Two-timescale response of a large Antarctic ice shelf to climate change

Naughten, Kaitlin A.; Rydt, Jan De; Rosier, Sebastian; Jenkins, Adrian; Holland, Paul R.; Ridley, Jeff

doi:10.1038/s41467-021-22259-0

Cited by 90 publications

(110 citation statements)

References 55 publications

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“…MISMIP and MISMIP+; Pattyn et al, 2012;Cornford et al, 2015), and more recently on an ice sheet scale as part of the ISMIP6 project (Seroussi et al, 2020). Recently, the use of uncertainty quantification techniques has become more common for estimating uncertainties in projections of, for example, sea level rise, based on the current knowledge of uncertainties associated with model parameters or forcing functions (parametric uncertainty) (Edwards et al, 2019;Schlegel et al, 2018Schlegel et al, , 2015Bulthuis et al, 2019;Aschwanden et al, 2019;Nias et al, 2019;Wernecke et al, 2020). This includes techniques that weight model parameters and outputs according to some performance measures, to provide a probabilistic assessment of sea level change (Pollard et al, 2016;Ritz et al, 2015).…”

Section: Uncertainty Quantificationmentioning

confidence: 99%

Quantifying the potential future contribution to global mean sea level from the Filchner–Ronne basin, Antarctica

et al. 2021

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Abstract. The future of the Antarctic Ice Sheet in response to climate warming is one of the largest sources of uncertainty in estimates of future changes in global mean sea level (ΔGMSL). Mass loss is currently concentrated in regions of warm circumpolar deep water, but it is unclear how ice shelves currently surrounded by relatively cold ocean waters will respond to climatic changes in the future. Studies suggest that warm water could flush the Filchner–Ronne (FR) ice shelf cavity during the 21st century, but the inland ice sheet response to a drastic increase in ice shelf melt rates is poorly known. Here, we use an ice flow model and uncertainty quantification approach to project the GMSL contribution of the FR basin under RCP emissions scenarios, and we assess the forward propagation and proportional contribution of uncertainties in model parameters (related to ice dynamics and atmospheric/oceanic forcing) on these projections. Our probabilistic projections, derived from an extensive sample of the parameter space using a surrogate model, reveal that the FR basin is unlikely to contribute positively to sea level rise by the 23rd century. This is primarily due to the mitigating effect of increased accumulation with warming, which is capable of suppressing ice loss associated with ocean-driven increases in sub-shelf melt. Mass gain (negative ΔGMSL) from the FR basin increases with warming, but uncertainties in these projections also become larger. In the highest emission scenario RCP8.5, ΔGMSL is likely to range from −103 to 26 mm, and this large spread can be apportioned predominantly to uncertainties in parameters driving increases in precipitation (30 %) and sub-shelf melting (44 %). There is potential, within the bounds of our input parameter space, for major collapse and retreat of ice streams feeding the FR ice shelf, and a substantial positive contribution to GMSL (up to approx. 300 mm), but we consider such a scenario to be very unlikely. Adopting uncertainty quantification techniques in future studies will help to provide robust estimates of potential sea level rise and further identify target areas for constraining projections.

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Section: Uncertainty Quantificationmentioning

confidence: 99%

Quantifying the potential future contribution to global mean sea level from the Filchner–Ronne basin, Antarctica

et al. 2021

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“…As the ocean component has warm biases at intermediate depth around the Antarctic margin, we apply an anomaly approach to avoid unrealistic high melting and obtain physically meaningful simulations of the coupled system. We add anomalies from the ocean model component to observed temperatures, similar to the approach in ISMIP6 (Jourdain et al, 2020;Nowicki et al, 2020). The difficulties to accurately simulate Antarctic shelf dynamics and deep water formation in the Southern Ocean with ocean general circulation models is a longstanding issue for the ocean modelling community, with almost no models of the CMIP5 generation able to do this successfully (Heuzé et al, 2013).…”

Section: Discussionmentioning

confidence: 99%

“…Evidence that the Holocene retreat of the West Antarctic Ice Sheet was driven by warm water intrusions onto the continental shelf was provided by the palaeo-proxy data analysis of Hillenbrand et al (2017) and supported by ensemble modelling for the Ross Embayment (Lowry et al, 2019). Ice sheets respond to changing oceanic and atmospheric conditions, but they also feed back to the Earth's climate in various ways, including through meltwater input into the oceans, sea level change, or change in atmospheric circulation and precipitation patterns resulting from changes in orography and albedo (Nowicki et al, 2020;Vizcaíno et al, 2014). To study interactions and feedbacks between the Antarctic Ice Sheet and the ocean, such as through melt-induced freshwater input into the ocean, numerical models are an important tool.…”

