Ice shelves in a warming world: Filchner Ice Shelf system, Antarctica

Lead Research Organisation: NERC British Antarctic Survey
Department Name: Science Programmes

Abstract

That our planet is warming is undeniable. Recent increases in greenhouse gas concentrations have seen an associated warming of the atmosphere and oceans, a reduction in the total amount of snow and ice and a rise in sea level of approximately 3 mm/year. Although the precise rate of future temperature rise may be uncertain, there is little doubt that it will increase.

In response to a warmer climate, large areas of the Antarctic Ice Sheet could become unstable, resulting in sudden and permanent loss of ice. Indeed for one relatively well-studied region, the Amundsen Sea Sector, this may already be underway. However, our understanding of the processes, the likelihood of collapse and the potential impact on sea-level remains poor, especially in the very different climatic regime of the Weddell Sector. This project aims to address what will happen in the near-future to a region that spans one fifth of Antarctica and the impact changes here could have on global sea-level by the end of this century. We aim to do this in three stages:

We will study and understand the intricate relationships between the atmosphere, the ocean and the ice sheet in the important Weddell sector of Antarctica, which contains Filchner Ice Shelf and its catchment basins. We will determine how the atmosphere determines the ocean conditions, and how these in turn determine the melting at the base of the ice shelf. In a carefully designed field campaign we will collect data both to improve the way the models work, and also to validate their results. This first stage will yield a system of models that gives a detailed representation of the physical processes currently at work, and by using the natural variability in the system we will determine the sensitivity to change of each linked process.

The next step is to force the boundaries of our modelled system with the best available estimate of the atmospheric and oceanographic properties expected over the 21st century. We will then be in a position to determine how the ocean conditions beneath the ice shelf will change, together with the rate of melting at the ice shelf base. As the melt rate changes, so will the ice shelf geometry: we will determine how the rate of ice flow from the continent responds to these changes, and its impact on sea-level rise.

In the final stage we will widen the scope of the study from our large, yet still regional area, to a global context. The models to be used in the first two steps, (atmosphere, ocean and ice) are high resolution, state-of-the-art but limited-area models. We will work with our Project Partner, the Met Office Hadley Centre (MO), to incorporate our improved understanding of processes and their sensitivities within the next generation of global earth-system predictive models. Finally, we will assess the reliability of our predictions. This will be done first by ensuring consistency between the different regional models, run both within the project and by our project partners at the Alfred Wegener Institute (AWI) in Germany. We will then use a limited ensemble of runs of the new generation of MO coupled climate models to quantify the uncertainty in our predictions of the contribution of the Antarctic Ice Sheet to sea level change.

The future contribution of the Antarctic Ice Sheet to sea level rise remains the least well constrained component in the budget. By bringing together from across the community leading experts in polar meteorology, oceanography, ice-ocean interaction, glaciology and model uncertainty, this project will provide the largest single improvement in the prediction of future sea level change. New observations and data are essential, but expensive. Rather than using costly commercially-available infrastructure, AWI and NERC will share the logistic burden with the project delivering excellent value as a result.

Planned Impact

The 'near-future' timescale of producing credible sea-level projections for the remainder of the 21st century gives this research immediacy and relevance to many sectors of society. Not only will it fill a gap in our current understanding of how a large part of Antarctica will respond in the near future to a warmer world, but the enhanced ability to produce reliable projections of sea-level rise will benefit considerably sea defence policy planning and business investment decision-making. The research proposed will remove the present observational constraints and foster the theoretical work that will lead to reliable projections.

Specific goals for maximising the impact of our research outcomes include:
1. Informing the work of national and international bodies such as the Environment Agency, the Scientific Committee on Antarctic Research, and the Council of Managers of National Antarctic Programmes.
2. Establishing knowledge exchange and dialogue with policy officials from UK Government departments such as the Department of Energy and Climate Change (DECC), the Department for the Environment and Rural Affairs (DEFRA); and the Department for Business, Innovation and Skills (BIS).
3. Disseminating new knowledge to UK and international business leaders.
4. Outreach: A rise in global sea-level rise affects us all, hence, this project has considerable potential to raise awareness and educate the public. However, public understanding of the cryosphere is in general poor. Therefore, to facilitate an appreciation of the system we have proposed a novel approach, employing "Game Based Learning" to allow people to become immersed in the environment and learn how the system functions and responds to change via a free online game, and as an "app" for mobile devices.

