NSFPLR-NERC: Processes, drivers, predictions: Modeling the response of Thwaites Glacier over the next century using ice/ocean coupled models
Lead Research Organisation:
University of Edinburgh
Department Name: Sch of Geosciences
Abstract
We propose to conduct coupled ice-ocean numerical simulations of Thwaites Glacier (TG) to predict its future contribution to global sea level change, and to provide both statistical and structural error estimates using three state-of-the-art ice flow numerical ice-flow models (ISSM, Úa and STREAMICE) coupled with the ocean model MITgcm. We will implement and improve the representation of several key physical processes (calving, ice damage, mechanical basal conditions) that have either not been included, or poorly represented in previous ice-flow modelling work.
We will quantify the relative role of different proposed external drivers of change (e.g., ocean-induced ice-shelf thinning, loss of ice-shelf pinning points), and explore systematically the stability regime of TG with the aim of identifying internal thresholds separating stable and unstable grounding line retreats.
Using inverse methodology, we will produce new physically consistent high-resolution (300 m) data sets on ice-thicknesses from available radar measurements. Furthermore, we will generate several new remote sensing data sets on ice velocities and rates of elevation change. These will be used to constrain and validate our numerical models, and will also be highly valuable as stand-alone data sets.
We will quantify the relative role of different proposed external drivers of change (e.g., ocean-induced ice-shelf thinning, loss of ice-shelf pinning points), and explore systematically the stability regime of TG with the aim of identifying internal thresholds separating stable and unstable grounding line retreats.
Using inverse methodology, we will produce new physically consistent high-resolution (300 m) data sets on ice-thicknesses from available radar measurements. Furthermore, we will generate several new remote sensing data sets on ice velocities and rates of elevation change. These will be used to constrain and validate our numerical models, and will also be highly valuable as stand-alone data sets.
Planned Impact
We will engage with policy makers and the public in several ways. Individually, each academic institution will make use of local options and opportunities available to them. Jointly, we will commission the production of series of short high-quality videos explaining to the general both the results of our work and the generally modelling methodology.
PI Mathieu Morlighem and Co-PI Daniel Goldberg will each share the results of this study through seminars dedicated to undergraduate students and include this project in their respective courses "Modeling the Earth" (General Education class, UC-Irvine) and "Ice and Climate" (Geography course, UoE), thereby exposing many undergraduate and graduate students to the field of glaciology for the first time. In addition, the ISSM team organizes a yearly workshop. This workshop aims at fostering discussions in ice sheet modeling, where new results specific to this field can be presented. It also showcases the new capabilities developed for ISSM, and involves young research scientists that are starting in the field of Cryospheric Science. Within this workshop, time will be allocated to present the new capabilities resulting from this project, and significant scientific results in which ISSM is involved. This workshop will therefore be a platform for presenting the software and scientific products of this project to a young audience. Finally, we plan on integrating a Thwaites Model to the Virtual Earth System Laboratory, a platform used by high-school and middle school students to model ice sheets and glaciers with a simple web-based interface. The Thwaites model will be a simplified version of our modeling effort and will allow the public to "play" with the model and test its sensitivity to ocean warming.
Co-PI Das is actively involved in outreach and classroom activities through Lamont Open House, World Science Festival and museum activities at NY. She will use these venues for reaching out to the public about the science and results of this project. Policy makers will be targeted through contributions that face this audience, e.g. NERC Planet Earth and NERC Science Days.
To reach the general public in much broader way we plan the production of professional videos for a specific project-related YouTube channel. As a project involving numerical models and big data, our proposed research is exceptionally well suited for visually compelling presentations depicting physically realistic-looking flow of ice masses. These can be generated directly from our proposed model runs. We aim to target informed audience interested in global climate issues, and to produce series of highly-professional videos. These will explain both the results of our science, but also demystify how ice-flow modelling is done. We will explain our work in simple terms, but also include more background information than one would typically expect to be provided in the traditional news media. Together with the BAS press office we have already had informal discussions with companies generating computer graphics for a number of BBC documentaries and have arrived at realistic cost estimates. We understand that as a part of this NSF+NERC call there may well be an argument for a combined outreach plan, and we can envision our plans to from a part of such a jointed effort.
PI Mathieu Morlighem and Co-PI Daniel Goldberg will each share the results of this study through seminars dedicated to undergraduate students and include this project in their respective courses "Modeling the Earth" (General Education class, UC-Irvine) and "Ice and Climate" (Geography course, UoE), thereby exposing many undergraduate and graduate students to the field of glaciology for the first time. In addition, the ISSM team organizes a yearly workshop. This workshop aims at fostering discussions in ice sheet modeling, where new results specific to this field can be presented. It also showcases the new capabilities developed for ISSM, and involves young research scientists that are starting in the field of Cryospheric Science. Within this workshop, time will be allocated to present the new capabilities resulting from this project, and significant scientific results in which ISSM is involved. This workshop will therefore be a platform for presenting the software and scientific products of this project to a young audience. Finally, we plan on integrating a Thwaites Model to the Virtual Earth System Laboratory, a platform used by high-school and middle school students to model ice sheets and glaciers with a simple web-based interface. The Thwaites model will be a simplified version of our modeling effort and will allow the public to "play" with the model and test its sensitivity to ocean warming.
Co-PI Das is actively involved in outreach and classroom activities through Lamont Open House, World Science Festival and museum activities at NY. She will use these venues for reaching out to the public about the science and results of this project. Policy makers will be targeted through contributions that face this audience, e.g. NERC Planet Earth and NERC Science Days.
