In a recently published study, scientists have discovered a new way that the ocean and ice interact, all but resetting estimates of how high they expect sea levels to rise as a result of climate change and melting polar ice.
The study comes from a group of researchers from the University of California, Irvine and NASA’s Jet Propulsion Laboratory. It was published in the Proceedings of the National Academy of Sciences.
The researchers share in their findings that they have discovered a new way in which ice and the ocean interact from observations of the Petermann Glacier’s grounding line in northwest Greenland.
A grounding line is “The point at which an outlet glacier no longer lies on bedrock but starts to float over an open body of water as an ice shelf,” according to Polarpedia.
According to the study, the glacier’s grounding line shifts substantially during tidal cycles, allowing warm ocean water to enter the glacier and melt it at faster rates than previously believed.
The researchers were able to make these observations thanks to satellite radar data from three European missions.
Traditionally, scientists believed that grounding lines beneath ocean-reaching glaciers did not migrate during tidal cycles or experience ice melt, but now they’ve observed the opposite.
From 2016 to 2022, the researchers found that the Petermann Glacier’s grounding line had retreated almost 4 kilometers, with warm water melting a 670-foot-tall cavity in the underside of the ice.
Eric Rignot, a UCI professor of Earth system science and NASA JPL research scientist, shared in the study that their findings show glaciers are far more sensitive to the warming oceans than previously thought.
Even more concerning is how Rignot says this will affect projections concerning the rising sea level.
“These dynamics are not included in models, and if we were to include them, it would increase projections of sea level rise by up to 200 percent -- not just for Petermann but for all glaciers ending in the ocean, which is most of northern Greenland and all of Antarctica,” Rignot said.
Researchers shared that they hope their findings will improve models and projections for future sea level rise to better prepare those who will be affected.
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