A high‐resolution record of Greenland mass balance

McMillan, Malcolm; Leeson, Amber; Shepherd, A.; Briggs, K.; Armitage, Thomas; Hogg, Anna E.; Munneke, Peter Kuipers; Broeke, Michiel van den; Noël, Brice; Berg, Willem Jan van de; Ligtenberg, Stefan; Horwath, Martin; Groh, Andreas; Muir, Alan; Gilbert, Lin

doi:10.1002/2016gl069666

Cited by 167 publications

(196 citation statements)

References 49 publications

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“…More recent estimates suggest that the mass balance of the RHA was −6.9 ± 7.4 Gt between 2004(Matsuo and Heki, 2013 and that thinning rates increased to −0.40 ± 0.09 m a −1 between 2012/13 and 2014, compared to the long-term average of −0.23 ± 0.04 m a −1 (1952 and 2014) (Melkonian et al, 2016). The RHA is, therefore, following the Arctic-wide pattern of negative mass balance and glacier retreat that has been observed in Greenland (Enderlin et al, 2014;McMillan et al, 2016), Svalbard (Moholdt et al, 2010a, b;Nuth et al, 2010), and the Canadian Arctic (Enderlin et al, 2014;McMillan et al, 2016). However, the RHA has been studied far less than other Arctic regions, despite its large ice volumes.…”

Section: Introductionmentioning

confidence: 85%

Exceptional retreat of Novaya Zemlya's marine-terminating outlet glaciers between 2000 and 2013

et al. 2017

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Abstract. Novaya Zemlya (NVZ) has experienced rapid ice loss and accelerated marine-terminating glacier retreat during the past 2 decades. However, it is unknown whether this retreat is exceptional longer term and/or whether it has persisted since 2010. Investigating this is vital, as dynamic thinning may contribute substantially to ice loss from NVZ, but is not currently included in sea level rise predictions. Here, we use remotely sensed data to assess controls on NVZ glacier retreat between 1973/76 and 2015. Glaciers that terminate into lakes or the ocean receded 3.5 times faster than those that terminate on land. Between 2000 and 2013, retreat rates were significantly higher on marine-terminating outlet glaciers than during the previous 27 years, and we observe widespread slowdown in retreat, and even advance, between 2013 and 2015. There were some common patterns in the timing of glacier retreat, but the magnitude varied between individual glaciers. Rapid retreat between 2000 and 2013 corresponds to a period of significantly warmer air temperatures and reduced sea ice concentrations, and to changes in the North Atlantic Oscillation (NAO) and Atlantic Multidecadal Oscillation (AMO). We need to assess the impact of this accelerated retreat on dynamic ice losses from NVZ to accurately quantify its future sea level rise contribution.

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Section: Introductionmentioning

confidence: 85%

Exceptional retreat of Novaya Zemlya's marine-terminating outlet glaciers between 2000 and 2013

et al. 2017

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“…Dynamic ice losses were roughly equal to surface melt and runoff in the period 2000-2008, but the share was somewhat less during the exceptionally high-surface melt years of 2009-2012. Taken together, dynamic ice losses and runoff of surface meltwater exceed snow accumulation over the Greenland Ice Sheet, so the overall mass balance of the ice sheet is negative. Analysis of surface elevation and mass changes from CryoSat-2 and GRACE satellite data indicates that the Greenland Ice Sheet had a net annual mass balance of − 269 ± 51 Gt/year from Jan 2011-Dec 2014 [14]. Dynamic ice loss from marine outlet glaciers makes a large contribution to this deficit, particularly from Kangerdlugssuaq in the east, Jakobshavns Isbrae, Upernavik Isstrøm and Steenstrup Glacier on the west coast, and Zachariae Isstrøm in the north-east.…”

Section: Contribution Of Calving Glaciers To Greenland's Mass Budgetmentioning

confidence: 99%

Glacier Calving in Greenland

Benn

Cowton

Todd

et al. 2017

Curr Clim Change Rep

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In combination, the breakaway of icebergs (calving) and submarine melting at marine-terminating glaciers account for between one third and one half of the mass annually discharged from the Greenland Ice Sheet into the ocean. These ice losses are increasing due to glacier acceleration and retreat, largely in response to increased heat flux from the oceans. Behaviour of Greenland's marine-terminating ('tidewater') glaciers is strongly influenced by fjord bathymetry, particularly the presence of 'pinning points' (narrow or shallow parts of fjords that encourage stability) and overdeepened basins (that encourage rapid retreat). Despite the importance of calving and submarine melting and significant advances in monitoring and understanding key processes, it is not yet possible to predict the tidewater glacier response to climatic and oceanic forcing with any confidence. The simple calving laws required for ice-sheet models do not adequately represent the complexity of calving processes. New detailed process models, however, are increasing our understanding of the key processes and are guiding the design of improved calving laws. There is thus some prospect of reaching the elusive goal of accurately predicting future tidewater glacier behaviour and associated rates of sea-level rise.

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“…In addition to directly removing more of the ice sheet into the sea, melting reduces the reflectivity of the ice sheet and can warm the perennial snowpack (through latent heat release when the meltwater refreezes), both of which act as a positive feedback to further enhance melt. These processes also alter the dielectric properties of the ice sheet surface, which makes it more difficult to measure surface height change using satellite-borne radar instruments (McMillan et al, 2016). An understanding of the location, frequency, duration and magnitude of melting is therefore necessary to (1) understand the ice sheet's response to climate change, (2) interpret contemporary measurements of ice sheet volume change and (3) constrain predictions of future ice sheet state.…”

Section: Introductionmentioning

confidence: 99%

Extreme temperature events on Greenland in observations and the MAR regional climate model

2018

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Abstract. Meltwater from the Greenland Ice Sheet contributed 1.7-6.12 mm to global sea level between 1993 and 2010 and is expected to contribute 20-110 mm to future sea level rise by 2100. These estimates were produced by regional climate models (RCMs) which are known to be robust at the ice sheet scale but occasionally miss regional-and local-scale climate variability (e.g. Leeson et al., 2017;Medley et al., 2013). To date, the fidelity of these models in the context of short-period variability in time (i.e. intra-seasonal) has not been fully assessed, for example their ability to simulate extreme temperature events. We use an event identification algorithm commonly used in extreme value analysis, together with observations from the Greenland Climate Network (GC-Net), to assess the ability of the MAR (Modèle Atmosphérique Régional) RCM to reproduce observed extreme positive-temperature events at 14 sites around Greenland. We find that MAR is able to accurately simulate the frequency and duration of these events but underestimates their magnitude by more than half a degree Celsius/kelvin, although this bias is much smaller than that exhibited by coarse-scale Era-Interim reanalysis data. As a result, melt energy in MAR output is underestimated by between 16 and 41 % depending on global forcing applied. Further work is needed to precisely determine the drivers of extreme temperature events, and why the model underperforms in this area, but our findings suggest that biases are passed into MAR from boundary forcing data. This is important because these forcings are common between RCMs and their range of predictions of past and future ice sheet melting. We propose that examining extreme events should become a routine part of global and regional climate model evaluation and that addressing shortcomings in this area should be a priority for model development.

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A high‐resolution record of Greenland mass balance

Cited by 167 publications

References 49 publications

Exceptional retreat of Novaya Zemlya's marine-terminating outlet glaciers between 2000 and 2013

Exceptional retreat of Novaya Zemlya's marine-terminating outlet glaciers between 2000 and 2013

Glacier Calving in Greenland

Extreme temperature events on Greenland in observations and the MAR regional climate model

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