Hidden rivers of meltwater are eroding from beneath Antarctica’s glaciers, a new study has found — meaning sea levels could be rising faster than scientists feared.
Accelerated melting rates alter the balance of freshwater and saltwater in the oceans, affecting both ocean circulation and global climate in unknown ways. According to the findings Published Friday in Science Advances.
The study focused on two Antarctic glaciers — which hold enough water to raise global sea levels by 5 feet.
Scientists have long known that Antarctica’s Denman Glacier — like across the once vast Icelands of the polar regions — is melting from below.
But it’s not clear whether that will have an effect on sea-level rise, said the University of California, Irvine scientists.
In 2021, the research team realized that Denman was melting much faster than its neighbor, Scott Glacier, even though both entered oceans with nearly identical temperatures and salinity levels.
The reason for this change was that Denman was melting from below faster than expected.
As that process accelerates — and begins to catch up with neighboring Scott Glacier — it could raise global sea levels by 15 percent more than expected, the study found.
That equates to about one-sixth of an inch at 2300, which the researchers called a “conservative estimate.”
It doesn’t look like it on its own—but it comes on top of melting from burning fossil fuels, which can lead to a three-quarter-inch rise in sea level from the Denman and Scott glaciers.
Scientists estimate that in a world where fossil fuel burning was unrestricted, the total rise of these glaciers would be 0.86 inches.
Denman is not the only glacier melting on both sides.
For example, the massive Thwaites Glacier – an Antarctic glacier the size of Florida, whose dangerous condition earned it its nickname. “Doomsday Glacier” – melting from below, According to a study Released in February.
Scientists have long known that the reasons for the slow decline of all these glaciers differ between their tops and bases.
Above, glacier melting is happening for a familiar reason: global warming from the uncontrolled burning of fossil fuels.
This is a major factor in ice loss, emphasized study co-author Jamin Greenbaum, a Scripps Institution of Oceanography researcher.
“If there’s a doomsday story here it’s not a subglacial discharge,” Greenbaum said.
“The real doomsday story is still emissions, and humanity still has its finger on the button.”
But that doomsday story is being swept away by a different process of melting from beneath the ice.
Where the ice meets the rock, it can be heated by geothermal heat released by the Earth, which must be a hair above 32 F to melt the ice.
Then friction occurs because the slow-moving ice grinding against the rock creates heat that melts the ice.
This melting is most significant where rivers of meltwater have the potential to reach the ocean, where they absorb warm saline water and accelerate the process of glacier collapse.
A particular concern is when the mouth of this melting river seeps beneath an ice sheet—the floating portion of a glacier extending into the ocean—creating a feedback loop that can lead to faster-than-expected sea-level rise. The study was released Friday.
Such feedback loops are beyond the ability to model, the researchers said. “We can’t yet say how much sea-level rise will be accelerated by this process,” Greenbaum said.
Copyright 2023 Nexstar Media Inc. All rights reserved. This content may not be published, broadcast, rewritten or redistributed.