Climate change forces glaciers to retreat in Canada's Arctic

UAlberta glaciologists capture footage of ice calving events on the Belcher Glacier.

Many impacts of climate change have been observed since the term drifted into common usage in the late 1970s and 80s. Although declining animal populations and statistics regarding rising sea levels and global temperatures have taken root in our daily lives and news cycles, many events in recent years have added stark, concrete images to the climate change discussion.

These tableaus range from out-of-the-ordinary polar bear migrations to the polar vortex aching its way across North America in early 2019. There has also been an increase in the discharge of icebergs from tidewater glaciers into Arctic waters by a process known as iceberg calving, and this has become a clear focus (and perhaps a cause for concern) for many scientists investigating the effects of climate change.

While the occurrence of iceberg calving clearly predates recent climate change, increases in calving from Greenland tidewater glaciers have been linked to warming of the adjacent ocean, while in other areas, like the Canadian Arctic, it seems that atmospheric warming (which is largely responsible for driving the retreat of glaciers that terminate on land) may also play a role.

Understanding exactly what is going on in any single location requires continuous monitoring of:

  • the flow of the glacier,
  • changes in the position and geometry of its terminus,
  • local atmospheric and oceanographic conditions, and
  • the location, timing, and style of iceberg production at each glacier.

Time-lapse photography is very well suited for monitoring iceberg calving, along with changing conditions on the glacier (like snow cover, surface melting, and glacier flow). It's also suitable for exploring how factors like tidally induced changes in water level at the glacier terminus and the presence or absence of sea ice in front of the glacier might affect the calving process.

What is ice calving?

Iceberg calving, or glacier calving, is a process where sections of a glacier's ice cliff fracture and break off from the glacier and enter the fjord or ocean into which the glacier drains. The resulting icebergs are different from sea ice, which consists of frozen ocean water. The two often exist in close proximity to each other, however, especially in late winter when bergs calved earlier in the season may be trapped in the sea ice close to the glacier terminus, forming ice melange.

Because glacier flow continually transports ice towards a glacier's terminus, calving is a regular part of the life cycle of glaciers that end in the ocean. It begins with a rift or fracture opening in the glacier's edge in response to the stresses that exist within the ice, and culminates with the fracture penetrating through enough of the glacier's thickness that bergs can break off.

A common stressor on glacier ice is the accumulation of meltwater in crevasses within the glacier. Because water is denser than ice, the meltwater that accumulates in the crevasses can stress the base of the crevasses enough to widen them through the full glacier thickness, triggering the calving of icebergs.

Calving in the Belcher Glacier

Although calving is a natural process for glaciers to shed mass, the rate at which this process occurs may be affected by such factors as rising air and ocean temperatures, changing sea levels, and changes in the degree to which sea ice may reinforce the terminal ice cliff.

The Belcher Glacier is one such glacier where ice calving has been observed by UAlberta scientists and others. It is a large tidewater glacier that drains the northeastern sector of the Devon Island Ice Cap in Nunavut, Canada. It calves icebergs into the ocean where the glacier terminates, which, in this case, is in Lady Ann Strait.


Stages of ice calving

The images of the Belcher Glacier above, captured over one summer by glaciologists Colleen Mortimer and Martin Sharp of the University of Alberta's Department of Earth and Atmospheric Sciences, have also been rendered into a time-lapse video to better illustrate the process of glacier calving.

This time-lapse video is made using images collected by a solar-powered camera mounted on the valley wall to the east of the glacier terminus over a time-period from May (end of winter) to the following Fall. The camera's field of view is from east to west across the terminus, from which point the processes of calving could be easily observed for the entire summer season.

One Summer in the life of a melting glacier

Images courtesy of Martin Sharp, with camera deployment by Colleen Mortimer at the University of Alberta. Equipment courtesy of James Balog and the Extreme Ice Survey. Time-lapse video courtesy of Jeff Allen Productions.

Timeline of glacier calving

In the video, many calving events are captured. The summary of events provided below is keyed by the time (in seconds) into the video at which they occur.

00:16 Glacier melting: Meltwater ponds in crevasses on the glacier surface in the lower left and center left of the image (deep blue color). The near side of the glacier terminus advances.
00:20 Sea ice breaks down: The sea ice breaks up and is flushed away from the glacier along with much of the melange of floating ice. Floating ice then remains only at the far side of the terminus. There is still water in the crevasses on the near side of the glacier.
00:21 Ice advances: The mobile ice melange advances along the glacier terminus towards the camera.
00:23 Ice thins: The melange thins out and retreats to the far side of the glacier and then comes back towards the camera and piles up on the camera side of the bay.
00:24 Glacier drainage system opens: Turbid (brownish) water emerges below the ice cliff on the near side of the glacier and pushes the sea ice melange away from the ice cliff. This water is probably coming from the glacier bed and rising to the fjord surface because it is fresh and less dense than the sea water. Its appearance suggests that the meltwater drainage system inside the glacier has opened up for the summer.
00:26 Ice berg appears: A large iceberg enters the bay.
00:27 Glacier surface melts: Turbid water upwelling continues in front of the ice cliff on the camera side of the bay and drives the ice melange away from the ice cliff. This may indicate a melting event on the glacier surface.
00:30 Bay flushes: Sea ice is flushed from the bay, and there is still meltwater in the crevasses.
00:32 Iceberg calving: Most of the sea ice has now gone. Initially, the meltwater turbid plume is clearly visible on the near side of the bay but it then disappears (maybe indicating cooler weather and less meltwater production). There is an iceberg calving event in the middle of the embayment, the glacier terminus retreats abruptly, and there are new icebergs in the bay.
00:35 Influx of ice: Ice blows into the bay from the right and piles up against the glacier terminus. A few large bergs enter the bay.
00:38-00:40 Influx of bergs: More brash ice (a mix of sea ice and berg fragments) is pushed up against the glacier terminus, and several more large bergs enter the bay.
00:40 Ice flush: Ice is flushed from the bay.
00:42-00:43 Cliff collapse: A pulse of turbid meltwater from the glacier flushes the small bergs from the bay, then two sections of the terminal cliff collapse, producing plumes of brash ice in the bay.
00:45 Terminus advances: The glacier terminus appears to advance, but bedrock areas in the background also move to the right so it is more likely that the camera was rotated (by wind-by polar bear?).
00:49 Larger, numerous calving events: The ice promontory in the middle of the embayment collapses, releasing lots of icebergs and brash ice into the bay. Iceberg calving events spread along the ice cliff towards the camera and there is a lot of ice in the bay as a result.
00:50-00:51 Bay cleared: Brash ice clears from the bay.

We thank the Nunavut Research Institute and the peoples of Grise Fjord and Resolute Bay for permission to work on the Devon Ice Cap; the Polar Continental Shelf Project for outstanding logistic support; and the Natural Sciences and Engineering Research Council of Canada, Northern Science Training Program, the Circumpolar Boreal Alberta Research (C-BAR) Grants program, and the Canadian Foundation for Innovation for supporting our research.

Related articles on arctic ice

For more information involving the effects of climate change on Canada's glaciers, check out the following articles featuring more of Martin Sharp's research.