NSFGEO-NERC: Ice-shelf Instability Caused by Active Surface Meltwater Production, Movement, Ponding and Hydrofracture
Lead Research Organisation:
University of Cambridge
Department Name: Scott Polar Research Institute
Abstract
The floating ice shelves around Antarctica provide a buffer against rapid ice flow from the continent's interior to the ocean. If that buffer is reduced or removed, there will be more rapid ice flow to the ocean contributing to sea level rise. Understanding the controls on ice shelf stability, therefore, is important for the assessment and prediction of possible ice shelf shrinkage or collapse. Evidence shows that one source of ice shelf instability comes from surface melting and the movement of the meltwater. The decade-long development of >2500 surface lakes on the Larsen B Ice Shelf, followed by their abrupt drainage, were the two most conspicuous precursors to the ice shelf's sudden collapse in 2002.
This project will investigate how ice shelves fracture when subjected to strong surface melting using a suite of geophysical observations on the George VI Ice Shelf (GVIIS) of the Antarctic Peninsula. The leading processes to be observed are viscoelastic ice-shelf flexure and fracture in response to surface meltwater movement, loading, and unloading. The team's prior fieldwork provided the first direct measurements of these processes on the McMurdo Ice Shelf (McMIS). However, the results were somewhat limited in their application to other ice shelves due to a heterogeneous debris cover and therefore atypical ablation rates, sparsely-distributed ponds, and ice-flexure measurements made close to an active rift.
Compared to the McMIS, the GVIIS provides a near-perfect opportunity to observe meltwater loading processes, as satellite imagery shows it hosts hundreds of lakes and displays features of viscoelastic rebound in response to lake drainage. Furthermore, GVIIS is thought not to be at risk of imminent breakup due to its compressive stress regime, making the ice shelf a safe working environment. The proposed 4-year project will conduct a 27-month period (November 2019 - January 2022) of measurements on the GVIIS. Seismometers, global positioning system (GPS), water pressure transducers, two automatic weather stations, and thermistor strings will be deployed to record fracture seismicity, ice shelf flexure, water depths, and surface and subsurface melting, respectively, in and around identified meltwater features. These instruments will be deployed in a 20 x 20 km field area immediately adjacent to BAS's Fossil Bluff Station. Field data will be used to validate and extend the team's existing approach to modelling ice-shelf flexure and stress that can lead to hydrofracture, drainage of surface water to the ocean below, and possible Larsen-B style ice-shelf instability.
This project will investigate how ice shelves fracture when subjected to strong surface melting using a suite of geophysical observations on the George VI Ice Shelf (GVIIS) of the Antarctic Peninsula. The leading processes to be observed are viscoelastic ice-shelf flexure and fracture in response to surface meltwater movement, loading, and unloading. The team's prior fieldwork provided the first direct measurements of these processes on the McMurdo Ice Shelf (McMIS). However, the results were somewhat limited in their application to other ice shelves due to a heterogeneous debris cover and therefore atypical ablation rates, sparsely-distributed ponds, and ice-flexure measurements made close to an active rift.
Compared to the McMIS, the GVIIS provides a near-perfect opportunity to observe meltwater loading processes, as satellite imagery shows it hosts hundreds of lakes and displays features of viscoelastic rebound in response to lake drainage. Furthermore, GVIIS is thought not to be at risk of imminent breakup due to its compressive stress regime, making the ice shelf a safe working environment. The proposed 4-year project will conduct a 27-month period (November 2019 - January 2022) of measurements on the GVIIS. Seismometers, global positioning system (GPS), water pressure transducers, two automatic weather stations, and thermistor strings will be deployed to record fracture seismicity, ice shelf flexure, water depths, and surface and subsurface melting, respectively, in and around identified meltwater features. These instruments will be deployed in a 20 x 20 km field area immediately adjacent to BAS's Fossil Bluff Station. Field data will be used to validate and extend the team's existing approach to modelling ice-shelf flexure and stress that can lead to hydrofracture, drainage of surface water to the ocean below, and possible Larsen-B style ice-shelf instability.
