Sea Level Rise Facts
Global warming causes a rise in ocean temperatures and the expansion of water. The higher temperatures also cause ice sheets and glaciers to melt, which adds water to the ocean. Both phenomena result in higher global sea levels. In many coastal areas, the ocean will progress towards the land and nibble into it. Another contributor to sea level rise is land sinkage. Although a generally small contributor, in some places it’s responsible for more than half of the sea level rise.
NASA tracks the Global Mean Sea Level, which has steadily increased since the 1990s:
Regional sea levels behave differently. Some factors cause sea levels to increase in certain parts of the planet, decrease in others, and may even cause it to remain relatively flat in some places.
In this blog we cover:
- How Sea Level Rise Impacts Buildings
- Saltwater Intrusion
- Decrease in Home Prices
- Forced Migration
- What can be done?
- By the Federal Government/States
- By Cities
- By You - the Homeowner
- Final Thoughts
Is your home at risk of being affected by sea-level rise? You can start by looking at the global interactive map created by NOAA. The map shows the changes in the sea level on the coasts across the world.
NASA created an interactive sea-level projection tool based on the IPCC’s 6th assessment report. By selecting a location on the map, you can learn about the forecasted sea-level rise in the specified location up to the year 2150.
Note that even if a location is currently experiencing a specific rising sea level trend, it can and probably will change. For example, research shows that the California coast, although relatively flat in recent decades, is predicted to experience a sea-level rise in the coming century.
NOAA provides several scenarios of the sea level rise for the next century, but scientists are not certain of the rate of increase since the rate at which the ice is melting is difficult to forecast.
Thanks to Climate Central, you can now visualize the effect of sea-level rise in different cities worldwide. The image below illustrates that if we keep our current carbon path, we may need a boat to get to the San Francisco Museum Of Modern Art:
How Sea Level Rise May Affect Buildings?
Erosion is the removal of soil and sand by the forces of wind and water.
Since most of the available land bordering the ocean (coastlines) is developed for housing, the erosion of beaches is a necessary concern. Wave action can cause erosion capable of destroying house support, causing it to tumble into the ocean.
In the United States, coastal erosion is responsible for roughly $500 million per year in coastal property loss, including damage to structures and loss of land. For example, homes along Lake Michigan were damaged and completely demolished due to a record high water levels during the year 2019.
During extremely high tides, also known as nuisance tides, the sea spills onto land in some locations, inundating low-lying areas with seawater.
High-tide flooding is generally very localized, occurring at a scale of city blocks. Projecting flood risk involves estimating future sea-level rise but also comparing it against land elevations. Unfortunately, accurate elevation data is not easily accessible, which clouds understanding of where and when sea-level rise could affect coastal communities. Climate Central shares predictions that six countries are projected to be below the elevation of an average annual flood in 2050.
We detail the floods’ impacts on buildings in our blog on coastal floods along with strategies to mitigate the damage.
Water resources along the coasts are at risk from saltwater intrusion, partly due to rising sea levels. It increases the vulnerability of drinking water in coastal regions. It occurred in Florida when sea levels increased relative to the fresh groundwater levels, allowing higher gradient saltwater to flow toward the groundwater supplies.
Other saltwater intrusions due to sea level rise in Florida caused leaking saltwater inland canals, leakage between aquifers, or even upwelling of saltwater from depth.
Saltwater intrusion can increase the need for treatment in water utilities, relocating water intakes, or the development of alternative sources of freshwater. In some cases, saltwater intrusion may diminish the availability or quality of drinking water utilities.
Decrease in Home Prices
According to research from 2019, homes exposed to sea level rise sell for approximately 7% less than observably equivalent unexposed properties equidistant from the beach. The price reduction has grown over time, driven by sophisticated buyers and communities concerned about global warming.
Another research affirmed that the rate of price appreciation for single-family properties in Miami Dade County, Florida, is positively related to a higher elevation due to an increase in nuisance flooding.
Scientists from the non-profit First Street Foundation found that $7.4 billion has been lost in home value across five coastal states from 2005 to 2017. The organization built a team of leading modelers, researchers, and data scientists to develop a comprehensive, publicly available flood risk model in the United States. Matthew Eby, an Executive Director at First Street Foundation says that with no action, the rate of home value loss will only accelerate.
Forced migration due to sea level rise is not only a problem for places such as Bangladesh or Kiribati Island. A study from 2020 estimates that the United States will also experience human migration due to sea-level rise when inland areas immediately adjacent to the coast and urban areas in the southeast U.S. will be most affected. The study even attempts to predict the safest places to move within the U.S. concerning climate change.
Another study from 2016 by Nature Climate Change found that a sea level rise of 0.9 m by the year 2100 will put 4.2 million people at risk of inundation, whereas a scenario of 1.8 m sea-level rise will affect 13.1 million people. These results suggest that the absence of protective measures could lead to U.S. population movements of a magnitude similar to the twentieth-century Great Migration of southern African-Americans.
What Can Be Done?
