I created RockyGlaciers.org (originally RockyGlaciers.co.uk) back in 2015 whilst doing a PhD on debris-covered glaciers in the Everest region of Nepal. The idea was to provide an outreach platform to share research on debris-covered glaciers. The old website worked fine but was managed 'offline', which made updating/adding new pages very time consuming.
The domain change from .co.uk to .org came after discussions and a donation from the International Association of Cryospheric Sciences Working Group on Debris covered glaciers to cover the costs of the switch. RockyGlaciers is still hosted on HelioHost, so is run on a voluntary basis with the occasion donation from myself to increase our storage/switch servers when things break. Going forward, the new-look RockGlaciers uses the open source Joomla content management system, which makes updating a whole lot easier, so stay tuned for more content...
A team of researchers from the University of Leeds and the University of Sheffield recently completed a four week field campaign on Khumbu Glacier in Nepal. Khumbu Glacier is the highest in the world and every year a small section of the upper glacier becomes the home to Everest Basecamp in Nepal. Access to the Khumbu valley was by a five day walk with two additional acclimatisation days along the Everest Basecamp trail. Our team camped just off-glacier, a short walk from a small number of trekking lodges at Lobuche. Logistical support and research permissions were organised by Himalayan Research Expeditions. Our guides were invaluable on the glacier and the kitchen team were always ready with hot food on our return! Data collection involved Structure-from-Motion ice cliff surveys, GCP georeferencing, and supraglacial pond depth surveys and instrumentation.
It is widely known that Himalayan Glaciers in this region are losing mass year on year, though the presence of rocky debris on the surface of glaciers prolongs their response to climate change. The debris cover, which is generally thickest at the terminus of a glacier and becoming thinner at higher elevations, changes the spatial distribution of maximum surface lowering, which occurs where debris is thinner owing to the insulating effect of a thick rock cover. The ablative role of supraglacial ponds and ice cliffs, which are widespread on such glaciers, is little quantified. This is predominantly owing to difficult and hazardous access for collecting field data. Ponds and ice cliffs therefore form the basis of my research on Khumbu Glacier.
Ongoing remote sensing analysis from fine-resolution satellite imagery is been used to reveal multi-temporal supraglacial pond dynamics by semi-automatically classifying water bodies. An increasing trend observed on other glaciers in the region is of interest and concern for several reasons. Large glacial lakes forming at the terminus of debris-covered glaciers can pose a potential outburst flood risk in some circumstances, requiring monitoring and remediation efforts to avoid a high-magnitude flood which can travel long distances downstream. Supraglacial water storage also has the potential to mitigate increases in meltwater generated under a warming climate. Ponded water also absorbs incoming solar radiation and this thermal energy is transmitted to the ice below, although this may be through a saturated sediment and debris layer. Exposed ice cliffs often exist adjacent to dynamic ponds and may feature a thin debris layer, reducing their albedo and hence increasing their capacity to melt. Capturing pond and ice cliff dynamics using satellite imagery alone is not possible, owing to revisit times, potential cloud cover and illumination issues, and cost of acquisition. Field access to the features permits surveys and instrumentation to be left in situ to allow continuous monitoring. This is particularly important in supraglacial ponds which exhibit a diurnal thermal regime and can drain englacially, transmitting the stored thermal energy into the glacial interior.
My field strategy involved repeat Structure-from-Motion (SfM) surveys of ice cliffs, dGPS ground control point identification, and the deployment and retrieval of thermistor strings and pressure transducers in several supraglacial ponds.
SfM is a way of generating fine-resolution 3d models of a surface using photographs from a standard camera which are taken at different positions. The technique was implemented using ground surveys around the ice cliff, although airborne surveys are equally possible and are more time efficient. In this case we did not have access to an aerial platform and helicopter traffic to Everest Basecamp would likely restrict permissions for deployment. A range of cliff sizes, aspects, and locations was captured to allow comparisons of melt rate and morphological evolution. Each survey required a distribution of GCPs around the ice cliff before the photographic survey could be undertaken. GCP markers were distributed and georeferenced with a dGPS on the first ‘lap’ of the ice cliff. Photographs would then be taken during one or two more circuits of the cliff to allow a range of vantage points including high and low viewpoints. GCPs would then be collected on a final circuit. The surface of the dynamic areas of the glacier studied were generally rugged and unstable which limited surveys to two cliffs on a given day.
Velocity measurements of glaciers are generally conducted using remotely sensed imagery. On debris-covered glaciers this can be with optical or radar imagery. Typically the availability of appropriate imagery means velocities below 10 m per year cannot be resolved and these regions are defined as ‘stagnant’. Recently it was shown using fine-resolution imagery from an unmanned aerial vehicle that this categorisation may only loosely be applied, since notable surface motion may still occur. During the Khumbu field campaign I identified a number of boulders distributed in the lower ablation area of the glacier which were georeferenced with a dGPS. A repeat survey in May and October 2016 will reveal both horizontal and vertical displacement, which can be used to validate remotely sensed observations since the precision is far greater (on the order of mm - cm).
Pond surveys were tailored to assessing water storage dynamics and thermal characteristics. Thermistor strings with temperature loggers at 1 m intervals were used to monitor temperature changes, in addition to a pressure transducer to capture water level change. Most ponds encountered were partially frozen at the start of the field campaign, limiting measurements of depth, which were taken with a plumb line. In May 2016 a robotic surface water vehicle will be deployed with the aim of obtaining fully distributed depth and temperature measurements.
Most ponds were frozen on the surface by the end of the campaign, requiring access though up to 10 cm of ice for instrument retrieval.
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!
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.
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’
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.