Surface mass balance and melting projections over the Amundsen coastal region, West Antarctica

2020 ◽  
Author(s):  
Nicolas Jourdain ◽  
Marion Donat-Magnin ◽  
Christoph Kittel ◽  
Cécile Agosta ◽  
Charles Amory ◽  
...  
Keyword(s):  
Mass Balance ◽  
Projection Method ◽  
Surface Mass Balance ◽  
West Antarctica ◽  
Ice Shelf ◽  
Near Surface ◽  
Surface Mass ◽  
Ice Shelves ◽  
The Future ◽  
Surface Melt

<p>We present Surface Mass Balance (SMB) and surface melt rates projections in West Antarctica for the end of the 21<sup>st</sup> century using the MAR regional atmosphere and firn model (Gallée 1994; Agosta et al. 2019) forced by a CMIP5-rcp85 multi-model-mean seasonal anomaly added to the ERA-Interim 6-hourly reanalysis.</p><p> </p><p>First of all, we assess the validity of our projection method, following a perfect-model approach, with MAR constrained by the ACCESS-1.3 present-day and future climates. Changes in large-scale variables are well captured by our anomaly-based projection method, and errors on surface melting and SMB projections are typically 10%.</p><p> </p><p>Based on the CMIP5-rcp85 multi-model mean, SMB over the grounded ice sheet in the Amundsen sector is projected to increase by 35% over the 21<sup>st</sup> century. This corresponds to a SMB sensitivity to near-surface warming of 8.3%.°C<sup>-1</sup>. Increased humidity, resulting from both higher water vapour saturation in warmer conditions and decreased sea-ice concentrations, are shown to favour increased SMB in the future scenario.</p><p> </p><p>Ice-shelf surface melt rates at the end of the 21<sup>st</sup> century are projected to become 6 to 15 times larger than presently, depending on the ice shelf under consideration. This is due to enhanced downward longwave radiative fluxes related to increased humidity, and to an albedo feedback leading to more absorption of shortwave radiation. Interestingly, only three ice shelves produce runoff (Abbot, Cosgrove and Pine Island) in the future climate. For the other ice shelves (Thwaites, Crosson, Dotson, Getz), the future melt-to-snowfall ratio remains too low to produce firn air depletion and subsequent runoff.</p><p> </p>

scholarly journals Diverging future surface mass balance between the Antarctic ice shelves and grounded ice sheet

2020 ◽  
Author(s):  
Christoph Kittel ◽  
Charles Amory ◽  
Cécile Agosta ◽  
Nicolas C. Jourdain ◽  
Stefan Hofer ◽  
...  
Keyword(s):  
Mass Balance ◽  
Sea Level Rise ◽  
Sea Level ◽  
Ice Sheet ◽  
Surface Mass Balance ◽  
Near Surface ◽  
Surface Mass ◽  
Ice Shelves ◽  
The Future ◽  
The Antarctic

Abstract. The future surface mass balance (SMB) will influence the ice dynamics and the contribution of the Antarctic ice sheet (AIS) to the sea-level rise. Most of recent Antarctic SMB projections were based on the 5th phase of the Coupled Model Intercomparison Project (CMIP5). However, new CMIP6 results have revealed a +1.3 °C higher mean Antarctic near-surface temperature than in CMIP5 at the end of the 21st century enabling estimations of future SMB in warmer climates. Here, we investigate the AIS sensitivity to different warmings with an ensemble of four simulations performed with the polar regional climate model MAR forced by two CMIP5 and two CMIP6 models over 1981–2100. Statistical extrapolation allows us to expand our results to the whole CMIP5 and CMIP6 ensembles. Our results highlight a contrasting effect on the future grounded ice sheet and the ice shelves. The SMB over grounded ice is projected to increase as a response to stronger snowfall, only partly offset by enhanced meltwater runoff. This leads to a cumulated sea-level rise mitigation (i.e. an increase in surface mass) of the grounded Antarctic surface by 5.1 ± 1.9 cm sea-level equivalent (SLE) in CMIP5-RCP8.5 and 6.3 ± 2.0 cm SLE in CMIP6-ssp585. Additionally, the CMIP6 low-emission ssp126 and intermediate-emission ssp245 scenarios project a stabilised surface mass gain resulting in a lower mitigation to sea-level rise than in ssp585. Over the ice shelves, the strong runoff increase associated with higher temperature is projected to lower the SMB with a stronger decrease in CMIP6-ssp585 compared to CMIP5-RCP8.5. Ice shelves are however predict to have a close-to-present-equilibrium stable SMB under CMIP6 ssp126 and ssp245 scenarios. Future uncertainties are mainly due to the sensitivity to anthropogenic forcing and the timing of the projected warming. While ice shelves should remain at a close-to-equilibrium stable SMB under the Paris Agreements, MAR projects strong SMB decrease for an Antarctic near-surface warming above +2.5 °C limiting the warming range before potential irreversible damages on the ice-shelves. Finally, our results reveal the existence of a potential threshold (+7.5 °C) that leads to a lower grounded SMB increase. This however has to be confirmed in following studies using more extreme or longer future scenarios.