NERC is committed to engage with the public and media about the science behind how our environment works. The assembled national and international team have an excellent record in disseminating results to scientific and public audiences.
Much of the impact of the work will be via the modelling communities. Their effectiveness at dissemination will be by published results in high impact journals and presenting work at international conferences. Both NERC Centres (BAS and NOC) and our UK Project Partner, The Met Office Hadley Centre, each have a strong track-record of direct communication with policy-makers and their advisors. Specifically, the UK Government programme, Living with Environmental Change (LWEC) will be directly informed of results. Project Partner, The Alfred-Wegener-Institute Helmholtz-Centre for Polar and Marine Research (AWI), is one of the internationally leading institutions for research in the high latitudes. The institute coordinates polar research for all German scientists and directly advises the German government on climate-change related matters.
We will link to the Scientific Committee on Antarctic Research's (SCAR) research programme, AntClim21 (Antarctic Climate Change in the 21st Century). Their objective: 'to produce improved projections of the magnitude and patterns of change to Antarctica's physical environment over the next 100+ years', directly matches the prime aim of this project. SCAR has observer status on the Intergovernmental Panel on Climate Change (IPCC).

Datasets acquired during the project, from a region that straddles both the East and the West Antarctic Ice Sheet, will be used to optimise multiple atmospheric, oceanographic and ice sheet models. AWI, BAS and the Met Office will undertake a detailed intercomparison of the response of differing models to identical forcing. The process will facilitate model improvement, robust projections of the response to specific forcing and improved knowledge of the physical processes giving rise to that response. The datasets, consisting of contemporaneous time-series, synoptic under ice surveys and definitive mapping of topography, will be made available.

Publications

10 25 50
 
Description In the southern Weddell Sea, sea ice forms at the ocean surface in winter as a result of heat loss to the overlying atmosphere. The waters on the continental shelf therefore have a temperature that is close to the surface freezing point almost everywhere. That water can nevertheless melt ice from the base of the vast Filchner-Ronne Ice Shelf because the elevated pressure beneath the ice shelf lowers the local freezing temperature. It has therefore been suggested that the melt rate of the ice shelf should be relatively insensitive to climate change. The atmosphere could warm significantly while still remaining cold enough in winter to drive sea ice formation, and the ocean should therefore retain its near-freezing temperature. However, modelling studies conducted as part of the "Ice shelves in a warming world: Filchner Ice Shelf system, Antarctica" project have shown that changes in the salinity of the waters on the continental shelf can change the strength of the ocean circulation beneath the ice shelf and that that can change the melt rates even when the water temperature remains near the freezing point. While similar results have been discussed before, the importance of the new findings is that they point to a major role for far-field ocean processes in setting the shelf water salinity. Rather than salinity of the waters near the ice shelf simply being a function of how much sea ice grows over the continental shelf in winter, as previously thought, the new results show that changes in sea ice formation over the broader Weddell Sea, or in the salinity of the waters brought into the Weddell Gyre from even farther afield, impact the continental shelf salinity and consequently the ice shelf melt rates. These findings change our understanding of how the Filchner-Ronne Ice Shelf could respond to climate change, and that in turn alters our perception of the likely future contribution of the Weddell Sea sector of the Antarctic Ice Sheet to sea level rise.
Exploitation Route These results alter the way people think about climate change impacts on Antarctica's largest ice shelves in the Ross and the Weddell sea. Previously the focus was changes in sea ice production over the continental shelf and how those might impact the sub-ice-shelf circulation. This work shows that the large-scale structure and flow of the Ross and Weddell gyres also has an important role to play. Far-field changes in the waters that are brought to the continental shelf do impact the melt rate, and that means that we need to consider the impacts of climate change over a much broader region when considering how the ice shelves, and in consequence, the ice sheet will respond.
Sectors Environment

 
Description A blog during the 15/16 field campaign
First Year Of Impact 2015
Sector Education,Environment
Impact Types Cultural,Societal

