Researchers have mapped 1,943 valleys beneath Greenland’s ice sheet, connecting features that earlier maps missed or left fragmented, NASA said in a September 28 overview of the work.
About a third were newly identified. Many known valleys also extend farther inland than previous mapping suggested, according to NASA Earth Observatory.
The underlying Geophysical Research Letters paper was first published on June 30. The September feature brings attention to that research; it is not a claim that all of the valleys were discovered this week.
How do you map land beneath an ice sheet?
The team used Ice Flow Perturbation Analysis, which draws on measurements of surface elevation and ice movement. Buried ridges and valleys leave subtle patterns in the ice above them, allowing researchers to infer features of the bedrock.
The paper explains why another established approach, based on mass conservation, is more useful near the ice sheet’s margins than in its slower-moving interior. Sparse measurements there have left large gaps in the representation of the landscape.
This is an interpretation of observations using a physical model, rather than a photograph taken through the ice.
Why the shape of the bedrock matters
Valleys help channel moving ice toward Greenland’s coast. Knowing where those routes continue inland can improve researchers’ understanding of how flow may change as the ice sheet retreats.
The pattern also holds clues to an older landscape. The study links many valleys to southern and eastern highlands and suggests that groundwater and past tectonic deformation helped shape the network.
Those are interpretations to investigate further. The mapping does not, on its own, provide a new date for ice-sheet collapse or a precise forecast of future sea-level rise.