scholarly journals Diverging future surface mass balance between the Antarctic ice shelves and grounded ice sheet

2021 ◽  
Author(s):  
Christoph Kittel ◽  
Charles Amory ◽  
Cécile Agosta ◽  
Nicolas C Jourdain ◽  
Stefan Hofer ◽  
...  
Keyword(s):  
Mass Balance ◽  
Sea Level Rise ◽  
Sea Level ◽  
Ice Sheet ◽  
Surface Mass Balance ◽  
Near Surface ◽  
Surface Mass ◽  
Ice Shelves ◽  
The Future ◽  
The Antarctic

<p>The future surface mass balance (SMB) will influence the ice dynamics and the contribution of the Antarctic ice sheet (AIS) to the sea-level rise. Most of recent Antarctic SMB projections were based on the 5th phase of the Coupled Model Intercomparison Project (CMIP5). However, new CMIP6 results have revealed a +1.3°C higher mean Antarctic near-surface temperature than in CMIP5 at the end of the 21st century enabling estimations of future SMB in warmer climates. Here, we investigate the AIS sensitivity to different warmings with an ensemble of four simulations performed with the polar regional climate model MAR forced by two CMIP5 and two CMIP6 models over 1981--2100. Statistical extrapolation allows us to expand our results to the whole CMIP5 and CMIP6 ensembles. Our results highlight a contrasting effect on the future grounded ice sheet and the ice shelves. The SMB over grounded ice is projected to increase as a response to stronger snowfall, only partly offset by enhanced meltwater runoff. This leads to a cumulated sea-level rise mitigation (i.e. an increase in surface mass) of the grounded Antarctic surface by 5.1 ± 1.9 cm sea-level equivalent (SLE) in CMIP5-RCP8.5 and 6.3 ± 2.0 cm SLE in CMIP6-ssp585. Additionally, the CMIP6 low-emission ssp126 and intermediate-emission ssp245 scenarios project a stabilised surface mass gain resulting in a lower mitigation to sea-level rise than in ssp585. Over the ice shelves, the strong runoff increase associated with higher temperature is projected to lower the SMB with a stronger decrease in CMIP6-ssp585 compared to CMIP5-RCP8.5. Ice shelves are however predict to have a close-to-present-equilibrium stable SMB under CMIP6 ssp126 and ssp245 scenarios. Future uncertainties are mainly due to the sensitivity to anthropogenic forcing and the timing of the projected warming. Furthermore,  we compare the MAR projected SMB to the ISMIP6-derived SMB, revealing large local and integrated differences between MAR and the respective forcing ESM highlighting the need of additional projections relying on more models including both RCMs and ESMs. While ice shelves should remain at a close-to-equilibrium stable SMB under the Paris Agreements, MAR projects strong SMB decrease for an Antarctic near-surface warming above +2.5°C limiting the warming range before potential irreversible damages on the ice-shelves. Finally, our results reveal the existence of a potential threshold (+7.5°C) that leads to a lower grounded SMB increase. This however has to be confirmed in following studies using more extreme or longer future scenarios.</p>

scholarly journals Future surface mass balance and surface melt in the Amundsen sector of the West Antarctic Ice Sheet

2021 ◽  
Vol 15 (2) ◽  
pp. 571-593
Author(s):  
Marion Donat-Magnin ◽  
Nicolas C. Jourdain ◽  
Christoph Kittel ◽  
Cécile Agosta ◽  
Charles Amory ◽  
...  
Keyword(s):  
Mass Balance ◽  
Liquid Water ◽  
Ice Sheet ◽  
Surface Mass Balance ◽  
Surface Mass ◽  
Ice Shelves ◽  
Net Production ◽  
West Antarctic ◽  
Surface Liquid ◽  
Surface Melt

