The National Science Foundation and the U.K.’s Natural Environmental Research Council this month announced a joint 5-year, $25 million effort to study Antarctica’s Thwaites Glacier.
Nicknamed the “world’s most dangerous glacier,” Thwaites Glacier already is contributing to rising seas; if it collapsed it would raise global sea level by about three feet. The glacier may also act as a linchpin on the whole West Antarctic Ice Sheet, which could raise sea level by much more.
University of Washington glaciologists will participate in one of the eight projects funded through the International Thwaites Glacier Collaboration to better understand the glacier and predict what it will do next.
“About 100 scientists are involved in this initiative, which is the largest Antarctic deep-field effort in 70 years,” said Knut Christianson, assistant professor of Earth and space sciences and the UW’s principal investigator on the project. “This is one of the largest deep-field efforts ever attempted in West Antarctica, and is on a scale neither the U.S. nor the U.K. — or anyone else — could accomplish alone.”
The UW is participating in the Geophysical Habitat of Subglacial Thwaites, or GHOST project, that will collect on-the-ground data to see the details of the glacier’s internal structure and better map the surface underneath.
The information they collect will provide better data to feed into the computer models that scientists are using to forecast the future of Earth’s climate.
“It’s unlikely that the ice-sheet modelers have the big story wrong,” Christianson said. “But if you’re looking for shorter-term estimates, having detailed information about the bed conditions or how ice is flowing over a ridge can be useful for understanding how the glacier might behave over the next few decades or century.”
That’s the kind of timeline that would be useful on the ground. A 2014 UW study found that Thwaites Glacier would likely collapse within 200 to 1,000 years, though other estimates also exist. More data could provide a firmer timeline.
The GHOST team plans to spend two 60-day seasons in the field during the Antarctic summer, beginning in late 2019 and late 2020. An initial trip later this year will install equipment and fuel caches and survey potential base camps.
During the field campaign, the team will begin near the glacier’s coastal terminus, where the most rapid changes are occurring. Christianson, UW postdoctoral researcher Nick Holschuh and a graduate student will conduct the scans. The UW team plans to travel by snowmobile, surveying about 50 km (31 miles) of the glacier per day. Every week or so the entire GHOST project’s science team will move and set up a new camp, gradually working its way uphill toward the ice sheet’s interior.
The UW researchers will use two different radars to map individual layers of snow and ice, and the underlying bedrock. The first technology, ground-penetrating radar, has been used by Christianson’s group for years and can penetrate through more than 2 miles of ice. His team’s data will complement airborne surveys being done by other teams.
“To map out a glacier’s internal structure, it’s advantageous to have a ground-based survey,” Christianson said. “If you want to recover very steeply-sloped layers of ice where the ice has folded, you can acquire higher-quality data if you’re driving on the ground. These layers tell us about the past flow structure of the ice, as well as the current deformation: where it’s bending in response to a sticky edge, or an area where there’s a lot of friction at the base.”
The other method the UW team will use is a newer tool developed by the British Antarctic Survey that sends similar waves into the glacier but is designed for determining relative rates of change between layers in the ice detected by the radar. This technique allows detection of changes in glacier internal structure with a scale of just fractions of an inch, rather than several feet. Christianson hopes to repeat these scans a few weeks apart to see the details of Thwaites Glacier’s movement during a single summer.
“By taking the difference of two measurements we can see the ice deform and study how it flows in near-real time,” Christianson said. “This technique has been used in glaciology for about the last five years, but we’ll be doing it on a new scale for this project.”
The GHOST project is led by Sridhar Anandakrishnan at Pennsylvania State University and Andy Smith at the British Antarctic Survey, and involves scientists from several other U.S. and U.K. institutions.
Source: University of Washington