Antarctic Ice Shelves Research Articles

Oceanic Regime Shift to a Warmer Continental Shelf Adjacent to the Shackleton Ice Shelf, East Antarctica

AbstractThe long‐held view that the East Antarctic margin is isolated from warm offshore waters has been challenged by recent observations showing incursions of warm modified Circumpolar Deep Water (mCDW) reaching several East Antarctic ice shelves. However, large areas of the East Antarctic continental shelf remain poorly observed, making it challenging to determine if the supply of oceanic heat to the ice shelves is changing. Here, we use temperature and salinity profiles to the west of the Shackleton Ice Shelf (SIS; ≈100°E) spanning 60 years to assess the variability of the water masses in the context of a changing climate. We document warming and freshening of shelf waters. Prior to 1996, cold mCDW water (θ < −1.6°C) was found below the surface mixed layer and cold Dense Shelf Water (DSW) with a salinity of >34.5 dominated the water column. After 2010, warm mCDW (≥−1.0°C) was widespread over the continental shelf and DSW with salinity over 34.5 was no longer present. The mixing ratio of glacial meltwater indicates that warm mCDW observed in 2011 caused basal melting of the SIS, possibly reducing the salinity of DSW. Increased access of warm waters to the continental shelf may have also occurred on the eastern side of the ice shelf, where glaciological evidence shows the grounding line has retreated. These observations suggest a shift occurred prior to 2011 that has increased the ocean heat supply to the continental shelf and to the SIS, increasing basal melt and reducing DSW formation.

The role of fresh water in driving ice shelf crevassing, rifting and calving

Meltwater is widely implicated in the disintegration of ice shelves and the lower density of fresh meltwater relative to salty seawater can reconcile observations and models of ice shelf rifting. Advanced numerical models predict that a seawater-filled basal crevasse will break through a shelf to form a rift only where extensional stresses equal those at the seaward shelf edge. However, rifts open in ice shelf interiors where resistance to flow at the sides and base of the ice shelf, or buttressing, is estimated to significantly reduce extensional stresses compared to those at the shelf edge. The stress in a shelf is often quantified in terms of a buttressing number and rifts are seen to open in areas where the estimated buttressing number is between 0.2 and 0.3. Numerical models assuming fresh meltwater-filled basal crevasses predict rift opening for buttressing numbers up to about 0.2. Published estimates indicate that about a quarter of the area of the Antarctic ice shelves are characterized by buttressing numbers less than 0.2. The present results indicate that those areas are directly vulnerable to rifting in the presence of abundant meltwater and that calving of those areas could drive further rifting. The numerical results suggest that rifting can be understood in terms of a horizontal force balance, justifying derivation of a simple analytic relation between the density of water infilling a rift and the maximum buttressing number allowing rifting. This analytic relation should hold for any spacing of crevasses or any vertical variations in ice rheology. Enforcing a horizontal force balance also allows derivation of an analytic relation between the heights of closely spaced ice shelf crevasses and buttressing numbers.

Direct observations of melting, freezing, and ocean circulation in an ice shelf basal crevasse.

Ocean conditions near the grounding zones of Antarctica's ice shelves play a key role in controlling the outflow and mass balance of the ice sheet. However, ocean observations in these regions are largely absent. Here, we present a detailed spatial survey collected with an underwater vehicle in a basal crevasse located in the ocean cavity at the Ross Ice Shelf grounding zone. The observations depict fine-scale variability in ocean forcing that drives asymmetric melting along the lower crevasse sidewalls and freezing in the upper reaches of the crevasse. Freshwater release from melting at depth and salt rejection from freezing above drives an overturning circulation. This vertical circulation pattern overlays a dominant throughflow jet, which funnels water parallel to the coastline, orthogonal to the direction of tidal currents. Importantly, these data reveal that basal crevasses influence ocean circulation and mixing at ice shelf grounding zones to an extent previously unknown.

