The Role of Differential Ablation and Dynamic Detachment in Driving Accelerating Mass Loss From a Debris-Covered Himalayan Glacier

Ann V. Rowan*, David L. Egholm, Duncan J. Quincey, Bryn Hubbard, Owen King, Evan S. Miles, Katie E. Miles, Josephine Hornsey

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

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Abstract

Sustained mass loss from Himalayan glaciers is causing supraglacial debris to expand and thicken, with the expectation that thicker debris will suppress ablation and extend glacier longevity. However, debris-covered glaciers are losing mass at similar rates to clean-ice glaciers in High Mountain Asia. This rapid mass loss is attributed to the combined effects of; (a) low or reversed mass balance gradients across debris-covered glacier tongues, (b) differential ablation processes that locally enhance ablation within the debris-covered section of the glacier, for example, at ice cliffs and supraglacial ponds, and (c) a decrease in ice flux from the accumulation area in response to climatic warming. Adding meter-scale spatial variations in supraglacial debris thickness to an ice-flow model of Khumbu Glacier, Nepal, increased mass loss by 47% relative to simulations assuming a continuous debris layer over a 31-year period (1984–2015 CE) but overestimated the reduction in ice flux. Therefore, we investigated if simulating the effects of dynamic detachment of the upper active glacier from the debris-covered tongue would give a better representation of glacier behavior, as suggested by observations of change in glacier dynamics and structure indicating that this process occurred during the last 100 years. Observed glacier change was reproduced more reliably in simulations of the active, rather than entire, glacier extent, indicating that Khumbu Glacier has passed a dynamic tipping point by dynamically detaching from the heavily debris-covered tongue that contains 20% of the former ice volume.

Original languageEnglish
Article numbere2020JF005761
Number of pages20
JournalJournal of Geophysical Research: Earth Surface
Volume126
Issue number9
DOIs
Publication statusPublished - 29 Aug 2021

Keywords

  • Everest region
  • glacier dynamics
  • glacier model
  • Himalaya
  • mass balance
  • mountain glacier
  • Climatology
  • Snow
  • Regional climate change
  • Air/sea constituent fluxes
  • Air/sea interactions
  • Volcano/climate interactions
  • Mass balance
  • Glaciology
  • Explosive volcanism
  • Volcanic effects
  • Theoretical modeling
  • Volcanic hazards and risks
  • Surface waves and tides
  • HYDROLOGY
  • Numerical modeling
  • BIOGEOSCIENCES
  • Atmospheric effects
  • Oceans
  • Mud volcanism
  • Gravity and isostasy
  • Climate impact
  • Avalanches
  • GEODESY AND GRAVITY
  • NATURAL HAZARDS
  • General circulation
  • SEISMOLOGY
  • Climate dynamics
  • Volcano monitoring
  • Land/atmosphere interactions
  • Water cycles
  • Global change from geodesy
  • Benefit‐cost analysis
  • INFORMATICS
  • PALEOCEANOGRAPHY
  • Cryospheric change
  • OCEANOGRAPHY: PHYSICAL
  • Oceanic
  • Impacts of global change
  • Radio oceanography
  • Physical modeling
  • Risk
  • GLOBAL CHANGE
  • Disaster risk analysis and assessment
  • Modeling
  • VOLCANOLOGY
  • Atmospheric
  • Geological
  • Ocean/atmosphere interactions
  • Climate change and variability
  • Dynamics
  • Climate variability
  • Numerical solutions
  • Hydrological cycles and budgets
  • Earth system modeling
  • RADIO SCIENCE
  • Modeling in glaciology
  • Decadal ocean variability
  • Tsunamis and storm surges
  • Research Article
  • MARINE GEOLOGY AND GEOPHYSICS
  • ATMOSPHERIC PROCESSES
  • Effusive volcanism
  • Ocean monitoring with geodetic techniques
  • Ocean/Earth/atmosphere/hydrosphere/cryosphere interactions
  • Snow and ice
  • Solid Earth
  • ATMOSPHERIC COMPOSITION AND STRUCTURE
  • Ice
  • Climate impacts
  • Abrupt/rapid climate change
  • COMPUTATIONAL GEOPHYSICS
  • Sea level: variations and mean
  • Sea level change
  • Volcano seismology
  • CRYOSPHERE
  • OCEANOGRAPHY: GENERAL
  • Ocean influence of Earth rotation
  • Glaciers
  • POLICY SCIENCES
  • Earthquake ground motions and engineering seismology
  • Climate and interannual variability
  • Regional modeling

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