After a summer of heat warnings and record-breaking temperatures, Whistler residents can feel lucky to have a dedicated set of eyes on our backyard glaciers. This year marks 50 years of monitoring on Wedgemount Glacier and 38 years on Overlord Glacier.
Measurements of our glaciers in September 2023 over a two-day excursion showed the expected effects of a warm and dry year. Significant recession of the terminuses (front edges) of Wedgemount and Overlord Glaciers coupled with severe ablation (evaporation/melting) of their surfaces have left thin and debris-covered ice and the formation of ice tunnels. We have also been monitoring new lake basins at both locations uncovered and filled by the melting glaciers—Tupper Lake at Wedgemount and Investigator Lake at Overlord.
Sept. 2, after the brutal heat of the summer, saw Wedgemount Glacier recede 20 metres since last year. Now with a “perched” terminus some 118 metres in elevation above Wedgemount Lake, and a lesser but significant height above intervening Tupper Lake, this is more than double last year’s recession of eight metres. It’s worth noting the recession measurement could have been much more, since the toe of the glacier has only a flimsy connection with the rest of the glacier (a finger of ice over an ice cave).
On a rainy Sept. 3, we had 45 minutes on the ground to measure the significant six-year recession of the terminus (117.5 metres or 19.6 metres per year). The aerial inspection included three to four laps around the lake, with video cameras in action to try and answer the question: is the lake in a stable basin, or quasi-stable, and will further glacial melt see it enlarge and find a way for it to drain?
Because the emerging Investigator Lake at Overlord is a potential downstream hazard if it suddenly emptied into Fitzsimmons Creek (which runs through Whistler Village), this year we called upon new personnel to help assess the risk: Dr. Gwenn Flowers, a glacio-hydrologist at Simon Fraser University; James Hallisey and Andrew Tucker from the Resort Municipality of Whistler’s (RMOW) engineering staff; and former RMOW 1970s head engineer Doug Wiley, who is now archiving glacier photos.
Though we found nothing immediately concerning, stay tuned; next year’s work schedule will see ice and lake depth measurements and ice edge/surface measurements.
Since the surveying began five decades ago, Wedgemount Glacier has receded 700 metres from where it used to sit in Wedgemount Lake. The average recession is 14 metres per year, and in those five decades it registered a minuscule advance from 1983 to 1984. The glacier was severely “whacked” by a 57-metre collapse above Tupper Lake between 2020 and 2021. For Overlord Glacier, Karl’s on-the-ground research from 1986 to 2023 showed it receded 385 metres, or an average of 10.4 metres per year.
After 50 years of surveying, Karl is retiring, and has handed off this monitoring project to a younger generation of researchers. How future summers affect these glaciers will be determined by our future climatic patterns, but we can at least be confident this dedicated community of professionals and keen youth will be keeping a careful eye on them.
Naturespeak is prepared by the Whistler Naturalists. To learn more about Whistler’s natural world, go to whistlernaturalists.ca. n