Researchers have found a link between sea ice conditions and the melting rate of the Totten glacier, which releases enough ice into the ocean to fill lake Erie in about a week.
The team looked at super-salty water (brine) that forms in the openings of sea ice. They hoped to gain insight into how ice sheets are affected by the ocean, a NASA's Jet Propulsion Laboratory news release reported.
"This is an issue bigger than Totten or even Antarctica. It lies with the debates societies and countries are currently having about the effects of global climate change and how to address them," lead author of the study Ala Khazender of NASA's Jet Propulsion Laboratory told Headlines and Global News in an e-mail.
Khazender noticed the Totten glacier was rapidly changing, while the one next to it wasn't really changing at all. The researchers made observations using ocean numerical modeling, and suggested that an increase in brine would speed up glacial melt.
The study has important implications for the future of Antarctic ice.
"This study can help [us] to contribute to the large ongoing effort by many colleagues around the world to better project Antarctica's contribution to sea level rise for the next 50 or 100 years. In general, we already understand that many parts of Antarctica are losing mass to the ocean because the ocean temperatures have risen. We, however, still need to better understand the mechanisms by which these changes are taking place in order to better quantify how much mass Antarctica will discharge into the ocean, and how fast," Khazender told HNGN.
Ice loss is generally blamed on a rise in ocean temperature, but the "regional variations" have had scientists stumped.
Ice shelves ("the floating front edges of glaciers that extend tens to hundreds of miles offshore") melt more rapidly from ocean water than from sunlight, but when the underside of the glacier starts to melt abnormally quickly it is a sign that something is off.
The researchers used the numerical computer models to see how these ice shelves reacted with their basins. The ocean basins contain polynyas, which are "annually recurring openings in the winter sea ice cover."
A computer model found these annually varying changes greatly affected glacial melt.
The team hypothesized that brine collecting under the Totten Ice Shelf and mixed with the water, which lowered the temperature; this would slow down the glacier's melt rate. If this were the case, reducing the salt concentration in water would actually cause the glacier to melt faster than it would when exposed to brine.
If the polynyas are reduced it could cause the hollow areas of Totten to fill with warm water instead of colder brine.
"If that happens, the glacier's flow could be significantly destabilized, causing it to discharge even more ice into the ocean," Khazender said in the news release.
A data set of passive microwave measurements from the Defense Meteorological Satellite Program showed that during the study the amount of brine (and the extent of polynyas) decreased and the thinning rate of the glacier increased.
The team plans to continue their study on how ocean water affects glacial melt.
"Concerning Antarctica as whole, we are interested in investigating other places were this process is occurring. We have already identified a few
glaciers and ice shelves of which we think the melting rates might be affected by the mechanism we uncovered in the case of Totten," Khazender told HNGN.
