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The canary in the icefield

Scientists have tracked the fate of the Peyto Glacier in the Rocky Mountains for decades as a global reference point. It’s disappearing faster than expected — a warning sign for communities downstream.

On a sunny August day, University of Saskatchewan Prof. John Pomeroy steps out of a helicopter, and into an other-worldly landscape.

Surrounded by rock and ice, he stands at the toe of the Peyto Glacier: an ancient slab of ice within Banff National Park that’s been observed by scientists and enjoyed by ski-tourers and mountaineers for decades.

But things are not as they’ve always been. A large and growing lake has formed where the base of the glacier once stood.

Just in the last year, a new river and a waterfall have formed at the toe of the glacier, and icebergs that were previously floating in the glacier lake are nowhere to be seen.

“It’s very challenging to see it disappear like this,” said Pomeroy, a renowned hydrologist and director of the university’s Global Water Futures program, who has been coming to the glacier for decades.

“To have the landscapes of your memory disappear is always disturbing.”

University of Sask. Prof. John Pomeroy drills a hole in the ice for a piece of monitoring equipment to measure the depth of Peyto Glacier in August 2023. (Dan McGarvey/CBC)

Driving along the Icefields Parkway, it can be difficult for an average observer to spot the decline of Canada’s famous Rocky Mountain glaciers.

But Peyto, which is one of the longest-studied glaciers in the world, has been deteriorating since about the year 2000, and the extent of the loss has recently accelerated, researchers say.

Extreme weather only makes things worse. This year, a combination of low winter snowfall, prolonged, unseasonably hot weather and falling soot from wildfire smoke are coming together to create what Pomeroy describes as a glacial “death spiral.”

Measurements taken from Pomeroy’s research station near the base of the glacier show it’s undergone 6.5 metres of melt since last August. That’s on par with the previous record melt year of 2021, when an extreme heat wave scorched much of Western Canada, Pomeroy said.

It’s also retreated 80 metres horizontally, around four times the long-term average retreat of 20 metres.

A sequence of aerial images from Peyto Glacier show it, from left to right, in 2019, 2020, 2021 and 2022. (University of Sask. Smart Water Systems Laboratory)

As a reference point for other glaciers in the Canadian Rockies, Peyto is a sort of canary in the coal mine. To see it change so rapidly is an indication of what’s likely happening at hundreds of other glaciers in Western Canada, researchers say, and a sign that we must prepare for a time when they’re no longer around — sooner, rather than later.

Pomeroy expects we’ll start to see the end of these glaciers within our lifetimes, a situation that will affect the water supply in Alberta and throughout the prairie provinces.

Glacier meltwater provides a small but important source of river flow during hot, dry summers. Without glaciers around to feed rivers during these periods, cities and provinces will have to prepare for hydrological droughts that are “more severe than any we’ve experienced,” he said.

“This is the final end of our ice age — it’s happening right now,” said Pomeroy.

WATCH | Scientists uncover dramatic change in Peyto Glacier in past year:

A deeper understanding

Part of what makes the changes on the Peyto Glacier so significant is that researchers can truly understand their context.

Historical photos of Peyto date back to the 1890s, with some research beginning in the 1920s. It’s been studied in earnest since the late 1960s, when it was chosen to be a reference glacier as part of the United Nations International Hydrological Decade research initiative.

The Peyto Glacier has been studied extensively since the 1960s, and historical photos date back much farther, including this one taken in 1902. (Peyto Glacier (No. 149), 1902, Vaux Family fonds, V653 / NA 1127/Whyte Museum of the Canadian Rockies)

“You can go back and compare what we’re seeing today to what we saw 10, 15, 20, 30, 40 years ago,” said Mark Ednie, a scientist with Natural Resources Canada.

His team does fieldwork at Peyto and other glaciers in Western Canada multiple times a year, and submits their data to the World Glacier Monitoring Service, which compiles information from reference glaciers around the world.

Like Pomeroy, Ednie has seen Peyto melting before his eyes. When he started his work in 2011, there was barely any lake at the foot of the glacier, he said, and ice-cored moraines — piles of rock underlain by glacier ice — dotted the surface of the glacier.

“Now they’re practically all gone,” he said. “Those are, you know, 50-metre high mountains of ice covered in rock that are now gone completely.”

One of few icebergs left floating in the newly formed lake at the toe of Peyto Glacier. There used to be more, Pomeroy said, but they've since melted. (Dan McGarvey/CBC)
Natural Resources Canada scientist Mark Ednie is pictured inside a pit used for measuring snow density on Peyto Glacier in the spring of 2022. (Submitted by Mark Ednie)
These old research huts used to sit at the toe of the glacier. Now they stand alone, high on a hilltop far from any ice. (Dan McGarvey/CBC)

A key metric that Ednie’s team measures is mass balance, which he likens to the glacier’s bank account.

They measure snow depth and density in the spring, to see how much was deposited, and ice surface melt in the summer and fall, to see how much was withdrawn.

While Ednie’s team is still combing through this year’s numbers, early results taken from an upper point on the glacier show it’s on track for a historic melt year.


Data taken from halfway up the glacier shows that area has melted by about 1.6 metres from May to mid-August, roughly triple the average melt rate of 50 centimetres in the last seven years. The recent years’ average is itself an increase compared to the longer-term, he said, due in part to higher-than-usual annual air temperatures.

