Glacier-related slope failures are geohazards that occur in mountainous regions. They are marked by the rapid movement of substantial amounts of material down the mountain slopes due to factors such as glacier thinning and changes in thermal conditions that lead to glacier destabilization. These events take the form of avalanches and glacier collapses. Beyond the immediate devastation caused by them, the significant displacement of material during these failures can trigger additional hazards. For instance, they can initiate glacial lake outburst floods, wherein water and debris previously confined within glacial lakes are abruptly released, posing a downstream flooding risk.

  Aru glacier collapse in western Tibetan Plateau Credit: Tandong Yao

With the acceleration of global warming and glacier retreat, a correlation between climate change and the rise in these hazardous events has been observed. However, establishing a definitive connection between climate change and glacier-related slope failures has been challenging since these events are influenced by both climate-related factors and natural geological processes such as erosion, earthquakes, and volcanic activity.

To determine the role of climate change in these incidents, a research team led by Associate Professor Weicai Wang, who heads the Third Pole Environment (TPE) management team at the Institute of Tibetan Plateau Research at Chinese Academy of Sciences, has recently conducted a comprehensive analysis of glacier-related slope failures that occurred worldwide from 1901 to 2019. They examined the patterns and changes in the frequency of these events over the years and accounted for the influence of climate change by excluding cases linked to natural events.

“The goals of this study were to collect historical events from numerous types of literature to compile a global-scale inventory of glacier-related slope failures and to conduct further analysis on their frequency, impacts, and potential climatic drivers,” explains Dr. Wang.

By scrutinizing 727 glacier-related slope failures across North America, the Andes, the Third Pole, the Caucasus, European Alps, Iceland, Scandinavia, and the Southern Alps, the team found a notable increase in the frequency of these incidents over the years. After excluding events caused by earthquakes and volcanic activity, they found that the annual rate of these failures increased fivefold, from an average of 3.4 incidents between 1960 and 1979 to 16.3 failures between 2000 and 2019.

After 1986, the frequency of these incidents rose by about 0.4 instances each year. This pattern in glacier-related slope failures was found to be closely linked to the rise in temperatures observed around 1971, suggesting a delay of around 15 years between temperature variations and corresponding changes in the frequency of glacier-related slope failures. This relationship was observed consistently across different types of failures, such as glacier collapse, ice avalanches, ice-rock avalanches, and rock avalanches on glaciers, providing conclusive evidence of the impact of climate change on glacier-related slope failures.

As these events become more frequent, there is growing concern for the safety of communities living in high mountainous areas. The researchers found a stark increase in fatal events between 2010 and 2019, particularly in regions such as the Himalayas, Southeastern Tibet, and the Peruvian Andes. Notably, about two-thirds of the destructive failures were due to hazardous events accompanying glacier-related slope failures, such as mudflows, dammed lakes, glacial lake outburst floods, and even lake or sea tsunamis.

As glaciers continue to recede due to climate change, this study underscores the need to address the growing risks posed by glacier-related slope failures. “Considering the increase in destructiveness of the failures observed in recent years, it is necessary to conduct detailed risk assessments in key areas, such as developed tourist locations, exposed human communities, and hydropower projects, and to formulate appropriate prevention and mitigation measures,” concludes Dr. Wang.