Jeremy Bassis, an assistant professor in Climate and Space Sciences and Engineering, studies glaciers both past and present to better predict the future of the ice sheets over Greenland and Antarctica – and the implications for humans.
In 2013 Bassis developed a new model to simulate iceberg calving, the complex process by which chunks of glacier break off of an ice sheet and float away.
Calving accounts for about half of the ice lost by glaciers. It contributes to rising sea levels, and changes fresh water supplies, yet it’s not reflected in most climate change models. Bassis’s model was the first to explain the physics of iceberg calving in both the land-based glaciers of the northern hemisphere and the ocean-floating ice sheets of the southern hemisphere.
Some of his work suggests large chunks of the western Antarctic ice sheet could break loose in less than 1,000 years, contributing to faster-than-expected rises in sea level and corresponding changes to fresh water supplies.
“If it happened on the order of a couple of centuries, we could see 3-4 meters of sea level rise, and that much ice in the ocean could alter patterns of circulation,” said Bassis, whose work is decidedly big-picture, not only spanning the globe from north to south, but also covering hundreds of thousands of years. “This is all pretty speculative, but the safest scenario would be for it to disintegrate over thousands of years.”
The Laurentide ice sheet, which once covered Michigan and parts of Canada, went through its own periods of rapid (by glacial standards) change as it retreated. By comparing what’s known about the way that glacier formed and retreated to measurements from existing glaciers, Bassis can better explain and predict future changes in Greenland and Antarctica.
“I think we’re at the stage now where we’re going to try to get back to Antarctica and Greenland to take more measurements,” he said. “We’re really interested in how the ocean is affecting the ice.”
“We spend most of our time in our offices with computers, but occasionally we get to go out into some really spectacular places. And yeah, it’s incredible to be on an icebreaker in the middle of the sea ice, where it’s totally calm and you look out and see whales or sea lions or penguins.”
Bassis didn’t set out to become a glaciologist. He was a math and physics major at Pennsylvania State University, doing undergraduate research work with lasers in a windowless basement lab when he started looking for other ways to apply physics to a career.
He enrolled in an exploratory class that met in a big, unfamiliar building, and got lost on the way to class the first day. By the time Bassis arrived, class had already started, so as quietly as possible, he took the only seat left in the room – in the middle of the front row. About 10 minutes later, he realized he was in the wrong room. But he’d already made a late and very visible entrance, and didn’t want to just get up and leave in the middle of class.
“Probably half an hour in, I realized I was actually pretty interested in the stuff they were talking about – maybe even more so than the course I was supposed to be taking.” he said.
Bassis asked around the atmospheric science department about projects that might have a place for a physics major and ended up working on an atmospheric chemistry project led by meteorology department head Bill Brune, building instruments and traveling around the country to deploy them.
Graduate school took him to Scripps Institution of Oceanography in San Diego, but when he arrived at Scripps, Bassis learned the professor he’d hoped to work with was on sabbatical. Biding his time until the professor returned, Bassis found an alternate project that sounded interesting – three months in Antarctica studying how giant cracks develop in one of the major Antarctic ice shelves.
“You’d fly in by helicopter, drop on the ground, and the helicopter would bounce up and down a couple of times to make sure you weren’t on a crevasse,” he said. “Then you would install the instrument and jump back in the helicopter and go to next spot.”
After 12 weeks, they repeated the process to retrieve the instruments, and during the intervening months they camped on the ice, exploding sticks of dynamite embedded in the ice and using the explosions’ travel times to measure ice thickness.
“I think it really helps if you’re open-minded to different things and willing to take a few risks on a few opportunities. I always figured if things didn’t work out I could go back to the project I originally planned to work on.”
Bassis sometimes describes his career path as a bunch of random coincidences, but it helped him recognize the importance of keeping your eyes and mind open. He encourages his students to work outside their comfort zones and tries to assign them some tasks that don’t align with their natural strengths.
“If they don’t like a research area, fine, but maybe they learn that they actually do like it,” he said. “That’s sort of what happened to me with glaciology. What I really want is for them to be able to discover things for themselves.”