February 26, 2024

Future Sea-Level Rise May Be Much Higher Than Thought – Ice Loss in Greenland “Vastly Underestimated”

” Our previous projections of ice loss in Greenland till 2100 are greatly undervalued,” said very first author Shfaqat Abbas Khan, Professor at DTU Space.
” Models are mainly tuned to observations at the front of the ice sheet, which is easily available, and where, visibly, a lot is happening.”
Animation of modeled frontal positions from 2007 to 2100. Credit: Animation by Shfaqat Abbas Khan, DTU Space, Denmark
Ice loss happens more than 200 km inland
The research study is partly based on information collected from a network of exact GPS stations reaching as far as 200 km inland on the Northeast Greenland Ice Stream– situated behind the Nioghalvfjerdsfjord Gletscher and Zachariae Isstrøm glaciers, among Earths most hostile and remote surfaces. The GPS data were combined with surface-elevation information from the CryoSat-2 satellite objective and high-resolution numerical modeling.
” Our information show us that what we see happening at the front reaches far back into the heart of the ice sheet,” stated Khan.
” We can see that the entire basin is thinning, and the surface area speed is accelerating. Every year the glaciers weve studied have pulled back further inland, and we predict that this will continue over the coming years and centuries. Under present-day climate requiring, it is tough to develop how this retreat could stop.”
Animation of designed surface area elevation change from 2007 to 2100. Credit: Animation by Shfaqat Abbas Khan, DTU Space, Denmark
Significant contribution to rising sea levels
Considering that northeastern Greenland is a so-called Arctic desert– precipitation is as low as 25 mm per year in locations– the ice sheet is not regrowing enough to mitigate the melt. Estimating how much ice is lost and how far into the ice sheet the procedure takes place is not simple.
” It is genuinely incredible that we are able to identify a subtle speed modification from high-precision GPS information, which ultimately, when integrated with a design of ice flow, inform us on how the glacier slides on its bed,” said coauthor Mathieu Morlighem, a teacher of earth sciences at Dartmouth College.
” It is possible that what we find in northeast Greenland may be occurring in other sectors of the ice sheet. If this is appropriate, the contribution from ice characteristics to the general mass loss of Greenland will be bigger than what existing models suggest.”
The Zachariae Isstrøm was steady up until 2004, followed by steadily retreat of the ice front up until 2012, when a large portion of the drifting sections became disconnected. As more accurate observations of change in ice velocity are consisted of in models, it is most likely that IPCCs estimates of 22-98 cm worldwide sea level rise will require to be fixed upwards.
” We predict extensive modifications in international sea levels, more than presently predicted by existing models,” said coauthor Eric Rignot, teacher of Earth system science at the University of California, Irvine.
” Data gathered in the large interior of ice sheets, such as those explained herein, assist us much better represent the physical procedures included in mathematical designs and in turn supply more practical forecasts of international sea-level increase.”
Reference: “Extensive inland thinning and speed-up of Northeast Greenland Ice Stream” by Shfaqat A. Khan, Youngmin Choi, Mathieu Morlighem, Eric Rignot, Veit Helm, Angelika Humbert, Jérémie Mouginot, Romain Millan, Kurt H. Kjær and Anders A. Bjørk, 9 November 2022, Nature.DOI: 10.1038/ s41586-022-05301-z.

River of meltwater on the Zachariae Glacier, northeast Greenland. Credit: Shfaqat Abbas Khan, DTU Space
A brand-new study combined GPS, satellite information, and mathematical modeling. It discovered ice loss from northeast Greenland might be six times higher by the end of the century than previously believed.
Ice is continuously streaming off Greenlands melting glaciers at an accelerating rate, dramatically increasing international sea levels. New results published in the journal Nature on November 9 show that existing designs have underestimated just how much ice will be lost throughout the 21st century. Hence, its contribution to sea-level increase will be considerably greater.
By 2100, the Northeast Greenland Ice Stream will contribute six times as much to the rising sea level as previous models recommended, including in between 13,5 to 15,5 mm (0.53 to 0.61 inches), according to the new research study. This is comparable to the whole Greenland ice sheets contribution in the previous 50 years. Researchers from Denmark, the United States, France, and Germany performed the research.

Ice is constantly streaming off Greenlands melting glaciers at an accelerating rate, considerably increasing global sea levels. By 2100, the Northeast Greenland Ice Stream will contribute six times as much to the rising sea level as previous designs recommended, including in between 13,5 to 15,5 mm (0.53 to 0.61 inches), according to the brand-new research study. Approximating how much ice is lost and how far into the ice sheet the procedure takes place is not simple.” It is possible that what we discover in northeast Greenland may be occurring in other sectors of the ice sheet. If this is appropriate, the contribution from ice characteristics to the overall mass loss of Greenland will be bigger than what present designs suggest.”