August 13, 2025
University of Washington researcher Dominik Gräff (pictured on the left) and a crew member head for shore on a Zodiak boat. The analysis vessel Adolf Jensen floats on the fjord’s icy floor within the background and the calving entrance is seen on the left.Julia Schmale
As glaciers soften, big chunks of ice break away and splash into the ocean, producing tsunami-size waves and forsaking a robust wake as they drift away. This course of, referred to as calving, is vital for researchers to grasp. But the entrance of a glacier is a harmful place for knowledge assortment.
To resolve this downside, a staff of researchers from the University of Washington and collaborating establishments used a fiber-optic cable to seize calving dynamics throughout the fjord of the Eqalorutsit Kangilliit Sermiat glacier in South Greenland. This allowed them to doc — with out getting too shut — one of many key processes that’s accelerating the speed of glacial mass loss and in flip, threatening the steadiness of ice sheets, with penalties for world ocean currents and native ecosystems.
“We took the fiber to a glacier, and we measured this crazy calving multiplier effect that we never could have seen with simpler technology,” stated co-author Brad Lipovsky, a UW assistant professor in Earth and area sciences. “It’s the kind of thing we’ve just never been able to quantify before.”
Their findings were published in Nature on Aug. 13.
The calving entrance of Eqalorutsit Kangilliit Sermiat in South Greenland.Dominik Gräff
The Greenland ice sheet — a frozen cap about thrice greater than Texas — is shrinking. Scientists have documented its retreat for the past 27 years as they scramble to grasp the results of continued mass loss. If the Greenland ice sheet have been to soften, it might launch sufficient water to lift world sea ranges by about 25 toes, inundating coastlines and displacing thousands and thousands of individuals.
Researchers additionally speculate that ice loss is weakening the Atlantic meridional overturning circulation, a world present system that controls the local weather and nutrient distribution by circulating water between northern and southern areas.
“Our whole Earth system depends, at least in part, on these ice sheets,” stated lead creator Dominik Gräff, a postdoctoral researcher in Earth and area sciences. “It’s a fragile system, and if you disturb it even just a little bit, it could collapse. We need to understand the turning points, and this requires deep, process-based knowledge of glacial mass loss.”
For the researchers, that meant taking a area journey to South Greenland — the place the Greenland ice sheet meets the Atlantic Ocean — to deploy a fiber-optic cable. In the previous decade, researchers have been exploring how these cables can be utilized for distant knowledge assortment by expertise referred to as Distributed Acoustic Sensing, or DAS, that data floor movement primarily based on cable pressure. Before this examine, nobody had tried to file glacial calving with a submarine DAS cable.
“We didn’t know if this was going to work,” stated Lipovsky. “But now we have data to support something that was just an idea before.”
Researchers dropped a 10-kilometer cable from the again of their boat close to the mouth of the glacier. They related it to a small receiver and picked up floor movement knowledge and temperature readings alongside the size of the cable for 3 weeks.
Julia Schmale, an assistant professor at École Polytechnique Fédérale de Lausanne (left), and Manuela Köpfli, a UW graduate pupil in Earth and area science (proper), unspool the fiber optic cable from a big drum, sending it right down to the fjord-bottom to file knowledge.Dominik Gräff
The backscatter sample from photons passing by the cable gave researchers a window beneath the floor. They have been capable of make nuanced observations concerning the monumental chunks of ice rushing previous their boat. Some of which, stated Lipovsky, have been the scale of a stadium and buzzing alongside at 15 to twenty miles per hour.
Glaciers are big, and most of their mass sits beneath the floor of the water. Mass loss proceeds sooner underwater, consuming away on the base and creating an unstable overhang. During a calving occasion, the overhanging portion breaks off and splashes into the ocean. Gradual calving chips away on the glacier, however on occasion, a big occasion happens. During the experiment, the researchers witnessed a big occasion each few hours.
“Icebergs are breaking off and exciting all sorts of waves,” stated Gräff.
Following the preliminary influence, floor waves — referred to as calving-induced tsunamis — surged by the fjord. This stirs the higher water column, which is stratified. Seawater is hotter and heavier than glacial soften and thus settles on the backside. But lengthy after the splash, when the floor had stilled, researchers noticed different waves, referred to as inner gravity waves, propagating between density layers.
Although they weren’t seen from the floor, the researchers recorded inner waves as tall as skyscrapers rocking the fjord. The slower, extra sustained movement created by these waves extended water mixing, bringing a gentle provide of hotter water to the floor whereas driving chilly water right down to the fjord backside.
Gräff in contrast this course of to ice cubes melting in a heat drink. If you don’t stir the drink, a cool layer of water types across the ice dice, insulating it from the hotter liquid. But if you happen to stir, that layer is disrupted, and the ice melts a lot sooner. In the fjord, researchers hypothesized that waves, from calving, have been disrupting the boundary layer and rushing up underwater soften.
The bow of the sector crew’s analysis vessel Adolf Jensen reducing by the ice of the fjord.Dominik Gräff
Researchers additionally noticed disruptive inner gravity waves emanating from the icebergs as they moved throughout the fjord. This sort of wave isn’t new, however documenting them at this scale is. Previous work relied on web site particular measurements from ocean backside sensors, which seize only a snapshot of the fjord, and temperature readings from vertical thermometers. The knowledge may assist enhance forecasting fashions and assist early warning programs for calving-induced tsunamis.
“There is a fiber-sensing revolution going on right now,” stated Lipovsky. “It’s become much more accessible in the past decade, and we can use this technology in these amazing settings.”
Other authors embrace Manuela Köpfli, a UW graduate pupil in Earth and area science; Ethan F. Williams a UW postdoctoral researcher in Earth and area science, Andreas Vieli, Armin Dachauer, Andrea Knieb-Walter, Diego Wasser, Ethan Welty of University of Zurich; Daniel Farinotti, Enrico van der Loo, Raphael Moser, Fabian Walter of ETH Zurich; Jean-Paul Ampuero, Daniel Mata Flores, Diego Mercerat and Anthony Sladen of the Université Côte d’Azur; Anke Dannowski and Heidrun Kopp of GEOMAR | Helmholtz Centre for Ocean Research Kiel; Rebecca Jackson of Tufts University; Julia Schmale, of École Polytechnique Fédérale de Lausanne; Eric Berg of Stanford University; and Selina Wetter of the Université Paris Cité.
This analysis was funded by the U.S. National Science Foundation, the University of Washington’s FiberLab, the Murdock Charitable Trust, the Swiss Polar Institute, the University of Zurich, ETH Zurich, and the German Research Center for Geosciences GFZ.
For extra data, contact Dominik Gräff at graeffd@uw.edu.
Tag(s): Brad Lipovsky • College of the Environment • Department of Earth and Space Sciences • Dominik Gräff • glaciers