Words :: Erin Moroz. Decades of research by a husband-and-wife team of limnologists has revealed the dimming of a Canadian icon. From across the globe, people flock to stand on the shores of impossibly blue-green mountain lakes—however, the blue is fading. Losing Blue, an artistic translation of the couple’s scientific research and the newest film by Canmore filmmaker Leanne Allison will screen at this year’s Banff Centre Mountain Film & Book Festival.
Blue. The most uncommon colour in nature. The brilliant turquoise of Lake Louise; the opaque aquamarine of Peyto Lake; an otherworldly glow firmly rooted in the geographical epochs of our planet. The interplay of nature and time delivers a spectacle, and people from around the world come to bear witness to what seems like an impossibility. How can a body of water deliver a cleansing breath? How can a thing so utterly terrestrial be so ethereal?
You may know, or perhaps you don’t, where these brilliant blues come from—or rather, where they go. The lakes are a time capsule for glacial melt, millennia-old bedrock ground down into a fine rock flour by the movement of primordial ice. The trickle of melting glacier ice in the spring and summer then delivers the ground particles of bedrock to the lakes where the flour becomes suspended particles in the water column. Lake water absorbs the warmer colours of the rainbow spectrum and the cooler blue and green colours remain. The glacial flour reflects these colours back to our eyes, scattered and brilliant and at times making the ancient lakes appear to glow.
The trickle of melting glacier ice in the spring and summer then delivers the ground particles of bedrock to the lakes where the flour becomes suspended particles in the water column.
The Science
But the lakes are changing, constantly. The depth of blue, the brilliance of the reflected rock flour shifts and reconfigures by time of day, by season of the year. The trickle of glacier melt ebbs and flows with the warming atmosphere, summer versus winter, day versus night. Only that’s changing too—for the first time this past winter, scientists from the Centre of Hydrology and Coldwater Laboratory in Canmore recorded loss of ice over the winter season in one of the world’s most studied glaciers: the Peyto Glacier. Located 90 kilometres north of the Banff townsite and part of the Wapta Icefield, the Peyto was declared a “reference glacier”—a harbinger if you will—by the UN decades ago.
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In August 2022, John Pomeroy, director of the Coldwater Lab, and his team set up their weather stations and ultrasonic depth transducer on the Peyto to record the change in surface elevation and thus calculate a melt rate. The exceptionally long, warm fall of 2022 saw the glacier melting into October and when Pomeroy and his team returned in June, the toe of the Peyto had lost three metres in thickness.
Loss of glacier ice is not news, per se, but the way the loss is occurring is also changing. Soot from rampant wildfires accumulates on glaciers, absorbing heat and accelerating the pace of melt, as does newly observed algae blooms whose filaments hold the soot in place year after year.
What this ultimately means is the otherworldly glow of glacier-fed lakes is fleeting, says American limnologist Janet Fischer from Franklin & Marshall College in Pennsylvania. Fischer and her husband and collaborator, Mark Olson, have been studying lakes in the Canadian Rockies for 18 years. To draw attention to the implications of shrinking glaciers on lake colour, they enlisted the help of Canmore filmmaker Leanne Allison (whom you may remember from Being Caribou, Finding Farley and Bear 71).
Allison was charged with turning the science into art, with a few stipulations from the scientists: they didn’t want to be in the film, and they didn’t want the film to be a run-of-the-mill science documentary.
“These lakes mean so much more to us than just numbers,” says Fischer. “Our connection to them is personal. It’s become our life’s work. We visit the same lakes year after year and it’s fascinating to document how they’re changing and why.”
Their decades-long research is a family affair, one that saw the couple carting their two kids, now 16 and 22, along on trips deep into the Rockies to study the relationship between lakes and their catchments. Fischer smiles as she recalls her son being packed into Opabin Lake in Yoho National Park and then pushing off in an inflatable boat to collect data as her wee’un napped on the shore. “I feel incredibly fortunate I didn’t have to choose (between my career and motherhood),” she says.
As the atmosphere warms and the glaciers shrink then ultimately disappear, lake colours will change. Lakes with abundant vegetation in their catchments will darken and become greener as decomposing plants deposit dissolved organic carbon into the water. Lakes with barren catchments will go through a long period where the settling and loss of rock flour will transform their frigid waters from turquoise to rich sapphire blue. Then as vegetation colonizes the catchment and treelines advance upslope—a process which takes decades according to a 2020 study by ecologist Andrew Trant and others—the sapphire will give way to green, says Olson. The famous iridescent blue-green of the alpine lakes will be a flash in the pan of geological time, something we were lucky to witness. Fischer and Olson estimate their grandchildren will not be so fortunate.
The Film
Lakes are generally born from significant geological events such as volcanic activity or glaciers, and that had Leanne Allison thinking on a different time scale for the film. “We started experimenting with footage and thinking of deep time,” she says.
“And [scriptwriter James Mackinnon and I] didn’t need to hit people over the head with global warming,” says Allison, adding that recent climate events such as 2021’s atmospheric river and heat dome and the onslaught of wildfires have made climate change an undeniable reality.
The impetus was to slow time down and have viewers really experience the achingly poetic film. “The colour of these lakes makes them universally compelling. Millions of people come to see Lake Louise every year and almost no one knows the colour is disappearing. It makes you wonder, what else are we losing and don’t even know it?” says Allison.
“Losing Blue doesn’t tell people what to feel or what to do about climate change. It invites them to wonder what it means to be in the presence of these otherworldly blue-green lakes today. As James writes in the script: ‘Do you see heaven in it? Infinity? What is this feeling? What is this mystery? What would it mean if it was gone?’”
Watch the film online now on the Banff International Film Festival site.
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