Radar images from deep within Greenland’s ice sheet are unveiling surprising features that twist the layers formed over thousands of years. Recently, scientists believe they’ve unraveled the mystery behind these unusual plume-like structures. Modeling suggests that they result from convection, a process usually associated with molten rock beneath the Earth’s surface.
Glaciologist Robert Law from the University of Bergen points out, “It’s quite intriguing that thermal convection can occur in ice. Ice is much softer than the Earth’s mantle, yet the physics add up.”
The Greenland ice sheet, which covers 80% of the island, is critical for understanding rising sea levels as it melts into the ocean. Investigating what’s happening inside the ice is crucial for predicting its future changes.
Using ice-penetrating radar, scientists send radio waves through the ice, revealing different internal layers formed by historic snow. Each layer has its unique properties, like varying acidity and dust content. Back in 2014, research identified strange upward-buckling structures deep within northern Greenland’s ice, unrelated to the ground below, posing a conundrum for researchers.
Previous theories tried to attribute these structures to things like meltwater freezing or moving slippery spots, but the concept of convection needed testing. So, Law and his team created a computer model to see if warming from below could generate similar structures.
They modeled a 2.5-kilometer thick slab of ice and tweaked various factors like snowfall and ice density. Remarkably, under the right conditions, the model produced plume-like upwellings resembling what radar detected. These plumes formed only when the ice at the base was warmer and softer than typically believed, suggesting the real ice may defy previous assumptions.
The heat driving these plumes aligns with the warmth from Earth’s core, gradually produced by radioactive decay and leftover heat from the planet’s formation. While this effect is minor, over time, it could accumulate, softening layers of ice above.
Climatologist Andreas Born notes, “It’s wild to realize that parts of the Greenland ice sheet behave like a bubbling pot.” Importantly, this doesn’t mean the ice is melting faster or becoming slushy; it still flows slowly over millennia.
Understanding these hidden processes is vital. Greenland’s ice sheet, more than a thousand years old, is unique as it has a culture and permanent communities at its edges. As Law emphasizes, “The more we learn about the ice’s processes, the better we can prepare for the future of coastlines worldwide.”
This research sheds light on how internal dynamics affect Greenland’s ice and has been detailed in the journal The Cryosphere.
For more on the effects of climate change on ice sheets, check this report from NASA.
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