A topographical map of estimated sea level rise intrusion on the Miami area.

Sea level rise is not on the radar for many people.  But in terms of our financial security, it could become one of the most important things to calculate sea level rise when buying a home or planning for the future.

That may sound dramatic, but the oceans are rising at an increasingly faster rate.

According to some studies, the impact of the rising sea level on our homes affects over 600 million people worldwide—forty percent of the population lives near a coastal area

A picture of a small home surrounded by flooding.
Depending on your location, your risk of sea level rise may vary. For my fellow Floridians, that risk is higher than most.

In this article, we focus on understanding sea level rise, factors to consider when finding or planning where you’ll live, and long-term effects on your home value and overall future wealth.

If you want to jump directly to our calculator – click here.

What is Sea Level Rise Anyway?

Sea level rise refers to an increase in the level of oceans across the world. According to NASA’s Global Climate Change, sea level rise results from human-induced global warming.

The short version is that the earth is heating up, mainly due to human activity and global warming. This creates an expansion of the ocean’s water.

According to NASA’s Global Climate Change website:

“Sea level rise is caused primarily by two factors related to global warming: the added water from melting ice sheets and glaciers and the expansion of seawater as it warms.”

Let’s look at how it all happens, leading us back to the global warming phenomenon:

Glaciers and Ice Sheets

These are large masses of ice on the inland. As the earth’s temperature keeps rising due to human activities, these masses of ice start melting.

As they do, the water flows into the oceans. As you would expect, more water makes the ocean surface to rise, eroding the coastline.

Water Expansion

Water expands with temperature. To put this into perspective, increasing the temperature of a given unit of water by one degree Celsius causes an expansion of about 0.000208 of the same unit.

Therefore, as the world continues to battle global warming, the high temperatures are causing water expansion in oceans. The high volume of water that results from this expansion causes a rise in the sea level.

The melting of the Antarctic ice sheets is an excellent example of our case. Studies have also linked the melting of the Greenland ice sheet to the rising sea levels.

With the above information, you can now appreciate that the rate at which the sea level rises keeps accelerating by year due to the rising global warming. For instance, in 2021, the global sea level rose to 97 mm, indicating a 3.8-inch rise compared to 1993.

The rate at which the sea level has been rising almost doubled between 2006 and 2015, from 1.4 mm (0.06 inches) in 2006 to 3.6 mm (0.14 inches) in 2015. You should expect this level to keep accelerating due to increased human activities contributing more to global warming. 

Nature Doesn’t Care What We Think

While this issue has been heavily politicized, especially in the United States, it doesn’t matter what you or I think. Facts are facts, and I would argue that if you’re looking at living in or buying a home anywhere near the coastline, you’ll want to take a few minutes at least to see how rising seas may affect your home over the years.

Because like it or not, nature doesn’t care about what we believe.

Here are the usual suspects for rising global sea levels from 1993-2018. Courtesy of Climate.gov – Contributors to Global Sea Level Rise 1993-2018

Florida: A Case Study in Sea Level Rise

Florida has a population of over 21 million people, with thousands of people moving here daily.  This scenario makes for a good example of what’s happening in real-time regarding sea level rise and real estate.

Many people (myself included) enjoy living here for the beaches, low taxes, sunshine, and great weather year-round. But the effects of sea level rise persist daily.

Sporting over 8,000 miles of shoreline, Florida is especially at risk from rising water levels.

A study from Climate Central estimates that 65,000 homes in Florida (worth over $35 billion) are expected to be underwater or impacted daily by high tides in 2040.

Much of Florida’s land is at or just a few feet above sea level. Much of this land, particularly in the South Florida region, is low-lying and made of porous limestone underneath the surface.

This means that as seawater rises, it creeps inland and underneath existing homes.

It infiltrates freshwater supplies and effectively rises from underneath you instead of just from the coastlines, among other things.

Miami

This city has been in the spotlight over the past few years, serving as the “canary in the coal mine,” so to speak.

The city passed a $400M general obligation bond paid for by local residents to fight back against rising ocean currents. According to the Southeast Florida Climate Compact:

“Nearly half of the bond proceeds will be directed toward reducing flooding risks and sea level rise mitigation, with another quarter invested in improving affordable housing. The remaining will be split among enhancing public safety and improving parks, cultural facilities, streets, and infrastructure.”

Change in sea level since 1880. Courtesy of Climate.gov

Sunny Day Flooding

In addition to hurricane activity and tidal surge, the term “sunny day floods” has now become a thing.  In some cases, sea level rise has created flooding for 40 straight days

There are many great resources and documentaries online for more info, but you get the idea. This is an example of what’s happening right now in many cities and towns around the world.

Projecting the different scenarios for levels of sea level rise. Courtesy of Climate.gov

The Effects of Rising Seas On Your Home: Factors to Consider

Bringing this back to how it affects you and your home, here are some very real and specific consequences of how sea level rise can hit home (pun intended).

Overflowing Sewage

Many cities have decaying or leaky pipes directly below the surface.

When the seas rise enough to submerge the sewage system, naturally, there’s nowhere to go.

You can use your imagination (hopefully, you’re not eating), but cities like Fort Lauderdale are already dealing with spills into rivers and canals and pipes backing up, among other things.

