Deep inside Greenland’s vast ice sheet, scientists are uncovering hidden pockets of heat that are quietly reshaping how the ice moves and how quickly it can pour into the ocean. That buried warmth, combined with record surface melting and extreme Arctic weather, is turning Greenland from a slow, frozen giant into a more dynamic engine of global sea level rise. I see a pattern emerging in the latest research: the forces speeding up Greenland’s ice are stacking on top of one another, and the trapped heat below the ice is the least visible but potentially most destabilizing piece.
Greenland’s hidden heat engine
For years, most public attention has focused on the sunlight and warm air attacking Greenland from above, but new work is revealing a powerful heat source from below. Scientists have identified trapped heat beneath Greenland that is warming the base of the ice sheet, altering how the ice slides over rock and how quickly it can surge toward the coast. That basal warmth, stored in the ground and in water circulating under the ice, is now understood to be directly impacting ice sheet motion and future sea level rise.
This underground heat does not melt the surface in dramatic floods that make headlines, but it weakens the ice from the bottom up, making it more prone to fracture and faster flow once surface meltwater finds its way down. As the base warms, friction between ice and rock drops, allowing glaciers to slide more easily, a process that can accelerate even if surface temperatures hold steady. The discovery that this hidden heat is already influencing Greenland’s behavior suggests that some of the ice sheet’s future instability is effectively preloaded into the system, waiting for surface melt and crevasses to connect the top and bottom.
A three-decade slide into continuous ice loss
Greenland’s recent history shows how quickly a stable ice sheet can tip into chronic decline. Researchers tracking its mass balance report that Greenland is closing in on three decades of continuous annual ice loss, with 1995 to 96 identified as the last period when the ice sheet gained more mass than it lost. Since then, the balance has flipped, and every year has chipped away at the total volume of ice locked on the island. That long run of losses means the system is no longer just wobbling around a stable average; it is trending steadily downward.
Current assessments of the Greenland Ice Sheet show that this is not a temporary blip tied to one or two hot summers but a structural shift in how the ice responds to a warming climate. Analyses of the Greenland Ice Sheet Alert describe committed sea level rise that is already locked in by past emissions and by the ice that has been lost over the past four decades. In other words, even if global emissions were cut sharply, the ice sheet would not simply snap back to its earlier state, because the cumulative damage and the internal heat now stored in the system keep pushing it toward further thinning and retreat.
Why Greenland’s ice matters for every coastline
The stakes of Greenland’s transformation are not confined to the Arctic. As the Greenland Ice Sheet melts, sea level rises, and that simple relationship is one of the core reasons scientists track its health so closely. Analyses of Greenland’s role in the global climate system emphasize that Sea level responds directly to how much ice remains on the island, and that As the Greenland Ice Sheet continues to shrink, it adds fresh water to the oceans that cannot be quickly reversed on human timescales.
That extra water does not rise evenly like a bathtub. Coastal communities from low-lying Pacific atolls to major cities such as Miami and Rotterdam are already grappling with more frequent flooding, saltwater intrusion and the need for higher defenses. Research on the Greenland ice sheet, sea level rise, and coastal communities underscores that polar ice sheets are shrinking and that their contribution to global sea level is now a central concern in international climate negotiations under the United Nations Framework Convention on Climate Change. When I look at those findings alongside the new evidence of trapped heat, it is clear that Greenland’s internal dynamics are not an abstract scientific curiosity but a direct driver of future coastal risk.
Surface melt, meltwater pools and a dangerous feedback loop
While heat from below is loosening Greenland’s grip on its bedrock, the surface is being reshaped by pools and rivers of meltwater that amplify warming. Thousands of small pools and streams of melted water now sit on top of Greenland’s massive ice sheet each melt season, darkening the surface and absorbing more solar energy than bright, untouched snow. Studies show that these Thousands of meltwater features are speeding up melting more than expected, because they create a feedback loop: more meltwater darkens the ice, which absorbs more heat, which produces even more meltwater.
Once that water finds cracks or vertical shafts in the ice, it can plunge to the base, lubricating the contact between ice and rock and further accelerating glacier flow. Reporting on similar patterns highlights how Thousands of surface ponds and channels in Greenland are creating a dangerous cycle in which meltwater not only erodes the ice from above but also primes it to slide more quickly toward the sea. When I connect that surface feedback to the newly documented basal heat, the picture that emerges is of an ice sheet being attacked from both sides, with water acting as the messenger between the two.
