<meta http-equiv="refresh" content="0; url=https://r.sealevelrise.org/https://sealevelrise.org/states/louisiana/"/> Louisiana’s Sea Level Rise - Sea Level Rise

Overview

Louisiana’s Sea Level Has Risen 24” Since 1950

And It's Already Costing Over $25 Billion

The sea level around Louisiana is 24 inches higher than it was in 1950.1 This increase is mostly due to sinking land, and it’s causing major issues. New Orleans is the largest population center at risk from sea level rise in the country and is now experiencing one of the highest rates of sea level rise in the world. Because the state is already losing approximately 25 square miles of land per decade due to sea level rise,2 Louisiana’s coastal marshes, which provide protection for inland communities and habitat for countless species, are threatened. The state is planning over $25 billion in sea level rise solutions, which include building levees, restoring shorelines, and relocating entire communities.

Sea level rise is speeding up

Although the sea has only risen by 24 inches since 1950, its speed of rise has accelerated over the last ten years and it’s now rising by over 1 inch every 2 years.1 We know this because the sea level is measured every 6 minutes.4 Scientists use different equipment like satellites, floating buoys off the coast, and tidal gauges to accurately measure the local sea level as it accelerates and changes.

Created with Highcharts 6.2.0

SEA LEVEL MEASUREMENT FROM GRAND ISLE AREA TIDE GAUGE SINCE 1950

Causes & Complications

Why Are Sea Levels Rising?

While there are four causes of sea level rise in Louisiana, land sinkage is the main contributor.5 Recent studies have shown that Louisiana is losing approximately a football field of land every hour,2 which makes the state particularly vulnerable to an increased rate of sea level rise in the future. Click here to learn more about these causes.

How Land Sinkage Increases Sea Level Rise

Most flooding happens during the fall

King tides are unusually high tides that are created during months when the sun, moon, and earth align. The combined gravitational pull of the moon and the sun creates much higher tides, called king tides. In some places, king tides are brought on by changes in the weather and ocean patterns. In places like Louisiana, king tides are typically nearly a foot higher than normal tides.1 Add that to the 24 inches of sea level rise since 1950, and you end up with flooding even on sunny days.1

Solutions aren’t simple

New Orleans is the largest population center at risk from sea level rise in the country and is now experiencing one of the highest rates of sea level rise in the world.6 The main contributors to Louisiana’s sea level rise are a combination of land sinkage and erosion, which makes finding solutions complicated.

Cities that flood-hazard mitigate their buildings and build protective structures to prevent flooding, are the most sustainable communities in the future. These are the communities that will be able to continue to fund important adaptations.

Roderick D. Scott, Flood Hazard Mitigation Specialist and Technical Education Provider, L & R Resources, LLC
Roderick Scott

Forecast

What's the Future of Sea Level Rise?

In the last decade, the speed at which Louisiana’s sea level is rising has increased, and is now rising by over an inch every 2 years.1 Around Grand Isle, it took 20 years for the sea level to rise around 10 inches.1 Scientists now forecast that the sea will rise another 10 inches in just the next 15 years.7

Scientists are not certain how fast the ocean will warm and ice will melt. They expect water levels to continue to rise faster, but are not sure just how fast. Therefore scientists from the National Oceanic and Atmospheric Administration (NOAA) and the US Army Corps of Engineers (USACE) have made predictions based on ranges from low to high.

Below you can see the range of the NOAA and USACE high and intermediate forecasts for various locations around Louisiana.8 We are currently closest to the USACE high forecast, which is the darkest red line.

New Orleans, 2005

Eugine Island
Created with Highcharts 6.2.0Eugine Island Sea Level Rise Forecasts

Flooding

Why Are Floods More Frequent?

When the ocean rises high enough, high tides cause flooding even on sunny days. Even though the sea level has only risen by around 9 inches, tidal flooding has increased by 100% in Louisiana since 2000.9

Flooding
How sea level rise affects Louisiana

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.

Drain A
Drainage Under Normal Tidal Conditions
Drainage With King Tide / Sea Level Rise

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.

hurricane katrina louisiana image

Hurricane Katrina, 2005

Higher sea levels create a higher launching point for storm surge. These small changes in sea level rise are enough to turn what were 100-year storm surges into much more frequent events. In fact, in a third of 55 coastal sites studied throughout the US, 100-year storm surges will be 10-year or more frequent events by 2050.10

This means that in many coastal cities, if you bought a house with a 30-year mortgage today, by the time you paid off your mortgage you could be experiencing extreme 100-year storm surges ten times more frequently due to sea level rise alone. This does not include the added risk of more intense storms resulting from warmer water and a warmer atmosphere, which could further increase storm surge damage.

In 2005, Hurricane Katrina hit Louisiana as a Category 3 hurricane, causing parts of the levee system in New Orleans to fail and $165 billion in damages.11 Without sea level rise, Hurricane Katrina’s estimated 28 foot storm surge would have been lower.12

hurricane katrina louisiana image

Hurricane Katrina, 2005

Costs

What's at Risk in Louisiana?

There’s a lot at risk from sea level rise and flooding in Louisiana, particularly because the state has already lost approximately 25 square miles of land per year in the last decade due to sea level rise.13 Louisiana’s coastal marshes, which provide protection for inland communities and habitat for countless species, are threatened. Saltwater intrusion is beginning to kill vegetation and without major efforts to rebuild the state’s wetlands, communities along the coast will not be able to withstand the rate of sea level rise.14 The state is host to a robust economic system; the Port of New Orleans alone supports a $37 billion economy and businesses rely on shipments to remain open.15

Coastal Wetlands
Coastal Wetlands

Sea level rise can disrupt coastal wetlands, which puts important ecosystems in danger, threatens habitats, and leaves communities exposed to dangerous storm surge.

Homes & Cars
Homes & Cars

Storm surges or flooding can damage the underside of your car or the first level of your home.

Business & Economy
Business & Economy

Flooding can damage sales, shop interiors, and merchandise, and force businesses to close. Tourism and port industries can be impacted or shut down by sea level rise.

Communities that are not flood-hazard mitigating their buildings will realize property value loss, and the vital revenues used to fund adaptation, will slowly disappear.

Roderick D. Scott, Flood Hazard Mitigation Specialist and Technical Education Provider, L & R Resources, LLC
Roderick Scott

Louisiana is spending over $25 billion

Some cities have sufficient resources to deal with this problem while others do not. Louisiana will need solutions at the individual, local, state, and federal levels to protect its coastal communities.

Louisiana
Louisiana

Louisiana has a $25 billion master plan to deal with sea level rise and flooding, which includes projects to build levees, pump sediment into sinking areas, and build natural infrastructure.16

Grand Isle
Grand Isle

There is a $216 million project underway in Grand Isle to restore and improve the shoreline.17

Jean Charles
Jean Charles

Isle de Jean Charles residents will be relocated in a move costing $58 million.18

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.