Abstract. We present projections of West Antarctic surface mass balance (SMB) and surface melt to 2080–2100 under the RCP8.5 scenario and based on a regional model at 10 km resolution. Our projections are built by adding a CMIP5 (Coupled Model Intercomparison Project Phase 5) multi-model-mean seasonal climate-change anomaly to the present-day model boundary conditions. Using an anomaly has the advantage to reduce CMIP5 model biases, and a perfect-model test reveals that our approach captures most characteristics of future changes despite a 16 %–17 % underestimation of projected SMB and melt rates. SMB over the grounded ice sheet in the sector between Getz and Abbot increases from 336 Gt yr−1 in 1989–2009 to 455 Gt yr−1 in 2080–2100, which would reduce the global sea level changing rate by 0.33 mm yr−1. Snowfall indeed increases by 7.4 % ∘C−1 to 8.9 % ∘C−1 of near-surface warming due to increasing saturation water vapour pressure in warmer conditions, reduced sea-ice concentrations, and more marine air intrusion. Ice-shelf surface melt rates increase by an order of magnitude in the 21st century mostly due to higher downward radiation from increased humidity and to reduced albedo in the presence of melting. There is a net production of surface liquid water over eastern ice shelves (Abbot, Cosgrove, and Pine Island) but not over western ice shelves (Thwaites, Crosson, Dotson, and Getz). This is explained by the evolution of the melt-to-snowfall ratio: below a threshold of 0.60 to 0.85 in our simulations, firn air is not entirely depleted by melt water, while entire depletion and net production of surface liquid water occur for higher ratios. This suggests that western ice shelves might remain unaffected by hydrofracturing for more than a century under RCP8.5, while eastern ice shelves have a high potential for hydrofracturing before the end of this century.

scholarly journals Interannual Variability of Summer Surface Mass Balance and Surface Melting in the Amundsen Sector, West Antarctica

2019 ◽  
Author(s):  
Marion Donat-Magnin ◽  
Nicolas C. Jourdain ◽  
Hubert Gallée ◽  
Charles Amory ◽  
Christoph Kittel ◽  
...  
Keyword(s):  
Mass Balance ◽  
Interannual Variability ◽  
Climate Models ◽  
Surface Wind ◽  
Surface Melting ◽  
Surface Mass Balance ◽  
Climate Trends ◽  
West Antarctica ◽  
Near Surface ◽  
Surface Mass

Abstract. Understanding the interannual variability of Surface Mass Balance (SMB) and surface melting in Antarctica is key to quantify the signal to noise ratio in climate trends, identify opportunities for multi-year climate predictions, and to assess the ability of climate models to respond to climate variability. Here we simulate summer SMB and surface melting from 1979 to 2017 using the regional atmospheric model MAR at 10 km resolution over the drainage basins of the Amundsen glaciers in West Antarctica. Our simulations reproduce the mean present-day climate in terms of near-surface temperature (mean overestimation of 0.10 °C), near-surface wind speed (mean underestimation of 0.42 m s-1), and SMB (relative bias

scholarly journals Antarctic Atmospheric River Climatology and Impacts

2020 ◽  
Author(s):  
Jonathan Wille ◽  
Vincent Favier ◽  
Irina V. Gorodetskaya ◽  
Cécile Agosta ◽  
Jai Chowdhry Beeman ◽  
...  
Keyword(s):  
Mass Balance ◽  
Surface Mass Balance ◽  
Ice Shelf ◽  
Surface Mass ◽  
Atmospheric Rivers ◽  
Atmospheric River ◽  
Dronning Maud Land ◽  
Antarctic Continent ◽  
Surface Melt ◽  
The Antarctic