Mapping Antarctic crevasses and their evolution with deep learning applied to satellite radar imagery

Abstract. The fracturing of glaciers and ice shelves in Antarctica influences their dynamics and stability. Hence, data on the evolving distribution of crevasses are required to better understand the evolution of the ice sheet, though such data have traditionally been difficult and time-consuming to generate. Here, we present an automated method of mapping crevasses on grounded and floating ice with the application of convolutional neural networks to Sentinel-1 synthetic aperture radar backscatter data. We apply this method across Antarctica to images acquired between 2015 and 2022, producing a 7.5-year record of composite fracture maps at monthly intervals and 50 m spatial resolution and showing the distribution of crevasses around the majority of the ice sheet margin. We develop a method of quantifying changes to the density of ice shelf fractures using a time series of crevasse maps and show increases in crevassing on Thwaites and Pine Island ice shelves over the observational period, with observed changes elsewhere in the Amundsen Sea dominated by the advection of existing crevasses. Using stress fields computed using the BISICLES ice sheet model, we show that much of this structural change has occurred in buttressing regions of these ice shelves, indicating a recent and ongoing link between fracturing and the developing dynamics of the Amundsen Sea sector.

Annual mass budget of Antarctic ice shelves from 1997 to 2021.

Antarctic ice shelves moderate the contribution of the Antarctic Ice Sheet to global sea level rise; however, ice shelf health remains poorly constrained. Here, we present the annual mass budget of all Antarctic ice shelves from 1997 to 2021. Out of 162 ice shelves, 71 lost mass, 29 gained mass, and 62 did not change mass significantly. Of the shelves that lost mass, 68 had statistically significant negative mass trends, 48 lost more than 30% of their initial mass, and basal melting was the dominant contributor to that mass loss at a majority (68%). At many ice shelves, mass losses due to basal melting or iceberg calving were significantly positively correlated with grounding line discharge anomalies; however, the strength and form of this relationship varied substantially between ice shelves. Our results illustrate the utility of partitioning high-resolution ice shelf mass balance observations into its components to quantify the contributors to ice shelf mass change and the response of grounded ice.

A Surface Radiation Balance Dataset from Siple Dome in West Antarctica for Atmospheric and Climate Model Evaluation

Abstract A field campaign at Siple Dome in West Antarctica during the austral summer 2019/20 offers an opportunity to evaluate climate model performance, particularly cloud microphysical simulation. Over Antarctic ice sheets and ice shelves, clouds are a major regulator of the surface energy balance, and in the warm season their presence occasionally induces surface melt that can gradually weaken an ice shelf structure. This dataset from Siple Dome, obtained using transportable and solar-powered equipment, includes surface energy balance measurements, meteorology, and cloud remote sensing. To demonstrate how these data can be used to evaluate model performance, comparisons are made with meteorological reanalysis known to give generally good performance over Antarctica (ERA5). Surface albedo measurements show expected variability with observed cloud amount, and can be used to evaluate a model’s snowpack parameterization. One case study discussed involves a squall with northerly winds, during which ERA5 fails to produce cloud cover throughout one of the days. A second case study illustrates how shortwave spectroradiometer measurements that encompass the 1.6-μm atmospheric window reveal cloud phase transitions associated with cloud life cycle. Here, continuously precipitating mixed-phase clouds become mainly liquid water clouds from local morning through the afternoon, not reproduced by ERA5. We challenge researchers to run their various regional or global models in a manner that has the large-scale meteorology follow the conditions of this field campaign, compare cloud and radiation simulations with this Siple Dome dataset, and potentially investigate why cloud microphysical simulations or other model components might produce discrepancies with these observations. significance statement Antarctica is a critical region for understanding climate change and sea level rise, as the great ice sheets and the ice shelves are subject to increasing risk as global climate warms. Climate models have difficulties over Antarctica, particularly with simulation of cloud properties that regulate snow surface melting or refreezing. Atmospheric and climate-related field work has significant challenges in the Antarctic, due to the small number of research stations that can support state-of-the-art equipment. Here we present new data from a suite of transportable and solar-powered instruments that can be deployed to remote Antarctic sites, including regions where ice shelves are most at risk, and we demonstrate how key components of climate model simulations can be evaluated against these data.

