Research press release


Nature Geoscience

Climate science: Greenland ice streams rapidly stopped thousands of years ago

グリーンランド氷床北東部に広がる高速で動く氷の流れは、数千年前に停止し、突然再構成されたと報告する論文が、Nature Geoscienceに掲載される。この発見は、グリーンランド氷床の将来の気候シナリオにおける安定性の理解を助ける可能性がある。


Steven Frankeたちは今回、レーダーのデータを解析して北東グリーンランド氷床深部に埋もれた層を追跡し、これを使ってこの地域における過去の氷流の状態を再構築した。その結果、現在の北東グリーンランド氷流の北に、速い氷の流れがあったことを示唆する一連の明瞭な褶曲があることが見いだされた。褶曲の方向や変形の仕方から、少なくとも2つの氷流が存在し、現在は活動していないことが示唆された。これらの特徴の正確な年代を特定することは困難であるが、著者らは、少なくとも完新世初期(およそ1万1500年前)にかけて活動しており、現在の氷流よりもさらに北の地域の氷を流出させていたことを示唆している。


Streams of fast-moving ice that extended into the northeastern Greenland Ice Sheet stopped and were abruptly reconfigured thousands of years ago, according to a study published in Nature Geoscience. The findings may help inform our understanding of the stability of the Greenland Ice Sheet under future climate scenarios.

Ice accumulated from snowfall in the interior of Greenland generally moves towards the coast, partly via quickly-moving conduits called ice streams. Along with direct surface melting, this is one of the primary ways in which mass is lost from the ice sheet. The Northeast Greenland Ice Stream is a prominent example that drains a large sector of the current Greenland ice sheet. Despite the importance of ice streams in understanding the overall behaviour of this and other ice sheets, it is unclear exactly why they occur and how stable they are through time.

Steven Franke and colleagues analysed radar data to trace layers buried deep in the northeastern Greenland Ice Sheet, which were then used to reconstruct past ice flow regimes in the region. They found a series of prominent folds indicative of quickly flowing ice to the north of the current Northeast Greenland Ice Stream. The orientation of the folds, as well as the ways they have been deformed, indicate the existence of at least two ice streams that are no longer active. Although it is difficult to assign exact ages to these features, the authors suggest they were active at least into the early Holocene (around 11,500 years ago), and that they drained areas further north than the modern ice stream.

The precise cause of the shift in ice stream locations is unknown, but the authors conclude that Greenland ice streams can rapidly adjust to shifting glaciological conditions and that ongoing warming might lead to similar reconfigurations in the future, with implications for sea level rise.

doi: 10.1038/s41561-022-01082-2


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