 
Title An update to Greenland and Antarctic ice sheet topography, cavity geometry, and global bathymetry (RTopo-2.0.4), supplement to: Schaffer, Janin; Kanzow, Torsten; von Appen, Wilken-Jon; von Albedyll, Luisa; Arndt, Jan Erik; Roberts, David H (in review): Bathymetry constrains ocean heat supply to Greenland's largest glacier tongue. Nature Geoscience 
Description As an update to the RTopo-2.0.1 data set (https://doi.org/10.1594/PANGAEA.856844), RTopo-2.0.4 contains new original bathymetry data for the Northeast Greenland continental shelf. In the Southern Ocean, we added the Rosier et al. (JGR Oceans, 2018) bathymetry grid below Filchner Ice Shelf. This work was supported in part through the Deutsche Forschungsgemeinschaft (DFG) within the Special Priority Program (SPP) 1889 "Regional Sea Level Change and Society" (grant OGreen79), the German Federal Ministry for Education and Research (BMBF) within the GROCE project (Grant 03F0778A), the Natural Environment Research Council (NERC) large grant "Ice shelves in a warming world: Filchner Ice Shelf System" (NE/L013770/1), the NERC project "Greenland in a warmer climate: What controls the advance & retreat of the NE Greenland Ice Stream" (Grant NE/N011228/1), and the Helmholtz Climate Initiative "Regional Climate Change" (REKLIM). 
Type Of Material Database/Collection of data 
Year Produced 2019 
Provided To Others? Yes  
 
Title Timeseries from GPS units deployed on ice streams and the adjoining ice shelf across the Filchner-Ronne region, Antarctica, 2005-2016 
Description This is a collection of GPS data from dual-frequency GPS units deployed on the Filchner-Ronne Ice Shelf and adjoining ice streams. Filenames contain ice stream code and, in some cases, where the ice stream code is followed by a plus or minus sign, the approximate distance in kilometres upstream from the ice stream's grounding line, although in other cases the number is arbitrary. The naming convention has been preserved for legacy reasons. The ice streams are Evans (E & XX), Rutford (R), Institute (IIS), Talutis (T & TT) and Foundation (H) ice streams. Each GPS unit's data are given in a netCDF4_classic file containing 4 columns: "Date number", as the number of days from January 0, 0000 in the proleptic ISO calendar; "Latitude" & "Longitude", both in decimal degrees in the WGS 1984 EPSG:4326 co-ordinate system; "height", in metres above the reference ellipsoid. The data have been collated from daily files, processed using the Bernese 5.0 software, using precise point positioning at intervals of 30 seconds. Note that data have not been corrected for inverse barometer or ocean tide loading effects. These data were collected as part of a systemic campaign to look for modulation in ice flow through ocean tidal forcing. The vertical tidal motion of floating ice shelves generates stresses which cause a change in horizontal ice velocity at periods of hours to years. These signals can travel far upstream of ice stream grounding lines and often exhibit a change in frequency from the astronomical tides that generate them. As such, they can act as a natural experiment with which we can learn about ice rheology and subglacial processes. 
Type Of Material Database/Collection of data 
Year Produced 2017 
Provided To Others? Yes  
 
Title Water column and ice thickness measurements of the Filchner-Ronne Ice Shelf derived from point seismic observations collected between 2015-2017 
Description This data consists of single point seismic data collected across the Filchner-Ronne Ice Shelf. The data were collected over the course of three seasons by a number of field parties, consisting of two main surveys between the 15/16 and 16/17 austral summers and several smaller surveys, as part of a joint initiative between the British Antarctic Survey (BAS) and the Alfred-Wegener-Institute (AWI) in the framework of the "Filchner Ice Shelf System" (FISS) and the "Filchner Ice Shelf Project" (FISP). A total of 256 point seismic measurements were made, of which 248 had clearly visible reflectors and were deemed usable. Each data point consists of a location, together with measurements of ice thickness and water column thickness. 
Type Of Material Database/Collection of data 
Year Produced 2018 
Provided To Others? Yes  
 