Warming beneath an East Antarctic ice shelf due to increased subpolar westerlies and reduced sea ice

Understanding how climate change influences ocean-driven melting of the Antarctic ice shelves is one of the greatest challenges for projecting future sea level rise. The East Antarctic ice shelf cavities host cold water masses that limit melting, and only a few short-term observational studies exist on what drives warm water intrusions into these cavities. We analyse nine years of continuous oceanographic records from below Fimbulisen and relate them to oceanic and atmospheric forcing. On monthly time scales, warm inflow events are associated with weakened coastal easterlies reducing downwelling in front of the ice shelf. Since 2016, however, we observe sustained warming, with inflowing Warm Deep Water temperatures reaching above 0 °C. This is concurrent with an increase in satellite-derived basal melt rates of 0.62 m yr−1, which nearly doubles the basal mass loss at this relatively cold ice shelf cavity. We find that this transition is linked to a reduction in coastal sea ice cover through an increase in atmosphere–ocean momentum transfer and to a strengthening of remote subpolar westerlies. These results imply that East Antarctic ice shelves may become more exposed to warmer waters with a projected increase of circum-Antarctic westerlies, increasing this region’s relevance for sea level rise projections.

Unveiling spatial variability within the Dotson Melt Channel through high-resolution basal melt rates from the Reference Elevation Model of Antarctica

Abstract. The intrusion of Circumpolar Deep Water in the Amundsen and Bellingshausen Sea embayments of Antarctica causes ice shelves in the region to melt from below, potentially putting their stability at risk. Earlier studies have shown how digital elevation models can be used to obtain ice shelf basal melt rates at a high spatial resolution. However, there has been limited availability of high-resolution elevation data, a gap the Reference Elevation Model of Antarctica (REMA) has filled. In this study we use a novel combination of REMA and CryoSat-2 elevation data to obtain high-resolution basal melt rates of the Dotson Ice Shelf in a Lagrangian framework, at a 50 m spatial posting on a 3-yearly temporal resolution. We present a novel method: Basal melt rates Using REMA and Google Earth Engine (BURGEE). The high resolution of BURGEE is supported through a sensitivity study of the Lagrangian displacement. The high-resolution basal melt rates show a good agreement with an earlier basal melt product based on CryoSat-2. Both products show a wide melt channel extending from the grounding line to the ice front, but our high-resolution product indicates that the pathway and spatial variability of this channel is influenced by a pinning point on the ice shelf. This result emphasizes the importance of high-resolution basal melt rates to expand our understanding of channel formation and melt patterns. BURGEE can be expanded to a pan-Antarctic study of high-resolution basal melt rates. This will provide a better picture of the (in)stability of Antarctic ice shelves.

Linear analysis of ice-shelf topography response to basal melting and freezing

Floating ice shelves in Antarctica and Greenland limit land-ice contributions to sea-level rise by resisting the flow of grounded ice. Melting at the surface and base of ice shelves can lead to destabilization by promoting thinning and fracturing. Basal melting often results in channelized features that manifest as surface topography due to buoyancy. The assumption of hydrostatic flotation commonly underlies estimates of basal melting rates. However, numerical simulations and ice-penetrating radar data have shown that narrow topographic features do not necessarily satisfy the local flotation condition. Here, we introduce a linearized model for ice-shelf topographic response to basal melting perturbations to quantify deviations from hydrostatic flotation and the stability of topography. While hydrostatic flotation is the dominant behaviour at wavelengths greater than the ice thickness, ice elevation can deviate from the perfect flotation condition at smaller wavelengths. The linearized analysis shows that channelized features can be stable when the time scale of extensional thinning is small relative to the time scale of viscous flow towards the channel. When extension is non-negligible, channels can break through the ice column. We validate the linearized analysis by comparing numerical solutions to a nonlinear ice-flow model with steady-state solutions obtained via a Green’s function.

