Greenland is in the global spotlight after the new US security deal — now scientists have mapped the hidden world beneath its ice

Greenland has rarely been far from international headlines lately.

On September 22, the United States, Denmark and Greenland signed a security agreement that allows an expanded US military presence on the Arctic island, following months of tension over Washington’s interest in Greenland. The agreement includes plans for additional US access to military sites, while Greenland remains a self-governing territory within the Kingdom of Denmark.

Now, attention is turning to a very different part of Greenland — one that cannot be seen from the ground.


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Scientists have produced a new and unusually detailed picture of the landscape buried beneath the Greenland Ice Sheet.

Using subtle changes in the surface of the ice, researchers have mapped 1,943 valleys beneath the ice, with about one-third identified as new features. Some previously known valleys also appear to extend hundreds of kilometres farther inland than earlier maps suggested.

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The findings offer a new look at Greenland's geological past while giving researchers more information about how the ice sheet may behave in the future.

Beneath Greenland's ice is a landscape no one can see directly

The Greenland Ice Sheet covers about 1.7 million square kilometres and reaches more than 3 kilometres in thickness at its deepest point. Hidden below it is a bedrock landscape shaped by processes that began long before the modern ice sheet took form.

Until now, scientists have had to piece together that terrain using different sources of geophysical information. The new research adds another layer of detail by examining the way the ice itself responds to the landscape beneath it.

The researchers used a technique called Ice Flow Perturbation Analysis. The basic idea is that buried ridges and valleys can influence the movement of ice above them. Those changes can leave tiny variations in the ice surface, which satellites are capable of detecting.

Scientists can then work backwards from those surface patterns to estimate the shape of the bedrock below.

The method is being used to improve BedMachine Greenland, a high-resolution dataset that maps the terrain beneath the ice sheet.

The resulting picture is far more complex than a simple sheet of ice covering flat ground. Beneath Greenland lies an intricate system of valleys, mountains and other variations in the bedrock that continue to influence how the ice moves today.

Nearly 2,000 buried valleys change the picture of Greenland

The researchers manually mapped 1,943 subglacial valleys, including hundreds that had not previously been identified in this form. The study also found that roughly half of the valleys already included in BedMachine Greenland — particularly those closer to the ice sheet's edge — extend farther inland than previously mapped. In some cases, the difference reaches hundreds of kilometres.

Some of the newly mapped terrain fits existing ideas about Greenland's geological development.

Many valleys appear to originate around the southern and eastern highlands, areas believed to have played a role in the early development of the Greenland Ice Sheet. In the eastern part of the island, the map also reveals a buried mountain range accompanied by interconnected valleys.

Some of these alpine-style features may have remained beneath the ice since at least the Pliocene, a period that began more than five million years ago.

But not every feature is easy to explain.

In west-central Greenland, researchers found numerous valleys that are unusually long, straight and aligned in a southwest-to-northeast direction. Their orientation raises the possibility that ancient tectonic structures influenced where water travelled and where valleys developed.

NASA cryospheric scientist Joe MacGregor, a co-author of the study, described this pattern as a puzzle because Greenland is generally regarded as a relatively stable block of ancient rock.

Ancient groundwater may have helped carve the hidden valleys

The shape of the valley network offers another clue about what happened beneath Greenland long before today's ice sheet covered it.

Researchers examined the angles at which the valleys branch. Their relatively broad branching patterns suggest that surface runoff alone may not explain how the network formed.

Instead, the scientists propose that a widespread groundwater system may have played a role.

Water moving upward through the bedrock could have gradually eroded surrounding rock and helped create the valleys before the Greenland Ice Sheet developed. That would mean some of the landscape now influencing modern glaciers began taking shape in a very different climate and environment.

The discovery is important because the buried terrain is not simply a geological record. It still affects the behaviour of Greenland's ice.

Ice tends to concentrate its movement through existing valleys. As glaciers flow through these natural channels towards Greenland's coast, the ice can become thicker and move faster. Faster-moving ice can, in turn, deepen the underlying valleys, creating a feedback between the bedrock and the ice above it.

The effect is particularly visible along western Greenland, where deeply carved valleys funnel ice towards the coast.

Why the hidden map matters for Greenland's future

The new map arrives at a moment when Greenland is receiving extraordinary attention for reasons far removed from geology.

The recent US-Denmark-Greenland security agreement has put the island's location and strategic importance back in the international spotlight. Reuters reported that the agreement provides for expanded US military access, including additional sites, after months of disagreement surrounding Greenland.

The scientific research is unrelated to that agreement, but it offers another way to understand why Greenland's geography matters.

What lies beneath the ice influences what happens on top of it.

As the Greenland Ice Sheet changes, glaciers are expected to continue following the underlying valleys that already channel their movement. Understanding those pathways could therefore help researchers model how changes at the ice sheet's edge may eventually affect ice farther inland.

That is particularly important for long-term projections. Scientists are not simply trying to establish what the bedrock looks like today; they want to understand how its shape could influence the movement of Greenland's ice over decades and beyond.

The new map does not provide a simple forecast for Greenland's future. Instead, it fills in a crucial part of the landscape that satellites cannot see directly.

For an island currently dominating headlines because of its position in the Arctic, scientists have found a reminder that some of Greenland's most consequential geography remains hidden — beneath kilometres of ice.

Frequently asked questions

1. What did scientists discover beneath Greenland's ice?
Researchers mapped 1,943 valleys beneath the Greenland Ice Sheet. About one-third were newly identified, while many previously mapped valleys were found to extend much farther inland than earlier estimates suggested.

2. How did scientists map the valleys beneath the ice?
They used a technique called Ice Flow Perturbation Analysis. It detects subtle changes in the surface of the ice caused by the bedrock features underneath and uses those patterns to infer the hidden terrain.

3. How old are the valleys beneath Greenland?
Many of the valleys formed before the modern Greenland Ice Sheet existed. Some alpine-style landforms in eastern Greenland may have survived beneath the ice since at least the Pliocene.

4. Why does the hidden landscape matter today?
The valleys influence how Greenland's ice flows. Ice can become concentrated and move faster through these channels, meaning the newly mapped terrain could help scientists improve longer-term projections of how the ice sheet will respond as conditions change.