Predictions from the edge of the world
Meet climate forecaster Mitch Bushuk
Note: This piece was originally written in January 2017 for a Princeton University course on science journalism. Published on my previous blog platform, I’m re-posting the article so that it might live on here.
Mitch Bushuk recalls being ‘focused’ while on board a helicopter over Jakobshavn Glacier in Greenland. “We’d search visually for open water, then we’d fly the helicopter towards the open water, hover over it,” Bushuk says. “We’d open up the side door, then we would basically try to throw the probe out the window and hit the patch of open water.” Bushuk acknowledges the task’s challenge. “It wasn’t trivial, I missed a few shots, basically. If you miss, then the probe’s stuck on ice and basically you’ve lost your probe.”
Bushuk was in Greenland in 2012 with one of Professor David Holland’s expeditions while pursuing his Ph.D. at NYU’s Center for Atmospheric Ocean Science (CAOS). The fieldwork showcases the cutting-edge research Bushuk has been a part of so early in his career.
Jakobshavn Glacier (pronounced “yakobshaven”) is the fastest flowing glacier in Greenland, and it rests over a fjord, which, as Bushuk explains, is the inverse of a peninsula—a little notch cut into the land. This fjord is completely choked with icebergs. Ordinarily, when oceanographers want to measure data for the ocean, they deploy CTD (conductivity, temperature, and depth-sensing) probes, into the water with a boat. Seeing as there’s no way a boat could get into Jakobshavn Glacier, the only way is to deploy dispensable CTD probes by helicopter.
After a probe was released, the data was sent back in real time to their computer through a copper wire that led all the way back to the helicopter. “The probe would fall down all the way down to the bottom of the fjord, which was something like 800 or 900 meters,” Bushuk says. “And when it hit the bottom, you could sort of see the data flat-line out, and then you just literally break the wire with your hands, and you throw it overboard, and that’s it.”
Bushuk explains that the data was important because it helped sample the ocean right next to a huge ice sheet on Greenland. “Understanding those properties right at the boundary of the ocean and the ice are really important, because the warmth of that water that’s actually touching that ice dictates how fast that ice melts,” Bushuk says. “It’s expensive data but important data for us to get.”
While performing the operation, they had to be aware of dangers particular to that environment. “We’d get as close as safely possible to the water,” Bushuk says. “But sometimes there would be icebergs quite high beside us. You’re always a little worried about icebergs rolling, and most of the iceberg is below the water, obviously.” Bushuk had recorded a video of deploying the probes to songs by Arcade Fire and Fun, so I guess he wasn’t too stressed about it.
Forecasting the future
I meet Bushuk outside the Geophysical Fluid Dynamics Laboratory (GFDL) on the Forrestal Campus of Princeton University. On the phone, Bushuk directs me to “the ominous-looking building.” Ominous it is. A black cube of glass and I-beams, a sign in silver lettering explains that the outfit is a collaboration between Princeton University and the U.S. Department of Commerce (of which NOAA, the National Oceanic and Atmospheric Administration, is a part).
Bushuk is tall, with short brown hair and blue eyes. He leads me through the GFDL’s security, and then brings me up to his office cubicle on the second floor. On the wall, there’s a poster of the Earth’s ocean with colors indicating thermal patterns and a map of the North Pole. The map has practical use; when Bushuk talks about Jakobshavn, he leans over the map and points out its location on the West Coast of Greenland. Above his computer are photographs of polar vistas. Science and math textbooks line the bookshelf.
“My first love was pure mathematics,” Bushuk says. “I eventually grew into enjoying theoretical physics. I enjoyed the connection to the real world, the physical world and the universe.” Though Bushuk grew up around a lot of snow and ice in Winnipeg, Manitoba, he said that his interest in climate developed over time. Part of why he likes climate research is because it involves a lot of applied mathematics and physics. “It’s a nice field for me to be in as a kind of young scientist,” Bushuk adds. “There’s a lot of new territory.”
Right now, Bushuk is a postdoctoral research associate at GFDL and the Atmospheric Ocean Science program at Princeton. As one of the “Arctic people” at GFDL, his research involves predicting sea ice conditions in the Arctic. “I’m trying to understand the key physical processes that happen in the Arctic, specifically the processes that affect sea ice,” Bushuk says. His work combines techniques from weather forecasting, which seeks to predict conditions for the next day or few days, with climate forecasting, whose time scales revolve around decades to centuries. “What I’m doing is kind of fitting between those two time scales,” Bushuk says, explaining that he works on what can be called “seasonal” forecasting, working with time scales that range from one month to four years. “To answer those kinds of questions, you have to worry about issues that are relevant for weather forecasting,” Bushuk says. First, the initial conditions, the starting point put into the simulations, must be as accurate as possible. “Then you also have to worry about how good your model is, how well are you simulating sea ice and all the other factors in the earth system that influence them,” Bushuk says. “It’s interesting in that sense, it kind of blends weather and climate applications, you have to really think about both things to get the problem right.”
Bushuk says he hopes to become a university professor one day. Given the ease at which he breaks down difficult concepts, defining terms in lockstep with his explanations, the job would be a natural fit.
