One of the most important scientific questions today is what is happening in Antarctica. We know that Northern ice is retreating, indicating significant warming, and possible changes to ocean levels and currents. But there is a whole lot more ice in Antarctica, and if it melts rapidly then sea levels will rise by several meters or more—which I guarantee everyone will notice.
Two new studies use satellite and airborne radar to measure the flow of some major glaciers in Western Antarctica. As these ice rivers flow into the sea, the ice melts. So what is going on?
A study by Bernd Scheuchl and colleagues document that over the past decades some glaciers are flowing much faster than others, as much as 900 meters per year (which is not bad for a glacier!). The faster moving glaciers are pumping more ice into the sea, and melting more ice, slower flow results in less melt.
Ala Khazendar and colleagues used radar from satellites and aircraft to measure the bottom of these glaciers, and found that the melting is much, much greater on the underside than the top. In particular, the fastest melting occurred where the bedrock allowed warm sea water to penetrate.
Thus, the rate of melting is not just due to atmosphere and ocean temperatures, but also to the (complex) topography of the bedrock under the ice.
These studies demonstrate the contribution of aerial remote sensing to the understanding of large scale phenomena, such as the evolution of the cryosphere. If we want to understand what is happening with Antarctica, satellite and airborne measurements will be crucial.
- Ala Khazendar, Eric Rignot, Dustin M. Schroeder, Helene Seroussi, Michael P. Schodlok, Bernd Scheuchl, Jeremie Mouginot, Tyler C. Sutterley, and Isabella Velicogna, Rapid submarine ice melting in the grounding zones of ice shelves in West Antarctica. Nature Communications, 7:13243, 10/25/online 2016. http://dx.doi.org/10.1038/ncomms13243
- Scheuchl, B., J. Mouginot, E. Rignot, M. Morlighem, and A. Khazendar, Grounding line retreat of Pope, Smith, and Kohler Glaciers, West Antarctica, measured with Sentinel-1a radar interferometry data. Geophysical Research Letters, 43 (16):8572-8579, 2016. http://dx.doi.org/10.1002/2016GL069287