Double‐Diffusive Layer and Meltwater Plume Effects on Ice Face Scalloping in Phase‐Change Simulations

AbstractAntarctic ice shelves are losing mass at increasing rates, yet the ice‐ocean interactions that cause significant ice loss are not well understood. A new approach of high‐resolution phase‐change simulations is used to model vertical ice melting into a stratified ocean. The ocean dynamics show complicated interplay between a turbulent buoyant meltwater plume and double‐diffusive layers, while the ice actively melts and changes topography. At room temperatures, the double‐diffusive layer thickness is closely linked to ice scalloping. At lower, more realistic ocean temperatures, the meltwater plume becomes prominent with a laminar‐to‐turbulent transition imprinting an indent on the melting ice. The double‐diffusive layer thickness is consistent with scaling prediction, while the real‐world application demonstrates reasonably good matching of the scaling prediction for some Antarctic regions. Our study is a key first step toward the future use of high‐resolution phase‐change fluid dynamics simulations to better understand Antarctic ice shelves in a changing climate.

The distribution and evolution of surface fractures on pan-Antarctic ice shelves

ABSTRACT Surface fractures have a great impact on ice shelf stability in Antarctica and can be considered precursors of ice shelf calving. However, our understanding of the spatial distribution and temporal evolution of surface fractures on the Antarctic ice shelf is limited. In this study, a ResUNet model was implemented on the Moderate Resolution Imaging Spectroradiometer (MODIS)-based Mosaic of Antarctica (MOA) to identify the spatial distribution of Antarctic ice shelf surface fractures in 2004, 2009, and 2014. The accuracy of identification had an F1 value of 0.771. Our model identified 44744.592619.61 km² of surface fractures in 2004, 43737.152644.60 km² in 2009, and 42978.67 2639.33 km² in 2014. The reduction is primarily attributed to the variation in surface fractures within 20 km of the ice front, paratactically in the Amundsen and Wilkes sectors. Ice shelves in the Amundsen sector typically have a widespread distribution of surface fractures, with particularly high concentrations found in the Thwaites Ice Shelf, Crosson Ice Shelf and Getz Ice Shelf. The Brunt Ice Shelf also exhibits numerous surface fractures. This study provides comprehensive and detailed information about surface fractures on Antarctic ice shelves, carrying implications for evaluating ice shelf vulnerability.

Widespread slowdown in thinning rates of West Antarctic ice shelves

Abstract. Antarctica's floating ice shelves modulate discharge of grounded ice into the ocean by providing a backstress. Ice shelf thinning and grounding line retreat have reduced this backstress, driving rapid drawdown of key unstable areas of the Antarctic Ice Sheet, leading to sea-level rise. If ice shelf loss continues, it may initiate irreversible glacier retreat through the marine ice sheet instability. Identification of areas undergoing significant change requires knowledge of spatial and temporal patterns in recent ice shelf loss. We used 26 years (1992–2017) of satellite-derived Antarctic ice shelf thickness, flow, and basal melt rates to construct a time-dependent dataset of ice shelf thickness and basal melt on a 3 km grid every 3 months. We used a novel data fusion approach, state-of-the-art satellite-derived velocities, and a new surface mass balance model. Our data revealed an overall pattern of thinning all around Antarctica, with a thinning slowdown starting around 2008 widespread across the Amundsen, Bellingshausen, and Wilkes sectors. We attribute this slowdown partly to modulation in external ocean forcing, altered in West Antarctica by negative feedbacks between ice shelf thinning rates and grounded ice flow, and sub-ice-shelf cavity geometry and basal melting. In agreement with earlier studies, the highest rates of ice shelf thinning are found for those ice shelves located in the Amundsen and Bellingshausen sectors. Our study reveals that over the 1992–2017 observational period the Amundsen and Bellingshausen ice shelves experienced a slight reduction in rates of basal melting, suggesting that high rates of thinning are largely a response to changes in ocean conditions that predate our satellite altimetry record, with shorter-term variability only resulting in small deviations from the long-term trend. Our work demonstrates that causal inference drawn from ice shelf thinning and basal melt rates must take into account complex feedbacks between thinning and ice advection and between ice shelf draft and basal melt rates.