Section: Introductionmentioning

confidence: 97%

“…Asay-Davis et al, 2017, for a more in-depth discussion). The latter approach is used, for instance, in the Ice Sheet Model Intercomparison Project for CMIP6 (ISMIP6; Nowicki et al, 2020;Seroussi et al, 2020;Jourdain et al, 2020), where stand-alone ice sheet models are forced by atmospheric and oceanic boundary conditions from CMIP5 (Taylor et al, 2012) to constrain Antarctic mass loss and sea level rise until the end of the century.…”

Section: Introductionmentioning

confidence: 99%

“…De Rydt and Gudmundsson, 2016) or regional set-ups (e.g. Naughten et al, 2021;Seroussi et al, 2017;Timmermann and Goeller, 2017). They can also be used to assess simple melt parameterizations from category 2 (e.g.…”

Section: Introductionmentioning

confidence: 99%

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Coupling framework (1.0) for the PISM (1.1.4) ice sheet model and the MOM5 (5.1.0) ocean model via the PICO ice shelf cavity model in an Antarctic domain

et al. 2021

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Abstract. The past and future evolution of the Antarctic Ice Sheet is largely controlled by interactions between the ocean and floating ice shelves. To investigate these interactions, coupled ocean and ice sheet model configurations are required. Previous modelling studies have mostly relied on high-resolution configurations, limiting these studies to individual glaciers or regions over short timescales of decades to a few centuries. We present a framework to couple the dynamic ice sheet model PISM (Parallel Ice Sheet Model) with the global ocean general circulation model MOM5 (Modular Ocean Model) via the ice shelf cavity model PICO (Potsdam Ice-shelf Cavity mOdel). As ice shelf cavities are not resolved by MOM5 but are parameterized with the PICO box model, the framework allows the ice sheet and ocean components to be run at resolutions of 16 km and 3∘ respectively. This approach makes the coupled configuration a useful tool for the analysis of interactions between the Antarctic Ice Sheet and the global ocean over time spans of the order of centuries to millennia. In this study, we describe the technical implementation of this coupling framework: sub-shelf melting in the ice sheet component is calculated by PICO from modelled ocean temperatures and salinities at the depth of the continental shelf, and, vice versa, the resulting mass and energy fluxes from melting at the ice–ocean interface are transferred to the ocean component. Mass and energy fluxes are shown to be conserved to machine precision across the considered component domains. The implementation is computationally efficient as it introduces only minimal overhead. Furthermore, the coupled model is evaluated in a 4000 year simulation under constant present-day climate forcing and is found to be stable with respect to the ocean and ice sheet spin-up states. The framework deals with heterogeneous spatial grid geometries, varying grid resolutions, and timescales between the ice and ocean component in a generic way; thus, it can be adopted to a wide range of model set-ups.

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A high-end estimate of sea-level rise for practitioners

Wal¹,

Nicholls

Béhar

et al. 2022

Preprint

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Sea-level rise (SLR) is a long-lasting consequence of climate change because global anthropogenic warming takes centuries to millennia to equilibrate for the deep ocean and ice sheets. SLR projections based on climate models support policy analysis, risk assessment and adaptation planning today, despite their large uncertainties. The central range of the SLR distribution is estimated by process-based models. However, risk-averse practitioners often require information about plausible future conditions that lie in the tails of the SLR distribution, which are poorly defined by existing models. Here, a community effort combining scientists and practitioners builds on a framework of discussing physical evidence to quantify high-end global SLR for practitioners. The approach is complementary to the IPCC AR6 report and provides further physically plausible high-end scenarios. High-end estimates for the different SLR components are developed for two climate scenarios at two timescales. For global warming of +2 ˚C in 2100 (RCP2.6/SSP1-2.6) relative to pre-industrial values our high-end global SLR estimates are up to 0.9 m in 2100 and 2.5 m in 2300. Similarly, for a (RCP8.5/SSP5-8.5) we estimate up to 1.6 m in 2100 and up to 10.4 m in 2300. The large and growing differences between the scenarios beyond 2100 emphasize the long-term benefits of mitigation. However, even a modest 2 ˚C warming may cause multi-meter SLR on centennial time scales with profound consequences for coastal areas. Earlier high-end assessments focused on instability mechanisms in Antarctica, while here we emphasize the importance of the timing of ice shelf collapse around Antarctica. This is highly uncertain due to low understanding of the driving processes. Hence both process understanding and emission scenario control high-end SLR.

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Two-timescale response of a large Antarctic ice shelf to climate change

Cited by 90 publications

References 55 publications

Quantifying the potential future contribution to global mean sea level from the Filchner–Ronne basin, Antarctica

Quantifying the potential future contribution to global mean sea level from the Filchner–Ronne basin, Antarctica

Coupling framework (1.0) for the PISM (1.1.4) ice sheet model and the MOM5 (5.1.0) ocean model via the PICO ice shelf cavity model in an Antarctic domain

A high-end estimate of sea-level rise for practitioners

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