A Picture Is Worth a Thousand Words: How Louisiana's Coastline Changed in 40 Years

The old proverb “A picture is worth a thousand words” reminds us that sometimes an image can reveal a story more powerfully than words ever could.

That is exactly what satellite images of southern Louisiana are showing.

NASA compared images of Louisiana’s coast taken in 1985 and 2024. Around Bay Dosgris, roughly 30 miles south of New Orleans, the images reveal a dramatic transformation: areas that were once covered by wetlands and marshes have, in many places, become open water.

The change did not happen overnight. It represents nearly four decades of gradual land loss caused by a combination of natural processes, rising water levels and human activities.

A Coastline Slowly Losing Ground

Louisiana’s coastal wetlands exist at a fragile boundary between land and sea.

Healthy marshes depend on a delicate balance. Vegetation adds organic material, rivers deliver sediment, and wetlands must remain high enough above the water to support plant growth.

When that balance is disturbed, the process can work in the opposite direction.

A wetland may first become increasingly waterlogged. Vegetation declines, open water expands and, over time, the marsh can disappear completely.

NASA’s comparison of Landsat 5 imagery from August 31, 1985, and Landsat 9 imagery from October 21, 2024, provides a visual record of this transformation.

What Changed Between 1985 and 2024?

In the older satellite image, Bay Dosgris contained extensive areas of marsh and wetland.

In the 2024 image, some of those areas appear as open water.

But scientists caution that not every apparent change from wetland to water represents permanent land loss. Temporary flooding, particularly after storms and hurricanes, can also make wetlands appear submerged.

The important distinction is between temporary flooding and permanent conversion of wetlands into open water.

In Louisiana, both processes can occur, but long-term erosion, subsidence and increasing inundation have contributed to lasting changes.

Why Is Louisiana Losing Its Wetlands?

The answer is not a single factor.

Louisiana’s disappearing wetlands are the result of several forces working together.

1. Reduced Sediment Supply

Historically, the Mississippi River carried huge quantities of sediment toward the delta.

That sediment helped build and maintain wetlands.

However, levees, dams and other river-control structures have restricted the natural movement of sediment into many coastal areas.

With less sediment arriving, wetlands have less material with which to rebuild themselves.

2. Land Subsidence

The ground itself is sinking in parts of coastal Louisiana.

Natural geological processes contribute to subsidence, while activities such as groundwater and oil and gas extraction can also influence land movement.

When land sinks while water levels rise, wetlands become increasingly vulnerable.

3. Canals and Coastal Development

Navigation and energy-development canals have changed the way water moves through Louisiana’s marshes.

These canals can create pathways for water to enter wetlands while exposing marsh edges to erosion.

Waves, tides and storms can then accelerate the loss.

4. Rising Sea Levels

Sea-level rise adds another major challenge.

According to research published in Nature Communications, present-day relative sea-level rise along coastal Louisiana averages around 12 millimetres per year, although rates vary across the region.

When water rises faster than a wetland can build elevation, the marsh becomes increasingly vulnerable to prolonged flooding.

Nearly 5,000 Square Kilometres Lost

The transformation seen in the satellite images is not an isolated event.

Research published in Nature Communications found that Louisiana lost approximately 5,000 square kilometres of coastal wetlands between 1932 and 2010.

Scientists have linked this loss to a combination of:

Reduced sediment delivery
River levees and dams
Navigation canals
Oil and gas activities
Land subsidence
Erosion
Sea-level rise
Storm impacts

This shows why Louisiana’s disappearing coastline cannot be explained by one cause alone.

The Proverb Behind the Picture

The proverb “A picture is worth a thousand words” is particularly appropriate here.

A table can tell us that wetlands are disappearing.

A scientific paper can explain erosion, subsidence and sea-level rise.

But placing a 1985 satellite image beside a 2024 image allows people to see the transformation directly.

The landscape itself becomes evidence.

Not All Wetlands Are Disappearing at the Same Rate

Another important lesson from the satellite record is that Louisiana’s coast is not changing uniformly.

Some areas are disappearing rapidly, while others remain relatively stable.

Elsewhere, restoration projects have helped rebuild vulnerable islands and wetlands.

Scientists therefore increasingly rely on long-term satellite observations to identify where land is being lost, where wetlands are recovering and where intervention could make the biggest difference.

What the Future May Look Like

Louisiana’s coastal wetlands provide important ecological and economic benefits. They support wildlife, store carbon and help protect inland areas from storms and waves.

But their future depends on whether wetlands can build elevation quickly enough to keep pace with rising water levels and other pressures.

The satellite record provides a warning as well as a source of knowledge.