Spatial competition in a global disturbance minimum; the seabed under an Antarctic ice shelf

The marine habitat beneath Antarctica's ice shelves spans ∼1.6 million km2, and life in this vast and extreme environment is among Earth's least accessible, least disturbed and least known, yet likely to be impacted by climate-forced warming and environmental change. Although competition among biota is a fundamental structuring force of ecological communities, hence ecosystem functions and services, nothing was known of competition for resources under ice shelves, until this study. Boreholes drilled through a ∼ 200 m thick ice shelf enabled collections of novel sub-ice-shelf seabed sediment which contained fragments of biogenic substrata rich in encrusting (lithophilic) macrobenthos, principally bryozoans – a globally-ubiquitous phylum sensitive to environmental change. Analysis of sub-glacial biogenic substrata, by stereo microscopy, provided first evidence of spatial contest competition, enabling generation of a new range of competition measures for the sub-ice-shelf benthic space. Measures were compared with those of global open-water datasets traversing polar, temperate and tropical latitudes (and encompassing both hemispheres). Spatial competition in sub-ice-shelf samples was found to be higher in intensity and severity than all other global means. The likelihood of sub-ice-shelf competition being intraspecific was three times lower than for open-sea polar continental shelf areas, and competition complexity, in terms of the number of different types of competitor pairings, was two-fold higher. As posited for an enduring disturbance minimum, a specific bryozoan clade was especially competitively dominant in sub-ice-shelf samples compared with both contemporary and fossil assemblage records. Overall, spatial competition under an Antarctic ice shelf, as characterised by bryozoan interactions, was strikingly different from that of open-sea polar continental shelf sites, and more closely resembled tropical and temperate latitudes. This study represents the first analysis of sub-ice-shelf macrobenthic spatial competition and provides a new ecological baseline for exploring, monitoring and comparing ecosystem response to environmental change in a warming world.

Coastal Polynyas Enable Transitions Between High and Low West Antarctic Ice Shelf Melt Rates

AbstractMelt rates of West Antarctic ice shelves in the Amundsen Sea track large decadal variations in the volume of warm water at their outlets. This variability is generally attributed to wind‐driven variations in warm water transport toward ice shelves. Inspired by conceptual representations of the global overturning circulation, we introduce a simple model for the evolution of the thermocline, which caps the warm water layer at the ice‐shelf front. This model demonstrates that interannual variations in coastal polynya buoyancy forcing can generate large decadal‐scale thermocline depth variations, even when the supply of warm water from the shelf‐break is fixed. The modeled variability involves transitions between bistable high and low melt regimes, enabled by feedbacks between basal melt rates and ice front stratification strength. Our simple model captures observed variations in near‐coast thermocline depth and stratification strength, and poses an alternative mechanism for warm water volume changes to wind‐driven theories.

Modelling Antarctic ice shelf basal melt patterns using the one-layer Antarctic model for dynamical downscaling of ice–ocean exchanges (LADDIE v1.0)

