Glaciers in equilibrium, McMurdo Dry Valleys, Antarctica

Fountain, Andrew G.; Basagic, Hassan J.; Niebuhr, S.

doi:10.1017/jog.2016.86

Cited by 13 publications

(16 citation statements)

References 64 publications

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“…The latter come as a list of elevation-band areas (at a resolution of 50 m in height) in the form of integer thousands of the glacier's total area 1 . Note that at present the RGI includes peripheral glaciers surrounding the Greenland Ice Sheet 50 but not the peripheral glaciers on the Antarctic Peninsula 51 and in the McMurdo Dry Valleys 52 . For future versions of the RGI, the inclusion of these peripheral glaciers in Antarctica should be considered in order to reach global completeness and consistency with the classification of peripheral glaciers in Greenland 50 .…”

Section: Methodsmentioning

confidence: 91%

Global glacier mass changes and their contributions to sea-level rise from 1961 to 2016

Zemp

Huss

Thibert

et al. 2019

Nature

804

585

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Glaciers distinct from the Greenland and Antarctic ice sheets cover an area of approximately 706,000 square kilometres globally 1 , with an estimated total volume of 170,000 cubic kilometres, or 0.4 metres of potential sea-level-rise equivalent 2. Retreating and thinning glaciers are icons of climate change 3 and affect regional runoff 4 as well as global sea level 5,6. In past reports from the Intergovernmental Panel on Climate Change, estimates of changes in glacier mass were based on the multiplication of averaged or interpolated results from available observations of a few hundred glaciers by defined regional glacier areas 7-10. For data-scarce regions, these results had to be complemented with estimates based on satellite altimetry and gravimetry 11. These past approaches were challenged by the small number and heterogeneous spatiotemporal distribution of in situ measurement series and their often unknown ability to represent their respective mountain ranges, as well as by the spatial limitations of satellite altimetry (for which only point data are available) and gravimetry (with its coarse resolution). Here we use an extrapolation of glaciological and geodetic observations to show that glaciers contributed 27 ± 22 millimetres to global mean sea-level rise from 1961 to 2016. Regional specific-mass-change rates for 2006-2016 range from −0.1 metres to −1.2 metres of water equivalent per year, resulting in a global sea-level contribution of 335 ± 144 gigatonnes, or 0.92 ± 0.39 millimetres, per year. Although statistical uncertainty ranges overlap, our conclusions suggest that glacier mass loss may be larger than previously reported 11. The present glacier mass loss is equivalent to the sea-level contribution of the Greenland Ice Sheet 12 , clearly exceeds the loss from the Antarctic Ice Sheet 13 , and accounts for 25 to 30 per cent of the total observed sea-level rise 14. Present mass-loss rates indicate that glaciers could almost disappear in some mountain ranges in this century, while heavily glacierized regions will continue to contribute to sea-level rise beyond 2100. Changes in glacier volume and mass are observed by geodetic and glaciological methods 15. The glaciological method provides glacier-wide mass changes by using point measurements from seasonal or annual in situ campaigns, extrapolated to unmeasured regions of the glacier. The geodetic method determines glacier-wide volume changes by repeated mapping and differencing of glacier surface elevations from in situ, airborne and spaceborne surveys, usually over multiyear to decadal periods. In this study, we used glaciological and geodetic data from the World Glacier Monitoring Service (WGMS) 16 , complemented by new and as-yet-unpublished geodetic assessments for glaciers in Africa,

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Section: Methodsmentioning

confidence: 91%

Global glacier mass changes and their contributions to sea-level rise from 1961 to 2016

Zemp

Huss

Thibert

et al. 2019

Nature

804

585

View full text Add to dashboard Cite

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“…Unfortunately, the lidar surveys were restricted to glacier ablation zones and did not cover any glacier entirely. Therefore, these changes cannot be considered glacier volume changes and cannot be compared directly to mass balance observations in the MDV (Fountain et al, 2016a). Commonwealth Glacier is the only glacier surveyed that also has a mass balance record.…”

Section: Discussionmentioning

confidence: 99%

“…2) have remained largely constant, leading to lake ice thinning (Obryk et al, 2016a), lake level rise, and enhanced glacier runoff (Gooseff et al, 2017). These physical changes have precipitated biotic and hydrological ecosystem responses to regional warming and thawing (Fountain et al, 2016a(Fountain et al, , 2016bObryk et al, 2016b;Gooseff et al, 2017). Fountain et al (2014) identified three major classes of landscape change in the MDV that are inferred to result from this recent pulse of warming: i) disintegration and thinning of glacier surfaces, ii) formation and expansion of thermokarst slumps and ponds, and iii) the generation of stream-channel thermokarst through bank undercutting.…”

