Researchers have uncovered a previously unseen way in which ice and an ocean interacts.
According to glaciologists, this could mean that the climate community has been vastly underestimating the magnitude of future sea level rise caused by polar ice deterioration. Using satellite radar data from three European missions, the team learned that the 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 ( Proceedings of the National Academy of Sciences).
The researchers found that as the Petermann Glacier’s grounding line retreated nearly 4 km 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.
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 pre-existing subglacial channels, with the highest melt rates occurring at the grounding zone, says a release.
