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. 

Abstracts:

Leif Anderson (GFZ Potsdam, Germany) - Ice dynamical controls on the rapid thinning of debris-covered glaciers (Invited)

James Ferguson (U. Zurich, Switzerland) - Historical Reconstruction and Numerical Modelling of Zmuttgletscher, Swiss Alps, Since the Little Ice Age

Dawa Tshering Sherpa (Kathmandu U., Nepal) - Spatial Distribution of Debris Thickness from Remote-Sensing and Modeling in Marshyangdi River Basin, Nepal

Eric Petersen (U. Arizona, USA) - The Transition from Alpine Glacier to Rock Glacier: A Case Study at Sulphur Creek, Wyoming

Alessandro Cicoira (U. Zurich, Switzerland) - Resolving the influence of climatic forcing on rock glacier dynamics: a numerical modelling approach

Morgan Monz (U. of Minnesota Twin Cities, USA) - Crystallographic preferred orientation in warm, coarse-grained ice: a case study, Storglaciären, Sweden

Jaakko Putkonen (U. North Dakota, USA) - Ancient Ice Preserved Under A Meter-Thick Layer Of Debris; Ong Valley, Transantarctic Mountains, Antarctica

Emilio Mateo (Ohio State U., USA) - Evaluation of inter-annual to decadal changes in tropical Andean stream chemistry below debris-covered glaciers

Pascal Buri (U. Alaska Fairbanks, USA) - From the Equator to the Pole: How Latitude Affects Incident Shortwave Radiation on Supraglacial Ice Cliffs

Acknowledgements:

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!

Debris-covered glaciers workshop at the Geological Society

Summary by Adina Racoviteanu & Lindsey Nicholson

Alarmist statements about retreating and thinning glaciers and the threat of glacier lake outburst floods (GLOFs) have caused heightened concern amongst local communities in high mountains. Debris covered glaciers and their associated lakes are at the heart of this debate, as their response to climate is variable and still an active research topic. Contradictory points of view of various research groups have led, in some instances, to a level of distrust of the science communicated to local communities, posing the need for meetings and activities to bridge different disciplines and backgrounds and to optimise and maximise our collective focus and productivity. The community of researchers interested in debris-covered glaciers is relatively recent but growing and pulls together researchers from different disciplines. Thus there is a need to (1) draw up consensus summaries of the state of the knowledge on these glacier systems and (2) deliver better communication of the key research findings to local communities. 

In a 2.5 day meeting held at the Geological Society in London in September 2019, (https://www.geolsoc.org.uk/GSL-Debris-Covered-Glaciers), a friendly group of 29 scientists interested in debris-covered glaciers and lake hazards gathered to discuss the current state of research and to agree upon future research priorities, in particular to address concerns related to the effects of climate change on glaciers and lakes in high mountains. This meeting was initiated by the UNESCO-IGCP 672 project “Himalayan Glaciers and risks to local communities” focused on developing methods for systematic monitoring of Glacier Lake Outburst Flood (GLOF) potential in the Himalaya using remote sensing, and disseminating the methodologies developed via training workshops for local institutions in India, Bhutan and Nepal.The meeting was closely aligned with the International Association of Cryospheric Sciences (IACS) and International Permafrost Association (IPA) working and standing groups on Debris Covered Glaciers and Glacier and Permafrost Hazards in Mountain Regions, both of which are open to membership and new contributions to anyone.

The workshop started with an afternoon of expert talks summaziring the state of research on debris covered glaciers and lakes (abstracts of the talks are available here):

• Dr Tobias Bolch – Mapping, area change and mass balance of debris-covered glaciers from space 
• Dr Evan Miles – Ice cliffs and supraglacial ponds: state of knowledge and research directions 
• Professor John Reynolds – An introduction to Glacial Lake Hazard Assessments 
• Dr Duncan Quincey – GAPHAZ – a Scientific Standing Group on high-mountain glacier and permafrost hazards 
• Dr Matt Westoby – GLOF modelling: state-of-the-art, opportunities, and complications 
• Dr Jonathan Carrivick – Impacts of glacier outburst floods within high mountain regions 
• Dr Scott Watson – Communicating earth observation data on Himalayan debris-covered glaciers and high mountain hazards

During the following two days, participants split into break-out sessions and addressed three main topics: 1) debris-covered glaciers; 2) glacial lake ranking schemes using remote sensing to assess hazard potential and 3) climate change and debris-covered glaciers. Additional smaller working groups focused on science communication and capacity building needs, drafted collaborative papers and developed a call for a PhD studentship. Some of the main conclusions of the workshop were: 

• Mapping the extent of debris covered glaciers is still a challenge despite improvements in remote sensing; an intercomparison study and a standardized open source tool is still pending

• Protocols for estimating glacier outburst flood potentials are still needed, and should include a ‘first pass’ scheme using remote sensing followed by detailed field investigations

• Capacity building initiatives are extremely valuable for local institutions and there is a need to support long term educational programs with support from local governments

In a collaborative BRAINSTORMING VISUALIZING PROCESSES, Naomi Lefroy, with input from Neil Glasser and Ian Willis, sketched a landscape map of a typical debris glacier ‘system’

For further information on the IGCP 672 project, current capacity building initiatives or meeting outputs then please contact Adina Racoviteanu (adr18@aber.ac.uk or racovite@gmail.com)

Acknowledgements: 

 
Thanks to the Geological Society for hosting and supporting this meeting, and to all contributors for making such a successful workshop – what a great community!

FUNDING: We acknowledge the funding sources which made this workshop possible. We wish to thank the Geological Society for providing support and  logistics in London. The IGCP 672 project, funded through UNESCO and IUGS has funded the participation of external project collaborators and co-leaders from Asia. The DISCOVER GLACIERS project funded through the from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 663830 is supporting the participation of project leader and workshop facilitator A. E. Racoviteanu using the Ser Cymru funds.