Seafloor Reveals a Period of Rapid Retreat for Thwaites Glacier
https://eos.org/articles/seafloor-reveals-a-period-of-rapid-retreat-for-thwaites-glacier
By Javier Barbuzano, Eos/AGU.
Excerpt: ...Thwaites is one of the main concerns of scientists studying Antarctic ice. As large as Florida and several kilometers thick, the melting of this mass of ice is responsible for 4% of present-day sea level rise worldwide. And warming waters and a seabed that deepens toward the ice sheet’s interior have primed the glacier for a rapid collapse that could raise sea levels by more than half a meter in the next century. ...In 2019, an expedition on board the Nathaniel B. Palmer icebreaker approached the front of the glacier and released a remotely operated submersible that mapped an area of 13 square kilometers of the seabed with specialized sonar and other instruments. As soon as the researchers recovered the submersible and looked at the images, they realized they had made an extraordinary finding. ...The images showed hundreds of parallel ridges covering an underwater plateau at depths ranging from 630 to 670 meters. The researchers think this plateau was a pinning point at a former grounding line, a region where the land-based glacier ends and the floating ice shelf begins. The ridges, ranging between 10 and 70 centimeters tall, were likely created by the glacier’s front as it bobbed up and down with the tides. When the tide fell, the glacier pressed the sediments to produce one rib. The distance between ribs reveals how much the glacier receded during the daily tidal cycle—typically between 6 and 7 meters every day, but reaching up to 10 meters in some cases.…