Planned Impact
PI Willis (together with collaborators funded via the NSF component of the grant: Banwell, MacAyeal and Stevens) will engage in a number of specific outreach and community activities designed to enhance the societal value of the science conducted. PI Willis is based at the Scott Polar Research Institute (SPRI), U. Cambridge, which has the largest polar museum in the UK with evolving exhibits showcasing current science and regular outreach programs extending into the local and regional communities, especially those in disadvantaged areas. The museum had over 50,000 visitors in 2017, including around 10,000 young people under 18. Over 17,000 visitors accessed the museum's online educational resources in 2017. Willis will work with the full time museum curator to produce an exhibit for both the museum and online which showcases our proposed ice-shelf research. Willis is also a regular contributor to the annual University Science Festival, where he will also showcase the proposed work in the form of a 'hands on' physical model of ice shelves aimed at young children, and a public lecture aimed at older children and adults.
The three NSF-funded collaborators will also engage in a range of outreach activities. Highlights include:
PI Banwell will continue to develop the Antarctic science/climate change component to a childrens' iPad/tablet app called 'Molly's World' a project led by Richard Weston, former Professor at Cardiff University, UK. The freely available app will be an ideal vehicle for reaching large numbers of children.
PI MacAyeal will continue interaction with an artist consortium called Luftwerk. With MacAyeal's help, this artist consortium developed the 'White Wanderer' display for an outdoor public space in the city of Chicago to draw attention to climate change and the large iceberg that calved from Larsen C, which made the New Yorker Magazine's top 10 sounds for 2017.
PI Stevens will continue to engage with the public through Columbia University, which hosts many outreach events in New York City throughout the year. Stevens will be an active participant in the LDEO Open House, Women in Science Graduate Research Symposium, Girls in Science and Engineering Day at the Intrepid Museum, and will strengthen her community ties in New York City, by working with the Climate Museum to develop programming on surface melt on Antarctic ice shelves.
Broader-impact activities will also involve developing and maintaining a website that will be hosted at U. Colorado Boulder, but mirrored by SPRI, University of Cambridge, designed to give non-scientists a vivid and interesting overview of the project. The website will also have some content intended for the glaciological community, and will enable the exchange of ideas about the project's methods and results, as well as to stimulate similar science by others. A dedicated Twitter account will also be set-up and updated regularly.
The three NSF-funded collaborators will also engage in a range of outreach activities. Highlights include:
PI Banwell will continue to develop the Antarctic science/climate change component to a childrens' iPad/tablet app called 'Molly's World' a project led by Richard Weston, former Professor at Cardiff University, UK. The freely available app will be an ideal vehicle for reaching large numbers of children.
PI MacAyeal will continue interaction with an artist consortium called Luftwerk. With MacAyeal's help, this artist consortium developed the 'White Wanderer' display for an outdoor public space in the city of Chicago to draw attention to climate change and the large iceberg that calved from Larsen C, which made the New Yorker Magazine's top 10 sounds for 2017.
PI Stevens will continue to engage with the public through Columbia University, which hosts many outreach events in New York City throughout the year. Stevens will be an active participant in the LDEO Open House, Women in Science Graduate Research Symposium, Girls in Science and Engineering Day at the Intrepid Museum, and will strengthen her community ties in New York City, by working with the Climate Museum to develop programming on surface melt on Antarctic ice shelves.
Broader-impact activities will also involve developing and maintaining a website that will be hosted at U. Colorado Boulder, but mirrored by SPRI, University of Cambridge, designed to give non-scientists a vivid and interesting overview of the project. The website will also have some content intended for the glaciological community, and will enable the exchange of ideas about the project's methods and results, as well as to stimulate similar science by others. A dedicated Twitter account will also be set-up and updated regularly.