<p>Atmospheric rivers, broadly defined as narrow yet long bands of strong horizontal vapor transport typically imbedded in a low level jet ahead of a cold front of an extratropical cyclone, provide a sub-tropical connection to the Antarctic continent and are observed to significantly impact the affected region’s surface mass balance over short, extreme events. When an atmospheric river makes landfall on the Antarctic continent, their signature is clearly observed in increased downward longwave radiation, cloud liquid water content, surface temperature, snowfall, surface melt, and moisture transport.</p><p>Using an atmospheric river detection algorithm designed for Antarctica and regional climate simulations from MAR, we created a climatology of atmospheric river occurrence and their associated impacts on surface melt and snowfall. Despite their rarity of occurrence over Antarctica (maximum frequency of ~1.5% over a given point), they have produced significant impacts on melting and snowfall processes. From 1979-2017, atmospheric rivers landfalls and their associated radiative flux anomalies and foehn winds accounted for around 40% of the total summer surface melt on the Ross Ice Shelf (approaching 100% at higher elevations in Marie Byrd Land) and 40-80% of total winter surface melt on the ice shelves along the Antarctic Peninsula. On the other side of the continent in East Antarctica, atmospheric rivers have a greater influence on annual snowfall variability. There atmospheric rivers are responsible for 20-40% of annual snowfall with localized higher percentages across Dronning Maud Land, Amery Ice Shelf, and Wilkes Land.</p><p>Atmospheric river landfalls occur within a highly amplified polar jet pattern and often are found in the entrance region of a blocking ridge. Therefore, atmospheric river variability is connected with atmospheric blocking variability over the Southern Ocean. There has been a significant increase in atmospheric river activity over the Amundsen-Bellingshausen sea and coastline and into Dronning Maud Land region from 1980-2018. Meanwhile, there is a significant decreasing trend in the region surrounding Law Dome. Our results suggest that atmospheric rivers play a significant role in the Antarctic surface mass balance, and that any future changes in atmospheric blocking or tropical-polar teleconnections may have significant impacts on future surface mass balance projections.</p>

scholarly journals Diverging future surface mass balance between the Antarctic ice shelves and grounded ice sheet

2021 ◽  
Vol 15 (3) ◽  
pp. 1215-1236
Author(s):  
Christoph Kittel ◽  
Charles Amory ◽  
Cécile Agosta ◽  
Nicolas C. Jourdain ◽  
Stefan Hofer ◽  
...  
Keyword(s):  
Mass Balance ◽  
Sea Level Rise ◽  
Sea Level ◽  
Ice Sheet ◽  
Surface Mass Balance ◽  
Near Surface ◽  
Surface Mass ◽  
Ice Shelves ◽  
Run Off ◽  
The Antarctic

Abstract. The future surface mass balance (SMB) will influence the ice dynamics and the contribution of the Antarctic ice sheet (AIS) to the sea level rise. Most of recent Antarctic SMB projections were based on the fifth phase of the Coupled Model Intercomparison Project (CMIP5). However, new CMIP6 results have revealed a +1.3 ∘C higher mean Antarctic near-surface temperature than in CMIP5 at the end of the 21st century, enabling estimations of future SMB in warmer climates. Here, we investigate the AIS sensitivity to different warmings with an ensemble of four simulations performed with the polar regional climate model Modèle Atmosphérique Régional (MAR) forced by two CMIP5 and two CMIP6 models over 1981–2100. Statistical extrapolation enables us to expand our results to the whole CMIP5 and CMIP6 ensembles. Our results highlight a contrasting effect on the future grounded ice sheet and the ice shelves. The SMB over grounded ice is projected to increase as a response to stronger snowfall, only partly offset by enhanced meltwater run-off. This leads to a cumulated sea-level-rise mitigation (i.e. an increase in surface mass) of the grounded Antarctic surface by 5.1 ± 1.9 cm sea level equivalent (SLE) in CMIP5-RCP8.5 (Relative Concentration Pathway 8.5) and 6.3 ± 2.0 cm SLE in CMIP6-ssp585 (Shared Socioeconomic Pathways 585). Additionally, the CMIP6 low-emission ssp126 and intermediate-emission ssp245 scenarios project a stabilized surface mass gain, resulting in a lower mitigation to sea level rise than in ssp585. Over the ice shelves, the strong run-off increase associated with higher temperature is projected to decrease the SMB (more strongly in CMIP6-ssp585 compared to CMIP5-RCP8.5). Ice shelves are however predicted to have a close-to-present-equilibrium stable SMB under CMIP6 ssp126 and ssp245 scenarios. Future uncertainties are mainly due to the sensitivity to anthropogenic forcing and the timing of the projected warming. While ice shelves should remain at a close-to-equilibrium stable SMB under the Paris Agreement, MAR projects strong SMB decrease for an Antarctic near-surface warming above +2.5 ∘C compared to 1981–2010 mean temperature, limiting the warming range before potential irreversible damages on the ice shelves. Finally, our results reveal the existence of a potential threshold (+7.5 ∘C) that leads to a lower grounded-SMB increase. This however has to be confirmed in following studies using more extreme or longer future scenarios.

