Sea level rise may proceed faster than expected in the coming decades, as a gargantuan flow of ice slithering out of Greenland’s remote interior both picks up speed and shrinks.
By the end of the century, the ice stream’s deterioration could contribute to Global sea level rise is expected to reach 16 millimeters — more than six times the amount scientists had previously estimated, researchers report November 9 in Nature.
This suggests that large ice flows in the inland may be slowing down and withering due to human-caused factors. Climate ChangeThis is because past research has likely underestimated the rate at which the sea level will rise due to the ice.SN: 3/10/22).
“It’s not something that we expected,” says Shfaqat Abbas Khan, a glaciologist at the Technical University of Denmark in Kongens Lyngby. “Greenland and Antarctica’s contributions to sea level rise in the next 80 years will be significantly larger than we have predicted until now.”
In the new study, Khan and colleagues focused on the Northeast Greenland Ice Stream, a titanic conveyor belt of solid ice that crawls about 600 kilometers out of the landmass’s hinterland and into the sea. It drains about 12 percent of the country’s entire ice sheet and contains enough water to raise global sea level more than a meter. Near the coast, the ice stream splits into two glaciers, Nioghalvfjerdsfjord and Zachariae Isstrøm.
These glaciers freeze, but they keep the ice behind. Do not rush into the oceanSimilar to dams that hold back water from a river,SN: 6/17/21). When the ice shelf of Zachariae Isstrøm collapsed about a decade ago, scientists found that the flow of ice behind the glacier Acceleration began. But whether those changes penetrated deep into Greenland’s interior remained largely unresolved.
“We’ve mostly concerned ourselves with the margins,” says atmosphere-cryosphere scientist Jenny Turton of the nonprofit Arctic Frontiers in Tromsø, Norway, who was not involved in the new study. That’s where The most dramatic changesWith the The greatest impact on sea level riseShe says that she has been observing them (SN: 4/30/22, SN: 5/16/13).
Khan and his associates used GPS to measure the small movements in the ice stream farinland. This has revealed the tortuous creeping of Tectonic plates (SN: 1/13/21). The team analyzed GPS data from three stations along the ice stream’s main trunk, all located between 90 and 190 kilometers inland.
Data showed that the ice stream had increased at all three points between 2016 and 2019. The data revealed that the ice speed at the station furthest inland increased by 344 meters per annum to 351 meters.
The GPS measurements were then compared to data from polar-orbiting spacecraft and aircraft surveys. The GPS analysis confirmed the aerial data. It revealed that the ice stream was speeding up to 200 km upstream. What’s more, shrinking — or thinning — of the ice stream that started in 2011 at Zachariae Isstrøm had propagated more than 250 kilometers upstream by 2021.
“This is showing that glaciers are responding along their length faster than we had thought previously,” says Leigh Stearns, a glaciologist from the University of Kansas in Lawrence, who was not involved in the study.
Khan and his colleagues then used the data to tune computer simulations that forecast the ice stream’s impact on sea level rise. The researchers predict that by 2100, the ice stream will have singlehandedly contributed between about 14 to 16 millimeters of global sea level rise — as much as Greenland’s entire ice sheet has in the last 50 years.
Stearns & Turton believe that past research likely underestimated sea-level rise rates caused by the ice stream. Similarly, upstream thinning acceleration in other large ice flows, such as those associated with Antarctica’s shrinking Pine Island and Thwaites glaciersTurton suggests that sea levels might rise faster than anticipated due to this factor.SN: 6/9/22, SN: 12/13/21).
Khan and his associates plan to explore inland sections from other large ice flows, including those in Antarctica and Greenland. Improved forecasts for sea level rise (SN: 1/7/20).
Stearns believes such forecasts are critical for adapting to climate changes. “They’re helping us better understand the processes so that we can inform the people who need to know that information.”