Abstract. A major source of uncertainty in future sea level projections is the ocean-driven basal melt of Antarctic ice shelves. While ice sheet models require a kilometre-scale resolution to realistically resolve ice shelf stability and grounding line migration, global or regional 3D ocean models are computationally too expensive to produce basal melt forcing fields at this resolution on long timescales. To bridge this resolution gap, we introduce the 2D numerical model LADDIE (one-layer Antarctic model for dynamical downscaling of ice–ocean exchanges), which allows for the computationally efficient modelling of detailed basal melt fields. The model is open source and can be applied easily to different geometries or different ocean forcings. The aim of this study is threefold: to introduce the model to the community, to demonstrate its application and performance in two use cases, and to describe and interpret new basal melt patterns simulated by this model. The two use cases are the small Crosson–Dotson Ice Shelf in the warm Amundsen Sea region and the large Filchner–Ronne Ice Shelf in the cold Weddell Sea. At ice-shelf-wide scales, LADDIE reproduces observed patterns of basal melting and freezing in warm and cold environments without the need to re-tune parameters for individual ice shelves. At scales of 0.5–5 km, which are typically unresolved by 3D ocean models and poorly constrained by observations, LADDIE produces plausible basal melt patterns. Most significantly, the simulated basal melt patterns are physically consistent with the applied ice shelf topography. These patterns are governed by the topographic steering and Coriolis deflection of meltwater flows, two processes that are poorly represented in basal melt parameterisations. The kilometre-scale melt patterns simulated by LADDIE include enhanced melt rates in grounding zones and basal channels and enhanced melt or freezing in shear margins. As these regions are critical for ice shelf stability, we conclude that LADDIE can provide detailed basal melt patterns at the essential resolution that ice sheet models require. The physical consistency between the applied geometry and the simulated basal melt fields indicates that LADDIE can play a valuable role in the development of coupled ice–ocean modelling.

Morphological changes and future projections of the Getz Ice shelf, western Antarctica—A statistical and geospatial approach

The study assessed the extent of the Getz Ice Shelf over a 19-year period using satellite data and divided it into three sectors. The average of rates (AOR), end point rate (EPR), and linear regression (LR) methods were employed to estimate the rate of change, with the LR method showing the strongest correlation. The analysis revealed a shrinkage rate of 42 m/year during February from 2003 to 2019. Over the last 17 years, recession was observed in 60% of transects, while progradation occurred in 40%. The recent decline in Getz ice shelf extent is closely linked to the record low sea ice extent in the Amundsen Sea sector. Predictions for 2024 and 2029 indicated progradation in Sector I and recession in Sectors II and III, as determined by LR analysis. The root mean square error values of transects in Sectors II and III showed good correlation with past positions and satellite-based observations of ice shelves. To validate the predicted ice shelf extent cross-verified with the satellite and predicted data from 2020 to 2022. These findings highlight the complex interactions between climatic forcings, such as wind speed, sea surface temperature (SST), and the Southern Annular Mode (SAM). Positive SAM and increased zonal winds can contribute to warm water upwelling near the Antarctic coast, impacting ice shelf extent. The relationship between ice mass loss and SST provides valuable insights into the dynamic processes of melting and progradation in the Getz Ice Shelf during February. Ocean warming plays a significant role in increased basal melting and changes in sea ice mass. The study emphasizes the significant impact of ocean-atmospheric factors on Antarctic ice shelf dynamics and highlights the necessity for ongoing satellite observations and enhanced comprehension of these processes to accurately predict future changes in Antarctic ice shelves.

A comparison of contemporaneous airborne altimetry and ice-thickness measurements of Antarctic ice shelves

AbstractEstimates of ice shelf mass loss are typically based on surface height measurements, assuming hydrostatic equilibrium and estimated firn thickness. Recent investigations, however, challenge the assumption that ice shelves are freely floating, particularly in proximity to narrow structures such as basal channels and shear margins. We compare contemporaneous measurements of Antarctic ice shelf thickness, from ice-penetrating radar, to freeboard height, from laser altimetry, acquired during multiple airborne surveys. On average, the hydrostatic thickness differs from observed thickness by at least ~17 ± 98 m, but this difference varies well beyond the propagated error within and among ice shelves, and depends on the corrections applied. We find that uncertainty in firn thickness can account for most, but not all, of the imbalance. Overall, errors in hydrostatic thickness do not significantly impact estimated basal melt rates. Our results indicate that localized approaches to estimating ice shelf thickness and rates of change are not applicable at large scales, and vice versa, and point to the need for more abundant and accurate firn and ice thickness measurements to improve estimates and predictions of ice shelf mass loss.

