CNN
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A new study reveals that the giant glacier in northern Greenland at the top of the world – long thought to be relatively stable – is in trouble.
Greenland’s last remaining ice shelf is rapidly weakening as the ocean warms. destabilize a nearby glacier And there are fears of potentially “dramatic” effects from rising sea levels. study It was published Tuesday in the journal Nature Communications.
Ice shelves are tongues of floating ice that protrude above the ocean and act as dams, holding back glaciers on land and slowing ice loss. As the ice melts and weakens, more land-based ice can slide into the ocean; sea level rise.
Scientists analyzed eight ice shelves that support glaciers in northern Greenland. These shelves hold enough ice to raise sea levels by 2.1 meters (almost 7 feet). If it breaks and completely melts.
“These glaciers are among the most important ice sheets,” says Romain Milan, a glaciologist at the University of Grenoble-Alpes. A French researcher and study author told CNN. “They are Greenland’s largest glaciers.”
Glaciers in other parts of Greenland began to lose mass in the 1980s and 1990s, but so far northern Greenland’s glaciers have “remained relatively stable,” he said.
However, according to reports, this no longer appears to be the case study.
Millan and his co-authors used thousands of satellite images, climate models and field measurements to better understand the drivers and timing of historical and current changes in ice shelves. .
They found that ice shelf loss has increased “significantly and broadly.” Since 1978, the ice shelves supporting glaciers in northern Greenland have lost more than 35% of their total volume, according to the study. They found that since the early 2000s, three have completely collapsed and the remaining five have melted and destabilized nearby glaciers.
“We can see that the ice shelf is weakening, and that’s new and important information that we didn’t know because we thought this area of Greenland was really stable,” Millan said. ” he said.
Copernicus Sentinel 2/ESA
Peterman Glacier in northwestern Greenland is one of the largest glaciers that connects the Greenland ice sheet to the Arctic Ocean. Peterman’s ice flow has accelerated in recent years.
The study found that the ice loss was caused by a combination of factors, including increased fragmentation (ice chunks break up to form icebergs) and surface melting.
But the main factor was basal melting, where warm ocean currents melt the ice from below. The study found that from 2000 to 2020, basal melt rates “widely increased” in roughly the same way as ocean temperatures rose.
Scientists pointed to direct effects on glaciers. As ice shelves melt, the study found that their “grounding line” – the point at which the glacier stops touching the ground and begins to float – is receding.
“These natural boundaries are really important parameters of glacier stability,” Milan says. As the grounding line recedes, “ice release into the ocean will also begin to increase,” he added.
Millan said ice shelves could become permanently weaker if the oceans continue to warm. “And it is even possible that they may collapse on certain timescales, which could have significant implications for the Greenland Ice Sheet’s contribution to sea level rise.”
The region is already playing a big role. The report found that between 2006 and 2018, the melting of Greenland’s ice sheet contributed to more than 17% of the observed sea level rise.
Milan said he could not give a timescale for when such a collapse would occur, but said changes had occurred rapidly since the early 2000s.
Research shows that after the Zakaria Istrom glacier ice shelf collapsed in 2003, the amount of ice flowing into the sea doubled. Millan said when he visited the glacier in 2016 and 2017, the changes were alarming. He described it as a “chaos of icebergs.”
Thomas Traasdal/Litzau Scanpics/AFP/Getty Images
October 4, 2023, a glacier in northern Greenland. Glaciers in the region are becoming more unstable as ice shelves melt, according to a new study.
The future of glaciers depends largely on what the world does to reduce pollution from global warming, Millan said.
The report continues to build on research findings to better assess how ice shelves will respond to climate change, particularly on the complex process of basal melting and its potential impact on sea level rise. I’m looking for something.
“This will ultimately provide insight into the future of these glaciers and the fate of Antarctica’s larger ice shelves,” the report states. A recent study in Antarctica found that the continent’s ice shelves could be melting rapidly. Now it’s “inevitable” Because it melts from the bottom.
Sophie Nowicki, an ice sheet expert in the Department of Geology at the University at Buffalo who was not involved in the study, said the findings provide insight into the causes and triggers of changes in the Greenland ice sheet. He said that it is important because it provides
“What’s new is the ‘long-term’ record and holistic view of ice shelf evolution,” she told CNN. “We knew that basal ice shelf melting was related to ocean temperatures, but the beauty of this study is that it gives us a better idea of the timing and magnitude of the changes.”
The study also furthers our overall understanding of how the polar regions are responding to the human-induced climate crisis, Nowicki said.
The polar regions were once thought to be “pretty boring,” but since scientists started observing them with satellites about 40 years ago, it has become clear that “the polar regions are dynamic and highly vulnerable regions.” She said it became.
As the Earth’s temperature continues to rise, “we should be concerned about how fast change is happening, but we shouldn’t be surprised,” she added.