Greenland Ice Sheet Exhibits Unexpected ‘Boiling Pot’ Behavior, Scientists Find
Deep beneath the surface of the Greenland ice sheet, scientists have discovered swirling, plume-like structures that are challenging conventional understanding of ice dynamics. New research suggests these features are caused by thermal convection – a process more commonly associated with the Earth’s mantle – essentially meaning parts of the ice sheet are churning like molten rock.
The findings, published in The Cryosphere, could reshape how researchers predict future sea level rise, according to scientists at the University of Bergen (UiB) in Norway. For over a decade, these mysterious plumes have puzzled the scientific community. Now, researchers believe they’ve cracked the code by applying mathematical principles used to understand continental drift.
“We typically think of ice as a solid material, so the discovery that parts of the Greenland ice sheet actually undergo thermal convection, resembling a boiling pot of pasta, is as wild as We see fascinating,” says Andreas Born, professor at the Bjerknes Centre for Climate Research and the Department of Earth Science at UiB.
Glaciologist Robert Law of the University of Bergen, and co-author of the study, described the phenomenon as an “exciting freak of nature.” He explained that while ice is at least a million times softer than the Earth’s mantle, the physics still allow for thermal convection to occur. “Finding that thermal convection can happen within an ice sheet goes slightly against our intuition and expectations,” Law said.
The Greenland ice sheet, covering 80 percent of the island, is a massive reservoir of frozen water and is expected to significantly contribute to rising sea levels as it melts. Understanding the processes occurring within the ice sheet is therefore crucial for accurate predictions.
Scientists use ice-penetrating radar to study the internal structure of the ice. Radio waves reflect differently off internal layers of snow that have been compressed into ice over time. These layers possess unique characteristics, such as varying acidity levels, dust content, and chemical composition. Radar images taken in 2014 first revealed the strange plume-like structures deep within the northern Greenland ice sheet.
Previous theories attempting to explain these structures included the freezing of glacial meltwater onto the underside of the ice sheet and the presence of migrating slippery spots. However, the possibility of thermal convection within the ice sheet had not been thoroughly investigated until now.
To test this hypothesis, Law and his team developed a computer model simulating a 2.5-kilometer-thick slice of the Greenland ice sheet. Using a geodynamics modeling package typically used for simulating convection in Earth’s mantle, they explored how varying factors like snowfall rate, ice thickness, and ice softness affected the formation of plume-like structures.
The model demonstrated that plumes formed under specific conditions: when the ice near the base was warmer and significantly softer than previously assumed. This suggests that the ice at the base of northern Greenland’s ice sheet may be more pliable than scientists once believed.
The heat required to drive these convection currents in the model is consistent with the heat continuously flowing from the Earth, generated by radioactive decay and residual heat from the planet’s formation. While this heat flow is minimal, it can accumulate over time under the insulating layer of ice.
“Greenland and its nature is truly special,” Law said. “The ice sheet there is over one thousand years old, and it’s the only ice sheet on Earth to have a culture and permanent population at its margins. The more we learn about the hidden processes inside the ice, the better prepared we’ll be for the changes coming to coastlines around the world.”
Further research is needed to fully understand the implications of thermal convection for the future of the Greenland ice sheet and its contribution to sea level rise.
