The role of supraglacial debris cover in affecting Himalayan glacier stability

Supervisors: Prof. Peter Nienow1, Dr. Noel Gourmelen1, Prof. Doug Benn2, Prof. Jemma Wadham3

1 - School of GeoSciences, Univ. of Edinburgh ([Email Address Removed]); 2 - School of Geography & Sustainable Development, Univ. of St Andrews; 3 - School of Geographical Sciences, Univ. of Bristol

Summary
This project aims to determine the extent to which recent glacier mass change in the Himalayan region has been modulated by the presence or otherwise of surface debris

Project background
The ice stored in Himalayan glaciers has been termed the ‘third pole’ or the ‘Asian water tower’1; these definitions reflect both the substantial quantity of ice currently present in the wider Himalayan mountain range and the importance of runoff from these glaciers as a critical resource to the more than one billion people living in downstream catchments. A number of recent studies have monitored, over a range of temporal and spatial scales, the ongoing mass balance or health of the Himalayan glaciers. These studies all indicate a declining ice volume2,3, though at different rates, with implications for the future longevity of the Himalayan ice fields. Projections of the likely trajectory of Himalayan glacier mass balance, and associated runoff, are unclear and this reflects, in addition to errors associated with climate predictions, a lack of understanding of several processes which affect glacier melt. In the Himalayas, arguably the biggest uncertainty in future projections of melt is associated with the role that supraglacial debris cover plays in perturbing melt rates.

Himalayan glaciers are characterised by surface debris layers of varying thickness which often blanket considerable proportions of the glacier. The thickness and extent of this debris cover has significant implications for each glaciers’ mass balance4 as debris can either insulate or promote surface melt (ablation) depending primarily on its thickness; and given the considerable thicknesses of Himalayan glacier debris cover, it has been argued that this debris may be crucial in extending the longevity of Himalayan glaciers by reducing ablation.

Aims and methodology
This project aims to determine the extent to which recent glacier mass change in the Himalayan region has been modulated by the presence or otherwise of surface debris. More specifically, it will use a range of remotely sensed data, weather station data and modelling in order to determine:

1) Temporal and spatial variations in glacier extent (area) and thickness (volume).
2) Time series of the evolving distribution of supraglacial debris cover.
3) Estimates of modelled glacier melt rates from local weather station data and wider downscaled regional climate data.

These data will be gathered across a large population of glaciers spanning the wider Himalayan range and over a four decade observational time-scale supported by a range of satellite missions including LandSat. The study will determine the extent to which local and regional variations in debris cover, in conjunction with climate forcing, have impacted glacier retreat rates. These findings will then be used with different climate projections to predict the future mass balance and runoff of glaciers across the wider Himalayan. The project aims ultimately to reduce the error bars on future projections of Himalayan glacier mass balance to 2100.

Research training
A comprehensive training programme will be provided comprising both specialist scientific training, for example in the analysis of remotely sensed imagery, and generic transferable and professional skills, in part linked to Edinburgh’s E3 NERC funded DTP. You will embedded within Edinburgh’s world class Glaciology research group. You will receive support to attend national and international conferences to present your results, will be expected to publish your findings in high impact scientific journals and will be encouraged to participate in international summer schools in glaciology. In addition, there is the opportunity to partake in field research to a debris covered glacier in the Himachal Pradesh Himalaya working with collaborators at Jawaharlal Nehru University, Delhi, India.