Section: Introductionmentioning

confidence: 99%

Decadal topographic change in the McMurdo Dry Valleys of Antarctica: Thermokarst subsidence, glacier thinning, and transfer of water storage from the cryosphere to the hydrosphere

et al. 2018

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Recent local-scale observations of glaciers, streams, and soil surfaces in the McMurdo Dry Valleys of Antarctica (MDV) have documented evidence for rapid ice loss, glacial thinning, and ground surface subsidence associated with melting of ground ice. To evaluate the extent, magnitude, and location of decadal-scale landscape change in the MDV, we collected airborne lidar elevation data in 2014-2015 and compared these data to a 2001-2002 airborne lidar campaign. This regional assessment of elevation change spans the recent acceleration of warming and melting observed by long-term meteorological and ecosystem response experiments, allowing us to assess the response of MDV surfaces to warming and potential thawing feedbacks. We find that locations of thermokarst subsidence are strongly associated with the presence of excess ground ice and with proximity to surface or shallow subsurface (active layer) water. Subsidence occurs across soil types and landforms, in low-lying, low-slope areas with impeded drainage and also high on steep valley walls. Glacier thinning is widespread and is associated with the growth of fine-scale roughness. Pond levels are rising in most closed-basin lakes in the MDV, across all microclimate zones. These observations highlight the continued importance of insolation-driven melting in the MDV. The regional melt pattern is consistent with an overall transition of water storage from the local cryosphere (glaciers, permafrost) to the hydrosphere (closed basin lakes and ponds as well as the Ross Sea). We interpret this regional melting pattern to reflect a transition to Arctic and alpine-style, hydrologically mediated permafrost and glacial melt.

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“…The focus of our study is Taylor Valley because it has a wealth of hydro‐meteorological measurements collected by the McMurdo Dry Valley Long Term Ecological Research project since the early 1990s (https://mcm.lternet.edu/; e.g., Doran & Fountain, 2019; Doran & Gooseff, 2018; Dugan et al., 2013; Fountain et al., 2016; Gooseff & Fountain, 2022; Gooseff & McKnight, 2016; Obryk et al., 2020). The valley is 24‐km long and is open to the Ross Sea at its eastern end, although a ∼90 m tall glacial moraine blocks stream drainage to the ocean.…”

Section: Site Descriptionmentioning

confidence: 99%

“…The MDV Long Term Ecological Research project has collected hydro‐meteorological data in Taylor Valley since the early 1990s. In addition to the meteorological stations, glacier mass balance is measured on four glaciers, stream discharge measured at 15 streams, and lake level and lake ice ablation on the three major lakes in the valley (Doran & Gooseff, 2018; Dugan et al., 2013; Fountain et al., 2016; Obryk et al., 2020). Glacier mass balance is measured twice a year, in late spring (November) and late summer (late January; Fountain et al., 2016).…”

Section: Modelmentioning

confidence: 99%

Physical Controls on the Hydrology of Perennially Ice‐Covered Lakes, Taylor Valley, Antarctica (1996–2013)

et al. 2022

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The McMurdo Dry Valleys, Antarctica, are a polar desert populated with numerous closed‐watershed, perennially ice‐covered lakes primarily fed by glacial melt. Lake levels have varied by as much as 8 m since 1972 and are currently rising after a decade of decreasing. Precipitation falls as snow, so lake hydrology is dominated by energy available to melt glacier ice and to sublimate lake ice. To understand the energy and hydrologic controls on lake level changes and to explain the variability between neighboring lakes, only a few kilometers apart, we model the hydrology for the three largest lakes in Taylor Valley. We apply a physically based hydrological model that includes a surface energy balance model to estimate glacial melt and lake sublimation to constrain mass fluxes to and from the lakes. Results show that lake levels are very sensitive to small changes in glacier albedo, air temperature, and wind speed. We were able to balance the hydrologic budget in two watersheds using meltwater inflow and sublimation loss from the ice‐covered lake alone. A third watershed, closest to the coast, required additional inflow beyond model uncertainties. We hypothesize a shallow groundwater system within the active layer, fed by dispersed snow patches, contributes 23% of the inflow to this watershed. The lakes are out of equilibrium with the current climate. If the climate of our study period (1996–2013) persists into the future, the lakes will reach equilibrium starting in 2300, with levels 2–17 m higher, depending on the lake, relative to the 2020 level.

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Glaciers in equilibrium, McMurdo Dry Valleys, Antarctica

Cited by 13 publications

References 64 publications

Global glacier mass changes and their contributions to sea-level rise from 1961 to 2016

Global glacier mass changes and their contributions to sea-level rise from 1961 to 2016

Decadal topographic change in the McMurdo Dry Valleys of Antarctica: Thermokarst subsidence, glacier thinning, and transfer of water storage from the cryosphere to the hydrosphere

Physical Controls on the Hydrology of Perennially Ice‐Covered Lakes, Taylor Valley, Antarctica (1996–2013)

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