To reach the general public in much broader way we plan the production of professional videos for a specific project-related YouTube channel. As a project involving numerical models and big data, our proposed research is exceptionally well suited for visually compelling presentations depicting physically realistic-looking flow of ice masses. These can be generated directly from our proposed model runs. We aim to target informed audience interested in global climate issues, and to produce series of highly-professional videos. These will explain both the results of our science, but also demystify how ice-flow modelling is done. We will explain our work in simple terms, but also include more background information than one would typically expect to be provided in the traditional news media. Together with the BAS press office we have already had informal discussions with companies generating computer graphics for a number of BBC documentaries and have arrived at realistic cost estimates. We understand that as a part of this NSF+NERC call there may well be an argument for a combined outreach plan, and we can envision our plans to from a part of such a jointed effort.
Organisations
Publications
Maddison J
(2019)
Automated Calculation of Higher Order Partial Differential Equation Constrained Derivative Information
in SIAM Journal on Scientific Computing
Malczyk G
(2023)
Constraints on subglacial melt fluxes from observations of active subglacial lake recharge
in Journal of Glaciology
Malczyk G
(2020)
Repeat Subglacial Lake Drainage and Filling Beneath Thwaites Glacier
in Geophysical Research Letters
Malczyk G
(2021)
Repeat Subglacial Lake Drainage and Filling Beneath Thwaites Glacier
Malczyk, George
(2023)
Constraints on subglacial melt fluxes from observations of active subglacial lake recharge
Morlighem M
(2021)
Mapping the Sensitivity of the Amundsen Sea Embayment to Changes in External Forcings Using Automatic Differentiation
in Geophysical Research Letters
Ockenden H
(2022)
Inverting ice surface elevation and velocity for bed topography and slipperiness beneath Thwaites Glacier
in The Cryosphere
Ockenden H
(2023)
Ice-flow perturbation analysis: a method to estimate ice-sheet bed topography and conditions from surface datasets
in Journal of Glaciology
Robinson A
(2021)
A comparison of the performance of depth-integrated ice-dynamics solvers
Robinson A
(2022)
A comparison of the stability and performance of depth-integrated ice-dynamics solvers
in The Cryosphere
Description | Scientifically Big picture (with selected publications) Barnes et al 2021: One can cast this as an important prerequisite to further work, (which most people would just totally ignore!). This paper establishes a baseline for model uncertainty amongst ISSM/STREAMICE/Úa and also of initialisation uncertainty -- both of which are small with variability well explained. Gudmundsson et al 2023: then establishes that most of the ice shelf is doing very little buttressing -- and hence anything that happens to the existing ice shelf does not have a significant impact on future SLR. Morlighem et al (submitted) in collaboration with DOMINOS, MICI is very unlikely to happen this century. So, these papers establish that (a) our models are "good" at least compared with others, (b) we are not missing MICI for century scale projections, and (c) ultimate losses from TG will depend only on melt and ice loss of newly formed ice shelf over the 21st century. And so in this sense, it sets things up for the coupled modeling we are doing now. Other work: PARSIN ice thickness and multibeam data integrated in the new release of BedMachine, and IBCSO (which is included in GEBCO) Does transient Calibration, through automatic differentiation, improve our ability to make future projections? (Goldberg et al., in prep) Next Steps Coupled ice-sheet ocean modeling is being carried out with three independent models focusing on the fast-thinning ice shelves and glaciers in the Amundsen Embayment, with experimental protocol downscaling ensembles based on 2 CMIP6 scenarios (Paris 2 target ensemble, and RCP85 target ensemble). Modeling is underway or nearing completion for all groups. |
Exploitation Route | it informs that the biggest threat to thwaites glacier is ice ocean interactions -- which will influence others not to focus on ice shelf collapse or marine cliff collapse |
Sectors | Environment |
Description | Findings have been presented in a SAGES (Scottish Assoc of Geoscience Env and Society) public outreach event, attended by 100 members of the general public |
First Year Of Impact | 2021 |
Sector | Environment |
Impact Types | Societal |
Title | Model data for "The transferability of adjoint inversion products between different ice flow models" |
Description | Inputs and outputs of experiments run for the paper "The transferability of adjoint inversion products between different ice flow models", published in The Cryosphere. Geometry inputs are from BedMachine Antarctica v.1 (Morlighem, 2019). Surface mass balance inputs derive from RACMO2.1 (Lenaerts et al., 2012). Velocity measurements and errors derive from a dataset first described in Mouginot et al. (2014). |
Type Of Material | Database/Collection of data |
Year Produced | 2021 |
Provided To Others? | Yes |
URL | https://zenodo.org/record/4701342 |
Title | Model output from Inverting ice surface elevation and velocity for bed topography and slipperiness beneath Thwaites Glacier |
Description | This model output dataset accompanies the draft paper 'Inverting ice surface elevation and velocity for bed topography and slipperiness beneath Thwaites Glacier'. |
Type Of Material | Database/Collection of data |
Year Produced | 2021 |
Provided To Others? | Yes |
URL | https://zenodo.org/record/5105686 |
Title | hockenden97/Inverting_ice_surface: Paper release |
Description | This code accompanies the draft paper 'Inverting ice surface elevation and velocity for bed topography and slipperiness beneath Thwaites Glacier'. |
Type Of Technology | Software |
Year Produced | 2021 |
URL | https://zenodo.org/record/5494599 |