Recent and future warm extreme events and high-mountain slope stability

Abstract

The number of large slope failures in some high-mountain regions such as the European Alps has increased during the past two to three decades. There is concern that recent climate change is driving this increase in slope failures, thus possibly further exacerbating the hazard in the future. Although the effects of a gradual temperature rise on glaciers and permafrost have been extensively studied, the impacts of short-term, unusually warm temperature increases on slope stability in high mountains remain largely unexplored.We describe several large slope failures in rock and ice in recent years in Alaska, New Zealand and the European Alps, and analyse weather patterns in the days and weeks before the failures. Although we did not find one general temperature pattern, all the failures were preceded by unusually warm periods; some happened immediately after temperatures suddenly dropped to freezing.We assessed the frequency of warm extremes in the future by analysing eight regional climate models from the recently completed European Union programme ENSEMBLES for the central Swiss Alps. The models show an increase in the higher frequency of high-temperature events for the period 2001-2050 compared with a 1951-2000 reference period. Warm events lasting 5, 10 and 30 days are projected to increase by about 1.5-4 times by 2050 and in some models by up to 10 times.Warm extremes can trigger large landslides in temperature-sensitive high mountains by enhancing the production of water by melt of snow and ice, and by rapid thaw. Although these processes reduce slope strength, they must be considered within the local geological, glaciological and topographic context of a slope.

Challenges and solutions for long-term permafrost borehole temperature monitoring and data interpretation

“…Delaloye and Lambiel, 2005) and in general to natural hazards from permafrost areas (e.g. Huggel et al, 2010;Ravanel and Deline, 2011;Luethi et al, 2015).…”

“…Recently increasing interest in the thermal state of permafrost is related to the construction of infrastructure (Bommer et al, 2010), rock-slope instability (e.g. Fischer et al, 2012;Gruber and Haeberli, 2007;Huggel et al, 2010;Krautblatter et al, 2013), rock glacier (e.g. Arenson et al, 2002;Kenner et al, 2014) and talus slope dynamics (e.g.…”

Holocene climate change, permafrost and cryogenic carbonate formation: insights from a recently deglaciated, high-elevation cave in the Austrian Alps

“…East-and west-Alpine glaciers show evidence of a major advance during the first half of the Bronze Age (culminating at ca. 3500 yr BP, known as Löbben oscillation; Patzelt and Bortenschlager, 1973;Nicolussi and Patzelt, 2001;Holzhauser et al, 2005;Ivy-Ochs et al, 2009;Luetscher et al, 2011) followed by a retreat during the second half of the Bronze Age and centered at about 3300 yr BP (Holzhauser et al, 2005;Joerin et al, 2006;Luetscher et al, 2011). Glaciers re-advanced during the early Iron Age, reaching a maximum at ca.…”

“…exceeds the area occupied by glaciers. Given the potential hazards associated with its degradation due to rising air temperatures, Alpine permafrost has been extensively studied and its physics is well understood (e.g., Gruber et al, 2004;Huggel et al, 2010;Boeckli et al, 2012;Springman et al, 2013). Much less well known, however, are changes in permafrost thickness and aerial extent on decadal, centennial and millennial timescales, largely because of lack of suitable archives.…”

Climate change and integrated analysis of mountain geomorphological systems

“…Huggel et al (2010) report an increase in frequency of large slope failures in high mountain regions over the past 2 to 3 decades. Short duration of unusually warm events (e.g.…”