연구자들은 그린란드 눈사태의 비밀을 밝힙니다.

2012년 NASA가 촬영한 이 이미지의 중심에는 그린란드 북서부의 피터만 빙하가 점차 바다를 향해 움직이고 있으며 많은 부분이 부서져 빙산처럼 표류하고 있습니다. UCI와 NASA JPL의 연구원들은 3개의 유럽 임무에서 위성 데이터를 사용하여 따뜻한 바닷물이 어떻게 빙하의 육지선을 이동시켜 빙하의 급속한 감소를 일으키는지 확인했습니다. 크레딧: NASA

이 연구는 미래의 해수면 상승 정도가 크게 과소평가될 수 있음을 시사합니다.

새로운 연구에 따르면 그린란드의 피터만 빙하(Petermann Glacier) 기준선이 조석 주기 동안 변화하여 따뜻한 바닷물이 얼음 녹는 속도를 높일 수 있습니다. 이 이전에 알려지지 않은 상호 작용으로 인해 모델에 포함되면 해양 종결 빙하의 해수면 상승 예측이 200% 증가할 수 있습니다.

그린란드 북서부의 Petermann Glacier에 대한 연구를 수행하는 동안 Irvine 캘리포니아 대학과 NASA의 제트 추진 연구소의 연구원들은 얼음과 바다가 상호 작용하는 이전에는 볼 수 없었던 방식을 발견했습니다. 빙하학자들은 그들의 발견이 기후 공동체가 극지 얼음의 악화로 인한 해수면의 미래 상승을 크게 과소평가했다는 것을 의미할 수 있다고 말했습니다.

3개의 유럽 미션, UCI/의 위성 레이더 데이터 사용[{” attribute=””>NASA team learned that Petermann Glacier’s grounding line – where ice detaches from the land bed and begins floating in the ocean – shifts substantially during tidal cycles, allowing warm seawater to intrude and melt ice at an accelerated rate. The group’s results are the subject of a paper published on May 8 in Proceedings of the National Academy of Sciences.

“Petermann’s grounding line could be more accurately described as a grounding zone, because it migrates between 2 and 6 kilometers as tides come in and out,” said lead author Enrico Ciraci, UCI assistant specialist in Earth system science and NASA postdoctoral fellow. “This is an order of magnitude larger than expected for grounding lines on a rigid bed.”

He said the traditional view of grounding lines beneath ocean-reaching glaciers was that they did not migrate during tidal cycles, nor did they experience ice melt. But the new study replaces that thinking with knowledge that warm ocean water intrudes beneath the ice through preexisting subglacial channels, with the highest melt rates occurring at the grounding zone.

The researchers found that as Petermann Glacier’s grounding line retreated nearly 4 kilometers – 2½ miles – between 2016 and 2022, warm water carved a 670-foot-tall cavity in the underside of the glacier, and that abscess remained there for all of 2022.

“These ice-ocean interactions make the glaciers more sensitive to ocean warming,” said senior co-author Eric Rignot, UCI professor of Earth system science and NASA JPL research scientist. “These dynamics are not included in models, and if we were to include them, it would increase projections of sea level rise by up to 200 percent – not just for Petermann but for all glaciers ending in the ocean, which is most of northern Greenland and all of Antarctica.”

The Greenland ice sheet has lost billions of tons of ice to the ocean in the past few decades, the PNAS paper stresses, with most of the loss caused by warming of subsurface ocean waters, a product of Earth’s changing climate. Exposure to ocean water melts the ice vigorously at the glacier front and erodes resistance to the movement of glaciers over the ground, causing the ice to slide more quickly to the sea, according to Rignot.

Reference: “Melt rates in the kilometer-size grounding zone of Petermann Glacier, Greenland, before and during a retreat” by Enrico Ciracì, Eric Rignot, Bernd Scheuchl, Valentyn Tolpekin, Michael Wollersheim, Lu An, Pietro Milillo, Jose-Luis Bueso-Bello, Paola Rizzoli and Luigi Dini, 8 May 2023, Proceedings of the National Academy of Sciences.
DOI: 10.1073/pnas.2220924120

Ciraci’s research was supported by the NASA Postdoctoral Program at the Jet Propulsion Laboratory. Joining Ciraci and Rignot on the project were Bernd Scheuchl, UCI associate project scientist; Valentyn Tolpekin and Michael Wollersheim of Finland’s Iceye mission; Lu An of China’s Tongji University; Pietro Milillo of the University of Houston; Jose-Luis Bueso-Bello of the German Aerospace Center; and Luigi Dini of the Italian Space Agency.