Radar surveys have previously mapped Greenland’s bedrock buried underneath a few thousand meters of ice. Mathematical models were used to fill in the gaps in survey data and infer bedrock depths. However, the reviews uncovered the long valley, which was segmented, preventing water from flowing freely through it.
Be that as it may, the peaks breaking the valley into segments appear in areas where the mathematical modeling was used to fill in missing data so that it couldn’t be real.
At Hokkaido University‘s Institute of Low-Temperature Science, scientists wanted to explore what might happen if the valley is open and melting increases at an area deep in Greenland’s interior known for melting.
In collaboration with scientists from the University of Oslo, scientists ran numerous simulations to compare water dynamics in northern Greenland with and without valley segmentation.
Their results show a dramatic change in how water melting at the base of the ice sheet would flow if the valley is indeed open. A distinct subglacial watercourse runs from the melting site to Petermann Fjord, located more than 1,000 kilometers away on the northern coast of Greenland. The watercourse only appears when valley segmentation is removed; there are no other significant changes to the landscape or water dynamics.
Christopher Chambers from Hokkaido University’s Institute of Low-Temperature Science said, “The results are consistent with a long subglacial river, but considerable uncertainty remains. For example, we don’t know how much water, if any, is available to flow along the valley, and if it does indeed exist at Petermann Fjord or is refrozen, or escapes the valley, along the way.”
If that water is flowing, the model recommends it could traverse the valley’s entire length because the valley is relatively flat, like a riverbed. This suggests no parts of the ice sheet form a physical blockade. The simulations also proposed more water flow towards the fjord with a level valley base set at 500 meters below sea level than when set at 100 meters below.
When melting is increased only in the deep interior at a known region of basal melting, the simulated discharge is increased down the entire length of the valley only when the valley is unblocked. This suggests that a finely tuned relationship between the valley form and overlying ice can allow a very long down-valley water pathway to develop.
Ralf Greve from the Hokkaido University’s Institute of Low-Temperature Science said, “Additional radar surveys are needed to confirm the simulations are accurate. This could introduce a fundamentally different hydrological system for the Greenland ice sheet. The correct simulation of such a long subglacial hydrological system could be important for accurate future ice sheet simulations under a changing climate.”
- Christopher Chambers et al. Possible impacts of a 1000 km-long hypothetical subglacial river valley towards Petermann Glacier in northern Greenland, The Cryosphere (2020). DOI: 10.5194/tc-14-3747-2020