Sea Level Rise: Risks for Real Estate Owners and Investors

Mitigation | Drought | Heat | Governance | Flood | Fire | Storm | Overview

Sea Level Rise Risks to Real Estate Properties

Rising sea levels are the number one threat to the real estate market. The global mean sea level has risen about 8 to 9 inches since 1880; by 2100 it has been forecasted to increase by 45 inches. Scientists track local sea levels using satellites, floating buoys, and tidal gouges. According to this data, sea levels are currently rising about 0.13 inches a year.

Flood - Projected sea level rise for US coastal cities

These rising water levels are primarily caused by two factors related to climate change: ice sheet and glacier meltwater and the thermal expansion of seawater as it forms. Secondary, and more locally based, causes of sea level rise include sinking land and the slowing of the gulf stream.

These changes pose a huge danger to coastal real estate, especially in areas that are prone to hurricanes and cyclones. A 2018 Union of Concerned Scientists study estimated that more than 300,000 coastal homes will be at risk of regular flooding by 2045. Sea levels are at the most risk to real estate when they are combined with high tides, winter storms, and severe weather like hurricanes. Higher sea levels will exacerbate storm surges, flooding and erosion.

Threats of Sea Level Rise

Sea level rise is increasing instances of tidal flooding. Twice a month during new and full moons, the combined gravitational pull of the sun and moon creates tides that rise higher than the average. At these times, water can flood into seaside communities if water levels reach too high. In most cases, the damage of tidal flooding is minor, but when high tides combine with storms, strong winds, and rainfall they can cause extensive and damaging floods.

Here are some definitions relevant to understanding the combined threat of rising sea levels, tides, and storms:

  • King Tide: The highest predicted high tide of the year for a coastal location, forecast by NOAA using data on the alignments and orbits of the earth, sun and moon. Also known as perigean spring tides.
  • High-Tide / Tidal Flooding: When sea levels temporarily rise above flood height thresholds and cause flooding to low-lying areas near the coast. Also called nuisance or sunny-day flooding. Usually occurs during high tide events such as full or new moons.
  • Storm Surge: The abnormal rise in seawater during a storm. Measured as the height of water above the normal height of the predicted tide. Storm surge is primarily caused by the strong winds of a hurricane or tropical storm as they force water in shallow areas upwards and onto shores.
  • Storm Tide: The combination of the height of the storm surge and the astronomical tide.
Flood - Storm Tide levels vs predicted tide and mean sea level

Costs of Rising Seas

The severity and impact of sea level rise in the U.S. varies by coast and region. Although meltwaters and thermal expansion are global issues, the geographic and climate conditions of some areas affect their levels of sea rise. On the East Coast, Americans are seeing faster rising waters than the national average due to subsidence and the slowing of the gulf stream. The West coast is rising slightly due to the shifting of tectonic plates which partially offsets sea level rise.

Rising waters are responsible for severely altering the natural geography of beachfront; this puts communities and ecosystems in further danger of flooding and storm surge. Accelerated coastal erosion is a cost of sea level rise, coastal flooding, and strong waves. This damage is responsible for billions of lost value to coastal real estate where beachfronts are eroding. Lost shoreline also causes the loss of coastal wetlands which are important for filtering water and protecting communities from flood.

Rising sea waters are disrupting fragile barrier islands in the Mississippi Delta, the East Coast, and the Arctic. Barrier islands are critical to protecting coasts from extreme weather. The beach dunes and grasses on barrier islands help to absorb some of the force of the wave before it hits the mainland. Without them, beachfront communities are more at risk.

Risks of Sea Level Rise for Real Estate

Low-lying and beachfront properties across the country are seeing the effects of rising tides. East coast and gulf coast properties are particularly at risk. Current projections have Florida suffering $66 billion in losses by 2100, 20 percent of total U.S. damages. Some investors and asset managers are starting to take climate risk into account in their real estate purchases. As more action to track climate damage occurs at the federal and state levels, it will become increasingly expensive to own or rent in high-risk areas. Despite these risks, Americans are still flocking to coastal properties for vacation homes and luxury seaside views.

Sea rise isn’t just a threat to residential property. As communities are threatened along the coastline by rising waters, essential land and buildings will be compromised. These include: schools, hospitals, airports, prisons, hazardous material sites, waste disposal sites, nuclear reactors, and historic buildings.

Mitigation Options

Coastal property owners will undoubtedly use adaptation options to attempt to prevent damages to their homes and businesses. In areas of moderate risk of water damage from coastal floods or hurricanes, mitigation can make a big difference. However, most large-scale preventative measures against sea-level rise are expensive or problematic for real estate within high-risk flood zones. Some options include raising houses through the use of pilings and hardening beaches using seawalls.

Here are some individual ways to protect your property:

  • Understand the risks of flooding, storm exposure, and erosion for your property. For more information on flooding risks, see our flood mitigation guide.
  • Add waterproof veneer to your foundation, exterior walls, windows, and doorways to prevent shallow flooding.
  • Use flood resistant non porous flooring materials
  • Buy sandbags and doorway flood barriers to divert moving water around buildings.
  • Get flood insurance if it is appropriate. Premiums will depend on your home’s risks.
  • Elevate your home, or raise other essential equipment such as electrical systems, HVAC systems, and plumbing.
  • If allowed by local and federal regulations, harden the shoreline using sea walls.
Flood - Sea Level Rise - Hardening shorelines against erosion and flooding

Community preparation can be a vital part of mitigation. Seawalls can be used to hold back the worst effects of rising waters. They can protect land, the base of cliffs, and buildings against erosion. But various ecological problems may arise from the construction of a sea wall such as beach sediment erosion, disruption of nesting and breeding grounds for important species, and the disturbance of migration patterns for wetland species. In addition, such structures cost millions for each mile of sea wall constructed. Such imposing structures can also be a detriment to tourism and seaside recreation.

One of the best options for tackling sea rise is the conservation and restoration of wetland habitats. Coastal habitats like marches, dunes, seagrass and oyster beds, coral reefs, and coastal forests keep waves and storm surge from flooding and eroding coastal property; for example, coral reefs can reduce the energy of waves that reach the shore by 85 percent.

Looking to the Future

We must prepare our communities for encroaching tides. Many property owners will have to grapple with chronic tidal flooding and frequent water damage. While there are tools to increase homeowners’ resilience to these climate-change induced changes, the best option is to reduce our carbon output to lower the severity of sea level rise in the future. We can help this process by building and renovating climate-friendly homes that reduce our greenhouse gas output.

Local and state governments will have to act to curtail development in high-risk flood areas and incentivize flood-resistant infrastructure. They will have to consider the costs and benefits of adaptation measures like natural buffers and sea walls. At the federal level, a comprehensive and coordinated response to sea level rise is needed. Investing in the infrastructure and resilience of coastal communities and reducing the pace of global warming by cutting carbon outputs will be crucial aspects of this plan.