Alexander A. Robel

Supraglacial melt lakes have been implicated in past ice shelf collapses that have enhanced Antarctica's contribution to sea-level rise. Despite their potential importance in determining ice sheet mass loss, supraglacial melt lakes are not represented in large-scale ice sheet models. In this study, we develop a new calving methodology to represent fracture depth due to viscous ice stresses and hydrostatic pressure from supraglacial melt lakes. We test this calving scheme in a benchmark simulation of Antarctic Ice Sheet evolution to 2300. Assuming that the depth of supraglacial melt lakes drives hydrofracture of crevasses results in 30\% more ice loss above flotation than a simulation that incorporates the depth of crevasses without meltwater collecting into lakes. The inclusion of supraglacial melt-lake depth-induced hydrofracture in ice-sheet simulations results in loss of floating ice area 25-30 years earlier compared to current state-of-the-art simulations.

Iceberg calving driven by crevasse propagation is an important source of ice loss from the Greenland and Antarctic ice sheets. However, simulating crevasse growth and interaction in 3D, spanning meters to kilometers length scales, remains computationally challenging for high‐fidelity models based on nonlocal continuum damage mechanics and phase‐field fracture approaches. The high computational cost of high‐fidelity models comes from the need to adequately resolve the damage/phase‐field length scale (often meters in scale) within the finite element method to capture complex crevasse patterns and interactions, involving stress redistribution, shielding, and coalescence. To overcome this difficulty, a scalable parallel implementation for crack evolution is developed using the open‐source finite element software FEniCS, which features a novel recursively adaptive mesh refinement (RAMR) algorithm to solve the stress‐based phase‐field fracture model equations in 3D. The RAMR algorithm automatically refines the mesh in the fracture process zones based on the phase field variable and a user‐defined finest cell size to capture crack propagation and coalescence accurately and efficiently. Idealized simulations of kilometer‐scale glacier domains show 13‐ to 45‐fold speedup compared to locally refined meshes, with less than 2% discrepancy in crevasse depth. This computational efficiency enables kilometer‐scale simulations of a field of closely spaced crevasses showcasing arcuate paths and crisscross patterns, resembling field and remotely‐sensed observations of glacier crevasses. The simulations also reveal that crevasse growth is predominantly governed by tensile principal stresses, which are determined by the initial crevasse spacing and margin boundary conditions.

Transportation professionals increasingly must handle disruptions ranging from extreme weather to cascading failures across infrastructure systems. Educators across disciplines are tasked with equipping future professionals with the skills needed to build resilience, defined as the ability to anticipate, withstand, and adapt to these complex and sometimes cross-sectoral disruptions. This study explores how transportation resilience is taught across engineering, planning, and related programs based on a syllabus review followed by a targeted survey of educators. The results include trends in topics taught, teaching methods, assignment types, and perceived student response for transportation resilience educational offerings. The paper then presents a flexible four-part module that emphasizes systems thinking, infrastructure interdependence, collaboration across disciplines and sectors, and uncertainty management. This work highlights the status of transportation resilience education and contributes a teaching-and-learning resource to help prepare future transportation professionals to protect critical infrastructure in an uncertain future.

Antarctica's floating ice shelves experience considerable surface melting, leading to the formation of supraglacial melt lakes. The presence of surface meltwater and the formation of these lakes leaves ice shelves vulnerable to meltwater-induced damage. This can lead to the loss of the buttressing effect provided by ice shelves on the grounded ice sheet, thus increasing Antarctica's potential sea level contribution. Understanding the surface hydrology of ice shelves in the present and the future is thus an essential first step to reliably project future vulnerability of Antarctic ice shelves to meltwater-driven hydrofracture and possible collapse events. Therefore, we have developed the first comprehensive 3-D Model for Antarctic Ice Shelf Hydrology and Stability, called MONARCHS. MONARCHS calculates the surface energy balance of the ice shelf, heat transfer through the ice shelf and the volume of any subsequent meltwater that is produced when the surface energy balance is positive. The model simulates both vertical and lateral movement of this meltwater through the firn, calculating refreezing and saturation of firn air space as well the related changes in temperature and density. When firn is saturated and surface melt lakes can form, the model simulates the full lake lifecycle, including lake depth increases and full refreezing. We present a case study focused on the George VI Ice Shelf on the Antarctic Peninsula where significant melt lake formation has been observed in recent years. The model shows reasonable agreement in lake extent and depth with observations. Furthermore, we demonstrate that the speed of lateral meltwater percolation through firn, a key uncertainty in firn modelling, has significant consequences for lake extent and depth, suggesting future research should focus on reducing this uncertainty. This community-driven, open-access model has been developed with input from observations, and will allows us to provide new insights into the surface meltwater distribution on Antarctica’s ice shelves.

Antarctica's floating ice shelves experience considerable surface melting, leading to the formation of supraglacial melt lakes. The presence of surface meltwater and the formation of these lakes leaves ice shelves vulnerable to meltwater-induced damage. This can lead to the loss of the buttressing effect provided by ice shelves on the grounded ice sheet, thus increasing Antarctica's potential sea level contribution. Understanding the surface hydrology of ice shelves in the present and the future is thus an essential first step to reliably project future vulnerability of Antarctic ice shelves to meltwater-driven hydrofracture and possible collapse events. Therefore, we have developed the first comprehensive 3-D Model for Antarctic Ice Shelf Hydrology and Stability, called MONARCHS. MONARCHS calculates the surface energy balance of the ice shelf, heat transfer through the ice shelf and the volume of any subsequent meltwater that is produced when the surface energy balance is positive. The model simulates both vertical and lateral movement of this meltwater through the firn, calculating refreezing and saturation of firn air space as well the related changes in temperature and density. When firn is saturated and surface melt lakes can form, the model simulates the full lake lifecycle, including lake depth increases and full refreezing. We present a case study focused on the George VI Ice Shelf on the Antarctic Peninsula where significant melt lake formation has been observed in recent years. The model shows reasonable agreement in lake extent and depth with observations. Furthermore, we demonstrate that the speed of lateral meltwater percolation through firn, a key uncertainty in firn modelling, has significant consequences for lake extent and depth, suggesting future research should focus on reducing this uncertainty. This community-driven, open-access model has been developed with input from observations, and will allows us to provide new insights into the surface meltwater distribution on Antarctica’s ice shelves.

