Collaborative Research: Improving Model Representations of Antarctic Ice-shelf Instability and Break-up due to Surface Meltwater Processes

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Ice shelves are the floating extensions of glaciers on land. They surround 75 percent of Antarctica and have an important role in regulating the rate that inland glacier ice is lost to the ocean, which leads to sea-level rise. Meltwater that ponds on the surfaces of these ice shelves has been observed to cause ice shelves to flex and fracture, and, in some cases, to experience large-scale collapse events. For example, the near-complete collapse of the Larsen B Ice Shelf in 2002 is thought to have been caused by the drainage of over 2000 surface lakes during just a number of weeks. Extensive ponding is observed on many of Antarctica’s ice shelves. As atmospheric temperatures increase, surface meltwater-induced ice-shelf breakup events are expected to increase in areal extent and frequency. However, future predictions of such events lack accuracy because no large-scale ice-sheet model is able to realistically simulate the processes involved in surface-meltwater-induced ice-shelf breakup. This project aims to address the current modeling limitation by developing a new component for the continental-scale Ice-sheet and Sea-level System Model (ISSM) that will be capable of simulating surface meltwater-induced flexure, fracture, and large-scale ice-shelf break-up. By forcing the model with a suite of future climate-change scenarios the project aims to deliver more accurate estimates of Antarctica’s contribution to future global sea-level rise over the remainder of this century and beyond.To achieve the project’s ultimate step of developing a new model component for the Ice-sheet and Sea-level System Model (ISSM), the team will first develop a coupled process-scale model of ice-shelf hydrology-flow-flexure-fracture (the H3F model). This is required because the physics involved in ice-shelf collapse typically occurs on finer temporal and spatial scales than captured by continental ice-sheet models such as ISSM. Once the H3F model is developed, it will be used to quantify relationships between surface meltwater processes, ice flow, viscoelastic flexure, and hydrofracture. The team will translate these relationships to the ice-sheet scale by developing a machine-learning-leveraged statistical emulator of the H3F model. This approach towards multi-physics modeling aims to provide new inroads to the computationally challenging problem of surface meltwater-induced ice-shelf collapse at both small- and continental-scales. Broader impacts of the project will include public education and engagement through development of a children’s web application, interaction with a Chicago-based artist collective, and development of ISSM’s outreach webpage to facilitate interactive visualizations of Antarctica ice-shelf collapse events under a range of future climate scenarios.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.