‘Freak of Nature’: Greenland Ice Sheet May Be Churning Like Molten Rock, New Models Show
Deep radar images have long revealed strange, plume-like structures folded into the internal layers of the Greenland Ice Sheet. New computer modeling now suggests those plumes can be produced by thermal convection inside the ice — a slow, churning motion more commonly associated with Earth’s molten mantle — and the finding may reshape how scientists evaluate future sea-level projections.
What the Greenland Ice Sheet plumes reveal
Radar surveys exposed large, upward-buckling features deep in northern parts of the ice that do not align with the topography of the bedrock beneath. Earlier hypotheses invoked mechanisms such as meltwater refreezing at the ice base or migrating slippery patches, but those ideas have not fully explained the observed patterns. The new work explored whether vertical temperature differences within the ice could drive convection that produces plume-like upwellings matching the radar signatures.
How models reproduced plume-like convection
Researchers built a simplified digital slice of the ice sheet and used a geodynamics modeling package typically applied to mantle convection. The virtual slab of ice in the experiments matched the approximate thickness revealed by radar observations. Modelers varied factors including snowfall rate, ice thickness, ice softness, and surface flow speed. When the basal ice was warmed and substantially softer than standard assumptions, the simulation produced slow, rising columns of ice that folded the overlying layers into shapes closely resembling the radar-detected plumes.
Why this matters for ice physics and sea-level uncertainty
The modeling indicates the heat required to produce these convection cells is consistent with the tiny but persistent heat flowing upward from the Earth: radioactive decay in the crust plus residual primordial heat. Trapped beneath a massive, insulating slab of ice, that modest heat may be sufficient over long time scales to warm basal ice enough for convection to occur. In the models, such convection only appears under conditions where the deep ice is significantly softer than commonly assumed — in some interpretations, perhaps an order of magnitude softer.
Researchers caution that finding softer, convecting ice does not automatically translate to faster surface melting or a direct increase in sea-level rise. Improved knowledge of internal ice physics is described as a key pathway toward reducing uncertainties in projections of ice-sheet mass balance and future sea-level changes. Further studies will be needed to isolate how convective behavior at depth interacts with other processes that control ice loss.
Next steps and open questions
The new modeling offers a coherent mechanism that reproduces radar observations, but it also raises questions that remain to be resolved. Critical unknowns include the precise thermal and rheological state of basal ice where plumes occur and how widespread such convective cells may be beneath the larger ice sheet. Additional observations and targeted modeling will be required to map where convection can occur and to test how these deep processes influence the ice sheet’s long-term evolution.
For now, the picture emerging from radar and modeling paints the Greenland Ice Sheet as more dynamic and internally complex than commonly assumed — a rare instance where ice may behave in a way that echoes the slow, viscous churning of Earth’s mantle. The discovery underscores the importance of peering beneath the surface to understand the forces that will shape coastlines in the centuries ahead.