Description Cruise PS111 
Organisation Alfred-Wegener Institute for Polar and Marine Research
Country Germany 
Sector Private 
PI Contribution Deployment of Autosub Long Range beneath Filchner-Ronne Ice Shelf, Antarctica
Collaborator Contribution Fifty day cruise on Polarstern to the southern Weddell Sea to deploy Autosub Long Range
Impact Autosub Long Range data were collected along two tracks beneath Filchner-Ronne Ice Shelf, totalling over 200 km.
Start Year 2018
 
Description Filchner Ice Shelf Project FISP 
Organisation Alfred-Wegener Institute for Polar and Marine Research
Country Germany 
Sector Private 
PI Contribution Sharing of logistics, knowledge exchange, data exchange
Collaborator Contribution Sharing of logistics, knowledge exchange, data exchange
Impact Successful Antarctic field season 15/16 Successful Antarctic field season 16/17
Start Year 2014
 
Description Filchner Ice Shelf Project FISP 
Organisation Uni Research AS
Country Norway 
Sector Charity/Non Profit 
PI Contribution Sharing of logistics, knowledge exchange, data exchange
Collaborator Contribution Sharing of logistics, knowledge exchange, data exchange
Impact Successful Antarctic field season 15/16 Successful Antarctic field season 16/17
Start Year 2014
 
Title ALR Under Ice 
Description Development of Autosub Long Range for under ice observations 
Type Of Technology New/Improved Technique/Technology 
Year Produced 2018 
Impact Enabled the first sub-ice-shelf observations with this vehicle, and is the starting for futher development of the under ice capability 
 
Title AWSbuoy 
Description A weather system deployed on sea ice 
Type Of Technology Systems, Materials & Instrumental Engineering 
Year Produced 2016 
Impact Three AWSbuoys were deployed on the sea-ice of the Weddell Sea. They are being used to validate climate models. There are named as 2016W1, 2016W2, 2016W3 
URL http://data.seaiceportal.de/gallery/index_new.php?ice-type=buoy®ion=s&submit3=display&lang=en_US&...
 
Title ApRES 
Description A novel radar system that measures the change in the thickness of an ice shelf and its vertical velocity. From these two measurements the melt rate is determined. The system will provide a time series of basal melting at two hour intervals over a complete year 
Type Of Technology New/Improved Technique/Technology 
Year Produced 2015 
Impact 19 units were deployed across the Filchner-Ronne Ice shelf and will give a spatial and temporal measure of the basal melt rate against which numerical models will be verified. 
 
Description "Ice Flows" - using "Game based Learning" to communicate change in the Cryosphere 
Form Of Engagement Activity Engagement focused website, blog or social media channel
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Schools
Results and Impact In order to facilitate public understanding of the system under investigation we use a novel approach, employing "Game Based Learning" to allow people to become immersed in the environment, and learn how the system functions and responds to change through playing a game.
Year(s) Of Engagement Activity 2016
URL http://www.iceflowsgame.com/index.html
 
Description A daily twitter posting from the team drilling through the ice shelf. Stats: Tweets 101, Following 1,154, Followers 889 
Form Of Engagement Activity Engagement focused website, blog or social media channel
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact A daily twitter posting from the team drilling through the ice shelf. Stats: Tweets 101, Following 1,154, Followers 889. Our Project partners and associates also disseminated the information.
Year(s) Of Engagement Activity 2016
URL http://twitter.com/HotWaterOnIce
 
Description CVC ALR talk 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Schools
Results and Impact Presentation on Antarctic Science in general, and Autosub work on Polarstern in particular, to Year 7 pupils at Cottenham Village College
Year(s) Of Engagement Activity 2018
 
Description The Guardian spent 24 hours focusing on climate change happening on 2nd Feb 2017 
Form Of Engagement Activity A magazine, newsletter or online publication
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact Project members collaborated with the Guardian to get exclusive video back from the Antarctic, The short information video outlined the work and the reason for the research.
Year(s) Of Engagement Activity 2017
URL http://www.theguardian.com/environment/live/2017/jan/19/global-warning-live-from-the-climate-change
 
Description presentation to Sir Mark Walport 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Policymakers/politicians
Results and Impact Presentation given to Sir Mark Walport, the Goverment Chief Scientific Adviser on the 'role of ice shelves in a warming world'
Year(s) Of Engagement Activity 2016