Understanding the Ice-Rock Avalanche in Blatten: A Cascade of Processes in a Warming Climate

• Post by: Randy Muñoz
• June 12, 2025
• Comments off

Three days after the devastating ice-rock avalanche in Blatten (Lötschental, Switzerland), EClim member Christian Huggel shared a detailed analysis of the contributing geophysical and climatic factors behind the event, highlighting how climate change plays a critical, though complex, role.

📌 Key causes and mechanisms:

• Roughly 3 million m³ of rock debris were deposited on the glacier days before the avalanche, dramatically increasing shear stress.
• This load raised pressure on the glacier ice, likely causing basal melting, more subglacial water, and a reduction in shear strength, triggering slope failure.
• The glacier tongue had been accelerating in recent years, potentially due to earlier debris loadings, leaving it unable to adapt dynamically to the sudden stress increase.

📌 Climate change connections:

• The Birch glacier has lost significant mass since the 1980s, resulting in debuttressing, a known trigger of slope instability in paraglacial environments.
• The rock mass of Kleines Nesthorn is in deep permafrost, which has warmed considerably over recent decades, weakening slope stability.
• Loss of snow and firn cover has exposed bedrock to enhanced warming, further destabilizing steep rock faces.

Huggel stresses that while precise attribution is essential, denying a role of anthropogenic warming in such disasters is scientifically unfounded. He calls for accurate and nuanced language in the climate-risk dialogue, particularly as it becomes increasingly political.

🔗 Read Christian Huggel’s full comment on LinkedIn