A major Greenland glacier is melting away with the tide, which could signal faster sea level rise, study finds
The researchers' work raises more concerns for the already worrisome prospect of sea level rise, which threatens coastlines around the world.
This Aug. 16, 2010, image shows a piece of the Petermann Glacier that cracked in Greenland. A study in the Proceedings of the National Academy of Sciences on Monday, May 8, 2023, found that tides and climate change are rapidly melting ice in the grounding line zone of the Petermann Glacier. That’s the point where glaciers go from being on land to floating on water. (Jesse Allen and Robert Simmon/NASA Earth Observatory via AP)
A major glacier in northwest Greenland is interacting with the ocean tides, scientists reported Monday, resulting in previously unaccounted-for melting and potentially faster sea level rise.
The group of glaciologists from the University of California, Irvine and NASA's Jet Propulsion Laboratory published the study in the Proceedings of the National Academy of Sciences on Monday.
Observations from the Petermann Glacier revealed that the glacier's grounding line — the area where the ice sheet begins to extend out on top of the ocean — can shift significantly as tides come in and out each day.
Petermann's grounding line "migrates between 2 and 6 kilometers (1.2 to 3.7 miles) as tides come in and out," according to Enrico Ciracì, the lead author of the study and a scientist at UCI.
This is a satellite image of a massive iceberg calving from the Petermann Glacier in Greenland, collected on July 19, 2012. (Photo DigitalGlobe via Getty Images via Getty Images)
This is an important finding: The traditional view among scientists was that the grounding line did not migrate with the tides -- and this introduces another major source of melting that could be accelerating sea level rise.
Between 2016 and 2022, warmer tidal cycles melted a 670-foot-tall hole in the underside of the glacier along the grounding line — big enough that two Statues of Liberty could be stacked on top of one another inside it.
The phenomenon could worsen in the coming years and decades as ocean temperatures climb. CNN recently reported that sea surface temperatures were at their highest on record this spring — a spike that has alarmed scientists who are concerned it could be part of a worrying new trend.
A 1964 photo of the Petermann Glacier, where it ends at the sea on the coast of Greenland's Daugaard Jensen Land. (Photo by ©CORBIS/Corbis via Getty Images)
The study raises more concerns for the already worrisome prospect of sea level rise, which threatens coastlines around the world. Greenland's melting ice is the single largest contributor to sea level rise, according to NASA, which has been accelerating in recent years. But current projections do not account for this newfound contribution from under-ice interactions with warming tides.
"These ice-ocean interactions make the glaciers more sensitive to ocean warming," said co-author Eric Rignot, a professor at UCI and NASA JPL research scientist, in a statement. "These dynamics are not included in models, and if we were to include them, it would increase projections of sea level rise by up to 200 percent -- not just for Petermann but for all glaciers ending in the ocean, which is most of northern Greenland and all of Antarctica."
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