View of the fjord and the rupture front of the Eqalorutsit Kangilliit Glacier Sermiat, in southern Greenland. The fiber optic cable was placed a few hundred meters from the ice wall, at a depth of 300 meters on the seabed. In the foreground is the radar system of the University of Zurich which measures breakup events and ice movements.
Andreas Vieli, University of Zurich
The masses of ice detached from the glaciers accelerate the melting of the Greenland INLANDSIS. This is what an international research group has just shown by means of an optical fiber technology also used in the study of Swiss glaciers.
Greenland’s ice cream cap, faster and faster. Since 2002, it has lost 270 billion tonnes of ice per yearExternal link On average, causing an elevation of the ocean level of almost two centimeters.
The dropping of large blocks of ice (calving) is one of the most visible effects of the loss of mass of the INLANDESIS caused by climate change. A phenomenon which, in turn, intensifies the cast iron. Because the collapse of an iceberg in the sea brings up the surface of the warmer water, which accelerates the process of cast iron of the glacier.
It is the discovery signed by an international research group conducted by the universities of Zurich and Washington, which for the first time measured the way in which the dislocation of ice accelerates the decline in the Arctic cap of Greenland. An integral part of the Greenfjord project of the Swiss Polar Institute, the study has just been published on August 13 in NatureExternal link.
“We better understand the process involved when the ice falls into the sea. The ice does not only detach herself, it also increases the melting below the surface of the water,” explains Swissinfo Andreas Vieli, professor of glaciology at the University of Zurich and co -author of the study.
These observations improve knowledge about Greenland ice cream, deployed over an area of forty times Switzerland. A fragile system whose complete melting would have serious consequences on the ocean currents, the climate and the coastal areas of the planet.
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Giant waves bring hot water back to the surface
The universities research teams of Zurich and Washington studied the effects of calving on the Eqalorutsit Kangilliit Sermiat glacier, located in a southern Greenland fjord. This glacial language loses 3.6 km3 of ice each year. Almost three times the volume of the Rhône glacier, in the Swiss Alps.
The impact of ice falling in the sea produces surface waves, similar to tsunamis, which agitate the upper part of the water column. But calving also causes waves in depth, invisible to the naked eye. They can have the height of a skyscraper and bring back hot water from depths to the surface, intensifying the cast iron and erosion processes of the glacier.
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A researcher at the University of Washington and the main author of the study, Dominik Gräff compares this process to the melting of an ice cube in a hot drink. If you do not stir, a layer of cold water is formed around the ice cube, the insulation of the warmer liquid. By mixing, this layer is disturbed and the ice cube melts much faster.
Regarding the Greenland ice cap, about half of the current loss of mass is due to the submarine melting and the iceberg detachment, specifies Andreas Vieli.
Optical fiber in the Greenland seabed
To measure what is going on in depth, researchers set a fiber optic cable ten kilometers on the seabed. By means of so -called technology Distributed Acoustic Sensing (DAS)they recorded the deformations of the fiber-elongation or compression-caused by the underwater waves.
“The fiber optic cable allowed us to measure this incredible multiplier effect of the break of ice, something impossible so far,” says Dominik Gräff in a press releaseExternal link of the University of Zurich.
Two researchers descend the fiber optic cable from the coil to the seabed in order to make the measurements.
Dominic Stars, Universities the Washington
The importance of seawater and dynamics of icebergs detachment has been known for a long time. But measuring them directly on the ground has great difficulties. The high number of icebergs in the fjords means a constant risk of falling ice masses.
What is more, traditional satellite remote sensing methods do not act below the surface of the ocean, where the interactions between seawater and glaciers occur, explains Andreas Vieli. “With the fiber optic cable, we have virtually a thousand sensors under the glacier front.”
A technology used on Swiss glaciers
The use of fiber optics in the study Les glaciers is relatively recent. In Switzerland as in Alaska and other mountainous regions, scientists began to use it to detect micro-vibrations and other potentially announcing signals of instability within glaciers.
“Optical fiber allows us to detect extremely low seismic events, which other technologies are not even measured,” the seismologist of the Federal Polytechnic of Zurich (EPFZ) Thomas Hudson told Swissinfo.
In 2023, the latter installed 1.2 km of fiber optic cables on the Swiss Gorner glacier. He recorded thousands of seismic waves there. Vibrations capable of providing indications on the changes arising in the glacier.
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This content was published on
01 Jul 2025
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Optical fiber is also a source of information on the structure and composition of the glacier. Its advantage compared to traditional seismic sensors, placed in very specific places, is the possibility of monitoring significantly larger surfaces due to its relative ease of installation.
This technology would allow you to monitor the entire glaciers, including in land that is difficult to access.
Text reread and verified by Reto Gysi von Wartburg, translated from Italian by Pierre-François Besson/Ptur