By the Federal Government and States
In OECD countries, the implementation of measures to protect from sea level rise is too slow. Most countries are increasing investments to understand climate risks, but there has been far less action in updating regulations. Unfortunately, in places such as Isle of Sheppey, England, homeowners are left to figure out how to protect their homes on their own, while some houses are tumbling down the cliff.
Here are key actions that governments should take to increase protection from sea level rise:
- Prevent new development in areas at risk of flood or erosion through land-use regulation/zoning.
- Form plans with future conditions in mind, not based on past data.
- Change building codes and design standards to account for sea-level rise, such as building elevation and foundation design.
- Provide better access to information, tools, and guidance for flood protection. For example, updating flood maps to include future flood projections.
- Help coastal communities fund programs that plan and implement protection strategies from sea level rise.
“Flooding does not have to be a way of life for coastal communities. Cities can take measures to mitigate the impact and protect property values,” said Matthew Eby, executive director at First Street Foundation.
Cities like Norfolk, VA, New York, NY, and Miami, FL, already suffered the impacts of sea level rise and extreme weather and they hold protection and resilience plans.
Here are some strategies that can protect coastal cities from sea level rise:
- Prevent new development in areas at risk of flood or erosion through land-use regulation/zoning
- One common but controversial strategy for dealing with coastal erosion is beach nourishment—placing additional sand on a beach to serve as a buffer against erosion or enhance the beach's recreational value. Its controversiality derives from cost, maintenance, longevity, and environmental considerations. A recently published study reveals that in the last century, the beaches of over 475 U.S. communities have been restored with beach nourishment. Six states account for over 83% of the 1.2 billion cubic meters (m3) of sand placed on beaches: California, Florida, New Jersey, North Carolina, New York, and Louisiana.
- Coastal Restoration: Healthy coastal ecosystems have proven many benefits such as diffusing storm surges, boosting water quality by filtering pollutants, providing additional areas for recreation and tourism that raise real estate values, and generating economic activity. A report from 2014 shows that an investment in coastal restoration can give back as much as $8 to $24 in benefits for every $1 invested.
- Living Shorelines: a range of shoreline stabilization techniques along estuaries, bays, tributaries, and other sheltered shorelines. Living shorelines are not typically used on beaches on the open ocean. It incorporates natural vegetation or other living, natural ‘soft elements alone or in combination with some type of harder shoreline structure, like oyster reefs, rock sills, or anchored large wood for added stability. The living shorelines academy highlights living shoreline projects in States such as North and South Carolina, Florida, and Louisiana.
- Upgrade infrastructures such as the upgrade of the sewage system in Florida and raising the roads in Miami.
- Build/maintain stern defenses such as seawalls/floodwalls or stormwater pumps. An analysis by the Center for Climate Integrity projects that in 19 small, mostly unincorporated communities, the cost of seawalls from a moderate amount of sea-level rise by 2040 will be higher than $1,000,000 per person. In 43 communities higher than $500,000 per person, and in 178 communities the cost of basic coastal defenses will be more than $100,000 per person.
- In some cases, the only way to prevent structures from harm may be to remove them entirely. After removing the structures, communities usually dedicate the land to public open space or transfer it to land trusts for protection. Research on a beach in North Carolina found many benefits in potential “targeted acquisitions.”
What you can do
In our blog on adapting buildings to floods, we discuss in-depth strategies for buildings to withstand the damages caused by floods. Here are the key solutions:
- When purchasing a property, consider choosing a location further inland, rather than close to the coast. Experts believe that in some cases, there will be no choice but to move out of your beach house.
- Elevation of the whole house. If this isn’t feasible, another option is to elevate mechanical systems and appliances above the floodplain to prevent damage.
- Increase the green infrastructure around your home: increase vegetation and install green roofs. The more vegetation around your home, the more water is absorbed before it reaches your house. Make sure to minimize impervious surfaces such as concrete to allow floodwater to penetrate the ground, and choose a palette of grass and soil instead.
- Use flood resistive materials that can quickly recover after a flood with reduced damage.
- If not too expensive, purchase flood insurance. See our climate insurance blog.
For inspiration, the Urban Land Institute highlights commercial projects designed to withstand sea level rise. Also, check out a residential house designed for folks who were forced to move from their previous homes due to sea level rise climate change.
Sea levels are rising at an undetermined pace and faster than previously predicted by the IPCC. This profoundly affects communities in coastal cities, risking the quality and supply of potable water, setting buildings at higher risk for erosion and flooding, and reducing their value.
If you are considering buying a new home, consider a location further inland rather than close to the coast.
If you already own a beach home, check the estimated sea level in your area, but keep in mind that past and current sea level changes do not necessarily project future sea levels. Safety measures and protection strategies are highly advised even if you are currently at low risk for sea-level rise.
Governments have an essential role in providing tools and education, while cities hold the crucial responsibility for implementing plans to protect residents who live close to the coast. Many cities are already planning and implementing protection strategies.
Still, we are responsible for our own homes, and there are strategies that we can implement to protect them from the impacts of sea-level rise.
KEEP COOL. BUILD RESILIENCE. EAMPACT.