URI oceanographers travel to Antarctica to examine rapid melting of Pine Island Glacier
Todd McLeish, 401-874-7892
NARRAGANSETT, R.I. – May 13, 2014 – University of Rhode Island oceanographer Brice Loose and graduate student Arash Bigdeli spent six weeks on the coast of Antarctica in February and March examining a perplexing question that has implications for the rising sea level around the globe.
Loose and Bigdeli joined an international team of scientists studying how and how fast Pine Island Glacier, part of the West Antarctica ice sheet, is melting. It’s a pressing question, since Pine Island Glacier is the fastest melting glacier on Antarctica, and it is holding back large quantities of ice from flowing into the Southern Ocean.
“If the ice on Antarctica starts to move into the ocean quickly, that would have huge implications for sea level rise,” said Loose, an assistant professor at the URI Graduate School of Oceanography. “The melting of Antarctica has the potential to raise sea level by 57 meters, though that’s not a realistic scenario any time soon. But to be able to track sea level rise year by year, we have to know the melt rate from this area.”
The reason for the concern in this region is that the relatively warm waters of the Antarctic Circumpolar Current, which carries water eastward around the continent, comes quite close to Pine Island Glacier and is penetrating beneath the glacier and melting it from below.
“The question is how does the water get up onto the continental shelf,” Loose said. “The shelf is quite shallow, and the current can be 500 to 2000 meters deep, but somehow the water from the current gets up onto the shelf. If we can predict how much water from the current is sneaking onto the shelf, we can begin to determine how much meltwater it will produce.”
The part of the project that Loose and Bigdeli focused on during their time aboard the British icebreaker RRS James Clark Ross was to trace the meltwater that flows from underneath the ice shelves and into the surrounding bay. They collected dozens of water samples to extract concentrations of helium, neon, argon, krypton and xenon.
“Those noble gases appear in high concentrations within the ice, so when the ice melts, we can pick up that gas signal in the water, even far away from the source of the melt,” Loose said. “Then we’ll be able to estimate how much meltwater is on the continental shelf and where it goes as it flows into the southern ocean.”
Although the URI scientists still have months of analysis to conduct, they can already tell that the water in the region around Pine Island Glacier was not as warm as it had been in previous years.
“We think that’s because of a very large iceberg, known as B31, that broke off the front of the glacier and is moving around in the bay,” he explained. “It stirred up the water and disrupted the normal flows.
“When you get close to the ice shelf, though, you can see this tremendously strong, fast flowing water coming out from underneath the ice shelf and continuing to ascend, almost like a boil in the water. It’s moving about two feet per second, like a river in the ocean,” he added.
When not conducting their own studies aboard ship, Loose and Bigdeli helped other researchers with their work, including attaching measuring devices to Weddell seals to collect water temperature and salinity data when the animals dive, and using underwater vehicles to map the sea floor.
“Ultimately, we want to know how climate change is affecting the ice sheets around Antarctica, because the ice sheets affect sea level rise, the coastal ocean, the deep ocean, and the ocean’s function as a sink for heat and carbon dioxide,” Loose concluded. “We need to know how these interconnected processes work in order to understand how it’s going to affect us and all the things the ocean does for us and to us.”