Like his explanations, Bushuk’s professional website is clean, concise and descriptive. Striking graphics and photos accompany abstracts of his research publications, revealing his attention to detail and organization. Aside from his amusing videos of flying over Greenland, Bushuk’s website is relatively open about his personal life and projects. His site notes his membership of the “Psycho Jackpot and the Coyotes” hockey team in the Chelsea Piers Mens Hockey League, his captainship of an intramural volleyball team “Set Theory” in the Courant Department of Mathematics at NYU, and his occasional rock climbing with the “Brooklyn Boulders.” His site lists three blogs: the history blog of his wife, Minju, a PhD student at Temple, a blog that he and his wife both moderate, and a personal travel blog. Bushuk’s interest in classification even extends to his friends in academia, for whom he lists and provides links to their public profiles.
Under his research experience, one particular listing caught my eye—with another David Holland-led team, Bushuk had traveled to Antarctica in 2013, an incredible experience to one of the most remote places on Earth.
Pine Island Glacier
Pine Island Glacier is the fastest flowing glacier in Antarctica, flowing at roughly four kilometers a year, whereas Jakobshavn flows at ten or fifteen kilometers a year. “It’s not quite as fast as Jakobshavn, but for Antarctica, it’s quite a fast glacier,” Bushuk says, explaining that Pine Island Glacier (PIG) is an ice shelf, a tongue of a glacier 500 meters thick that extends off the bedrock of the land and floats on the ocean. Bushuk was part of a fifteen-person team that spent two weeks on this camp on the ice shelf itself. “We actually didn’t have any bedrock below us, only ocean below us, but 500 meters of ice, of course,” Bushuk says. “It’s somewhat dangerous work, in the sense that it’s very remote.” To get to Pine Island Glacier, they had to travel to McMurdo, the main American base in Antarctica, and then take a four or five hour flight from McMurdo to the base camp on site. Then, they had to fly a small Twin Otter plane to the middle of the glacier. “If anything goes wrong out there, you’re a long way from civilization,” Bushuk says. “On the actual glacier itself, it’s not a smooth, continuous ice cube. Especially in certain zones, it’s extremely broken up and there’s all these sort of fissures and cracks in the ice itself, called crevasses.”
As for the temperature on Pine Island Glacier, Bushuk said it actually wasn’t that cold. Bushuk was working to dig out stations that took high frequency GPS readings. Installed a year previous to his visit, the stations had been buried by three to six feet of snow. “My basic job was just to unearth these stations from the snow, and then kind of reposition them just on the snow surface, so we could get another year’s worth of data before it got totally buried by snow cover,” Bushuk says. “So, when I was working, I was pretty warm. Most days I was just wearing a very light long-sleeve T-shirt.” The temperature ranged between -5° and 5° Celsius (23° and 41° Fahrenheit).
“If you have these five stations, you can get a sense, first of all of how the glacier is moving in time, but also how the two points are moving relative to each other,” Bushuk explains. “You can get a sense if the glacier is just moving forward as one plug of ice that’s all connected, or [if it is] sort of shearing where one point is moving faster than the other point.” In the end, the team made an interesting discovery: “There was this interesting lagged relationship between ocean temperatures and glacier velocity, where the velocity response of the glacier lagged 200 days behind the ocean temperatures. If you had a cold ocean, the glacier slowed down 200 days after the ocean got cold.” The findings provided insight into the heating dynamics of the ocean and ice shelf system, information that helps scientists create more accurate models, and as a result, better climate forecasts. And making more accurate forecasts is Bushuk’s main task at GFDL.
“I should probably mention that my current work involves no fieldwork,” Bushuk says, emphasizing that in Antarctica he was just one cog in a huge machine. Bushuk’s current work involves working with computer models to forecast sea ice trends. “My goal is to try to create as most accurate a forecast of sea ice as I possibly can,” Bushuk says, “All the science I do is geared toward that one simple goal. So my metric is basically: can I predict the area of sea ice coverage in certain regions of the Arctic for certain months of the year?”
One of the big challenges for Bushuk and other climate scientists right now is accounting for the strong negative trend in sea ice extent in the Arctic over the last 30 years. “Our model does quite well in the 1980s and 1990s, but recently we’ve found that our forecast skill has actually been decreasing,” Bushuk says. “Is the current Arctic just harder to predict than the Arctic was in the past? Of course, it is possible that our predictions are equally good, since we only have ten years of the new Arctic climatology, and maybe we’ve had bad luck in those years.”
One of the ways Bushuk tries to answer that question is through the wealth of sea ice data produced in the last 30 years. Satellites have allowed for a robust, continuous data set for Arctic sea ice since 1979. The launch of the Cryosat-2 satellite in 2010, which takes measurements that help determine sea ice thickness, has been a huge catalyst for Bushuk’s research. “I’m constantly working with that observational sea ice data as my ground truth, and I’m trying to see how well our models can reproduce that past record of sea ice,” Bushuk says. “And by trying to reproduce that past record, hopefully we can make better predictions of the future as well.”
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