Wednesday, 8 January 2020

Session on debris-covered glaciers processes at AGU Fall Meeting

by Pascal Buri

Although considerable progress has been made in recent years in understanding the behaviour of debris-covered glaciers, many fundamental processes on, within and surrounding this glacier type remain ill-understood. As debris-covered glacier processes cross the fields of glaciology, geology, geomorphology, hydrology and meteorology in unique ways, a wide range of expertise is required to bridge our knowledge gaps. 

The session we organized for the AGU Fall Meeting in California in December 2019, co-organized by the Cryopshere and Earth and Planetary Surface Processes focus groups, aimed to improve process understanding related to debris-type glaciers and brought together expertise from quite different fields, e.g.:

  • Jaako Putkonen (University of North Dakota, USA) found glacier ice in ice cores more than 1 million years old, protected from sublimation by a thick debris layer on a glacier in Ong Valley (Transantarctic Mountains, Antarctica).
  • Leif Anderson (GFZ Potsdam, Germany) explored the causes of glacier thinning under debris by numerically modelling sub-debris melt, debris-transport and ice dynamics in 2D. The theoretical simulations showed that the zone of maximum glacier thinning propagates from upglacier into the debris-covered part of the glacier, suggesting that reduced ice flow from upglacier leads to increased glacier thinning under debris. James Ferguson (University of Zurich, Switzerland) used a similar approach in order to simulate numerically the behaviour of debris-covered Zmuttgletscher (Swiss Alps), which could be compared to a 150-year record of historical topographical data.
  • Eric Petersen (University of Arizona, USA) showed how a debris-covered glacier can be a transitional state between a debris-free alpine glacier and a rock glacier, by using observational data from Galena Creek Rock Glacier (Wyoming, USA). 
  • Alessandro Cicoira (University of Zurich, Switzerland) revealed the importance of water input for velocity-variations of rock glaciers in the Swiss Alps by using a numerical model with meteorological observations. 



Thanks to the co-conveners of this session, Bob Anderson, Caroline Aubry-Wake and Jakob Steiner, for making this session happen, and to all the participants at our AGU session for great posters and exciting discussions across fields!