Constraining Antarctica's contribution to sea-level change: development of a new glacial isostatic adjustment model for Antarctica

Lead Research Organisation: Durham University
Department Name: Geography

Abstract

The Antarctic Ice Sheet is currently melting and undergoing rapid dynamic change. However, the rate at which it is melting, and hence its contribution to sea-level rise, is currently poorly known. The aim of my Fellowship is to derive a better estimate of current ice-mass change across Antarctica. Such an estimate can be derived from satellite gravity data, which are used to infer ice-mass changes from measurements of the Earth's gravity field. However, these data must be corrected for the ongoing effects of postglacial rebound (also known as glacial isostatic adjustment; GIA).
Satellite gravity measurements cannot distinguish between changes in ice mass and mass movement of the solid Earth. During the last glaciation the Antarctic Ice Sheet was much larger and the extra mass caused the land beneath the ice to subside. As the ice sheet shrank towards its present size, the land began to rebound. This process - GIA - continues today due to the viscous nature of Earth's mantle. In fact, the GIA signal, as recorded by satellite gravity data, can be of the same magnitude as the signal due to current ice-mass change. Therefore, it is vital to constrain the pattern of GIA as accurately as possible in order to determine the pattern of ice-mass change.
I will address two fundamental problems with the methods currently used to model GIA in Antarctica, thus significantly reducing the uncertainty on Antarctica's sea-level contribution.
In the first part of my Fellowship I will model the 3D Earth structure beneath Antarctica. Current Antarctic GIA models do not account for variations in crustal thickness or mantle viscosity. However, such variations are known to be large because East and West Antarctica have very different geological histories: the crust beneath East Antarctica is old and 'stiff' and thus will not deform easily under loading. In contrast, the crust beneath West Antarctica is young and 'weak' and so deforms more easily under loading. In order to realistically determine the rebound signal, spatial variations in Earth structure must be accounted for so that the correct response to loading is calculated; not doing so can alter the rebound signal by up to 30%. The recent acquisition of new data relating to Antarctic Earth structure, and GIA model developments, make this aspect of my proposal very timely.
The second problem I will address is related to sea-level change. West Antarctica is a marine-based ice sheet meaning that its bed is grounded below present sea level. In order to model changes in ice extent over time, and hence determine the GIA signal, it is necessary to consider feedbacks between sea-level change and ice dynamics. Sea level directly controls the position where an ice sheet begins to float and thus where ice is lost to the ocean. However, due to GIA, sea level does not vary uniformly over time: In areas where the ice sheet grows the land is pushed down by the extra load and the sea surface is drawn upwards due to the increased gravitational attraction of the ice sheet, resulting in an increase in sea level. The opposite happens when ice retreats. In both cases, feedbacks influence the dynamical behaviour of the ice sheet. Such feedbacks are not accounted for in current ice-sheet models, despite their potential to increase the stability of an ice sheet: Their inclusion could fundamentally alter predictions of ice-sheet behaviour under future sea-level rise scenarios. In the second component of my project I will therefore develop a coupled GIA-ice-sheet model. Both fields of research will benefit from improved model capabilities.
These model improvements will be used to derive a more realistic estimate of GIA across Antarctica. The model will be calibrated to fit field constraints relating to former ice extent, past sea-levels, and present-day rebound. It will then be used to correct satellite data for the effects of GIA, and hence determine a more accurate map of current Antarctic ice-mass change.

Planned Impact

The PI will work with a graphic designer to produce 5 large-format graphic images around the theme of 'Perceptions of Climate Change'. These will be displayed for several months at the Centre for Life, Newcastle, and at the 2014 British Science Festival in Birmingham.

The aim of the project is to challenge the general public's perceptions of climate change. This will be achieved by producing images which both quickly convey a simple message, but also to invite you to look closer and explore the details of the image. An example of this is the use of many smaller images to make up a larger image, essentially a mosaic. The concept is very similar to the challenge facing scientists who study climate change and the impact of climate change: typically, only the smaller images are available to us - a regional temperature record, or local tide gauge data - and these must be pieced together to understand the bigger picture. These parallels will be explored in producing the images, and easy-to-grasp facts will be include in infographic designs to increase the impact of the message. The images will enable the general public to identify the signs of climate change around them, and appreciate the challenge faced by scientists of understanding the bigger picture.

