And now there are only five large shelves left. From the fjord we head towards the Greenland Sea and the Arctic Ocean. These include three major glaciers: Petermann Glacier, Ryder Glacier Glacier, and Niogarffjällsvlei Glacier (often referred to as 79 degrees north due to its latitudinal location), each of which is completely melted. could ultimately cause sea level rise of 3.6 feet. It takes centuries to play.
“These are the last remaining ice shelves on the ice sheet,” said Romain Milan, lead author of the study published in the journal Nature Communications and a scientist at Grenoble-Alpes University in France. speaks. “Everything else has collapsed or retreated.”
Overall, ice loss from Greenland caused about 17 percent of the sea level rise observed around the world between 2006 and 2018. But things could get worse in the future.
If Greenland’s five remaining ice shelves were to collapse, it would not only mean even faster sea level rise, but the major ice shelves would remain only in the southern hemisphere. Many glaciers across Antarctica still boast large floating areas like this, sometimes the size of a city, state, or even country.
Currently, there are huge ice sheets in both hemispheres of the Earth. The latest news, coming during a year of record global heat, is that Greenland’s ice sheet is deeply compromised by global warming, with potentially significant future consequences. It’s even more emphasized.
“We’re moving toward a northern hemisphere with no ice shelves,” Millan said.
Scientists based in French institutions, The United States and Denmark contributed to a new study that uses satellite data, ocean observations, and climate modeling to measure changes in the spatial area and thickness of Arctic ice shelves. They also assessed where the shelf touches the ocean floor, called the grounding line. The region, where floating shelves end and surface glaciers begin, retreats inland over most of its length. All shelves are an important sign of weakening, as warm seawater melts them from below.
Stef Lhermitte, a scientist who specializes in satellite observation of glaciers at the Delft University of Technology in the Netherlands, said: “The direct relationship between ice shelf changes and the dynamics of Greenland’s glaciers has become clear, and these The significance of this discovery is profound.” Not involved in the current study. “Retreating the grounding line and increasing ice shedding are clear signs that the ice shelf system is weakening.”
Take Greenland’s largest northern ice shelf, 79, for example. The ice shelf edge is approximately 300 feet thick and flows outward to the Greenland Sea, both to the north and east. It is home to more than 6 percent of Greenland’s total ice, which equates to about 2 feet of potential. sea level rise.
And 79 North once had a twin shelf named Zachariæ Iström. Together they constituted the seaward terminus of a unique landform called the . The Northeast Greenland Ice Stream is a river of ice approximately 400 miles long and 40 miles wide that flows toward the coast. recent research This suggests that this may be a particularly vulnerable sector of the ice sheet.
Between 2003 and 2012, the floating section of Zakaria Istrom collapsed. Millan said glaciers have lost 105 billion tonnes of mass and are now largely unchecked, accelerating their flow into the ocean, creating 18 billion tonnes of ice a year. (360 billion tons required (raise global sea level by 1 millimeter).
Two other small northern Greenland ice shelves also shattered during the first decade of the 2000s, revealing ice loss. The shelf is reaching its highest and coldest latitudes. ice sheet.
It’s no wonder there’s so much attention on Peterman, Ryder, and especially 79 North right now.
The Washington Post visited Peterman in 2016 and witnessed rain falling on the ledge, which worsened already wet conditions on the ice and led to cascading runoff. . Just recently, scientists documented an alarming process that may be accelerating the melting of glaciers. The entire ice shelf rises and falls with the tides, allowing increasingly warm Atlantic water to flow beneath it, carving out a large space beneath the glacier. This may help explain why Peterman’s grounding line has rapidly retreated inland toward the center of Greenland in recent years.
Peterman’s most serious concern is that the glacier is actually located at the seaward end of a deep subglacial canyon, which could eventually lead to ocean penetration into the center of the Greenland Ice Sheet. Thing. The first step in this process is the removal of the Peterman Ice Shelf.
Meanwhile, lidar showed the most aft grounding line retreat of any glacier in northern Greenland that still boasts an ice shelf. This very remote glacier, whose ice flows outward toward the North Pole, has seen its grounding line retreat more than 5 miles inland along the ocean floor since 1992, a new study finds. did. If just the lidar were completely lost, sea levels could rise around 5 inches around the world.
And then there’s 79 North, Greenland’s largest, where even more is at stake.
For a while, this shelf seemed very stable. One reason for this is that it is anchored above several small islands on the east side of the island. These points are sometimes called “ice ridges” because they appear as visible high points as the islands push up beneath the ice. Scientists sometimes call them “pinpoints.”
“79 North, I’ve thought for a long time that it’s really hard to kill,” said the researcher at Germany’s Alfred Wegener Institute, who has led several field campaigns and studies related to glaciers. Angelica Humbert said.
However, the image is changing. warm atlantic water It was recently measured to reach the base of Route 79 North, deep channel On the underside of the ice shelf near the glacier’s grounding line.
And then there’s this image that Humbert sent to the Post over the summer. It shows that a large iceberg, about 8 square miles in size, broke off the edge of the glacier. 79 north. In a recent paper published in the journal Cryosphere, Humbert et al. not only predicted the glacier’s destruction, but also found that the current shift at 79 degrees north means the glacier is “at the beginning of a potentially major retreat phase.” It is claimed that it suggests.
The crack pattern seen here is different from previous situations when 79 North released icebergs. These icebergs used to form further outward toward the ocean, and the cracks ran laterally across the front of the glacier, rather than pointing inward toward the center of the glacier as they do today. Ta.
Humbert said the next thing to look at is the area in the image above that scientists have dubbed the “Ice Bridge.” The area connects a floating glacier with a rocky fjord wall along its southern border. Researchers fear this could be the next site to be compromised after 79 North.
If this all plays out as their study predicts, it would mean fewer pinpoints blocking it and accelerating the flow of 79 North into the ocean. “This is a large glacier, and if it accelerates, it could significantly increase sea level rise,” Humbert said.
“Greenland’s next major outlet glacier is also likely to collapse, which will cause even more damage.” [the] “Global sea level rise is increasing,” added Nicolai Larsen, a researcher at the University of Copenhagen. Who has it in Denmark published In my comments on Humbert’s paper, I mentioned the vulnerability of the Northeast Greenland ice stream.
But Humbert has one objection to the latest research.she said in an email Rapid ocean cooling between 2017 and 2020 slowed melting at 79 degrees north latitude, at least temporarily, a new study says.
“The whole idea of withdrawal is correct,” Humbert added.
The photo is truly alarming.
“Human actions remain extremely important to the long-term future of the Greenland Ice Sheet and what that means for sea levels on our coasts, but they are already set in stone by past human actions. “The warming that we are experiencing will continue to cause ice loss,” said Twila Moon, a Greenland expert at the National Snow and Ice Data Center in Boulder, Colorado, who was not involved in the study.
“Sadly, it also means that Greenland’s remaining ice shelves will continue to collapse and weaken,” President Moon said.