Organisations
People |
ORCID iD |
Ian Willis (Principal Investigator) |
Publications
Banwell A
(2021)
The 32-year record-high surface melt in 2019/2020 on the northern George VI Ice Shelf, Antarctic Peninsula
in The Cryosphere
Benedek C
(2021)
Winter drainage of surface lakes on the Greenland Ice Sheet from Sentinel-1 SAR imagery
in The Cryosphere
Boxall K
(2022)
Seasonal land-ice-flow variability in the Antarctic Peninsula
Boxall K
(2022)
Seasonal land ice-flow variability in the Antarctic Peninsula
Boxall K
(2022)
Seasonal land-ice-flow variability in the Antarctic Peninsula
in The Cryosphere
Boxall K
(2024)
Circum-Antarctic seasonality in grounded ice flow
Boxall, K
(2022)
Seasonal Land Ice Flow Variability in the Antarctic Peninsula
Boxall, K
(2022)
Seasonal land ice-flow variability across the Antarctic Peninsula
Deakin K
(2023)
Oscillatory response of Larsen C Ice Shelf flow to the calving of iceberg A-68
in Journal of Glaciology
Dell R
(2020)
Lateral meltwater transfer across an Antarctic ice shelf
Dell R
(2021)
Supervised classification of slush and ponded water on Antarctic ice shelves using Landsat 8 imagery
in Journal of Glaciology
Dell R
(2020)
Lateral meltwater transfer across an Antarctic ice shelf
in The Cryosphere
Dell R
(2020)
Lateral meltwater transfer across an Antarctic ice shelf
Dell R
(2022)
Supervised classification of slush and ponded water on Antarctic ice shelves using Landsat 8 imagery - CORRIGENDUM
in Journal of Glaciology
Dunmire D
(2020)
Observations of Buried Lake Drainage on the Antarctic Ice Sheet.
Dunmire D
(2020)
Observations of Buried Lake Drainage on the Antarctic Ice Sheet.
in Geophysical research letters
MacAyeal D
(2021)
Treatment of ice-shelf evolution combining flow and flexure
in Journal of Glaciology
MacAyeal D
(2020)
Diurnal lake-level cycles on ice shelves driven by meltwater input and ocean tidal tilt
in Journal of Glaciology
Description | Our fieldwork and therefore data collection has been affected by COVID. We completed a successful field season in Nov 2019 deploying all the instruments we'd planned to install. Due to the pandemic, we were unable to visit Antarctica to download data as planned in Nov 2020. We were able to visit the sites in Nov 2021 for a limited time. Several instruments were irretrievable or had lost data. We successfully downloaded all the data we could (about 1/3 of the total we'd hoped) and reset instruments to log for another year. We also cored 2 shallow ice cores (up to 10 m) to identify variable ice facies. We had our 3rd and final field season in November 2022. All instruments from 2021 had survived. We downloaded all data and brought in all the instruments we could. We also cored another shallow ice cores (up to 10 m) to identify variable ice facies. Between November 2021 & November 2022, we presented preliminary findings at two conferences: European Space Agency, Living Planet, May 2022 and International Glaciological Society, Cryosphere 2022: Ice Snow and Water in a Warming World. We also analysed and worked up some of our data retrieved in 2021 and submitted a paper to the Journal of Glaciology in Dec 2022 which is in the final stages of a rather long review process. Using GPS and time lapse camera data it charts the partial filling and draining of a lake in a depression on the George VI Ice Shelf and the creation of a ring fracture in response - the first such time this phenomenon has been observed. Our work, and related work by Postdoctoral Research Fellow, Becky Dell, and PhD student, Karla Boxall, was been presented at EGU 2023 and will be presented at EGU 2024. |
Exploitation Route | Rather too early to say, but we are in discussions with a glaciologist colleague who has one of the most detailed physically-based ice shelf lake evolution models about coupling it to our ice flexure and fracture model. |
Sectors | Education Environment Transport |
Description | Reference to me and my research in House of Lords debate about Net Zero |
Geographic Reach | National |
Policy Influence Type | Citation in other policy documents |
URL | https://hansard.parliament.uk/Lords/2023-03-30/debates/331186DC-70F4-4250-AE96-292A488DE031/ClimateC... |
