Harrison et al. (2025) Will landscape responses reduce glacier sensitivity to climate change in High Mountain Asia?

Identification

• Journal: ˜The œcryosphere
• Year: 2025
• Date: 2025-09-30
• Authors: Stephan Harrison, Adina Racoviteanu, Sarah E. Shannon, Darren Jones, Karen Anderson, Neil F. Glasser, Jasper Knight, Anna Ranger, Arindan Mandal, Bramha Dutt Vishwakarma, Jeffrey S. Kargel, Dan H. Shugar, Umesh K. Haritashya, Dongfeng Li, Aristeidis Koutroulis, Klaus Wyser, Sam Inglis
• DOI: 10.5194/tc-19-4113-2025

Research Groups

• College of Environment, Science and Economy, Exeter University, Exeter, UK
• Université Grenoble Alpes, CNRS, IRD, IGE, Saint Martin d’Hères, France
• Bristol Glaciology Centre, Department of Geographical Science, University of Bristol, Bristol, UK
• Environment and Sustainability Institute, University of Exeter, Penryn Campus, Penryn, Cornwall, UK
• Centre for Glaciology, Department of Geography and Earth Sciences, Aberystwyth University, Aberystwyth, Wales, UK
• School of Geography, Archaeology & Environmental Studies, University of the Witwatersrand, Johannesburg, South Africa
• Interdisciplinary Centre for Water Research, Indian Institute of Science, Bengaluru, India
• Planetary Science Institute, Tucson, AZ, USA
• Department of Earth, Energy, and Environment, University of Calgary, Calgary, AB, Canada
• Department of Geology and Environmental Geosciences, University of Dayton, Dayton, OH, USA
• Sustainability Program, University of Dayton, Dayton, OH, USA
• Key Laboratory for Water and Sediment Sciences, Ministry of Education, College of Environmental Sciences and Engineering, Peking University, Beijing, China
• School of Chemical and Environmental Engineering, Technical University of Crete, Chania, Greece
• Rossby Centre, Swedish Meteorological and Hydrological Institute, Norrköping, Sweden
• ADM Capital Foundation, Queen’s Road Central, Hong Kong SAR, China

Short Summary

This paper proposes an alternative "Paraglacial Transition Model" for glacier evolution in High Mountain Asia (HMA), where increasing rock debris cover transforms glaciers into rock glaciers and other ice debris landforms, potentially prolonging ice persistence and reducing their sensitivity to climate warming, in contrast to conventional models predicting significant ice loss.

Objective

• To discuss whether landscape responses, specifically the development of extensive rock debris cover and the transition to rock glaciers, can reduce glacier sensitivity to climate change in High Mountain Asia (HMA).

Study Configuration

• Spatial Scale: High Mountain Asia (HMA), including the Himalayas (western, central, eastern), Karakoram, Pamir, and Qilian Shan.
• Temporal Scale: Projections to 2100 and beyond; historical analysis covering the Last Glacial Maximum (18 to 24 thousand years ago), Younger Dryas (12 880 to 11 640 years ago), and Little Ice Age (1300–1600 CE).

Methodology and Data

• Models used:
  • Climate model projections (general)
  • Coupled Model Intercomparison Project Phase 5 (CMIP5) and Phase 6 (CMIP6)
  • Glacier Model Intercomparison Project (GlacierMIP1, GlacierMIP2, GlacierMIP3)
  • Temperature index schemes and full energy balance models (types of glacier models)
  • Numerical models for individual glacier evolution (e.g., Khumbu Glacier)
• Data sources:
  • Randolph Glacier Inventory (RGI) v6 (global glacier outlines)
  • Ice thickness data (from Huss and Farinotti, 2012)
  • Compiled inventory of dated moraine sequences in the Himalayas
  • Rock glacier inventory (Jones et al., 2021; Racoviteanu et al., 2024)
  • Debris-covered glacier outlines (Herreid and Pellicciotti, 2020)

Main Results

• Conventional climate models project significant glacier mass loss in HMA, with reductions ranging from 60%–98% under RCP8.5 by 2100, or 49%–64% even with debris cover under various RCP scenarios.
• The "Paraglacial Transition (PT) view" suggests that increased valley-side instability leads to substantial rock debris cover on glacier surfaces, which, if thick enough, insulates the ice and inhibits melting.
• This process can lead to the formation of glacier-derived rock glaciers and other ice debris landforms, potentially extending the longevity of glacial ice in the landscape.
• Analysis of dated moraine sequences indicates that glaciers in the western and central Himalayas exhibited lower sensitivity to past climate changes (e.g., less than 2 kilometers retreat since the Neoglacial maximum) compared to eastern HMA, supporting the PT scenario for these regions.
• The PT scenario implies a decreased risk of Glacial Lake Outburst Floods (GLOFs) over time but a potential increase in rock slope failure hazards.
• The transition from Major Ice Loss (MIL) to PT pathways is most effective in areas with high debris fluxes from mountain slopes and where lateral moraines are absent or poorly developed, allowing sediment access to glacier surfaces.

Contributions

• Introduces and scientifically discusses the "Paraglacial Transition Model" as a plausible alternative to the dominant "Major Ice Loss" paradigm for glacier evolution in High Mountain Asia.
• Highlights the critical role of geomorphic landscape responses, particularly supraglacial debris cover and rock glacier formation, in buffering glacier melt and enhancing ice longevity under climate change.
• Synthesizes historical glacier behavior from dated moraine records to provide empirical support for regional variations in glacier sensitivity, favoring the PT scenario in certain HMA regions.
• Explores the differential implications of the MIL and PT pathways for regional water resources, cryospheric hazards, and the achievement of Sustainable Development Goals.
• Outlines key future research imperatives, including detailed debris flux determination, long-term mass balance monitoring, high-resolution climate modeling, and projections for various climate scenarios.

Funding

Not specified in the provided text.

Citation

@article{Harrison2025Will,
  author = {Harrison, Stephan and Racoviteanu, Adina and Shannon, Sarah E. and Jones, Darren and Anderson, Karen and Glasser, Neil F. and Knight, Jasper and Ranger, Anna and Mandal, Arindan and Vishwakarma, Bramha Dutt and Kargel, Jeffrey S. and Shugar, Dan H. and Haritashya, Umesh K. and Li, Dongfeng and Koutroulis, Aristeidis and Wyser, Klaus and Inglis, Sam},
  title = {Will landscape responses reduce glacier sensitivity to climate change in High Mountain Asia?},
  journal = {˜The œcryosphere},
  year = {2025},
  doi = {10.5194/tc-19-4113-2025},
  url = {https://doi.org/10.5194/tc-19-4113-2025}
}