Contamination of Fresh Water Supply

As time goes on and oceans continue to rise, there is an increased risk of salt contaminating freshwater aquifers and wells.

Saltwater contamination may contribute to increasing stress on freshwater supply. Courtesy of the National Environmental Education Foundation

Flooding and Flood Insurance

Beyond the water itself infiltrating your property and causing costly damage, flood insurance premiums are only getting more expensive.

If you’re in an official flood zone, lenders will require flood insurance on the property.

Depending on the price, this required insurance can add hundreds to the monthly costs of owning a home.

Other knock-on effects include slowing your personal wealth-building due to increased costs and suppressing home value over time as well.

The Numbers Don’t Work

There’s a real systemic issue arising from increased floods and sea level rise in addition to the above problems.

In some cases, private insurance companies are pulling out of cities and states. Those states are left only with the federally funded FEMA National Flood Insurance Program, which is financially underwater itself.

Graph of the National Flood Insurance Program Debt. Courtesy of FEMA

FEMA has a great tool where you can look up your exact flood zone by address here. The map will show different shades of flood map risk, and you can see whether or not you’ll need flood insurance.  Here’s an example:

Clear and orange (at risk) shaded areas: no insurance needed. The blue shaded area (needed) if you have a loan on the property. Courtesy of this interactive map from FEMA

Resale Value

As time goes on and seas only get higher, homes near or at sea level will go down in value. Usability, insurability, and mortgage default risk will all play into this. 

A home that faces continued flooding, unusable roads nearby, or prohibitively high insurance premiums will not be in demand. There are places around the country where this is already happening.

Ability to Get a Mortgage or Refinance

You may not have an issue getting a loan right now. But if you plan to keep the home for a long time, you may run into big problems in the future.

This is speculation, but let’s say that in fifteen years, you want to refinance or get a new loan. The house may now be considered high-risk, and you may be unable to get another 30-year loan on it.

Or, you may not be able to get it insured due to rising water levels. That will also prevent you from taking a loan on the property.

It’s also possible that you could get put into a much higher interest rate bracket since all the above scenarios put you at a higher risk of defaulting on your loan.

“Not only are the mortgage loans on these homes at growing risk of default if the value of the properties drops, but each successful sale of one of these homes represents the potential transfer of a major latent financial liability,” noted the authors of the Union of Concerned Scientists report. “Eventually, the final unlucky homeowners will hold deeds to significantly devalued properties.”

NPR

Personal Finance and Wealth-Building

We all work so hard to pay the bills and maybe save a little bit beyond that.

It’s widely accepted that real estate can be one of the best wealth-generating tools you’ll use in your lifetime.

And even if a particular home isn’t at risk at this moment, it may be in 10-20 years from now. These issues may not be visible right now. But there are potentially some significant problems lurking under the surface (OK, enough puns).

At the end of the day, someone will have to pay for all of this. And you can bet that insurance and mortgage companies will not be the ones wanting to do it.

There are different factors linked to every home, but you can imagine how sea level rise could affect things.

Measuring a Rise in Sea Level

Before we proceed to calculate sea level rise in your home, it’s worth having background knowledge on how the rise in sea level is measured. This way, you’ll know how the formula to calculate sea level rise in your home came about.

It’s impossible to stand at the shoreline with a big ruler to measure the ocean’s level because the level changes in the following ways:

  • By second through waves
  • By the hour, due to the tides
  • By the week, due to solar orbit and planetary changes

Scientists rely on tide gauges and satellite altimeters to combat these changes for a more accurate sea rise.

Tide gauge stations across the world constantly measure the daily highs and lows of the sea using automatic sensors. Scientists use this data to determine the rise in sea level.

Moreover, scientists use radar altimeters from space to measure the rise in sea levels. These altimeters rely on the return speed and intensity of radar pulses to come up with accurate information.

How to Calculate Sea Level Rise On Your Own Home

Whether you’re already in a home or looking to buy soon, it’s a good idea to know how the property could be affected in the future. Some may have no issues because they are well above any flooding or coastlines. If so, awesome!

But if you’re anywhere near water, spending a few minutes on it could give you some peace of mind.

The good news is that most of the work has been done already by some amazing scientists and organizations. Our calculator takes things further by:

1) Incorporating tools to find the elevation on your own address

2) Estimating the average sea level rise per day

3) Running scenarios going out 100 years

4) Including calculations for inches, feet, and meters

5) Creating a table showing you the potential new net elevation after sea levels rise through the years.

A picture of our 100-year table showing how to calculate sea level rise for your own address.
Here’s an example of inputting your own current elevation to estimate possible sea level rise over the next 100 years.

To get a copy for yourself, you can download it here for free. It’s an easy link to a Google Sheet, which requires no additional software or space on your computer –

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Your home may or may not be directly threatened by sea level rise. But we hope you’ve seen how rising sea levels affect all of us who live anywhere near a coastal region.

It’s on us to plan for the future instead of ignoring it until the water is on our doorstep. Together, we can adjust to the inevitable environmental changes in the most affordable and comfortable way for everyone.

For other equally destructive natural disasters, such as hurricanes, our articles on How Much It Costs To Hurricane Proof Your Home and Making Your Manufactured Home Hurricane-Resistant offer methods to prepare your home!

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