The general public will be the direct beneficiaries of the project, through an increased awareness of, and engagement with, issues surrounding climate change. The aim of the project is not to convey large amounts of complicated information to the general public, but to encourage them to explore their own perception of the process of climate change. The PI will attend the 2014 British Science Festival in order to maximise the impact of the images through direct contact with the general public. In addition, the possibility of hosting a 'Meet the Scientist' event, in conjunction with the longer-term exhibition at the Centre for Life, will be explored, to facilitate knowledge transfer and promote public discussion.

Secondary beneficiaries of the project will be local, regional, and national agencies that are involved with planning activities associated with mitigating against, or adapting to, climate change. It is hoped that the increased awareness by the general public of the challenge involved in understanding climate change will allow them to engage with proposed planning agency activities in a positive way, and to appreciate the long-term nature of the issue. Such planning agencies will be made aware of, and invited to engage with, the project.

The impact of this project will be to broaden public perception of the process of climate change. This will help to break down barriers between scientists, policy makers, and the general public, enabling us to work together towards understanding and adapting to the challenge of climate change.

Publications

10 25 50
 
Title Antarctic Exhibition Video 
Description A video was produced that was shown as part of a wider exhibition on Antarctic exploration and science (listed under engagement activities). 
Type Of Art Film/Video/Animation 
Year Produced 2015 
Impact Public awareness of current change in Antarctica. the exhibition was attended by ~4400 members of the public over three and a half months. 
 
Description When we interpret data relating to the magnitude of contemporary ice loss from Antarctica we must account for a signal that is related to past ice loss over the last few tens of thousands of years. We have shown that the signal associated with this process is smaller than previously thought, which has led to revisions to current estimates for the rate and location of contemporary ice loss from Antarctica. In addition to improving estimates of contemporary ice loss, the research carried out under this grant has led to increased understanding of the role that Earth rebound can play in controlling rates of past ice sheet change. In particular, work on understanding the properties of the mantle beneath Antarctica has allowed us to propose that Earth rebound previously played a role in enabling the Antarctic Ice Sheet to re-grow after a period of ice loss. This process is not currently considered in most projections of future ice sheet change.
Exploitation Route The findings of this work feed into a greater understanding of how the Antarctic Ice Sheet responds to external climate forcing, and provide updated estimates of the current sea-level contribution from Antarctica.
Sectors Education,Environment

 
Description NERC Standard Grant (New Investigator)
Amount £785,489 (GBP)
Funding ID NE/R002029/1 
Organisation Natural Environment Research Council 
Sector Public
Country United Kingdom
Start 01/2018 
End 12/2022
 
Description Visiting Scholar, University of Tasmania
Amount $6,120 (AUD)
Organisation University of Tasmania 
Sector Academic/University
Country Australia
Start 03/2015 
End 04/2015
 
Description 3D GIA modelling 
Organisation Delft University of Technology (TU Delft)
Country Netherlands 
Sector Academic/University 
PI Contribution Numerical modelling making use of data received from one partner, and delivery of model output to both partners
Collaborator Contribution Sharing of data and model code.
Impact Two publications have so far resulted from this collaboration (van der Wal et al., 2015; Nield et al., 2018).
Start Year 2013
 
Description 3D GIA modelling 
Organisation POLENET
Country Global 
Sector Charity/Non Profit 
PI Contribution Numerical modelling making use of data received from one partner, and delivery of model output to both partners
Collaborator Contribution Sharing of data and model code.
Impact Two publications have so far resulted from this collaboration (van der Wal et al., 2015; Nield et al., 2018).
Start Year 2013
 