scholarly journals Climate and surface mass balance of coastal West Antarctica resolved by regional climate modelling

2017 ◽  
Vol 59 (76pt1) ◽  
pp. 29-41 ◽  
Author(s):  
Jan T. M. Lenaerts ◽  
Stefan R. M. Ligtenberg ◽  
Brooke Medley ◽  
Willem Jan Van de Berg ◽  
Hannes Konrad ◽  
...  
Keyword(s):  
High Resolution ◽  
Mass Balance ◽  
Ice Sheet ◽  
Small Scale ◽  
Climate Modelling ◽  
Surface Mass Balance ◽  
West Antarctica ◽  
Surface Mass ◽  
West Antarctic ◽  
Surface Melt

ABSTRACTWest Antarctic climate and surface mass balance (SMB) records are sparse. To fill this gap, regional atmospheric climate modelling is useful, providing that such models are employed at sufficiently high horizontal resolution and coupled with a snow model. Here we present the results of a high-resolution (5.5 km) regional atmospheric climate model (RACMO2) simulation of coastal West Antarctica for the period 1979–2015. We evaluate the results with available in situ weather observations, remote-sensing estimates of surface melt, and SMB estimates derived from radar and firn cores. Moreover, results are compared with those from a lower-resolution version, to assess the added value of the resolution. The high-resolution model resolves small-scale climate variability invoked by topography, such as the relatively warm conditions over ice-shelf grounding zones, and local wind speed accelerations. Surface melt and SMB are well reproduced by RACMO2. This dataset will prove useful for picking ice core locations, converting elevation changes to mass changes, for driving ocean, ice-sheet and coupled models, and for attributing changes in the West Antarctic Ice Sheet and shelves to changes in atmospheric forcing.

Decreasing Antarctic surface mass balance due to runoff-dominated ablation by 2100

2020 ◽  
Author(s):  
Christoph Kittel ◽  
Charles Amory ◽  
Cécile Agosta ◽  
Nicolas Jourdain ◽  
Stefan Hofer ◽  
...  
Keyword(s):  
Mass Balance ◽  
Sea Level Rise ◽  
Sea Level ◽  
Ice Sheet ◽  
Surface Mass Balance ◽  
Ice Shelf ◽  
Antarctic Ice Sheet ◽  
Surface Mass ◽  
Ice Shelves ◽  
The Antarctic

<p><span>The surface mass balance (SMB) of the Antarctic ice sheet is often considered as a negative contributor to the sea level rise as present snowfall accumulation largely compensate</span><span>s</span><span> for ablation through wind erosion, sublimation and runoff. The latter is even almost negligible since current Antarctic surface melting is limited to relatively scarce events over generally peripheral areas and refreezes almost entirely into the snowpack. However, melting can significantly affect the stability of ice shelves through hydrofracturing, potentially leading to their disintegration, acceleration of grounded ice and increased sea level rise. Although a large increase in snowfall is expected in a warmer climate, more numerous and stronger melting events could conversely lead to a larger risk of ice shelf collapse. In this study, we provide an estimation of the SMB of the Antarctic ice sheet for the end of the 21st century by forcing the state-of-the-art regional climate model MAR with three different global climate models. We chose the models (from both the Coupled Model Intercomparison Project Phase 5 and 6 - CMIP5 and CMIP6) providing the best metrics for representing the current Antarctic climate. While the increase in snowfall largely compensates snow ablation through runoff in CMIP5-forced projections, CMIP6-forced simulations reveal that runoff cannot be neglected in the future as it accounts for a maximum of 50% of snowfall and becomes the main ablation component over the ice sheet. Furthermore, we identify a tipping point (ie., a warming of 4°C) at which the Antarctic SMB starts to decrease as a result of enhanced runoff particularly over ice shelves. Our results highlight the importance of taking into account meltwater production and runoff and indicate that previous model studies neglecting these processes yield overestimated SMB estimates, ultimately leading to underestimated Antarctic contribution to sea level rise. Finally, melt rates over each ice shelf are higher than those that led to the collapse of the Larsen A and B ice shelves, suggesting a high probability of ice shelf collapses all over peripheral Antarctica by 2100.</span></p>

scholarly journals Kinematic response of ice-rise divides to changes in ocean and atmosphere forcing

