Increasing rock avalanche size and mobility in Alaska has been linked to climate change in a new paper recently published in Landslides journal.
The study by Jeffrey Coe, Erin Bessette-Kirton and Marten Geertsema used Landsat imagery from 1984 to 2016 to create a landslide inventory and look at trends in the Glacier Bay National Park and Preserve.
Analysis identified that rock-avalanche magnitude, mobility, and frequency reveal a cluster of large, highly mobile rock avalanches that occurred from June 2012 through June 2016. The paper states that these rock avalanches began about two years after the long-term trend in mean annual maximum air temperature may have exceeded 0°C. “Possibly more important, most of these rock avalanches occurred during a multiple-year period of record-breaking warm winter and spring air temperatures,” said the authors.
According to the paper, the observations suggest that rock avalanches in the study area may be becoming larger because of rock-permafrost degradation. However, the authors add that other factors, such as accumulating elastic strain, glacial thinning, and increased precipitation, may also play an important role in preconditioning slopes for failure during periods of warm temperatures.
“This is the most convincing evidence that I have seen to date that increasing temperatures are driving a higher rate of rock slope failure in high mountains, a trend that we also seem to be seeing in for example the Alps in Europe and the Southern Alps in New Zealand,” said landslide specialist Dave Petley, who is pro-vice chancellor at East Anglia University. “It suggests that there is a pressing need for increased research into the processes occurring in high mountain slopes, including in situ monitoring. The implications are clear though – as climate change continues to drive warming in high mountain areas the risks associated with rock slope failure will increase.”