Seasonal variability in Antarctic ice shelf velocities forced by sea surface height variations

Abstract. Antarctica's ice shelves resist the flow of grounded ice towards the ocean through “buttressing” arising from their contact with ice rises, rumples, and lateral margins. Ice shelf thinning and retreat reduce buttressing, leading to increased delivery of mass to the ocean that adds to global sea level. Ice shelf response to large annual cycles in atmospheric and oceanic processes provides opportunities to study the dynamics of both ice shelves and the buttressed grounded ice. Here, we explore whether seasonal variability of sea surface height (SSH) can explain observed seasonal variability of ice velocity. We investigate this hypothesis using several time series of ice velocity from the Ross Ice Shelf (RIS), satellite-based estimates of SSH seaward of the RIS front, ocean models of SSH under and near RIS, and a viscous ice sheet model. The observed annual changes in RIS velocity are of the order of 1–10 m a−1 (roughly 1 % of mean flow). The ice sheet model, forced by the observed and modelled range of SSH of about 10 cm, reproduces the observed velocity changes when sufficiently large basal drag changes near the grounding line are parameterised. The model response is dominated by grounding line migration but with a significant contribution from SSH-induced tilt of the ice shelf. We expect that climate-driven changes in the seasonal cycles of winds and upper-ocean summer warming will modify the seasonal response of ice shelves to SSH and that nonlinear responses of the ice sheet will affect the longer trend in ice sheet response and its potential sea-level rise contribution.

Quantifying Antarctic‐Wide Ice‐Shelf Surface Melt Volume Using Microwave and Firn Model Data: 1980 to 2021

AbstractAntarctic ice‐shelf stability is threatened by surface melt, which has been implicated in several ice‐shelf collapse events over recent decades. Here, we first analyze cumulative days of wet snow/ice status (“melt days”) for melt seasons from 1980 to 2021 over Antarctica's ice shelves using passive and active microwave satellite observations. As these observations do not directly reveal meltwater volumes, we calculate these using the physics‐based multi‐layer snow model SNOWPACK, driven by the global climate‐reanalysis model Modern‐Era Retrospective analysis for Research and Applications Version 2. We find a strong non‐linear relationship between melt days and meltwater production volume. SNOWPACK's calculation of melt days shows agreement with observations of both cumulative days, and spatial and interannual variability. Highest melt rates are found on the Peninsula ice shelves, particularly in the 1992/1993 and 1994/1995 austral summers. Over all ice shelves, SNOWPACK calculates a small, but significant, decreasing trend in both annual melt days and meltwater production volume over the 41 years.

Estimating spatio-temporal changes in front edge of the Ronne Ice Shelf in context of climate change using remote sensing based integrated approach

Climate variability is thought to have an impact on the Ronne Ice Shelf (RIS), one of the largest ice shelf in Antarctica, located at the mouth of the Weddell Sea. However, investigations evaluating the impact of climate variability on the geometry (front edge) of this ice body have not yet been done. This study examines a spatial-temporal shift in the front edge of the Ronne Ice Shelf during the years 2004–2019 using an integrated approach based on remote sensing and climate data. The Moderate Resolution Imaging Spectro-radiometer (MODIS) satellite images have been used to study the changes in the ice shelf along transects drawn at a constant interval of 5 km throughout the 16-year period over the second half of the austral summer months (February to March). The study reveals that there has been net progradation of ∼20 km in the front edge of the ice shelf in the sector 2 between 2004 and 2019. This progradation in the ice shelf may be attributed to draining of upper ice streams to the RIS and the decrease in temperature. Thus, the present study establishes how a combination of the use of satellite imagery and statistics can effectively be used to comprehend and quantify changes in the variability of the front edge of the ice shelf.