In August, Adrienne White – an ice analyst at the Canadian Ice Service who monitors the Canadian Arctic for changes in sea ice – was reviewing satellite imagery when she spotted something remarkable. The enormous Milne ice shelf, which was the last intact ice shelf in Canada and which White had studied closely before as a PhD student, was dissolving.
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A huge chunk larger than Manhattan, roughly 43% of the shelf, broke off in one piece. And as it collapsed into the ocean, it took with it much of the equipment her former colleagues had left there.
“It is lucky that we were not on the ice shelf when this happened,” one colleague, Derek Mueller, wrote in a blog post following the discovery. “Our camp area and instruments were all destroyed in this event.”
Mueller had been studying a channel that ran below the surface of the Milne ice shelf, like a river. In 2017, a team of researchers discovered scallops, sponges, worms, and other organisms living some 20 meters deep, inside the ice shelf. Animals have been found living beneath ice shelves before, but never – to Mueller and his colleagues’ knowledge – inside of one.
Mueller is one of Canada’s leading ice shelf experts, along with Luke Copland, who supervised White’s PhD. Together and separately, the three have been studying the Arctic for years. They had observed rifts appearing over the Milne ice shelf throughout their careers. Still, the breakup – known as a calving event – is significant. Copland believe ice shelves are “a canary in the coal mine” in the climate crisis, given that they are especially susceptible to atmospheric changes.
We spoke them about what that day was like, and where they go from here.
How did you first learn of the calving event?
White: At the Canadian Ice Service, we use satellite imagery to chart sea ice in Canadian waters. We also use this imagery to monitor glaciers and ice shelves for calving events that can produce large ice islands. The day I discovered the Milne ice shelf calving event was a typical day; I came into work and was looking along the coastline of Ellesmere Island [to which the ice shelf was connected] for any changes; over the previous week, I’d noticed there was a lot of open water in the area, which can lead to destabilization.
Looking first at the optical imagery, the same type of imagery you would see on Google Earth, I could see that there was a darker area on the Milne, but there were a lot of clouds on the image that I couldn’t see through. Then I used radar satellite imagery, which can penetrate clouds, and with that we were able to clearly see the ice islands were separating from the ice shelf, and that the calving event was taking place.
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