Sea level rise effects: predictions and a map for real action

A house is built to last for decades and offer protection from the elements for those living in it. But for more than a century, sea levels have been rising over the world and it’s frighteningly safe to say these days it’s critical to account for the effects of climate change in the design process before you build a house or consider a large remodel to adapt an existing property for what’s to come.

Depending on where you live, the effects of climate change may differ. Temperature increases, more frequent heatwaves, more storms, and less rainfall are all possible outcomes. But at most coastal locations, sea level rise and greater storm surges are also potential consequences.

Oceanographers estimate that sea levels increase by about 3.6 mm per year (NOAA), and as the oceans rise, on the coast we have the risk of catastrophic storms and flooding with the most common and less harmful (on the surface) nuisance flooding.

Nuisance flooding (NF) refers to low levels of inundation that do not pose significant threats to public safety or cause major property damage, but can disrupt routine day-to-day activities, put added strain on infrastructure systems such as roadways and sewers, and cause minor property damage. 

Compared to extreme flooding and disasters, the occurrence and impacts of nuisance flooding are often ignored, but drive around a salt water flooded area to see the effects on your car parts.

Is Sea Level Rise really happening?

Some people seem to think that climate change is just something for future generations. But as coastal cities continue to become more and more flooded with sea levels rising every day, this problem isn’t going away anytime soon – even though it may initially seem like a distant threat when we are still alive today.

In Maryland, precipitation increased by 2.63 inches per decade, according to NOAA. The administration also found the Northeast Atlantic region saw 100 to 150 percent more flood days in 2020 than in 2000. 

Rising seas have induced a particular type of increased flooding around MD. A phenomenon, known as sunny day flooding because of the absence of rainfall as a trigger, happened more often in the last decade.

These are some locations in Maryland and Virginia that saw a higher occurrence of sunny day flooding in 2018.

• Cambridge, MD: 11 days
• Solomons Island, MD: 11 days
• Tolchester Beach, MD: 17 days
• Windmill Point, VA: 17 days
• Annapolis, MD: 18 days
• Lewisetta, VA: 20 days

The graphic below, shows clearly how days with nuisance flooding have doubled in Atlantic City, NJ compared to 1920. Increases in sea level are causing nuisance floods to be more constant according to a technical report by the National Oceanic and Atmospheric Administration. 

As sea levels rise and storm surges become more frequent, coastal towns have three options for dealing with the situation: protect (by building sea walls, for example), accommodate (by adapting to the impact), or retreat. When it comes to preparing for sea-level rise, homeowners have several alternatives.

• Home Elevation
• Ensuring the components of the home that may flood can cope (for example, the foundations)
• Building a limited-life home to reduce financial outlays
• Move your house somewhere else

It’s also possible that stormwater systems won’t be as effective in draining into the sea, which might lead to flooding further inland. The graphic below shows the same correlation of longer flood hours in a year, and flooded days in Charleston, SC.

NASA has been studying all aspects of sea level rise for decades now. Armed with satellites, airborne missions, shipboard measurements, and supercomputers, NASA launched the first satellite mission to measure ocean heights in 1992. Together with international and interagency partners, they monitor the causes of sea level rise with high accuracy and precision and estimated that global sea level is rising approximately 0.13 inches (3.3 millimeters) a year. 

In 2014, NASA created a Sea Level Change Science Team to bring together experts from across the agency and other institutions that study different aspects of this multidisciplinary problem. These experts study glaciers, ice sheets, ocean physics, land movement and more to tackle what sea level rise looks like now – and what it will look like in the future.

And they have defined the problem as caused mainly by a few factors: 

• Meltwater from ice from the glaciers and ice sheets
• Thermal expansion: Not only is more water flowing into the ocean from ice sheets and glaciers – the warmer water of the ocean is taking up more space, adding to sea level rise.
• Ocean circulation: Sea level rise isn’t consistent across the globe. Some coastal areas see triple the average rate of rise while others don’t observe any changes, or can even see a drop in sea level.
• Solid earth dynamics: Rising sea levels can also be compounded by sinking land. The Mississippi River Delta, for example, is essentially drowning as sinking ground from resource extraction, sediment loading, and the weight of the built environment is combined with higher sea levels. 

Blue sky flooding common in Florida as of lately

Tidal flooding was regularly filling the streets of St. Pete Beach in Florida in 2019 with sea water becoming a growing problem for some neighborhoods on the low-lying island. So much that the city approved an $869,000 improvement project that installed one-way valves that block sea water from coming up the storm drains to prevent King tide Bay water flooding in the streets and storm water flooding as well.

A local resident, Mary Palmer, 88, has lived in a home on E. Maritana Dr. in Saint Petersburg for the past 23 years and said for the first time she began planning her day around the high tides. She mentions having to watch the tide when she would go out to avoid driving through salt water which can be pretty bad for vehicles.

In places with relatively shallow continental shelves, such as along the North Carolina coast, nuisance floods have increased several-fold in the past couple of decades, with cities like Beaufort, North Carolina seeing 30-40 flood days a year this decade, compared with fewer than 10 in the 1980s. Many of these happen in the absence of stormy conditions, hence the name ‘blue sky flooding’.

