets, construction industries, and even supply chains could feel the consequences if millions of properties lose value or become uninsurable.

Communities are not powerless. Around the world, cities have experimented with defenses ranging from massive seawalls to natural solutions.

Hard Infrastructure

• Levees and Floodwalls: Effective but costly, and they can fail under extreme pressure (as seen during Hurricane Katrina).
• Pumps and Gates: Help in low-lying areas but require constant maintenance.

Natural and Hybrid Solutions

• Wetland Restoration: Absorbs floodwaters while supporting ecosystems.
• Living Shorelines: Combining vegetation, sand, and rock to reduce wave impact.
• Zoning and Elevation Rules: Preventing new construction in the most vulnerable areas.

The lesson is that no single strategy works alone. A mix of defenses, tailored to local geography and needs, is essential. Cities like New Orleans and New York are investing heavily in such layered strategies. Others, however, remain underprepared.

While governments build defenses, property owners must take steps of their own.

For Homeowners

• Review FEMA flood maps and local projections.
• Consider elevating homes or investing in flood-proofing technology.
• Store valuables and documents in waterproof, elevated locations.
• Purchase flood insurance—standard homeowners insurance does not cover floods.

For Businesses

• Develop business continuity plans that account for flood risk.
• Relocate critical equipment and data storage above flood levels.
• Diversify suppliers and distribution channels to reduce disruption.
• Engage in community adaptation efforts—resilient neighborhoods support resilient businesses.

Insurance is one of the most powerful tools for resilience. Yet many Americans remain underinsured for flood risk.

NFIP vs. Private Flood Insurance

The National Flood Insurance Program (NFIP) has long been the backbone of U.S. flood coverage. However, private insurers such as Neptune Flood are increasingly offering alternatives with higher coverage limits, shorter waiting periods, and customizable options.

Why Insurance Matters

• Even a few inches of water can cause tens of thousands of dollars in damage.
• Floods are the most common—and costliest—natural disaster in the U.S.
• Without coverage, homeowners and businesses are left to rely on limited federal disaster aid.

Securing coverage well before a disaster strikes is critical. Waiting until the storm is on the horizon is too late.

Adapting to flood risk is not just about individual actions—it requires coordinated responses.

• Urban Planning: Restricting development in high-risk zones and incentivizing resilient design.
• Federal and State Investment: Funding large-scale defenses, wetland restoration, and relocation support.
• Community Engagement: Ensuring that vulnerable populations, including low-income residents, are not left behind.
• Climate Migration Planning: Some areas may eventually become uninhabitable. Preparing for managed retreat is essential, though politically and socially challenging.

The projections through 2050 serve as a warning—but also as a roadmap. Communities that act now will be better positioned to withstand rising waters. Those that delay may find themselves overwhelmed by costs, damage, and displacement.

Flood risk is not only a coastal issue. As disasters ripple through housing, insurance, and supply chains, inland communities will feel the effects, too. The urgency is clear: adaptation is no longer optional.

Which U.S. cities are most at risk of flooding by 2050? 

The study highlights New York City, Miami, Charleston, New Orleans, Galveston, San Francisco, and others among the 32 coastal cities facing significant exposure.

What is subsidence and why does it matter?

Subsidence is the gradual sinking of land. In places like Louisiana, subsidence is outpacing sea-level rise, amplifying flood risk.

How much will sea levels rise in the U.S. by 2050?

Sea levels are projected to rise approximately one foot along U.S. coasts by 2050, though local conditions vary.

Does homeowners insurance cover flood damage?

No. Standard homeowners insurance excludes flood damage. Separate flood insurance is required.

What steps can property owners take to reduce flood risk at their homes?

Elevating homes, installing flood barriers, reviewing FEMA maps, and securing flood insurance are all critical steps.

Are flood defenses like levees and seawalls enough?

Not on their own. The best strategies combine hard defenses with natural buffers, zoning rules, and community preparedness.

What’s the difference between NFIP and private flood insurance?

NFIP offers federal coverage but with limits. Private insurers may provide higher coverage, faster claims processing, and broader options.

The study on sinking U.S. cities underscores a truth we can no longer avoid: the water is rising, and in many places, the land is sinking. Together, these forces threaten millions of people, billions in property, and the very fabric of coastal communities.

Yet this future is not set in stone. With proactive planning, investment in defenses, and individual responsibility—such as securing proper flood insurance—cities can adapt and thrive even in the face of mounting challenges.

The next 25 years will test the resilience of U.S. coastal communities. Those that act now may help reduce damage to homes and businesses and support the vitality of coastal life for generations to come.

Disclaimer: General information only—not legal, tax, HR, or insurance advice, and not a guarantee of coverage, pricing, discounts, or outcomes. Availability, terms, limits, deductibles, classifications, and rates vary by carrier, policy, industry, and jurisdiction. Refer to your policies for specific provisions and consult a licensed insurance professional for guidance specific to your situation.