Crevasses widening as the ice sheet fractures
The structural integrity of Greenland’s ice is also changing in ways that make it more vulnerable to both surface and basal heat. A new large-scale study of crevasses on the Greenland Ice Sheet finds that those cracks are widening faster as the climate warms, a sign that the ice is literally pulling apart under stress. Wider and deeper crevasses provide more pathways for meltwater to reach the interior and the base, where trapped heat can turn that water into an even more effective lubricant.
As crevasses expand, they also weaken the buttressing that helps hold back outlet glaciers at the coast. That makes it easier for large chunks of ice to calve into fjords, as seen in images of a glacier calving icebergs into a fjord off the Greenland ice sheet in southeastern Gre, a scene that illustrates how fractured ice can rapidly transfer mass from land to ocean. The combination of widening cracks, internal heat and surface meltwater means that Greenland’s glaciers are not just thinning; they are, in the words of one analysis, effectively falling apart under the combined weight of mechanical stress and thermal forcing.
Extreme heatwaves and the 2025 melt season
The year 2025 has offered a stark preview of how quickly Greenland can respond when atmospheric conditions line up against it. Earlier in the year, an unprecedented Arctic heatwave pushed temperatures far above normal, triggering a period when In May 2025, an unpreceden surge of warmth meant that Greenland Ice Melts 17x Faster as Extreme Heat Grips the Arctic. That spike in melting did not occur in isolation; it landed on top of the long-term trend of thinning ice and the internal heat that is already priming the system for rapid change.
Scientists tracking the event reported that Greenland ice melted much faster than average in the May heatwave, with By AFP and Agence France Presse highlighting how the early season melt set the tone for the rest of the summer. When I look at those accounts alongside the Greenland Ice Sheet Alert, which notes that the Greenland Ice Sheet continues Tracking Concerning Patterns and that Current trajectory points toward more frequent years of extreme mass loss, it becomes clear that 2025 is not an outlier but part of a new normal. Heatwaves are now interacting with an ice sheet that is structurally and thermally primed to respond with outsized melt.
How trapped heat and surface warming work together
To understand why the discovery of trapped heat beneath Greenland is so worrying, it helps to see how it interacts with the more familiar drivers of sea level rise. Hotter air temperatures melt the surface of the ice while warmer ocean water erodes ice shelves from the sides and below, allowing grounded ice to flow more quickly into the sea. Analyses of Hotter conditions explain that these processes together are already raising global sea levels and that there is no simple way to reverse them once large volumes of ice are lost.
Now add the internal heat documented beneath Greenland to that picture. Research on conditions beneath Greenland notes that this ice melting is heavily influenced by rising air temperatures and other conditions at the ice sheet surface, of co, but also by the thermal and mechanical properties of Earth’s interior. Those findings, summarized in work on what lies beneath Greenland, show that basal heat can precondition the ice so that when surface meltwater arrives, it triggers a faster and more sustained slide. In practical terms, that means every additional degree of warming at the surface may have a larger impact than models assumed when they treated the base of the ice as uniformly cold and rigid.
What this means for climate policy and coastal planning
For policymakers and coastal planners, the emerging science on Greenland’s trapped heat is not just an academic update; it is a warning that current risk estimates may be conservative. If the base of the ice sheet is warmer and more dynamic than expected, then projections of how quickly Greenland can contribute to sea level rise may need to be revised upward. That has direct implications for infrastructure decisions, from where to build new housing in flood-prone cities to how high to raise sea walls in places already struggling with high-tide flooding.
At the same time, the research underlines that mitigation and adaptation must move in parallel. Cutting emissions to limit further warming remains essential to slow the pace at which the Greenland Ice Sheet loses mass, but the committed sea level rise already identified in the Greenland Ice Sheet Alert means that adaptation for vulnerable communities cannot wait. When I connect the dots between trapped heat beneath the ice, surface melt feedbacks, widening crevasses and extreme heatwaves, the conclusion is hard to escape: Greenland’s internal heat is no longer a hidden background detail, it is an active player in a rapidly changing coastal future that governments, insurers and residents will have to confront head on.
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