It is possible, he said, that a massive snowfall could mitigate some of the damage before the end of the year, but so far it’s looking bleak.

“It’s scary, in a way, looking at how these glaciers are changing,” said Ednie, who says the full extent of this year’s melt will become clear during their fall research trip.

The decline of Peyto Glacier over the last decade can be seen in these comparison photos from 2011, left, and 2021 — a year of record melt due to the heat wave in Western Canada. (Mark Ednie/Natural Resources Canada)

Impact of heat waves

Through the 1970s, Peyto would post both positive and negative mass balances year to year, said Pomeroy. Some years it would grow, others it would shrink.

But lately, every year has been a negative year. The last time Peyto grew was around 2000, Pomeroy said, and some of the largest losses have come in recent years.

That’s largely because air temperatures are getting warmer, he said. Heat waves — such as in 2021 — make the problem worse.

“You think of what happens, you stick an ice cube outside on a hot day, that’s what happens to the glacier,” said Pomeroy.

This graphic shows how much Peyto glacier grew (blue) or shrank (red) from 1966 to 2022. The 1998 and 2021 heat waves can be seen as major melting years.

This year, a federal weather station in Banff National Park set a heat record for the month of May, according to Environment and Climate Change Canada, and temperatures throughout the rest of the spring and summer have also been above seasonal averages.

Combine these factors with a lack of snowfall during the winter, and Pomeroy said he predicts this will be one of the worst years for glacier loss on Peyto ever recorded.

Smoke from this year’s record wildfire season is likely to make the situation worse, he said.

Research that Pomeroy and his colleagues conducted on the Athabasca Glacier suggests that while smoke can, to a degree, shield the ice from the sun, in the long-term the soot darkens the ice and can cause melt to increase by as much as 10 per cent.

The top of the Wapta Icefield, which feeds into the Peyto Glacier, has darkened in places due to wildfire soot that's accumulated since 2014. (Dan McGarvey/CBC)

Drought-proofing service

The decline of the Rocky Mountain glaciers will eventually spell trouble for communities that depend on glacial meltwater, he said.

While most of the water that flows out of the Rockies comes from snow melt, Pomeroy said, glacier melt also provides a small but necessary source of water to several major river systems, such as the Bow, North Saskatchewan and Athabasca Rivers.

It becomes important when there are drought conditions at the end of the summer, when rains haven’t fallen and the snowpack has long since melted.

“[Glaciers have] provided a tremendous environmental benefit to Alberta,” he said. “It’s equivalent of having major reservoirs like the Americans have, but we never had to build the reservoir — nature provided the service for us.”

Glacial melt from Peyto, seen here in 2019, and other Rocky Mountain glaciers has helped buffer Prairie ecosystems and communities during times of drought. As the glaciers disappear, that backup source of moisture will too. (Mark Ferguson, Global Institute for Water Security)

In the near-term, Pomeroy said we can likely expect higher-than usual flows in glacier-fed rivers during these hot, dry periods, as warm weather accelerates the level of melt. But eventually, the switch will flip, and as glaciers disappear we’ll be less able to count on them as a stop-gap source of water.

That means preparing for worsening conditions during periods of drought, he said, and maintaining more water in reservoirs for the late summer.

“We’ll see impacts of this across the Prairie provinces,” he said.

Although the glaciers’ decline is already well underway, Pomeroy said there is still time to mitigate some of the damage. Peyto is likely toast, but other, larger glaciers like Athabasca could still be saved.

“There’s still time — there’s not much, but it’s there, but it means having very strong policies to reduce greenhouse gas emissions into the atmosphere, starting right now.”

Researchers stand in front of what was a huge ice cave within the toe of the glacier that recently collapsed. Rushing water now flows out of the ice and down to the lake. (Dan McGarvey/CBC)

The next canary

For Ednie, the retreat of the Peyto Glacier means making contingency plans.

The growing lake at the terminus of the glacier means it’s harder to get onto Peyto — they’ve even joked about taking a boat for part of the trip. Walking around on top of the glacier is also precarious, he said, because of the number of crevasses that have formed.

Another problem: some of the team’s mass-balance stakes — metal rods drilled into the ice to measure ice melt — are melting off the glacier.

“This summer we had such an extreme amount of melt we ended up losing a number of instruments,” said Ednie, who said they’re now starting to use other tools, like drones, to flesh out their research.

Part of their solution, he said, is to begin work on a backup Peyto. Since 2010, his team has started fieldwork on the nearby Saskatchewan Glacier, which will replace Peyto as a focus of research once it’s no longer viable.

While the Saskatchewan Glacier is melting and receding at a similar rate to Peyto, it’s also fed by a very large ice field and has a much larger accumulation area, so it is expected to survive much longer, Ednie said.


Research suggests Peyto and other nearby glaciers will lose most of their mass by 2100, but Ednie believes if current trends continue it will be much sooner than that.

As a scientist, he said, it’s an interesting trend to observe firsthand.

As a human being, it’s a sad one. He often thinks of his young daughter during his research trips, and wants to share his work with her while he still can.

“I would love to bring her out there and show her these alpine glaciers before they’re gone,” he said.

“Hopefully she’ll remember them when she’s older.”

Editor: Lisa Johnson | Video editor: Monty Kruger

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