The Circumpolar Deep Water (CDW, for short) is the main component of the Antarctic Circumpolar Current, and is several hundred meters deep. Before reaching the continental shelf warm waters go through deep depressions that lead to cavities beneath the Antarctic ice. If the volume of these waters increases in the boles, they can melt the bottom of the platform glaciers.
“The factors that affect the volume of CDW reaching the continental shelf and the cavities beneath the ice are largely unknown and are the subject of many investigations. Suspected to be related to changes in atmospheric circulation patterns, especially with increasing westerly winds , “declares Sinc Ala Khazendar, the Jet Propulsion Laboratory of NASA and co – author of a study on these waters they are causing the Antarctic glaciers melt faster.
The results of this research, published in the journal Nature Communications , support the hypothesis that the amount of hot water below the ice in the Amundsen Sea has increased significantly over the past 16 years.
The scientists studied data from NASA ‘s Operation IceBridge the behavior of three glaciers in West Antarctica in the Sea of Amundsen: The Smith, Pope and Kohler .
Measuring the loss of ice from the bottom of glaciers
This area is home to some of the planet’s glaciers are melting faster. So far the exact magnitude of the loss of ice was not quantified.
To measure the thickness and height of the ice, scientists used instruments radar and laser altimetry. Radar waves penetrate the glacier to its base, allowing directly assess their lower profiles and how they have changed the grounding lines between 2002 and 2014.
The authors have observed an intense and unbalanced melting glaciers between 2002 and 2009. The Smith, for example, lost 70 meters of ice a year and almost half a kilometer thick ice in total. Between 2009 and 2014, it has reduced the influx of hot water in the Pope and Kohler glaciers, which has resulted in less loss of ice.
“Recent research works indicate that some of the changes in West Antarctica are already irreversible, in particular, the rapid withdrawal line connection to the land and the loss of mass of the largest glaciers, as Thwaites. Several ice shelves on the Antarctic Peninsula, which has one of the fastest rates of warming over the past 50 years have collapsed, “adds Khazendar.
The question now is whether the rest of glaciers in West Antarctica behave like The Smith or more as Pope and Kohler.But researchers need more information on the source rock and the seabed as well as data on ocean circulation and temperature, to better predict how much ice of the glaciers will contribute to rising sea level.
