Complex interconnected and climate-sensitive cold-mountain systems have been intensely investigated at the Gruben site in the Saas Valley, Valais Alps, Switzerland. The Google Earth image shows the peaks of Fletschhorn (upper center, 3985 m a.s.l) and Lagginhorn (upper right, 4010 m a.s.l) with the rapidly retreating Gruben glacier (1).

Large masses of debris are perennially frozen (permafrost) and for millennia already undergo long-term, slow viscous creep, forming lava stream-like landforms usually called “rock glaciers” (2). As a consequence of global warming, a system of lakes (3) developed where the ice of Gruben glacier retreated and vanished. Outbursts of such lakes in 1968 and 1970 eroded a deep breach (4) into the moraines from earlier colder times with more extended glacier ice.

These outbursts triggered large debris flows, causing heavy damage in the main valley. Rock walls, especially on the shadow side of the mountains are frozen to great depth (rock permafrost: 5). Warming and thawing of this rock permafrost reduces the stability of affected slopes, leading to increased rock falls and rock avalanches. The tongue of Gruben glacier is heavily covered by such young rockfall material. Comprehensive analysis is necessary to understand the warming-affected evolution of this interconnected system, forming the basis for successful protection (access road for construction work: 6).

Own publications:

Haeberli, W., Kääb, A., Vonder Mühll, D. and Teysseire, Ph. (2001): Prevention of outburst floods from periglacial lakes at Grubengletscher, Valais, Swiss Alps. Journal of Glaciology, 47/156, 111-122.

Gärtner-Roer, I., Brunner, N., Delaloye, R., Haeberli, W., Kääb, A. and Thee, P. (2022): Glacier-permafrost relations in a high-mountain environment: 5 decades of kinematic monitoring at the Gruben site, Swiss Alps. The Cryosphere 16, 2083-2101. doi.org/10.5194//tc-16-2083-2022

Haeberli, W., Arenson, L.U., Wee, J., Hauck, C. and Moelg, N. (2024): Discriminating viscous creep features (rock glaciers) in mountain permafrost from debris-covered glaciers – a commented test at the Gruben and Yerba Loca sites, Swiss Alps and Chilean Andes. Invited Perspective, The Cryosphere 18, 1669-1683. doi.org/10.5194/tc-18-1669-2024

Wee, J., Vivero, S., Mathys, T., Mollaret, C., Hauck, C., Lambiel, c., Beutel, J. and Haeberli, W. (2024): Characterizing ground ice content and origin to better understand the seasonal surface dynamics of the Gruben rock glacier and the adjacent Gruben debris-covered glacier (southern Swiss Alps). The Cryosphere, 18, 5939–5963. https://doi.org/10.5194/tc-18-5939-2024