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How coastal erosion is threatening the world’s beaches

Posted on May 8, 2024

The number of seaside communities whose beaches are losing sand is growing exponentially. What are the explanations for coastal erosion, and what can be done to mitigate its devastating impact?

A 2018 study published in Nature stressed that examination of satellite-derived shoreline data reveals that more than a quarter of the Earth’s sandy beaches are experiencing erosion surpassing 0.5 meters per year (1.6 feet), and 16 percent losing more than 1 meter per year.

It’s not opinion – it’s a scientific fact.

The first signs of world beach erosion emerged in the 1980s.

Still, it was only when consistent, back-to-back yearly figures were confirmed in the field that local authorities, property owners, and national governmental agencies took measures to address the problem.

What Is Coastal Erosion?

Coastal erosion is the process by which the land along the coast, such as beaches and cliffs, is worn away or destroyed by the constant action of the sea, wind, rain, and even ice.

Coastal erosion: the impact of ocean swells and climate change is decimating California beaches | Photo: Jeff Vincent/Creative Commons

The slow and steady process can happen in various ways, including the force of waves crashing against the shore, the movement of water and sediment, and even the effects of storms and strong winds.

The sea’s constant interaction with the land causes erosion through five main mechanisms:

  1. Hydraulic Action: When waves hit cliffs and degrade their structure, causing caves. The force of the water against the land causes air to be compressed in cracks and joints in the rock, leading to explosive releases of pressure as the water recedes. The result is significant damage to the land, sometimes even breaking off large chunks of it;
  2. Attrition: When waves make pieces of rocks grind each other and make them smaller. Rocks and pebbles are carried by waves and collide with each other, breaking apart and wearing down the land. The process can also contribute to the formation of smoother surfaces over time;
  3. Solution: When seawater acids dissolve seaside minerals and rocks. Acids present in seawater dissolve certain types of rocks, such as limestone, which are more susceptible to erosion by these acids. The chemical process is slower compared to the mechanical actions of erosion but can still have significant effects over time;
  4. Abrasion: When waves hit cliffs and progressively erode them. The constant movement of sand and rocks against the land wears it down like sandpaper would wear down a surface. It’s a particularly common process in areas where there are strong waves and high-energy storm conditions;
  5. Corrosion: When the sea water’s pH slowly corrodes the headland;

The ocean and swells are by far the most powerful coastal erosion boosters.

Over time, particularly during winter, storm-generated waves hit the coast and carry tiny particles of sand, rock, and dirt away.

They move these particles along the shoreline or drag them out to sea, gradually changing the shape of the coast.

It is important to note that coastal erosion is a natural process that has been occurring for thousands of years.

It’s part of a coastline’s natural morphodynamics.

However, human activities such as climate change are increasing the erosion rate significantly.

The loss of sand in the world’s shorelines will be more noticeable and serious by the end of the 21st century.

This aggravation is caused by the expected rise in sea levels and the increased frequency and intensity of storms and strong winds brought about by climate change.

Cottons Point, California: the differences in sand availability between 2008 and 2021 | Photos: Bring Back Our Beaches

Other Relevant Factors

While the ocean and meteorological variables play a decisive role in coastal erosion, other natural and human-related activities help degrade dry beach availability.

For instance, weathering and transport slope processes are always present and difficult to control.

It includes the breakdown of rocks and soil due to weather conditions like rain, wind, and even temperature changes.

When rocks break down, they can be easily carried away by water, wind, or gravity, contributing to coastal erosion.

Water can also weaken the stability of the beach slope, making it more prone to erosion.

Plants play a crucial role in preventing erosion because their roots help hold the soil in place, reducing the risk of erosion caused by water and wind.

So, when vegetation is removed or damaged through deforestation or urban development, it can accelerate the loss of land near the sea.

The temptation is huge, but building residential areas along the coast can disrupt natural coastal processes and accelerate erosion.

Activities like mining sand and gravel from beaches or offshore areas can contribute to coastal erosion by removing sediment that would otherwise help protect the coast from erosion.

How territorial planners manage coastal areas can either exacerbate or mitigate the displacement of seaside sand strips.

Effective options such as building seawalls, implementing beach nourishment projects, and establishing zoning regulations can help protect coastlines, but the fine line is thin.

Improper or inadequate coastal management choices can easily worsen erosion problems, and unfortunately, they’re more common than we should expect.

Dunes are one of the most underrated weapons against beach degradation. They are the first line of defense against the elements.

good dune system promotes a healthy shift of sand through the seasons and protects inland structures against the sea’s ruthless incursions.

What about seaweed?

Removing seaweed from the beaches to make them look good and appealing is a mistake because it prevents crashing waves from sweeping sand out into the sea.

Impact on Human Activity

Coastal erosion has significant impacts on human activity and the environment.

For example, it can lead to the loss of land, damage to buildings, and even the destruction of entire coastal communities.

In some cases, erosion can also change the shape of the coastline, creating new landforms like tunnels, bridges, and pillars.

According to NOAA’s Office for Coastal Management, shoreline erosion causes around $500 million in property loss and damage in the United States annually.

The federal government allocates an average of $150 million annually towards beach nourishment and various shoreline erosion control strategies to address coastal erosion.

Coastal erosion is more than houses collapsing, headlands falling like melting icebergs, and waves invading city streets.

It also involves the loss of coastal wetlands and natural reserves, the destruction of wildlife habitats, the disappearance of fishing resources, the damage to railway tracks, and the harm to tourism attractions.

California is one of the world’s most affected areas by coastal degradation, with landslides becoming the new normal.

Beaches are shrinking more than they gain sand, and the strategies to minimize this issue are limited.

Beach nourishment is an expensive and temporary solution. Seawalls, jetties, breakwaters, and groins protect the coastline but slowly kill beaches.

The construction of strategically located human-made headlands and artificial reefs is being studied as the generation 2.0 softening solution for the dramatic consequences of coastal erosion.


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