Nunavut’s Milne Ice Shelf collapses
“This is definitely a victim of climate change”
When Adrienne White, an ice analyst at the Canadian Ice Service, sat down at her desk one morning last weekend, the first thing she checked on was Nunavut’s Milne Ice Shelf, located on the northwest coast of Ellesmere Island.
Although the satellite imagery was cloudy, White could make out a dark colour.
“I thought, OK, that doesn’t look right. I’ve been looking at this ice shelf for years and this doesn’t look normal,” she said.
Once the radar imagery came in, it was clear. Sometime between July 29 and 31, nearly half of the 4,000-year-old Milne Ice Shelf had broken off.
The result: a 79-square-kilometre ice island that’s roughly 50 percent larger than Manhattan or the city boundaries of Iqaluit and 70 to 80 metres high, 25 per cent taller than a Canadian football field is wide.
“I was definitely surprised to see the breakup,” said White. “But at the same time, the conditions were right.”
Prior to the calving event, White had noticed that the ice shelf was looking dirty on the surface, an indication that there has been a lot of melt.
In the weeks before, she had also noticed that there was a lot of open water along the northern coast of Ellesmere Island.
“In the past, this is an area that would have been perennially ice-covered,” said White.
“Over the past decade, we’re starting to see open water appear during the summer and with that, we’ve had these large calving events.”
Ellesmere Island saw major ice shelf breakup events in 2003, 2005, 2008, 2011 and 2012.
The Milne Ice Shelf was considered to be one of the least vulnerable to breakup as it was roughly twice as thick as other ice shelves and it is well-protected in Milne Fiord.
“This is definitely a victim of climate change,” said White.For others, like Derek Mueller, a professor in the Department of Geography at Carleton University, the breakup itself isn’t the surprise.
“You might have seen headlines like ‘last intact ice shelf’—I don’t actually think that’s true because the ice shelf has been fracturing over the last 10 years,” he said.
“Every time we come up, we see more and more fractures.”
This isn’t the first time Mueller has seen a shelf break up. He’s worked in the North since he was an undergraduate student in 1996, and he’s visited the Milne Ice Shelf 11 times since 2004.
For him, what is surprising is that the calving happened along new fractures.
“We’ve camped on that ice shelf, actually in a place that I initially thought would break up,” said Mueller.
“But it didn’t break up there.”
Originally, Mueller and his colleagues were slated to visit the shelf earlier in July, but the ongoing COVID-19 pandemic put those plans on ice.
“Hopefully next year [I’ll] get to the shelf and see what happened,” said Mueller.
“It’s very sad to see this breakup happen.”
For Mueller, the breakup of the ice shelf is also potentially a lost opportunity.
The Milne Ice Shelf acted as a sort of natural dam, trapping the meltwater at the head of the fiord and creating a rare epishelf lake—a layer of fresh water that floats directly on top of the ocean.
“They’re two fluids that are so different in their densities, they don’t mix,” said Mueller. “Like oil and water.”
From there the lake drained into the ocean by way of a channel that was carved through the bottom of the ice shelf.
“For over the last, almost, 10 years now, we’ve been working on this and we have a cool data set where we can see the [meltwater] temperatures and they rise up really high in the summer.”
As this warm water goes through the ice, it carves out small areas that Mueller and his colleagues recently discovered life inside, “nourishing themselves from the sediments that come from the fiord and are drifting by in the current,” he said.
There’s “a truly unique ecosystem of bottom-dwelling animals—scallops, sea anemones and so forth—living in the channel,” he said.
Satellite animation, from July 30 to August 4, shows the collapse of the last fully intact #iceshelf in #Canada. The Milne Ice Shelf, located on #EllesmereIsland in #Nunavut, has now reduced in area by ~43%. #MilneIceIsland #seaice #Arctic #earthrightnow #glacier pic.twitter.com/jjs1gawoxA
— ECCC Canadian Ice Service (@ECCC_CIS) August 4, 2020
Since the initial calving event, the single ice island has broken up into two smaller pieces and several icebergs.
While they are all currently free-floating, mobile and confined to the coastline by pack ice, White said that very often they’ll become grounded if they move into more shallow waters and melt there.
Alternatively, they continue to drift through the summer, eventually making their way into the Canadian Arctic archipelago, similar to the Ayles Ice Shelf in 2005.
White, along with her colleagues at the Canadian Ice Service, will continue to track the movement of these ice islands, which can last for years.
“A large ice island is easy to track,” said White.
“But if this island were to break into hundreds of pieces, then all of a sudden you have hundreds of icebergs that are potentially 80 meters thick, so this poses a hazard for shipping.”
For both White and Mueller, the breakup of the Milne Ice Shelf sends a clear message.
“It’s a bit of a wake-up call,” said Mueller.
At the beginning of the twentieth century, there was one massive ice shelf stretching along the entire northern coast of Ellesmere Island.
By the year 2000, it had split into six main ice shelves and decreased in size by almost 90 per cent.
Since then, sea ice extents have diminished dramatically, hitting an all-time low in 2012.
This past July was no different, setting a record for an all-time minimum for the month, which was capped off by the calving of the Milne Ice Shelf.
Mueller said he hopes the event will draw further attention to the impacts of climate change.
“If this helps get people moving on this issue, then that’s a big silver lining,” said Mueller.
“Because it’s not too late to make these changes, right? The sooner we make them, the better it will be overall.”