2019 ◽  
Vol 13 (10) ◽  
pp. 2673-2691 ◽  
Author(s):  
Clemens Schannwell ◽  
Reinhard Drews ◽  
Todd A. Ehlers ◽  
Olaf Eisen ◽  
Christoph Mayer ◽  
...  
Keyword(s):  
Mass Balance ◽  
Surface Mass Balance ◽  
Ice Shelf ◽  
Catchment Scale ◽  
Rock Outcrops ◽  
Local Flow ◽  
Surface Mass ◽  
Ice Shelves ◽  
Modelling Framework ◽  
Mesh Resolution

Abstract. The majority of Antarctic ice shelves are bounded by grounded ice rises. These ice rises exhibit local flow fields that partially oppose the flow of the surrounding ice shelves. Formation of ice rises is accompanied by a characteristic upward-arching internal stratigraphy (“Raymond arches”), whose geometry can be analysed to infer information about past ice-sheet changes in areas where other archives such as rock outcrops are missing. Here we present an improved modelling framework to study ice-rise evolution using a satellite-velocity calibrated, isothermal, and isotropic 3-D full-Stokes model including grounding-line dynamics at the required mesh resolution (<500 m). This overcomes limitations of previous studies where ice-rise modelling has been restricted to 2-D and excluded the coupling between the ice shelf and ice rise. We apply the model to the Ekström Ice Shelf, Antarctica, containing two ice rises. Our simulations investigate the effect of surface mass balance and ocean perturbations onto ice-rise divide position and interpret possible resulting unique Raymond arch geometries. Our results show that changes in the surface mass balance result in immediate and sustained divide migration (>2.0 m yr−1) of up to 3.5 km. In contrast, instantaneous ice-shelf disintegration causes a short-lived and delayed (by 60–100 years) response of smaller magnitude (<0.75 m yr−1). The model tracks migration of a triple junction and synchronous ice-divide migration in both ice rises with similar magnitude but differing rates. The model is suitable for glacial/interglacial simulations on the catchment scale, providing the next step forward to unravel the ice-dynamic history stored in ice rises all around Antarctica.

scholarly journals Future ice-sheet surface mass balance and melting in the Amundsen region, West Antarctica

2020 ◽  
Author(s):  
Marion Donat-Magnin ◽  
Nicolas C. Jourdain ◽  
Christoph Kittel ◽  
Cécile Agosta ◽  
Charles Amory ◽  
...  
Keyword(s):  
Mass Balance ◽  
Ice Sheet ◽  
Coupled Model ◽  
Water Vapour Pressure ◽  
Surface Mass Balance ◽  
Near Surface ◽  
Surface Mass ◽  
Ice Shelves ◽  
Surface Warming ◽  
West Antarctic

Abstract. We present projections of West-Antarctic surface mass balance (SMB) and surface melting to 2080–2100, under the RCP8.5 scenario and based on a regional model at 10 km resolution. Our projections are built by adding a CMIP5 (5th Coupled Model Intercomparison Project) multi-model-mean seasonal climate-change anomaly to the present-day model boundary conditions. Using an anomaly has the advantage to reduce CMIP5 model biases, and a perfect-model test reveals that our approach captures most characteristics of future changes, despite a 16–17 % underestimation of projected SMB and melt rates. SMB over the grounded ice sheet in the sector between Getz and Abbot increases from 336 Gt yr−1 in 1989–2009 to 455 Gt yr−1 in 2080–2100, which would reduce the global sea level changing rate by 0.33 mm yr−1. Snowfall indeed increases by 7.4 to 8.9 % per °C of near-surface warming, due to increasing saturation water vapour pressure in warmer conditions, reduced sea-ice concentrations, and more marine air intrusion. Ice-shelf surface melt rates increase by an order of magnitude along the 21st century, mostly due to higher downward radiation from increased humidity, and to reduced albedo in the presence of melting. Eastern ice shelves (Abbot, Cosgrove and Pine Island) experience significant runoff in the future, while western ice shelves (Thwaites, Crosson, Dotson and Getz) remain without runoff. This is explained by the evolution of the melt-to-snowfall ratio: below a threshold of 0.60 to 0.85, firn air is not entirely depleted by melt water, while entire depletion and runoff occur for higher ratios. This suggests that western ice shelves might remain unaffected by hydrofracturing for more than a century under RCP8.5, while eastern ice shelves have a high potential for hydrofracturing before the end of this century.

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