On a sunny August day, Professor John Pomeroy from the University of Saskatchewan steps out of a helicopter into another world.

Surrounded by rocks and ice, he stands at the foot of the Bow Glacier, an ancient sheet of ice within Banff National Park that has been observed by scientists and enjoyed by skiers and mountaineers for decades.

But things are not as they once were; a large, growing lake has formed where the base of the glacier once was.

Just last year, a new river and waterfall formed at the foot of the glacier, and the icebergs that used to float in the glacial lake can no longer be seen anywhere.

Pomeroy, a renowned hydrologist and director of the University’s Global Water Futures program, who has been coming to the glacier for decades, said, "It is incredibly hard to see it disappearing this way; the loss of a landscape from your memory is always distressing."

While driving along the Icefields Parkway, it may be difficult for any casual observer to notice the retreat of the famous glaciers in the Canadian Rockies.

But Bow, which is one of the longest-studied glaciers in the world, has been in decline since around 2000, and the rate of loss has recently accelerated, researchers say.

Severe weather makes things worse. This year, a mix of low winter snowfall, unusually prolonged heat, and soot from wildfire smoke have combined to create what Pomeroy described as a "glacial death spiral."

Measurements taken from Pomeroy’s research station near the base of the glacier show it has melted by 6.5 meters since last August. Pomeroy said this is on par with the previous record melt year of 2021, when a severe heatwave swept across much of western Canada, with a horizontal retreat of 80 meters—roughly four times the long-term average retreat of 20 meters.

As a reference point for other glaciers in the Canadian Rockies, Bow is like a canary in a coal mine. Researchers say watching it change so rapidly is an indicator of what is likely happening to hundreds of other glaciers in western Canada, and a sign that we need to prepare for the time when these glaciers are no longer there, sooner rather than later.

Pomeroy predicts we will begin to see the end of these glaciers within our lifetime, a situation that will impact water supplies in Alberta and throughout the Prairie Provinces, where meltwater from glaciers provides a small but critical source of river flow during hot, dry summer months.

He said that without glaciers to feed rivers during these times, cities and provinces will need to prepare for hydrological drought conditions that are "more severe than any heatwave we’ve seen."

Pomeroy added, "This is the final end of our ice age, and it’s happening now."

The importance of changes in the Bow Glacier is due to the fact that researchers can truly understand its context, as historical images of Bow date back to the 1890s, with some research starting in the 1920s. It has been seriously studied since the late 1960s when it was selected to be a benchmark glacier as part of the United Nations’ International Hydrological Decade research initiative.

Mark Eddy, a natural resources scientist with Canada, said, "You can go back and compare what we see today to what we saw 10, 15, 20, 30, or 40 years ago."

His team conducts fieldwork in Bow and other glaciers in western Canada multiple times a year, providing their data to the Global Glacier Monitoring Service, which aggregates information from benchmark glaciers around the world.

Like Pomeroy, Eddy has witnessed Bow melting before his eyes. When he started his work in 2011, there was almost no lake at the base of the glacier, he said, and the ice-cored moraines—piles of rocks covered in glacial ice—were scattered across the surface of the glacier.

He added, "They have all practically disappeared now. These mountains, you know, are 50-meter-tall ice mountains covered in rocks that are now completely gone."

One of the key metrics his team measures is the mass balance, which is similar to a bank account for the glacier.

They measure the depth of the snow and its density in the spring to know the amount of accumulation, and surface ice melt in the summer and fall to assess the amount of loss.

While Eddy’s team is still looking at the numbers for this year, early results taken from a high point on the glacier show it is on track for a historic melt year.

Data taken from halfway up the glacier shows the area has melted by about 1.6 meters from May to mid-August, nearly three times the average melt rate of 50 cm over the past seven years. He noted that the average of recent years itself represents an increase compared to the long term, partly due to annual air temperatures being higher than usual.

He added that heavy snowfall could potentially mitigate some of the damage before the end of the year, but things look grim so far.

Eddy said the full extent of this year’s melt will become clear during his research trip in the fall: "It’s somewhat frightening to look at how these glaciers are changing."

Pomeroy noted that during the 1970s, Bow oscillated between positive and negative mass balances from year to year. In some years it would grow, and in others, it would shrink.

But recently, every year has been a negative one. Pomeroy said the last time Bow grew was around 2000, with some of its largest losses occurring in recent years.

This is largely due to warming air temperatures, as heatwaves—such as the one in 2021—exacerbate the problem.

Pomeroy said, "When you think about what’s happening, you put an ice cube outside on a hot day, and that’s what’s happening to the glacier."

This year, the federal weather station in Banff National Park recorded a new heat record for May, according to Canada’s Environment and Climate Change Agency, and temperatures for the rest of spring and summer have remained above seasonal averages.

Combine these factors with low snowfall during the winter, and Pomeroy said he expects this to be one of the worst years on record for glacier loss at Bow. He added that smoke from this year’s record wildfire season is likely to make the situation worse.

Pomeroy stressed that the retreat of the glaciers in the Rockies will ultimately lead to problems for communities that rely on meltwater.

He explained that while most of the water flowing from the Rockies comes from snowmelt, glacier melt also provides a small but critical water source for many major river systems, such as the Bow River and the North Saskatchewan and Athabasca Rivers.

This becomes important when drought conditions emerge in late summer when there has been no rainfall and snow has long since melted.

He said, "Glaciers have provided a huge ecological benefit to Alberta. It’s like having large reservoirs like those owned by Americans, but we never had to build the reservoir—the nature provided that service for us."

For Eddy, the retreat of the Bow Glacier means planning for emergencies.

The growing lake at the end of the glacier means it is difficult to access Bow—they even joked about riding a boat for part of the trip. He added that navigating across the glacier is risky too, due to the number of crevasses that have formed.

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

Eddy said they have now started using other tools, such as drones, to supplement their research: "We had a lot of melt this summer, and we ended up losing a number of tools."

He noted that part of the solution is starting work on a backup to Bow, as since 2010 his team has been doing fieldwork on the nearby Saskatchewan Glacier, which will replace Bow as a research hub once it becomes unviable.

He added that while the Saskatchewan Glacier is melting and retreating at a similar rate to Bow, it is also fed by a very large ice field and has a much larger accumulation area, so it is expected to last for much longer.

Research indicates that Bow and other nearby glaciers will lose most of their mass by 2100, but Eddy believes that if current trends continue, it will be much faster than that.

As a scientist, he said it is an interesting trend to observe firsthand, as a human, it is sad. He often thinks of his young daughter during his research trips and wants to share his work with her while he still can.

He said, "I would love to take her out there and show her these glaciers in the Alps before they disappear, hoping she remembers them when she grows up."