Antarctica's floating ice shelves experience considerable surface melting, leading to the formation of supraglacial melt lakes. The presence of surface meltwater and the formation of these lakes leaves ice shelves vulnerable to meltwater-induced damage. This can lead to the loss of the buttressing effect provided by ice shelves on the grounded ice sheet, thus increasing Antarctica's potential sea level contribution. Understanding the surface hydrology of ice shelves in the present and the future is thus an essential first step to reliably project future vulnerability of Antarctic ice shelves to meltwater-driven hydrofracture and possible collapse events. Therefore, we have developed the first comprehensive 3-D Model for Antarctic Ice Shelf Hydrology and Stability, called MONARCHS. MONARCHS calculates the surface energy balance of the ice shelf, heat transfer through the ice shelf and the volume of any subsequent meltwater that is produced when the surface energy balance is positive. The model simulates both vertical and lateral movement of this meltwater through the firn, calculating refreezing and saturation of firn air space as well the related changes in temperature and density. When firn is saturated and surface melt lakes can form, the model simulates the full lake lifecycle, including lake depth increases and full refreezing. We present a case study focused on the George VI Ice Shelf on the Antarctic Peninsula where significant melt lake formation has been observed in recent years. The model shows reasonable agreement in lake extent and depth with observations. Furthermore, we demonstrate that the speed of lateral meltwater percolation through firn, a key uncertainty in firn modelling, has significant consequences for lake extent and depth, suggesting future research should focus on reducing this uncertainty. This community-driven, open-access model has been developed with input from observations, and will allows us to provide new insights into the surface meltwater distribution on Antarctica’s ice shelves.

Interannual variability of surface mass balance over the Greenland Ice Sheet has been increasing, which has been cited as an early-warning signal of ice sheet destabilization under current climatic conditions. A destabilized ice sheet would continue to lose mass and contribute to global sea level rise, even if climate stopped changing in the future. Here, we investigate the mechanisms driving nonstationarity of surface mass balance variability in a high-fidelity surface mass balance reconstruction, and a calibrated simple model. We show that, regardless of the proximity to destabilization, increasing variability in surface mass balance is an expected consequence of atmospheric warming on low-accumulation parts of the ice sheet. Autocorrelation of surface mass balance exhibits spurious multidecadal trends under a wide range of climatic conditions due to the slow response of ice sheets to climatic fluctuations, making this a poor early-warning signal of destabilization. Though these findings do not rule out the potential for destabilization under current or future climate, they provide a conceptual framework for understanding the drivers of surface melt variability.

Antarctica's floating ice shelves experience considerable surface melting, leading to the formation of supraglacial melt lakes. The presence of surface meltwater and the formation of these lakes leaves ice shelves vulnerable to meltwater-induced damage. This can lead to the loss of the buttressing effect provided by ice shelves on the grounded ice sheet, thus increasing Antarctica's potential sea level contribution. Understanding the surface hydrology of ice shelves in the present and the future is thus an essential first step to reliably project future vulnerability of Antarctic ice shelves to meltwater-driven hydrofracture and possible collapse events. Therefore, we have developed the first comprehensive 3-D Model for Antarctic Ice Shelf Hydrology and Stability, called MONARCHS. MONARCHS calculates the surface energy balance of the ice shelf, heat transfer through the ice shelf and the volume of any subsequent meltwater that is produced when the surface energy balance is positive. The model simulates both vertical and lateral movement of this meltwater through the firn, calculating refreezing and saturation of firn air space as well the related changes in temperature and density. When firn is saturated and surface melt lakes can form, the model simulates the full lake lifecycle, including lake depth increases and full refreezing. We present a case study focused on the George VI Ice Shelf on the Antarctic Peninsula where significant melt lake formation has been observed in recent years. The model shows reasonable agreement in lake extent and depth with observations. Furthermore, we demonstrate that the speed of lateral meltwater percolation through firn, a key uncertainty in firn modelling, has significant consequences for lake extent and depth, suggesting future research should focus on reducing this uncertainty. This community-driven, open-access model has been developed with input from observations, and will allows us to provide new insights into the surface meltwater distribution on Antarctica’s ice shelves.

Despite large uncertainties associated with future mass loss from the Antarctic Ice Sheet, ice-sheet models show that the rate of sea-level rise from Antarctic ice loss in 2025 is strongly predictive of the rate for the next several decades, regardless of emission pathway or model complexity. This finding is robust across all models that were considered in the Intergovernmental Panel on Climate Change Sixth Assessment Report global mean sea-level projections, including the low-likelihood, high-impact scenarios of sea-level rise. Given this strong near-term decadal predictability, ice-sheet models that can accurately reproduce present-day ice-mass loss provide a reliable basis for near-term sea-level planning and adaptation through to mid-century. The predictability breaks down by the end of the twenty-first century as feedbacks, such as those related to marine ice-sheet retreat, begin to emerge, leading to accelerating ice loss. Drawing on these results, we identify key feedback mechanisms that can account for the transition between near-term decadal predictability and the longer-term, feedback-driven evolution, and suggest priorities for ice-sheet model development aimed at resolving long-term sea-level rise uncertainty.