Scientists now know that major ice streams can shut down, shifting rapid ice transport to other parts of the ice sheet, within a few thousand years. This was found in reconstructions of two ice streams, based on ice-penetrating radar scans of the Greenland ice sheet by a team led by the Alfred Wegener Institute.
How quickly the sea level rises in the future will greatly depend on how dynamic or stable the Greenland ice sheet is. In addition to melting on its base and surface, the sheet loses mass through ice streams – essentially conveyer belts for rapid ice transport from the inner sheet to its edge.
The paths of past ice streams can now be accurately reconstructed in the now glacier-free areas at the sheet’s edge, as the landforms they leave behind offer clearly visible clues. However, until recently, very little was known about the activity of past ice streams in the interior Greenland ice sheet, since the area is difficult to monitor.
The solution is cutting-edge measuring technologies like high-resolution radar systems that can penetrate the ice to map structures that lie several thousand meters below the surface of the ice sheet.
“Thanks to our ice-penetrating radar data, we can show how quickly the Greenland ice sheet’s ice transport system reconfigured itself. Major ice streams can ‘shut down’ within a few thousand or even several hundred years, while others appear elsewhere at a similar speed. Until now, no-one had any idea that the streams of this scale could change so quickly,” explained AWI glaciologist Dr. Steven Franke, first author of the study.
https://phys.org/news/2022-12-radar-scans-greenland-ice-sheet.html