How CATALYST photogrammetric reconstruction and its Digital Elevation Model (DEM) has been used to unlock glacial centre line and areal extent changes across an entire region for more precise, accurate climate change modelling prediction.
As the face of climate change grows more familiar in the Pan-Arctic region, certain images have come to define its impact:
- Mass habitat loss.
- Coastal erosion.
- Extreme droughts and floods.
- A growing endangered species list.
Perhaps the most striking and most symbolic images, though, are the melting, retreating glaciers and ice caps.
The sights of flowing meltwater and exposed earth where ice should be are stark reminders of the profound changes happening globally, changes that will ultimately affect us all.
Mr. Wilson Cheung, a PhD candidate at Queen’s University, has been studying glacial retreat across Sirmilik and Auyuittuq National Parks in the Canadian Arctic.
His mission: to develop a more spatially and temporally precise picture of what the future holds by looking into the past and - for the first time - constructing a detailed picture of glacial change over the last six-and-a-half decades.
"Collection of long-term glacial monitoring data in this region has been limited since 1960," Cheung explains.
“Without historic data, we could never confidently project future climate models. We needed to better understand what happened in those lost years."
His research, focused on the glaciers of Baffin and Bylot Island, faced a challenge common to many Arctic regions—historically limited monitoring.
“The region has glacial coverage a third larger than Antarctica and Greenland, but it hasn't been studied as closely as other parts of the Arctic.
"We know the glaciers have been retreating, and that this is already affecting the local Inuit community—impacting hunting, access to fresh water, and travel. But without that long-term data, it’s hard to make accurate project to the future."
This is where CATALYST came in. While direct historical data collection had ceased for over 65 years, aerial and satellite imageries from the region didn’t, offering Cheung a critical starting point for reconstructing the past.
“We were able to access historical images from the National Air Photo Library in Ottawa,” says Cheung. “It came with all the metadata we needed—camera focal length, fiducial marks, and lens calibration reports.
"Using this raw data, we employed CATALYST workflows to create accurate high resolution digital elevation models (DEMs) and outlines of the change of glaciers across a vast area of the region over the past six decades.”
Despite the challenges posed by the historical aerial imagery—cloud cover, overexposure, and even tape repairs on damaged film—CATALYST workflows allowed Cheung to complete an analysis across the entire area.
"The precision of CATALYST’s high-resolution imagery analysis and DEMs meant we could capture even the smallest changes, down to two-meters resolution. This allowed us to study these glaciers in unprecedented detail."
The result was a chronicle of glacial change over six decades, revealing both expected and unexpected insights.
"You can see significant reductions in the centre lines of many glaciers, particularly in Auyuittuq National Park,” Cheung notes. “The Highway Glacier and Nakarpog Glacier, for example, have experienced dramatic retreat. And when we measure the total area of the glaciers, we see consistent reduction."
In Auyuittuq National Park, he found that glaciers with southern tips, facing sun in the summertime suffered the most.
“Between 1958 and 2022, the upper parts of these glaciers haven’t received enough snowfall to replenish the fast-melting ice at their lower, south-facing tips,” he explains.
“This is typical during the summer, but we’ve observed that this melting is now happening even in winter, which has accelerated the overall retreat.”
With this new data in hand, Cheung and his team revisited prediction models, combining CATALYST's detailed data with manual methodologies. The results, illustrated in their models, point to an alarming trend.
“The changes we’ve seen over the past 60 years—unless serious intervention happens—are likely to accelerate. We expect the glacier’s centre-line retreats to continue, with far-reaching consequences.”
The precision of CATALYST’s algorithms, combined with broader spatial and temporal detail, offered Cheung’s team a better understanding of the glaciological knowledge in the region and contributed to more accurate climate models.
“We can now say with confidence that this region is changing, and the impacts will be felt both locally and globally,” he says. “Increasing glacial melted fresh water will impact the ocean currents and climate pattern, and for the Inuit communities as a frontier of climate change, the dynamics are reshaping their home.”
For Cheung, the value of his work with CATALYST is clear: it starts with the local impact. “Inuit communities have lived here for over 5,000 years, and they’ve already seen and adapted to these changes,” he says. “But now, with this data, we have an opportunity to engage with them in new ways—to prepare the locals to face the future’s challenges.”
Cheung’s team shares their findings with the local communities, hosting open Q&A sessions and discussing what their work reveals.
“It’s important they know how their landscape is changing rapidly so that they—and future generations—can make more proactive adaptations,” he explains. For instance, the data now highlights areas the community should avoid during their travels. “One changing glacier indicates they may need to travel further to access fresh water in the future, which could become a significant challenge.”
Back home in Canada, Cheung reflects on the broader implications of his work.
"The data shows that the train is already leaving the station," he says. “These changes are happening now, and they’re only going to accelerate unless we take action.”
About Wilson Cheung
Wilson Cheung is currently working at ICElab, Queen's University, focusing on estimating the spatial distribution of ice thickness and volume across Bylot and Baffin Islands through a combination of intensive fieldwork and remote sensing techniques. In addition, he is a Fellow of the International Arctic Science Committee (IASC).
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