New Jersey used 47 years of coastal storm data to uncover a hidden erosion threat; the result revealed damaging storm conditions at Sandy Hook now occur twice as often as they did in 1979

For decades, North Beach at Sandy Hook looked like a quiet exception to coastal erosion in New Jersey. The beach was actually getting wider. Sand kept moving north and building new ground along the shoreline. But beneath that growing beach, scientists found a very different story.

A new study has uncovered evidence that damaging coastal storm conditions at Sandy Hook now occur about twice as often as they did in 1979. The finding does not mean New Jersey suddenly has twice as many storms. Instead, storms are more frequently producing the particular combination of high water and powerful waves that can strip sand from the shore.

That distinction matters. A coastline can appear stable, or even healthy, while its most damaging conditions are quietly becoming more common.

Coastal Erosion in New Jersey Was Hidden Beneath a Growing Beach

The discovery began with an unusual feature of North Beach at Sandy Hook. Unlike many beaches along the Jersey Shore, this part of the coastline has been expanding toward the Atlantic.

Researchers found that the beach moved seaward by roughly 1,300 feet, or 400 meters, during the past two decades. That amounts to an average expansion of about 66 feet each year. Sand traveling northward accumulated where the shoreline bends around Sandy Hook.

At first glance, that sounds like good news for coastal erosion in New Jersey. A growing beach seems less vulnerable than a shrinking one. Yet the researchers realized that the same process creating new beach was also preserving something valuable.

Fresh sand buried older surfaces created when powerful storms had temporarily torn the beach apart.

That turned North Beach into something scientists rarely get from a modern shoreline: a physical archive of storms.

Researchers used ground-penetrating radar to look beneath the sand. The equipment sends electromagnetic pulses into the ground and records reflections from different sediment layers. Those layers revealed structures that could not be seen from the surface.

The beach was telling a story that ordinary photographs could not.

What Did Researchers Find About Coastal Erosion in New Jersey?

The team identified 20 buried surfaces linked to major erosion events between 2009 and 2019. GPS measurements helped researchers compare those buried surfaces with earlier beach surveys. They then excavated trenches and examined sediment samples to confirm what the radar had detected.

The evidence showed how quickly storms can interrupt years of gradual beach growth.

A beach may build outward for months or years. Then a single powerful storm can remove dozens of feet of sand within hours or days. Eventually, calmer conditions may allow sediment to accumulate again.

One buried layer stood out.

It contained coarse sand, shells, pebbles and dark minerals associated with Superstorm Sandy in October 2012. The layer was about 12 inches thick and provided a striking physical signature of the storm's force.

This is important for understanding coastal erosion in New Jersey because short-term beach surveys can miss the larger pattern.

A survey taken before a storm shows one coastline. Another taken afterward shows a different one. If measurements are too widely spaced, scientists may know that the beach changed without knowing exactly what caused the change.

The buried layers fill that gap.

They preserve traces of storms that would otherwise disappear as waves rearrange the sand.

Why Are Damaging Storm Conditions Happening More Often?

The researchers then asked the question that makes this study especially important.

What exactly turns an ordinary storm into an erosion-producing event at North Beach?

To answer it, they used more than 1,000 computer simulations with XBeach, a model designed to examine how waves and changing water levels affect coastal areas. The simulations were compared with Sandy Hook tide-gauge measurements, offshore wave records and observed changes in the beach.

The analysis identified an approximate erosion threshold.

It is not simply about how strong a storm is.

Water level matters because higher water allows waves to travel farther up the beach. Large waves then have greater ability to move sand away from the shoreline.

That combination is the critical point.

Using storm records going back to 1979, researchers calculated how frequently conditions crossed the threshold associated with significant erosion. Their result was striking: such conditions now occur about twice as frequently as they did at the beginning of the record.

For coastal erosion in New Jersey, that may be more meaningful than simply counting storms.

A community does not lose a beach because a storm has a particular name. It loses sand when waves, water levels, wind and shoreline conditions interact in the wrong way.

The study therefore points toward a more useful way of thinking about coastal risk.

The question is not only, “How many storms are coming?”

It is also, “How often are storms reaching the conditions that can physically reshape this beach?”

Does the Sandy Hook Finding Mean Every New Jersey Beach Is at Risk?

There is an important caution.

The erosion threshold calculated by the researchers applies specifically to North Beach. It cannot simply be copied onto every beach in New Jersey.

Coastlines differ in shape, sediment supply, dunes, orientation and exposure to waves. A storm that causes severe coastal erosion in New Jersey at one location may have a smaller effect several miles away.

That is why the study's broader message is more nuanced than saying every Jersey Shore beach is now eroding twice as quickly.

Researchers believe the finding nevertheless has regional significance. Many of the major storms preserved in the Sandy Hook record were nor'easters or tropical cyclones capable of affecting large portions of the Mid-Atlantic coast.

The study also offers a useful warning about how people interpret a changing shoreline.

A beach that is growing is not necessarily a beach that is becoming safer.

North Beach demonstrates why.

Its long-term supply of sand has allowed it to expand despite repeated storm losses. But the frequency of the conditions capable of causing significant erosion has increased.

In other words, two things can be true at the same time. The beach can grow overall, and damaging erosion events can become more frequent.

That is one of the most important lessons from the new research.

What This Means for the Future of Coastal Erosion in New Jersey

The researchers had an unusual opportunity to test their findings during a real storm on January 10, 2024.

Forecasts indicated that waves and water levels would rise above the erosion threshold identified by the model. Afterward, measurements showed that the beach elevation had fallen by about 8 inches, or 21 centimeters. The sloping beach face also retreated roughly 6 to 8 feet, or 2 to 2.5 meters.

Another trench revealed coarse sand and a thin layer of dark minerals resembling signatures found in earlier storm deposits.

The real-world event supported the model.

That matters because long-term observations of individual storm impacts are surprisingly difficult to obtain. Beaches change constantly, while traditional surveys are often too short or too infrequent to capture every temporary transformation.

The new method could offer a way around that problem.

If researchers can identify similar buried storm records at other expanding beaches, they may be able to reconstruct much longer histories of coastal erosion in New Jersey and elsewhere.

There is also a practical benefit.

Researchers say locally calibrated erosion models could eventually be combined with National Oceanic and Atmospheric Administration forecasts for waves and water levels. That could help coastal managers identify storms likely to produce major beach erosion before they arrive.

That shift could change how communities prepare.

Instead of waiting until a storm removes sand, planners could watch for the physical conditions most likely to cause serious damage.

The deeper lesson from Sandy Hook is easy to miss.

Coastal change does not always announce itself through a disappearing beach. Sometimes the warning is hidden underground, inside layers of sand deposited years earlier.

North Beach happened to preserve those layers because it was growing. That unusual accident allowed scientists to reconstruct a history stretching back more than four decades.

And that history shows something the surface alone could not reveal.

The threat from coastal erosion in New Jersey is not simply about beaches becoming smaller. It is also about damaging combinations of waves and water arriving more frequently.

The shoreline may recover after one storm. Sand may return. A beach may even continue expanding.

But recovery does not erase the warning.

At Sandy Hook, the sand remembers what the eye cannot easily see: the storms capable of reshaping the coast are crossing a dangerous threshold more often than they once did.