Ancient Antarctic Ice Sheet Loss Dwarfs Modern Melting, Study Finds
More than a year ago, researcher Julian Dowdeswell boarded a research vessel at the edge of the Fimbul ice shelf to the east of the Antarctic Peninsula. He and six other scientists with the University of Cambridge were setting off as part of an expedition to study the ancient patterns of ice sheet retreat along the peninsula, what is one of today’s most vulnerable ice shelves.
The team analyzed the data gathered on that trip and has published a study in Science on Thursday. They have found that ice sheet retreat rates 10,000 years ago make today’s rate of retreat look like baby steps. This period saw ice shelves retreat more than 10 kilometers (6 miles) each year along the Larsen C shelf. That’s three to five times greater than the rates we’ve seen via satellite data over the last 25 years. These findings can improve how scientists’ model the future of ice and what it means for sea level rise.
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What’s going on under ice shelves—floating extensions of inland ice sheets that feed them—is of utmost importance. When warm water cuts under them, it thins the ice shelf by melting it from below. As the ice thins, it can lift off the seafloor and begin to bob with the tide. That up and down motion can form ridges on the seafloor close to where ice meets the seafloor, an area known as the grounding line. The team identified up to 90 ridges to paint an incredible story of ice melt over the past 10,000 years.
“The grounding zone of ice sheets and the processes that occur there are ‘holy grails’ for glaciologists and glacial geologists because they are so hard to access and image,” Graham said. “The methodology is robust.”
The space between the ridges helps scientists determine how old they are. Using the ridges as a proxy for ice shelf retreat, the study estimates that ice could have pulled back up to 40 to 50 meters (131 to 164 feet) per day. That has profound implications for what the future could hold. Warm water is currently wreaking havoc both along the Antarctic Peninsula and West Antarctic. The risk of rapid ice shelf collapse could raise sea levels 10 feet or more, and researchers are trying to understand just how fast the retreat could be.
https://earther.gizmodo.com/ancient-antarctic-ice-sheet-loss-dwarfs-modern-melting-1843732617Antarctic Ice Sheets Capable of Retreating Up to 50 Meters per Day
In the ASLR thread has another news article plus the links to the research.