Title | Code in support of "Supervised classification of slush and ponded water on Antarctic ice shelves using Landsat 8 imagery" by R.L. Dell and others. |
Description | Code in support of "Supervised classification of slush and ponded water on Antarctic ice shelves using Landsat 8 imagery" by R.L. Dell and others. |
Type Of Material | Computer model/algorithm |
Year Produced | 2021 |
Provided To Others? | Yes |
Impact | Enquiries from other researchers |
URL | https://www.repository.cam.ac.uk/handle/1810/332309 |
Title | Larsen C Ice Shelf velocity data supporting "Oscillatory response of Larsen C Ice Shelf flow to the calving of iceberg A-68" |
Description | This dataset contains the error filtered velocity, velocity difference and velocity difference error estimations for Larsen C Ice Shelf, Antarctic Peninsula, as reported in Deakin et al. (Journal of Glaciology, 2023). The data are presented in two subdirectories entitled 'velocity_filt' and 'velocity_diff', whose contents are detailed in the README file included in the dataset package. The compressed size of this dataset is 322Mb. |
Type Of Material | Database/Collection of data |
Year Produced | 2024 |
Provided To Others? | Yes |
Impact | Currently unknown |
URL | https://www.repository.cam.ac.uk/handle/1810/363910 |
Title | West Antarctic Peninsula grounding line location datasets supporting "Seasonal land-ice-flow variability in the Antarctic Peninsula" |
Description | This dataset contains the location of the grounding line along George VI Ice Shelf (West Antarctic Peninsula), Wilkins Ice Shelf and Bach Ice Shelf (Alexander Island), as determined from a compilation of datasets, including double-differential interferometric synthetic aperture radar (DInSAR) from Sentinel-1 imagery acquired May-October 2020, Sentinel-1 grounding-line information from 2018 (Mohajerani et al., 2021) and the MEaSUREs 1994-1996 grounding line dataset (Rignot et al., 2016). The dataset is provided in ESRI Shapefile (.shp) format. |
Type Of Material | Database/Collection of data |
Year Produced | 2022 |
Provided To Others? | Yes |
Impact | Currently unknown |
URL | https://www.repository.cam.ac.uk/handle/1810/341673 |
Title | West Antarctic Peninsula seasonal ice velocity products supporting "Seasonal land-ice-flow variability in the Antarctic Peninsula" |
Description | This dataset contains the seasonal ice velocity products calculated from SAR- and optically derived velocity fields of land ice draining to George VI Ice Shelf. The dataset is provided in TIFF image (.tiff) format. |
Type Of Material | Database/Collection of data |
Year Produced | 2022 |
Provided To Others? | Yes |
Impact | Currently unknown |
URL | https://www.repository.cam.ac.uk/handle/1810/341674 |
Description | Controls On Lake Formation on Ice Shelves |
Organisation | Delft University of Technology (TU Delft) |
Country | Netherlands |
Sector | Academic/University |
PI Contribution | Exchange of ideas with Stef Lhermite and Bert Wouters (University of Utrecht) who have a separate EU grant working on similar phenomena |
Collaborator Contribution | Discussions with me and Becky Dell |
Impact | Work in progress |
Start Year | 2021 |
Description | Controls On Lake Formation on Ice Shelves |
Organisation | European Space Agency |
Department | ESA Laboratories |
Country | European Union (EU) |
Sector | Public |
PI Contribution | I am host to and working along side Becky Dell (based at SPRI, University of Cambridge) who is funded via an ESA CCI Fellowship. |
Collaborator Contribution | Funding and mentoring of Becky Dell, who is collaborating with us on our grant. |
Impact | Work in progress. |
Start Year | 2021 |
Description | Seasonal land ice-flow variability in the Antarctic Peninsula |
Organisation | ENVEO |
Country | Austria |
Sector | Private |
PI Contribution | Analysis of satellite-derived products from ENVEO |
Collaborator Contribution | Supply of satellite-derived products (ice velocities of George VI Ice Shelf and surrounding glaciers from Sentinel 1 SAR data) |
Impact | Submission of a paper to The Cryosphere |
Start Year | 2021 |