Greenland’s coast gets a new face | Polarjournal
About 80 percent of Greenland’s surface is covered by a second largest ice sheet. At its edges, the glaciers flow into the sea, bringing fresh water and nutrients to the surrounding waters and to the coastal inhabitants. But all this is likely to change if glaciers continue to retreat. Picture: Michael Wenger

Greenland was a place of stability until the early 1990s, at least in terms of melting of its ice sheet. But that has changed fundamentally since then. Because the numerous glaciers flowing away from the world’s second-largest ice sheet seem to be behaving differently, and therefore, predictions about the evolution of behaviour and its impact on the coasts have been difficult. Now, however, a US research group has shown that the loss of ice actually has accelerated massively and that this will have a corresponding impact on coastal regions.

“The speed of ice loss in Greenland is stunning.”

Dr. Twila Moon, National Snow & Ice Data Center

The results of the study by Dr. Twila Moon of the National Snow and Ice Data Center in Boulder Colorado show that in the past 20 years basically all glaciers have retreated, some quite rapidly, changing the ice sheet sustainably, at least at the edges. “The speed of ice loss in Greenland is stunning,” explains the study’s first author. We can now see many signs of a transformed landscape from space. And as the ice sheet edge responds to rapid ice loss, the character and behavior of the system as a whole is changing, with the potential to influence ecosystems and people who depend on them. This, in turn, has the potential to influence ecosystems and the people who depend on them.”

NASA’s video shows how the Greenland ice sheet will change under various emission scenarios until the year 2300. Large parts of the Greenland coast will be alteredmassively, just as Moon et al (2020) show. Video: NASA

Moon and her colleagues compared data on the location of the ice edges, the height of the surface of the ice sheet, and the flow speeds of glaciers from 1985 to 2015. It turned out that from the mid-1990s onwards, the edges had retreated along the entire ice sheet and none of the 225 glaciers that flow into the sea had significant growth, even more so 200 had retreated. In addition, the flow speed is influenced by the topography of the substrate and by processes in the upper part of the glaciers, the researchers write in their work. And it is precisely these upper areas that have changed a lot: areas with rapid ice flows are becoming narrower, ice is diverted in other directions, and in some cases the flow is even slowing down. All of this has implications for coastal areas, as the team writes. This means that the water under the glacier flows differently and can change the supply of fresh water and nutrients into the sea, affect the drinking water supply of the communities and even change the topography of the coast by exposing new land or opening up new fjords.

The rivers of ice in the fjords, which appear to flow endlessly into the sea from some glaciers such as the Jakobshavnbrae near Ilulissat, will change due to the further loss of ice on the ice sheet and thus affecting the entire local system, according to the authors of the study. Picture: Michael Wenger

The authors of the work conclude that the behaviour of the individual glaciers in their complexity, which is influenced by the factors they mention, must be incorporated into the predictions and models. Alex Gardner of NASA’s Jet Propulsion Laboratory and co-author of the study said: “Understanding the complexity of individual glacier response is critical to improving projections of ice sheet change and the associated sea level rise that will arrive at our shores.” The researchers hope that the information gathered in this study will be used to predict future changes in the dynamics of the ice sheet, ice loss, and local to regional impacts, while global warming continues to change Greenland’s icy world.

Dr Michael Wenger, PolarJournal

Link to the study: Moon et al (2020) JGR Earth Surface, Rapid reconfiguration of the Greenland Ice Sheet coastal margin; doi: 10.1029/2020JF005585

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