Description Collaboration between field and modelling scientists 
Organisation British Antarctic Survey
Country United Kingdom 
Sector Academic/University 
PI Contribution Providing advice to field scientists on the sort of data that would be useful for calibrating and tuning numerical models of ice sheet change.
Collaborator Contribution The collection of new data that can help constrain the past history of the Antarctic Ice Sheet. This work is funded by a NERC standard grant; I am a project partner who provides guidance on the direction of the project.
Impact No outputs yet.
Start Year 2015
 
Description GPS and GIA 
Organisation Newcastle University
Country United Kingdom 
Sector Academic/University 
PI Contribution Ongoing collaboration with Matt King (University of Tasmania, formerly of Newcastle University, UK), Peter Clarke (Newcastle University, UK), and Terry Wilson (Ohio State University, PI of the NSF-funded POLENET project). My expertise is to produce numerical models of solid Earth deformation in response to changes in surface loading by ice sheets. Such models are tuned or tested using geodetic data.
Collaborator Contribution Matt King's expertise is polar geodesy; including the production and analysis of the polar geodetic data sets that are used to test my numerical models. Peter Clarke's expertise is in linking geodesy and geophysics; including understanding of the solid Earth processes that are represented in my numerical models. Terry Wilson runs the mulit-million dollar NSF-funded POLENET project that is responsible for much of the geodetic infrastructure across West Antarctica.
Impact This collaboration has led to the publication of 13 co-authored, peer-reviewed publications since 2011. I am a project partner on two current projects led by Matt King, which are funded by the Australian Research Council, and one project led by Terry Wilson, which is funded by NSF. I receive no financial input from these projects. I am the PI or Co-I of two NERC-funded projects on which Peter Clarke is a Co-I (reported elsewhere). Though this collaboration I have co-supervised two PhD students.
Start Year 2009
 
Description GPS and GIA 
Organisation POLENET
Country Global 
Sector Charity/Non Profit 
PI Contribution Ongoing collaboration with Matt King (University of Tasmania, formerly of Newcastle University, UK), Peter Clarke (Newcastle University, UK), and Terry Wilson (Ohio State University, PI of the NSF-funded POLENET project). My expertise is to produce numerical models of solid Earth deformation in response to changes in surface loading by ice sheets. Such models are tuned or tested using geodetic data.
Collaborator Contribution Matt King's expertise is polar geodesy; including the production and analysis of the polar geodetic data sets that are used to test my numerical models. Peter Clarke's expertise is in linking geodesy and geophysics; including understanding of the solid Earth processes that are represented in my numerical models. Terry Wilson runs the mulit-million dollar NSF-funded POLENET project that is responsible for much of the geodetic infrastructure across West Antarctica.
Impact This collaboration has led to the publication of 13 co-authored, peer-reviewed publications since 2011. I am a project partner on two current projects led by Matt King, which are funded by the Australian Research Council, and one project led by Terry Wilson, which is funded by NSF. I receive no financial input from these projects. I am the PI or Co-I of two NERC-funded projects on which Peter Clarke is a Co-I (reported elsewhere). Though this collaboration I have co-supervised two PhD students.
Start Year 2009
 
Description GPS and GIA 
Organisation University of Tasmania
Country Australia 
Sector Academic/University 
PI Contribution Ongoing collaboration with Matt King (University of Tasmania, formerly of Newcastle University, UK), Peter Clarke (Newcastle University, UK), and Terry Wilson (Ohio State University, PI of the NSF-funded POLENET project). My expertise is to produce numerical models of solid Earth deformation in response to changes in surface loading by ice sheets. Such models are tuned or tested using geodetic data.
Collaborator Contribution Matt King's expertise is polar geodesy; including the production and analysis of the polar geodetic data sets that are used to test my numerical models. Peter Clarke's expertise is in linking geodesy and geophysics; including understanding of the solid Earth processes that are represented in my numerical models. Terry Wilson runs the mulit-million dollar NSF-funded POLENET project that is responsible for much of the geodetic infrastructure across West Antarctica.
Impact This collaboration has led to the publication of 13 co-authored, peer-reviewed publications since 2011. I am a project partner on two current projects led by Matt King, which are funded by the Australian Research Council, and one project led by Terry Wilson, which is funded by NSF. I receive no financial input from these projects. I am the PI or Co-I of two NERC-funded projects on which Peter Clarke is a Co-I (reported elsewhere). Though this collaboration I have co-supervised two PhD students.
Start Year 2009
 