With funding from the National Oceanic Atmospheric Administration, Kent State University in Ohio has been working on mapping and creating models that can simulate the likelihood of blue sky floods weeks out, to help give communities a chance to prepare.

The project, funded for about $287,000 over three years, focuses on nuisance floods that result from short-term rises in sea level along the Atlantic and Pacific coasts of the United States.

A flood street on the town of Manteo in March 2018 on a clear day.

In North Carolina, the King Tide project is being funded by North Carolina Sea Grant and Carolinas Integrated Sciences and Assessments and began late Summer 2017 documenting extreme water level occurrences across the state. On the website, you can find several pictures taken by regular citizens documenting flooding in their communities.

How are cities preparing for extreme water level events?

The city of Miami Beach has had many programs in place in a multi-year multi-million-dollar program installing a series of storm water pumps, improved drainage systems, elevated roads and higher seawalls.

Despite his history of referring to climate change as a “hoax” and his recent rollback of emissions-slashing initiatives, ex-President Donald Trump is one of these property owners with a stake in the issue. The president frequently visits his Mar-a-Lago estate in Palm Beach, 75 miles (121km) north of Miami, which is itself an area experiencing flooding from high tides. There also are six Trump-branded residential buildings in Sunny Isles, one of which still provides the president with income, and a Trump-branded condominium complex in Hollywood.

But even without floods, the rising water table affects everything. The cities in South Florida are built on porous limestone and the water doesn’t just come over seawalls; it seeps up from beneath the streets. Nearly 90% of the drinking water in south Florida comes from aquifers, and in Hallandale Beach, a small city of just under 40,000 residents north of Miami, saltwater already has breached five of the eight freshwater wells that the city draws from, said Vice Mayor Keith London BBC News.

The other considerable issue is beach erosion. Florida’s sand may be one of its biggest draws for tourist dollars, but it, too, is vulnerable: though sand never stays put, rising sea levels and worsening storms mean the need to replenish beaches is intensifying.

Planning for sea level adaptation for your property

As cities work on public infrastructure to face the increasing problem, property owners should consider the effects of a rising sea level on their location when planning to buy or upgrading their home.

One of the most common residential adaptations is the HVAC systems, and electric meters being raised high enough that they are not affected when water levels rise during a flood. Again, these changes are suitable for both you and the expensive equipment in these areas because if they get flooded, there won’t be any need to replace anything.

The Construction Department sets performance standards for buildings built in bushfires, cyclone and flooding-prone regions. In addition to these minimal requirements, adaptive methods should be explored.

Consider the following questions as you design or redesign a home:

• Will the site and the structure be affected by expected sea level rise?
• In the event of severe weather, what are the likely repercussions for the house?

Managing shifting climate conditions can be made easier if you construct your home with flexibility in mind and pay attention to where it sits on your lot. One option is to make sure your site has enough area for additional rain or stormwater storage and drainage.

Action: Increasing the height of the floors to prevent flooding.

• Potential unintended result:  The use of fill to raise the floor could upset some type of soils and require more adaptation work afterwards, so do your research beforehand.
• It could make it more difficult for those who are less physically fit to use.
• Include ramps or other alternatives if applicable.

What is a house elevation project?

It takes a time and a lot of effort to raise a house. Each pillar of the home must be elevated equally. Different firms employ a wide range of technological approaches. There are a variety of methods for pulling a structure out from under. Some use hydraulic systems, while others rely on hand-operated jacks. A structural investigation of a house must be completed before beginning construction to determine the mass and stability of the structure. After that, the soil and building materials used to build the foundation, pillars, and walls will be tested.

There is a detailed architectural development and design plan to estimate costs, the time necessary for elevation, and the result. People start digging up the topsoil after the blueprints are ready to approach the building’s foundation, isolated from the walls and pillars. The house is raised uniformly using steel beams or jacks, either manually or hydraulically.

Why does someone need to elevate their house?

Lifting your house might be advantageous for a variety of reasons. After a natural disaster (or even before one), many people want to have their houses elevated to avoid floods. Lifting their home is an excellent solution for those who don’t have the option of expanding horizontally. You can build room for a basement or fix a shaky foundation by excavating. Whatever the cause, lifting your house is a major operation, and you’ll want a professional house lifter on the job to make sure it’s done right and safely. It’s time to go to work once your crew is put together. 

Some homeowners decide to lift their houses off the foundation and relocate them vertically to fix problems like flooding or a deteriorating foundation.

According to Norman Messier, proprietor of Messier House Moving & Construction in Barre, VT, who relocates a few homes each year, “it makes sense to consider relocating the structure when the foundation is in need of replacement.”

How do you increase the foundation of a house?

Moving or elevating a house is a four-step process:

• Building preparation

• Site preparation

• The elevation

• Placing the house in its new location

Most of the time, houses are yanked out from under the sills, says Messier. Most professional movers employ unified hydraulic jacking systems to lift the building to reduce the risk of structural damage. They’re supported by cribbing, and the structure is held together by a web of beams by a network of posts.

Frequently Asked Questions about sea level rise