Researchers are mapping glacier loss in western Canada using remotely sensed data and satellite imagery. Scientists compare the size and extent of glaciers over time using satellite images such as those produced by the long-running Landsat Earth observation satellite. By examining images from different years, we can track changes in the size, shape, and movement of glaciers.
How are Western Canada’s glaciers changing?
In 2022, researchers at the University of Northern British Columbia used Landsat imagery to map 14,329 glaciers (covering 30,063 square kilometers) in British Columbia and Alberta, Canada, between 1984 and 2020. The results of the research were presented. This study improves on a previous glacier inventory published in 2010, also conducted through remote sensing of his Landsat imagery, which examined the status of glaciers in western Canada in 1985, 2000, and 2005. doing.
Glaciers are amazingly large
The 2022 study found that the rate of shrinkage of these glaciers began to accelerate starting in 2011. By 2022, 1,141 glaciers (equivalent to 8%) have shrunk to a size where their presence cannot be detected on satellite images (detected at 0.05 km2). limit).
Between 1984 and 2010, the annual average clean glacier (debris-free glacier) loss was 49 square kilometers (19 square miles). Between 2011 and 2020, this increased sevenfold to an average annual glacier loss of 340 square kilometers (130 square miles). This glacier decline was even more pronounced among smaller glaciers on Vancouver Island, where shrinkage rates increased by a factor of 32.
Glaciers are breaking up into smaller pieces
Glaciers in western Canada are also fragmenting and retreating to higher elevations. Glacier fragmentation refers to the process by which glaciers break into smaller pieces or fragments. There are other physical processes that can cause glaciers to fragment, but climate change can increase temperature fluctuations and seasonal changes, which can cause glacier surfaces to expand and contract.
These fluctuations can lead to cracking and ultimately ice fragmentation. The 2022 study also found that fragmentation increased from an average of 26 pieces per year to about 88 pieces.
Freshwater lakes are increasing due to melting glaciers
Glacier melting contributes to increased development of preglacial lakes. In one example, comparing satellite images shows how the Klinaklini Glacier, the largest glacier in the western United States outside of Alaska, has changed over nearly 40 years. His two satellite images of Klinaklini Glacier, below, were taken almost 40 years apart, from September 26, 1984 (left) to September 22, 2023 (right).
Comparing satellite images reveals several changes. The length of the glacier’s terminus has decreased significantly, with the terminus now more than 5 kilometers (about 3 miles) further north.
Melting glaciers also contributed to the expansion of glacial lakes at their terminus. In 1984, the glacial lake at the edge of the glacier was barely visible in satellite images. As the ice melts, the area and volume of the lake increases, and by 2023, the lake will be 5 kilometers by 2 kilometers and support floating icebergs.
References
Bebbington, AR, Menunoism B. (2021). Accelerated changes in the glacier environment in western Canada revealed by trend analysis of optical satellite images (polygons) (version 2) [Data set]. Zenodo. https://doi.org/10.5281/zenodo.5900363
Bebbington, AR, B. Menounos (2022). Trend analysis of optical satellite imagery reveals accelerating changes in western Canada’s glacial environment. remote sensing of the environment, 270112862. https://doi.org/10.1016/j.rse.2021.112862
Borch, T., Menounos, B., and Wheat, R. (2010). Landsat-based Western Canada Glacier Inventory (1985-2005). remote sensing of the environment, 114(1), 127-137. https://doi.org/10.1016/j.rse.2009.08.015
Voiland, A. (January 29, 2024). Retreat at Clina Clini. NASA Earth Observatory. https://earthobservatory.nasa.gov/images/152378/retreat-at-klinaklini
