Students investigate the geophysics of Antarctic ice streams
Last year St. Olaf College Professor of Physics Bob Jacobel was part of a team of researchers that made international headlines when they successfully drilled through 800 meters of ice — almost half a mile — to take microbial samples from subglacial Lake Whillans in West Antarctica.
But the story doesn’t end there.
This summer Jacobel is working with Kevin Dalla Santa ’14, Brian Craig ’15, and Adam Wood ’16 to analyze all of the geophysical data gathered over the course of that project and present it in one, overarching paper.
“There’s more of the story yet to be told,” Jacobel says.
The summer project, supported by the National Science Foundation, is part of ongoing research at the college’s Center for Geophysical Studies of Ice and Climate (CEGSIC), which Jacobel directs. The project also falls under the umbrella of the college’s Collaborative Undergraduate Research and Inquiry (CURI) program.
Dalla Santa, Craig, and Wood are working with data that Jacobel and postdoctoral scientist Knut Christianson ’05 gathered while working with a team of scientists from eight different U.S. institutions on the Whillans Ice Stream in West Antarctica. The Whillans Ice Stream Subglacial Access Research Drilling (WISSARD) project is funded by the National Science Foundation and aims to study the geobiology of subglacial lakes in West Antarctica as well as the dynamics of ice sheets.
Looking at the dynamics of ice
Although WISSARD is primarily a study of subglacial ecology and extremophiles, organisms that thrive in conditions that are inhospitable to other forms of life, the geophysical data Jacobel has gathered has broader applications in glaciology. Working with this data is the primary goal of this summer’s project.
“The geophysics that we do helps define where the best place to drill is, what kind of conditions they’re likely to find down there, and how that spot relates to the areas around it,” Jacobel says. “But at the same time, we’re looking at the dynamics of the ice and how that can respond to climate change.”
Jacobel uses an ice-penetrating radar system to gather data about the topography beneath a glacier and the way an ice stream is flowing. The radar, which works the way sonar works in water, can tell researchers the thickness of the ice, where the ice has thawed and if there’s liquid water present beneath the ice — it can even detect layers of atmospheric fallout, like volcanic ash, that became buried in the ice over time.
“That provides a climate record, but the way that these layers deform also tells us about the way the ice is flowing,” Jacobel says. “All that is key to understanding the dynamics of what’s going on.”
WISSARD began in 2010 and is now in its final stages, with one more bore hole scheduled for the coming season. Though several of the most important geophysical findings have already been published, Jacobel and his students are working to present all the data CEGSIC has gathered over the course of the project in a single comprehensive paper.
As a part of the group’s summer activities, they also read and review papers and proposals from other scientists.
“Knut and I get proposals to evaluate as part of the peer-review process, and we think it’s important to share them with the students so they get an idea of how to be critical and helpful at the same time and how to be discerning of whether an idea is good or not,” Jacobel says. “It also teaches them how to write strong papers and proposals themselves.”
More research ahead
In addition to reviewing other research proposals, the group is planning for its own operations post-WISSARD. Jacobel and Christianson have submitted proposals for a new project in Greenland as well as on another ice stream in West Antarctica. That project would be similar to geophysics being done with WISSARD, and would center around an area of the ice sheet known as the “grounding line.”
“The grounding line is a very crucial area where the ice first comes in contact with the ocean,” Jacobel says. “It’s the important point of interaction where the whole thing can begin to collapse. During our spring exam period there were two papers that came out in the journals Science and Geophysical Research Letters that made headlines in all the national media because they said ‘Whoa! The retreat of the West Antarctic Ice Sheet has begun, and it’s irreversible!’ I think it was that word, irreversible, that caught everyone’s attention. Those papers were from studies at a grounding line at another place in West Antarctica similar to the one that we’re studying. So grounding lines are kind of where it’s at right now.”