Six Decades of Glacier Mass Changes around Mt. Everest Are Revealed by Historical and Contemporary Images

The accurate quantification of current and past Himalayan glacier mass budgets is vital if we are to understand the evolution of the Asian water tower, which provides water to the planet's most populous region. In this work, we generated a geodetic time series spanning six decades over 79 glaciers surrounding Mt. Everest and found consistent acceleration of glacier mass loss between the 1960s (−0.23 ± 0.12 mwe a⁻¹) and the modern era (−0.38 ± 0.11 mwe a⁻¹ from 2009 to 2018). Glacier mass loss has varied depending on glacier terminus type and surface characteristics, and glacier thinning is now occurring at extreme altitudes (>6,000 masl). Our time series also captures the first documented surge of a glacier in the Mt. Everest region. These multi-decadal observations of glacier mass loss form a baseline dataset against which physically based glacier evolution models could be calibrated before they are used for predicting future meltwater yield. Meltwater from Himalayan glaciers sustains the flow of rivers that are heavily depended on by downstream communities across the densely populated region of Southeast Asia. Himalayan glaciers are shrinking in response to a changing climate, and measurements of glacier mass loss are vital for the calibration of models used for predicting the future variability of meltwater runoff. Here, we produced the longest possible time series of glacier mass-change measurements from satellite archives and found that the rate of ice loss from glaciers close to Mt. Everest has consistently increased since the early 1960s. We show how glacial lakes in the region have amplified ice loss and illustrate how ice loss has begun to occur at extreme altitudes, where large volumes of ice that were formerly less susceptible to melt are stored. The rate of ice loss across the Himalaya is likely to increase in the coming decades in response to further warming, which could be amplified at high altitude. We generated the longest possible time series of glacier elevation-change measurements from satellite image archives to show how glaciers around Mt. Everest have reacted to climatic change since the 1960s. The rate of ice loss in the region has consistently increased over the last six decades, and ice loss is now occurring at extreme altitudes. Accurate, long-term measurements of ice-loss rates are vital if we are to understand the impact of glacier recession on local and regional hydrology.