March 22, 2014, killer landslide near Seattle (photo: Kings County Sheriff’s Office).
Last Saturday’s horrific mudslide 55 miles northeast of Seattle may unfortunately herald the shape of landmass movements to come, if climate change has its way with us. A new study in the European Alps elaborates.
In a draft article for Elsevier’s Science of The Total Environment journal (available online but part of a work in progress), investigators have studied the European Alps for evidence on how climate change can affect landslides.
They review cases of debris flows, rock slope failure, and landslide in the mountainous environments of the French, Italian, and Swiss Alps. Markus Stoffel (lead and corresponding author) of the University of Geneva’s Department of Earth Sciences and Institute for Environmental Sciences and the University of Bern’s Institute of Geological Science, and coauthors Davide Tiranti from the Regional Agency for Environmental Protection of Piemonte (ARPA Piemonte) and glaciologist Christian Huggel of the University of Zurich’s Physical Geography Division conducted the study.
Increases of heavy rainfall in spring and fall, anticipated with climate change, and larger amounts of sediment loosened by this water will likely enlarge downward flows of debris during the shoulder months of March, April, November, and December to levels without historic precedent.
“The frequency of rock slope failures is likely to increase, as excessively warm air temperatures, glacier shrinkage, as well as permafrost warming and thawing, will affect and reduce rock slope stability adversely.”
Among the other cited highlights:
• Events without historical precedents may occur due to unstable permafrost environments (in other words, locating potential areas may become more difficult).
• Debris flows are likely to occur more often in spring and fall, but less in summer.
• Shallow landslides will occur more often in early spring, but in smaller overall numbers.
• Fall landslides with large spatial densities of occurrences are likely to become scarcer.