Acceleration of snow melt in an Antarctic Peninsula ice core during the twentieth century

Abram, Nerilie J.; Mulvaney, Robert; Wolff, Eric W.; Triest, Jack; Kipfstuhl, Sepp; Trusel, Luke D.; Vimeux, Françoise; Fleet, Louise G.; Arrowsmith, Carol

doi:10.1038/ngeo1787

Cited by 178 publications

(211 citation statements)

References 46 publications

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“…The collapse of the Antarctic Peninsula ice shelves follows a multi-decade period of strong atmospheric warming in that area (Vaughan and others, 2003;Zazulie and others, 2010) unseen in the past millennium (Abram and others, 2013). As heuristic relations between ice-shelf collapse and atmospheric warming, both the À9 C annual isotherm (Morris and Vaughan, 2003) and the limit of 200 positive degree-days per year (Fyke and others, 2010) have been suggested to coincide with the limit of present-day ice-shelf viability.…”

Section: The Role Of Firn In Ice-shelf Collapsementioning

confidence: 99%

Firn air depletion as a precursor of Antarctic ice-shelf collapse

et al. 2014

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ABSTRACT. Since the 1970s, the sudden, rapid collapse of $20% of ice shelves on the Antarctic Peninsula has led to large-scale thinning and acceleration of its tributary glaciers. The leading hypothesis for the collapse of most of these ice shelves is the process of hydrofracturing, whereby a water-filled crevasse is opened by the hydrostatic pressure acting at the crevasse tip. This process has been linked to observed atmospheric warming through the increased supply of meltwater. Importantly, the low-density firn layer near the ice-shelf surface, providing a porous medium in which meltwater can percolate and refreeze, has to be filled in with refrozen meltwater first, before hydrofracturing can occur at all. Here we build upon this notion of firn air depletion as a precursor of ice-shelf collapse, by using a firn model to show that pore space was depleted in the firn layer on former ice shelves, which enabled their collapse due to hydrofracturing. Two climate scenario runs with the same model indicate that during the 21st century most Antarctic Peninsula ice shelves, and some minor ice shelves elsewhere, are more likely to become susceptible to collapse following firn air depletion. If warming continues into the 22nd century, similar depletion will become widespread on ice shelves around East Antarctica. Our model further suggests that a projected increase in snowfall will protect the Ross and Filchner-Ronne Ice Shelves from hydrofracturing in the coming two centuries.

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Section: The Role Of Firn In Ice-shelf Collapsementioning

confidence: 99%

Firn air depletion as a precursor of Antarctic ice-shelf collapse

et al. 2014

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“…As reported by Oliva and others (2017), the mean summer temperatures decreased by 0.3-0.6°C between 1996-2005 and 2006-2015 around the mentioned glaciers. The previous studies also show that the SSI glaciers are very sensitive to air temperatures (Braun and Hock, 2004;Jonsell and others, 2012;Abram and others, 2013;Sobota and others, 2015;Petlicki and others, 2017) and the associated changes in large-scale circulation pattern (Braun and others, 2001). The reported stronger sensitivity is also related to the fact that average summer temperatures on these glaciers often fluctuate around zero, and therefore even a small temperature change may cause a rapid shift from melting to freezing conditions or vice versa.…”

mentioning

confidence: 99%

Surface mass balance of small glaciers on James Ross Island, north-eastern Antarctic Peninsula, during 2009–2015

et al. 2018

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ABSTRACT. Two small glaciers on James Ross Island, the north-eastern Antarctic Peninsula, experienced surface mass gain between 2009 and 2015 as revealed by field measurements. A positive cumulative surface mass balance of 0.57 ± 0.67 and 0.11 ± 0.37 m w.e. was observed during the 2009-2015 period on Whisky Glacier and Davies Dome, respectively. The results indicate a change from surface mass loss that prevailed in the region during the first decade of the 21st century to predominantly positive surface mass balance after 2009/10. The spatial pattern of annual surface mass-balance distribution implies snow redistribution by wind on both glaciers. The mean equilibrium line altitudes for Whisky Glacier (311 ± 16 m a.s.l.) and Davies Dome (393 ± 18 m a.s.l.) are in accordance with the regional data indicating 200-300 m higher equilibrium line on James Ross and Vega Islands compared with the South Shetland Islands. The mean accumulation-area ratio of 0.68 ± 0.09 and 0.44 ± 0.09 determined for Whisky Glacier and Davies Dome, respectively, is similar to the value reported for Vega Island and within the range of typical values for high-latitude glaciers.