Description IMBIE 
Organisation European Space Agency
Country France 
Sector Public 
PI Contribution IMBIE: Ice-sheet Mass Balance Inter-comparison Exercise. This collaboration involves scientists from a large number of universities and international research institutes, and its aim is to quantify the current rate at which Antarctica and Greenland are melting. I am the scientific lead for the Glacial Isostatic Adjustment component of the project and hence am a member of the Executive Committee. My role involves coordinating the submission of model output from participants in the exercise, assessing the information that has been submitted, and liaising with the scientific leads of other components of the inter-comparison exercise.
Collaborator Contribution The overall project is coordinated by Andrew Shepherd (Leeds University), with assistance from Erik Ivins (JPL). These two scientists also represent the interests of ESA and NASA, who sponsor the project.
Impact High profile article documenting the results of the inter-comparison exercise were published in 2018. Picked up by hundreds of media outlets, Pippa Whitehouse interviewed on for three separate BBC broadcasts (World Service, Inside Science, BBC website) as well as a number of online media reports.
Start Year 2015
 
Description IMBIE 
Organisation National Aeronautics and Space Administration (NASA)
Country United States 
Sector Public 
PI Contribution IMBIE: Ice-sheet Mass Balance Inter-comparison Exercise. This collaboration involves scientists from a large number of universities and international research institutes, and its aim is to quantify the current rate at which Antarctica and Greenland are melting. I am the scientific lead for the Glacial Isostatic Adjustment component of the project and hence am a member of the Executive Committee. My role involves coordinating the submission of model output from participants in the exercise, assessing the information that has been submitted, and liaising with the scientific leads of other components of the inter-comparison exercise.
Collaborator Contribution The overall project is coordinated by Andrew Shepherd (Leeds University), with assistance from Erik Ivins (JPL). These two scientists also represent the interests of ESA and NASA, who sponsor the project.
Impact High profile article documenting the results of the inter-comparison exercise were published in 2018. Picked up by hundreds of media outlets, Pippa Whitehouse interviewed on for three separate BBC broadcasts (World Service, Inside Science, BBC website) as well as a number of online media reports.
Start Year 2015
 
Description NZ Sea Level 
Organisation Massey University
Country New Zealand 
Sector Academic/University 
PI Contribution Ongoing collaboration with Alastair Clement of Massey University, who carries out research into sea-level change around New Zealand. My contribution involves providing model predictions of sea-level change around New Zealand over the last ~10,000 years, thus aiding identification of the patterns and causes of sea-level change over this period.
Collaborator Contribution Alastair Clement is the overall project leader on this collaboration, and his roles include carrying out fieldwork and data analysis in New Zealand, as well as leading publications.
Impact Peer-reviewed article in Quaternary Science Reviews (An examination of spatial variability in the timing and magnitude of Holocene relative sea-level changes in the New Zealand archipelago). Securing of funding by Alastair Clement to pursue research questions raised in this preliminary study, including incorporation of results from 3D GIA modelling carried out by Pippa Whitehouse during her NERC-funded Independent Research Fellowship.
Start Year 2014
 
Description PhD Studentship at Newcastle University 
Organisation Newcastle University
Department School of Chemistry
Country United Kingdom 
Sector Academic/University 
PI Contribution Supervision of a PhD student based at Newcastle University. My role is to provide training and model predictions associated with the field of Glacial Isostatic Adjustment (GIA). The student will use model predictions that I have generated during my Fellowship to aid in the interpretation of the global deformation field, as measured by GPS, with the ultimate goal of gaining insight into the global water cycle.
Collaborator Contribution Two of the student's supervisors (including the lead supervisor) are based at Newcastle University. Research undertaken by the student feeds into research interests of both me and the supervisors at Newcastle University.
Impact No outcomes yet
Start Year 2016
 
