Antarctica is melting. Some places are melting faster than others.
We know from Greenland that one of the factors that influences the speed of melting is the presence of water under the ice.
So, it is significant that we know very little about what’s going on under the ice in Antarctica. We can’t really understand how fast the ice is melting unless we know about what’s under the ice.
This spring a group of researchers report observations of what is under the Williams Ice Sheet in West Antarctica [3]. The research measured low frequency conductivity from instruments on the ice sheet, i.e., field measurements on the ground.
This ice sheet is moving fast, shedding ice into the ocean. It slides along on top of a thin layer of water. The new study found that below the thin layer of liquid water there is as much as 1 km of groundwater in sedimentary rock.
The deep water is saline, suggesting that it may be “paleowater”, trapped from ancient seas, and possible kept warm by the heat of the deep rocks. The surface water below the ice, include a large under ice lake, seems to be leaking into the sedimentary rock, and possibly vice versa [2].
This vast amount of deep water and rather permeable interface makes the under ice picture more complicated. Meltwater flows down from the ice, but water may also percolate into and from the sedimentary water. This means there is a lot of liquid water under this ice sheet, but most of it isn’t in direct contact with the ice. On the other hand, there is a reservoir of water that might keep the underside lubricated independent of meltwater. Thus, the under ice is quite dynamic and complex, and changes may have delayed effects.
This study raises the question of what may be going on elsewhere across Antarctica. If the presence or absence of such groundwater influences the flow of ice and/or the rate of melting, then they need to be surveyed in order to accurately model the behavior of the ice [1].
- Jonathan Amos, Huge volume of water detected under Antarctic ice, in BBC News – Science & Environment, May 6, 2022. https://www.bbc.com/news/science-environment-61337864
- Winnie Chu, Groundwater under Antarctica goes deep. Science, 376 (6593):577-578, 2022/05/06 2022. https://doi.org/10.1126/science.abo1266
- D. Gustafson Chloe, Kerry Key, R. Siegfried Matthew, J. Paul Winberry, A. Fricker Helen, A. Venturelli Ryan, and B. Michaud Alexander, A dynamic saline groundwater system mapped beneath an Antarctic ice stream. Science, 376 (6593):640-644, 2022/05/06 2022. https://doi.org/10.1126/science.abm3301
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