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“…First, melt layers within bubble ice can be identified by visually analysing line scan profiles of the ice core (Abram et al, 2013). This technique works in the bubble ice zone in the absence of clathrates and is very sensitive as millimetre-thick melt layers can be reliably identified.…”

Section: Xe Air Ratio As Melt Layer Proxymentioning

confidence: 99%

Online technique for isotope and mixing ratios of CH<sub>4</sub>, N<sub>2</sub>O, Xe and mixing ratios of organic trace gases on a single ice core sample

et al. 2014

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Abstract. Firn and polar ice cores enclosing trace gas species offer a unique archive to study changes in the past atmosphere and in terrestrial/marine source regions. Here we present a new online technique for ice core and air samples to measure a suite of isotope ratios and mixing ratios of trace gas species on a single sample. Isotope ratios are determined on methane, nitrous oxide and xenon with reproducibilities for ice core samples of 0.15 ‰ for δ 13 C-CH 4 , 0.22 ‰ for δ 15 N-N 2 O, 0.34 ‰ for δ 18 O-N 2 O, and 0.05 ‰ per mass difference for δ 136 Xe for typical concentrations of glacial ice. Mixing ratios are determined on methane, nitrous oxide, xenon, ethane, propane, methyl chloride and dichlorodifluoromethane with reproducibilities of 7 ppb for CH 4 , 3 ppb for N 2 O, 70 ppt for C 2 H 6 , 70 ppt for C 3 H 8 , 20 ppt for CH 3 Cl, and 2 ppt for CCl 2 F 2 . However, the blank contribution for C 2 H 6 and C 3 H 8 is large in view of the measured values for Antarctic ice samples. The system consists of a vacuum extraction device, a preconcentration unit and a gas chromatograph coupled to an isotope ratio mass spectrometer. CH 4 is combusted to CO 2 prior to detection while we bypass the oven for all other species. The highly automated system uses only ∼ 160 g of ice, equivalent to ∼ 16 mL air, which is less than previous methods. The measurement of this large suite of parameters on a single ice sample is new and key to understanding phase relationships of parameters which are usually not measured together. A multi-parameter data set is also key to understand in situ production processes of organic species in the ice, a critical issue observed in many organic trace gases. Novel is the determination of xenon isotope ratios using doubly charged Xe ions. The attained precision for δ 136 Xe is suitable to correct the isotopic ratios and mixing ratios for gravitational firn diffusion effects, with the benefit that this information is derived from the same sample. Lastly, anomalies in the Xe mixing ratio, δXe/air, can be used to detect melt layers.

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Acceleration of snow melt in an Antarctic Peninsula ice core during the twentieth century

Cited by 178 publications

References 46 publications

Firn air depletion as a precursor of Antarctic ice-shelf collapse

Firn air depletion as a precursor of Antarctic ice-shelf collapse

Surface mass balance of small glaciers on James Ross Island, north-eastern Antarctic Peninsula, during 2009–2015

Online technique for isotope and mixing ratios of CH<sub>4</sub>, N<sub>2</sub>O, Xe and mixing ratios of organic trace gases on a single ice core sample

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Acceleration of snow melt in an Antarctic Peninsula ice core during the twentieth century

Cited by 178 publications

References 46 publications

Firn air depletion as a precursor of Antarctic ice-shelf collapse

Firn air depletion as a precursor of Antarctic ice-shelf collapse

Surface mass balance of small glaciers on James Ross Island, north-eastern Antarctic Peninsula, during 2009–2015

Online technique for isotope and mixing ratios of CH&lt;sub&gt;4&lt;/sub&gt;, N&lt;sub&gt;2&lt;/sub&gt;O, Xe and mixing ratios of organic trace gases on a single ice core sample

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Product

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About

Online technique for isotope and mixing ratios of CH<sub>4</sub>, N<sub>2</sub>O, Xe and mixing ratios of organic trace gases on a single ice core sample