Deep beneath the vast expanse of the Greenland Ice Sheet, scientists have uncovered evidence of a phenomenon more commonly associated with Earth fiery interior than with frozen landscapes: thermal convection.
In a study published in The Cryosphere, researchers report that strange, plume-like structures detected in radar surveys of northern Greenland are likely caused by slow, heat-driven churning within the ice itself a process that resembles the roiling motion of molten rock in Earth’s mantle.
The unusual formations were first identified in 2014 through ice-penetrating radar, which allows scientists to peer deep into the ice sheet by tracking how radio waves reflect off internal layers. These layers, formed from ancient snowfall compacted over thousands of years, typically lie in orderly stacks. But in some regions, they appear buckled upward in large, column-like distortions unrelated to the bedrock below.
For years, researchers debated possible explanations, ranging from meltwater refreezing at the ice base to shifting slippery zones. Now, glaciologist Robert Law of the University of Bergen and his colleagues believe they have found a more compelling answer.
Using a geodynamics modelling tool typically reserved for simulating convection in Earth’s mantle, the team constructed a simplified 2.5-kilometre-thick digital slice of the ice sheet. They tested whether warming at the base driven by the steady flow of geothermal heat from Earth interior could generate upward-moving plumes within the ice.
Under specific conditions, the model produced strikingly similar upwellings: rising columns of softer, warmer ice that folded overlying layers into shapes nearly identical to those captured in radar imagery.
The findings challenge conventional assumptions about ice sheet behaviour. Ice is far softer than rock roughly a million times less viscous than Earth mantle but over millennia, even subtle heat differences can trigger slow internal motion. Researchers emphasize that the ice remains solid; the movement occurs over thousands of years, not in dramatic, liquid-like flows.
The modelling suggests that the base of northern Greenland’s ice sheet may be warmer and mechanically softer than previously assumed. The heat required to drive such convection aligns with natural geothermal flux generated by radioactive decay in Earth crust and residual heat from the planet formation small in magnitude, but capable of accumulating beneath a massive insulating slab of ice.
Understanding these hidden dynamics is critical. The Greenland ice sheet, which blankets roughly 80 per cent of the island, is one of the world’s largest freshwater reservoirs and a major contributor to global sea-level rise as it melts.
While the discovery does not necessarily mean the ice sheet will melt faster, it adds a new layer of complexity to models used to forecast future changes. If parts of the ice sheet are indeed slowly “boiling” from within, scientists will need to account for that behaviour in long-term projections.
Researchers describe the phenomenon as both counterintuitive and remarkable a rare case where the physics of fire and ice unexpectedly converge.