Surface meltwater draining through cracks in an ice sheet can warm the sheet from the inside, softening the ice and letting it flow faster, according to a new study by scientists at the Cooperative Institute for Research in Environmental Sciences (CIRES) at the University of Colorado Boulder.
During the last decade, researchers have captured compelling evidence of accelerating ice flow at terminal regions, or “snouts,” of Greenland glaciers as they flow into the ocean along the western coast. The new CIRES research now shows that the interior regions also are flowing much faster than they were in the winter of 2000-01, and the paper proposes a reason for the speedup.
“Through satellite observations, we determined that an inland region of the Sermeq Avannarleq Glacier, 40 to 60 miles from the coast, is flowing about one and a half times faster than it was about a decade ago,” said Thomas Phillips, lead author of the new paper and a CIRES research associate at the time of the study. In 2000-01, the inland segment was flowing at about 130 feet (40 meters) per year; in 2007-08, that speed was closer to 200 feet per year (60 meters).
“At first, we couldn’t explain this rapid interior acceleration,” Phillips said. “We knew it wasn’t related to what was going on at the glacier’s terminus. The speedup had to be due to changes within the ice itself.”
To shed light on the observed acceleration, Phillips and his team developed a new model to investigate the effects of meltwater on the ice sheet’s physical properties. The team found that meltwater warms the ice sheet, which then—like a warm stick of butter—softens, deforms and flows faster.
Read more at: Phys.org