South Carolina's Sea Level Is Rising

The sea level off South Carolina’s coast is up to 10 inches higher than it was in 1950.¹ This increase is mostly due to ice melt, and it’s causing major issues. In the 1970s the city of Charleston experienced an average of 2 days of flooding per year,  but now it is projected that the City could experience 180 days of tidal flooding by 2045.² Across the state, flooding has increased 75% since 2000.³ Because of its low elevation, Charleston’s medical district is exceptionally vulnerable to flooding. During flood events, areas of MUSC become inaccessible, making it impossible to evacuate or move patients.⁴

There are already over 90,000 properties at risk from frequent tidal flooding in South Carolina.⁵ The state is planning over $2 billion in sea level rise solutions, which include beach renourishment, seawalls, drainage improvements, and raising roads.

Sea level rise is speeding up

The sea level around Charleston, South Carolina, has risen by 10 inches since 1950. Its speed of rise has accelerated over the last ten years and it’s now rising by about 1 inch every 2 years.¹ Scientists know this because the sea level is measured every 6 minutes using equipment like satellites, floating buoys off the coast, and tidal gauges to accurately measure the local sea level as it accelerates and changes.⁶

While there are four main causes of sea level rise in South Carolina, land sinkage is the largest contributor.⁷ Because the land is getting lower each year, due to a process called subsidence, South Carolina is particularly vulnerable to an increased rate of sea level rise in the future. Click here to learn more about these causes.

Most flooding happens during the fall

King tides are unusually high tides that generally occur during a new for full moon, or when the sun, moon, and earth align. In some places, king tides are brought on by changes in the weather and ocean patterns. In places like Charleston, king tides are typically nearly a foot and a half higher than normal.¹ Add that to the 10 inches of sea level rise since 1950, and you end up with flooding even on sunny days.

Solutions aren’t simple

In the 1970s, Charleston experienced just 2 days of tidal flooding per year on average; by 2016, the city saw 9 days of tidal flooding.³ Today, flooding across the state has increased by 75%.³ In Beaufort County, SC, the ground is sinking approximately 1 inch lower every 20 years.⁸ This makes buildings and streets more vulnerable to the rising sea and solutions more complicated, but also more urgent.

When the ocean rises high enough, high tides cause flooding even on sunny days. Even though the sea level has only risen by around 4 inches, tidal flooding has increased by 75% in some areas of South Carolina since 2000.²

Flooding even when there’s no rain

Drainage systems are designed to channel excess rainwater from the streets and drain it into the sea. But with the pressure from rising sea levels and higher tides, seawater can get pushed into these pipes and spill out into the streets. This causes flooding even on days without rain.

Increased storm surge flooding

Unfortunately, slightly higher sea levels make hurricanes even more damaging. Just a few more inches of sea level rise allow a hurricane to push more water onto the land, even if the hurricane itself doesn’t make landfall.

There’s a lot at risk from sea level rise and flooding in South Carolina. Charleston is home to many hospitals which have roads nearby that flood, making it impossible at times for emergency vehicles to get to these hospitals quickly.⁴ In addition to this and the residential areas that flood, the city also has historic areas that are becoming inundated with more water, more frequently. As sea level continues to rise, these issues will only become worse.

In Charleston there are 5,543 residential properties already at risk from repeated tidal flooding, by 2033 that number will increase to 8,349 as sea levels rise. In Mount Pleasant, 3,549 properties at risk will turn into 5,347 within 15 years. In Kiawah Island there are 850 properties at risk, which will become 1,355. And in Hilton Head Island, there are 1,180 properties at risk, which will increase to 2,603 by 2033. Click here to explore other coastal communities in South Carolina that are at risk at FloodiQ.com.

What can you do?

Individuals, mayors, legislators, governors, and Congress can work together to build protections before flooding, to build back stronger after flooding, and to create plans that future-proof our communities. Click here to see what solutions can help protect your home or what your community can do.