Glacier change along West Antarctica's Marie Byrd Land Sector and links to inter-decadal atmosphere–ocean variability

Christie, Frazer D. W.; Bingham, Robert G.; Gourmelen, Noël; Steig, Eric J.; Bisset, Rosie R.; Pritchard, Hamish D.; Snow, Kate; Tett, Simon F. B.

doi:10.5194/tc-12-2461-2018

Cited by 23 publications

(36 citation statements)

References 95 publications

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“…Besides the fast-changing Amundsen Sea Sector, the Bellingshausen Sea Sector at Abbot Ice Shelf is less studied but also vulnerable to CDW forcing (Christie et al, 2016). Just recently, the velocity at the grounding line increased (+20 %, 2007-2014), a dynamic thinning signal evolved which is related to ice dynamics and lower snowfall (Chuter et al, 2017), and minor grounding line retreat has occurred (Christie et al, 2016). The recent dynamic thinning signal observed by Chuter et al (2017) is in line with the glacier front retreat at Abbot Ice Shelf observed since the second decade, where westerlies increased by +0.24 m/s from the first to the second decade, indicating vulnerability to upwelling CDW.…”

Section: West Antarcticamentioning

confidence: 99%

Environmental drivers of circum-Antarctic glacier and ice shelf front retreat over the last two decades

et al. 2021

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Abstract. The safety band of Antarctica, consisting of floating glacier tongues and ice shelves, buttresses ice discharge of the Antarctic Ice Sheet. Recent disintegration events of ice shelves along with glacier retreat indicate a weakening of this important safety band. Predicting calving front retreat is a real challenge due to complex ice dynamics in a data-scarce environment that are unique for each ice shelf and glacier. We explore the extent to which easy-to-access remote sensing and modeling data can help to define environmental conditions leading to calving front retreat. For the first time, we present a circum-Antarctic record of glacier and ice shelf front change over the last two decades in combination with environmental variables such as air temperature, sea ice days, snowmelt, sea surface temperature, and wind direction. We find that the Antarctic Ice Sheet area decreased by −29 618 ± 1193 km2 in extent between 1997–2008 and gained an area of 7108 ± 1029 km2 between 2009 and 2018. Retreat concentrated along the Antarctic Peninsula and West Antarctica including the biggest ice shelves (Ross and Ronne). In several cases, glacier and ice shelf retreat occurred in conjunction with one or several changes in environmental variables. Decreasing sea ice days, intense snowmelt, weakening easterlies, and relative changes in sea surface temperature were identified as enabling factors for retreat. In contrast, relative increases in mean air temperature did not correlate with calving front retreat. For future studies a more appropriate measure for atmospheric forcing should be considered, including above-zero-degree days and temperature extreme events. To better understand drivers of glacier and ice shelf retreat, it is critical to analyze the magnitude of basal melt through the intrusion of warm Circumpolar Deep Water that is driven by strengthening westerlies and to further assess surface hydrology processes such as meltwater ponding, runoff, and lake drainage.

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Section: West Antarcticamentioning

confidence: 99%

Environmental drivers of circum-Antarctic glacier and ice shelf front retreat over the last two decades

et al. 2021

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“…Projections of 21st century Antarctic ice sheet evolution, however, vary widely, with projected upper bounds ranging from 30 cm of sea level equivalent (Ritz et al, 2015) to over 1 m (DeConto and Pollard, 2016), depending on model characteristics and physical processes, as well as the climate scenarios adopted. Previous efforts from the ice sheet modeling community for the IPCC-AR5 (Intergovernmental Panel for Climate Change Fifth Assessment Report; Church et al, 2013) tried to estimate the ice sheet evolution under several climate scenarios (Bindschadler et al, 2013;Nowicki et al, 2013a, b). These results had a large spread for all scenarios, as a consequence of differences in model characteristics and processes included, initialization methods, and the interpretation and application of model forcings (Nowicki et al, 2013b).…”

Section: Introductionmentioning

confidence: 99%

initMIP-Antarctica: an ice sheet model initialization experiment of ISMIP6

et al. 2019

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Abstract. Ice sheet numerical modeling is an important tool to estimate the dynamic contribution of the Antarctic ice sheet to sea level rise over the coming centuries. The influence of initial conditions on ice sheet model simulations, however, is still unclear. To better understand this influence, an initial state intercomparison exercise (initMIP) has been developed to compare, evaluate, and improve initialization procedures and estimate their impact on century-scale simulations. initMIP is the first set of experiments of the Ice Sheet Model Intercomparison Project for CMIP6 (ISMIP6), which is the primary Coupled Model Intercomparison Project Phase 6 (CMIP6) activity focusing on the Greenland and Antarctic ice sheets. Following initMIP-Greenland, initMIP-Antarctica has been designed to explore uncertainties associated with model initialization and spin-up and to evaluate the impact of changes in external forcings. Starting from the state of the Antarctic ice sheet at the end of the initialization procedure, three forward experiments are each run for 100 years: a control run, a run with a surface mass balance anomaly, and a run with a basal melting anomaly beneath floating ice. This study presents the results of initMIP-Antarctica from 25 simulations performed by 16 international modeling groups. The submitted results use different initial conditions and initialization methods, as well as ice flow model parameters and reference external forcings. We find a good agreement among model responses to the surface mass balance anomaly but large variations in responses to the basal melting anomaly. These variations can be attributed to differences in the extent of ice shelves and their upstream tributaries, the numerical treatment of grounding line, and the initial ocean conditions applied, suggesting that ongoing efforts to better represent ice shelves in continental-scale models should continue.

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“…While grounding line retreat has been observed since 2003 (ref. 24 ), the ice shelf is anchored at its seaward margin by eight large islands and over 23 pinning points which stabilise the ice shelf calving front, resulting in a relatively small area change over the past three decades 25 , 26 . Despite the absence of significant area change, strong ice shelf thinning (−16.1 m/decade) has been observed since the 1990s 27 , producing one of the largest sources of fresh water input to the Southern Ocean 28 , more than double that of the neighbouring Amundsen Sea ice shelves 29 .…”

Section: Introductionmentioning

confidence: 99%

Widespread increase in dynamic imbalance in the Getz region of Antarctica from 1994 to 2018

et al. 2021

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The Getz region of West Antarctica is losing ice at an increasing rate; however, the forcing mechanisms remain unclear. Here we use satellite observations and an ice sheet model to measure the change in ice speed and mass balance of the drainage basin over the last 25-years. Our results show a mean increase in speed of 23.8 % between 1994 and 2018, with three glaciers accelerating by over 44 %. Speedup across the Getz basin is linear, with speedup and thinning directly correlated confirming the presence of dynamic imbalance. Since 1994, 315 Gt of ice has been lost contributing 0.9 ± 0.6 mm global mean sea level, with increased loss since 2010 caused by a snowfall reduction. Overall, dynamic imbalance accounts for two thirds of the mass loss from this region of West Antarctica over the past 25-years, with a longer-term response to ocean forcing the likely driving mechanism.

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Glacier change along West Antarctica's Marie Byrd Land Sector and links to inter-decadal atmosphere–ocean variability

Abstract: Abstract. Over the past 20 years satellite remote sensing has captured significant downwasting of glaciers that drain

Cited by 23 publications

References 95 publications

Environmental drivers of circum-Antarctic glacier and ice shelf front retreat over the last two decades

Environmental drivers of circum-Antarctic glacier and ice shelf front retreat over the last two decades

initMIP-Antarctica: an ice sheet model initialization experiment of ISMIP6

Widespread increase in dynamic imbalance in the Getz region of Antarctica from 1994 to 2018

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