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

King, Owen; Bhattacharya, Atanu; Ghuffar, Sajid; Tait, Alex; Guilford, Sam; Elmore, Aurora C.; Bolch, Tobias

doi:10.1016/j.oneear.2020.10.019

Cited by 40 publications

(54 citation statements)

References 64 publications

(102 reference statements)

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“…a −1 between 1984 and 2001, and -0.44 ± 0.12 m w.e. a −1 between 2001 and 2018 (King, Bhattacharya, et al, 2020) in agreement with geodetic values from other studies of −0.27 ± 0.08 m w.e. a −1 between 1970 and 2007 (Bolch et al, 2011) and −0.45 ± 0.52 m w.e.…”

Section: Glacier Morphometrysupporting

confidence: 91%

“…a −1 during 2000–2016 compared to 1975–2000 in response to climate change (Maurer et al., 2019). The acceleration in mass loss is expressed by the rate of surface elevation change, which has increased dramatically at Khumbu Glacier since 1969 (King, Bhattacharya, et al., 2020). Glacier mass loss is occurring due to atmospheric warming and is regionally variable, due to topographic feedbacks between climate systems and ice flow (Dehecq et al., 2018).…”

Section: Introductionmentioning

confidence: 99%

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

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Supraglacial rock debris is present on 7% of the global mountain glacier area, dramatically affecting the sensitivity of these glaciers to climate change (Herreid & Pellicciotti, 2020). Debris-covered ice represents 30% of the glacier mass in ablation areas in High Mountain Asia (Kraaijenbrink et al., 2017). Supraglacial debris in the Everest region is typically sufficiently thick to reduce ablation by insulating the underlying ice surface (Nicholson & Benn, 2013). As a result, these debris-covered glaciers have experienced lower sensitivity to atmospheric warming than would be expected for climatically equivalent clean-ice surfaces (Benn 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 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.Plain Language Summary Glaciers in the Himalaya are shrinking rapidly in response to ongoing climate change. Many of these glaciers are covered with thick layers of rock debris that insulate the ice surface from atmospheric warming. Recent observations suggest that, contrary to expectations, debris-covered glaciers are losing mass at similar rates to clean-ice glaciers. We explore the processes driving the rapid loss of ice from a debris-covered glacier using a glacier model with a novel representation of sub-debris melt. Our model shows that the rapid ice loss from Khumbu Glacier, Nepal, since 1984 cannot be explained solely by accounting for variations in debris thickness and the presence of ice cliffs and ponds across the glacier surface. Instead, the glacier has passed a dynamic tipping point i...

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Section: Glacier Morphometrysupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

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

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“…Another study also found consistent acceleration of glacier mass loss around Mt. Everest region between the 1960s (−0.23 ± 0.12 m w.e.a −1 ) and the modern era (−0.38 ± 0.11 m w.e.a −1 from 2009 to 2018) 58 .…”

Section: Resultsmentioning

confidence: 64%

High Mountain Asian glacier response to climate revealed by multi-temporal satellite observations since the 1960s

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Knowledge about the long-term response of High Mountain Asian glaciers to climatic variations is paramount because of their important role in sustaining Asian river flow. Here, a satellite-based time series of glacier mass balance for seven climatically different regions across High Mountain Asia since the 1960s shows that glacier mass loss rates have persistently increased at most sites. Regional glacier mass budgets ranged from −0.40 ± 0.07 m w.e.a−1 in Central and Northern Tien Shan to −0.06 ± 0.07 m w.e.a−1 in Eastern Pamir, with considerable temporal and spatial variability. Highest rates of mass loss occurred in Central Himalaya and Northern Tien Shan after 2015 and even in regions where glaciers were previously in balance with climate, such as Eastern Pamir, mass losses prevailed in recent years. An increase in summer temperature explains the long-term trend in mass loss and now appears to drive mass loss even in regions formerly sensitive to both temperature and precipitation.

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“…In the Himalayas, the two reporting reference glaciers had negative balances averaging −487 mm. King et al (2019) identified that in the Mount Everest region mass loss has increased each of the last 6 decades. In 2020, the post-monsoon season and early winter were warm and dry in the Himalayas, leading to the ablation season extending into January with the snow line retreating over 100 m from October into January (Fig.…”

Section: ) Alpine Glaciers-m Peltomentioning

confidence: 99%

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et al. 2021

Bulletin of the American Meteorological Society

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For reasons other than the climate, 2020 was an extraordinary year. The COVID-19 pandemic has affected almost all of us, changing the lives of many people around the globe. While the economic disruption associated with COVID-19 led to modest estimated reductions of 6-7% (e.g., le Quere et al. 2020;Friedlingstein et al. 2020; BP Statistical Review of the World Energy 2021) in global anthropogenic carbon dioxide (CO 2 ) emissions, atmospheric CO 2 levels continued to grow rapidly-a reminder of its very long residence time in the atmosphere and the challenge of reducing atmospheric CO 2 . As we show in this chapter, the climate has continued to respond to the resulting warming from these increases in CO 2 and other greenhouse gases such as methane and nitrous oxide, which also experienced record increases in 2020.The year 2020 was one of the three warmest since records began in the mid-to-late 1800s, with global surface temperatures around 0.6°C above the 1981-2010 average, despite the El Niño-Southern Oscillation progressing from neutral to La Niña conditions by August (see section 4b). Lower tropospheric temperatures matched those from 2016, the previous warmest year. Meanwhile, stratospheric temperatures continued to cool as a result of anthropogenic CO 2 increases. Along with the above-average surface temperatures, an unprecedented (since instrumental records began) geographic spread of heat waves and warm spells occurred. Antarctica observed its highest temperature on record (18.3°C) at Esperanza in February. In August, Death Valley, California, reported the highest temperature observed anywhere on Earth since 1931 (preliminary value of 54.4°C).Consequently, many permafrost measurement sites experienced their highest temperatures on record; Northern Hemisphere (NH) snow cover was below the 51-year average and the fourthleast extensive on record. Glaciers in alpine regions experienced their 33rd consecutive year of negative mass balance and 12th year of average losses of more than 500 mm depth. On average, NH lakes froze over 3 days later and thawed 5.5 days earlier than the 1981-2010 average during the 2019/20 winter, which was the third-shortest ice cover season since 1979/80.The atmosphere responded to higher temperatures accordingly by holding more water. Total column water vapor was high relative to the 1981-2010 average, ranging from 0.75 to 1.06 mm over ocean and 0.58 to 0.94 mm over land, but did not reach the record values of 2016. At the surface, specific humidity over oceans was at record high levels (0.23 to 0.41 g kg −1 ) and was well above average over land (0.14 to 0.36 g kg −1 ). Conversely, relative humidity was well below average over land (-1.28 to -0.68 %rh), continuing the long-term declining trend. Precipitation increased compared to 2019, driven largely by land values, but there were few exceptional extreme precipitation events, coupled with below-average cloudiness over most of the land. More lakes showed positive water level anomalies than 2019, and in East Africa, Lake Victoria's level ...

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

Cited by 40 publications

References 64 publications

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

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

High Mountain Asian glacier response to climate revealed by multi-temporal satellite observations since the 1960s

Global Climate

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