CLIMATE
Tony Mclane on Daily Universe.
KIERAN BROWNIE
Finding Common Ground Is climate breakdown causing increased rockfall on the Stawamus Chief?
Nestled in the UNESCO biosphere region of Howe Sound, the iconic granite monolith, Siám’ Smánit, towers 700 metres above the water and surrounding town of Squamish. Also known as the Stawamus Chief, the landmark holds special significance for the local Skwxwú7mesh nation, whose traditions say it was once a longhouse that was transformed to stone by Xáays, the spirit-beings known as the Transformer Brothers in this area. Since the 1950s, local and visiting rock climbers have come to value Siám’ Smánit for its seemingly endless, high-quality climbing potential and ease of access. For climbers, the mountain is Canada’s answer to California’s famous Yosemite National Park. However, throughout 2021, an unprecedented number of rockfalls tumbled from the face of Siám’ Smánit, rattling the nerves of the Squamish community and closing a number of popular climbing routes. The year was also punctuated by severe weather events and periods of extreme temperatures. July saw Canada’s hottest recorded daytime temperature in Lytton BC, followed by severe rainfall,
flooding and landslides across the southern province in October, and extended cold snaps this past winter. Question is, are these extremes linked to the rockfalls on the Chief? Geologically formed by volcanic activity and glacial erosion, Siám’ Smánit is constantly battered by wind, rain, snow and weather funnelling up the Sound. According to Wesley Ashwood—a geotechnical engineer who often works on the Chief—rockfall is common under such conditions. However, the rate of significant change is traditionally so slow that we wouldn’t notice it. But as climate change appears to be fast-forwarding through extreme weather events and rapid temperature variability, it’s not a giant leap to assume these environmental factors are also impacting rock features more quickly than previously seen. Researchers in Yosemite (which is similar in setting and formation to Siám’ Smánit) studying thermal changes in the rock have confirmed that cracks expand and propagate into more significant fractures during heatwaves. Engineering geologist Sergio Sepúlveda says 37