Description SERCE 
Organisation Scientific Committee on Antarctic Research
Country United Kingdom 
Sector Charity/Non Profit 
PI Contribution I am the co-director of a Scientific Research Program (SRP) titled: Solid Earth Response and influence on Cryosphere Evolution (SERCE), hosted by the Scientific Committee on Antarctic Research (SCAR). This program aims to facilitate collaborative research in the field of Glacial Isostatic Adjustment. We have an annual budget of US$20,000, which is spent on running workshops and training activities associated with ice sheet - solid Earth feedbacks, and facilitating Early Career Researcher (ECR) attendance at these activities. Tasks associated with my role include: completing annual reports on program activities, sitting on the UK National Committee for Antarctic Research, co-organizing workshops and training schools, allocating ECR travel funds, and planning for future activities.
Collaborator Contribution My co-director (Matt King, University of Tasmania) makes an equal contribution to this activity.
Impact Co-sponsorship of training school on Glacial Seismology (2017). Co-sponsorship of workshop on Glacial Isostatic Adjustment and Elastic Deformation (2017). Co-sponsorship of workshop on Antarctic Heat Flux (2018) and Polar Geodesy (2018). Beneficiaries of SERCE support are encouraged to acknowledge this in publications where the author has benefited from attending SERCE-organised activities. High profile article published in 2019 describing the research aims and outstanding research questions associated with SERCE activities.
Start Year 2016
 
Description Antarctic exhibiton 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact I contributed to an exhibition on Antarctica that was open to the public for three and a half months between October 2015 and February 2016. The exhibition was hosted by Palace Green Library, Durham. My contribution involved providing material for an educational film on Antarctic Science which was available to watch at the exhibition, and material for an educational pack that was circulated to local schools.
Year(s) Of Engagement Activity 2015,2016
URL https://www.dur.ac.uk/palace.green/whatson/details/?id=23884
 
Description Blog on Antarctic Research 
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 I write an occasional blog about my research on Antarctica. The reason for writing the blog is to provide insight to the general public on why the research is important, and how we go about carrying out science in such a hostile environment. I receive very positive, informal feedback on the posts, either in person or via social media (Twitter). In particular, it has been a delight to be able to highlight the number of women working in Antarctica, or on Antarctic Science; people have expressed surprise at this, and hopefully my writing has made people think twice about what an 'Antarctic Scientist' might look like!
Year(s) Of Engagement Activity 2016,2017
URL http://antarcticpippa.blogspot.co.uk/
 
Description IMBIE press release 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Media (as a channel to the public)
Results and Impact Press release for high profile journal article related to the IMBIE project - Pippa Whitehouse was lead author on the Glacial Isostatic Adjustment modelling component, and one of four lead authors who participated in the press release activities in London. Media activities coordinated by the Science Media Centre, Whitehouse was interviewed for BBC News, BBC World Service, and 'Inside Science'.
Year(s) Of Engagement Activity 2018
 
Description International conference presentations relating to IRF 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Other audiences
Results and Impact Research talks presented by Pippa Whitehouse at international conferences, relating to research carried out during her NERC-funded Independent Research Fellowship (IRF) (invited talks are documented elsewhere):
SERCE/IAG workshop on Glacial Isostatic Adjustment modelling - Fairbanks 2015; Reykjavik 2017
IUGG conference - Prague 2015
PALSEA Workshop - Portland (USA) 2016; New Jersey 2018
SCAR Open Science Conference - Kuala Lumpur 2016; Davos 2018
Year(s) Of Engagement Activity 2015,2016,2017,2018
 
Description Karthaus Summer School 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact Invited Lecturer at the International Karthaus Summer School on Ice Sheets and Glaciers in the Climate System. Delivered lectures and one-to-one tuition on Glacial Isostatic Adjustment to PhD students and Postdoctoral Researchers from around the world.
Year(s) Of Engagement Activity 2012,2014
URL https://www.projects.science.uu.nl/iceclimate/karthaus/
 
Description RMETS Talks 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact Talks usually result in a good selection of questions and further debate afterwards.

n/a
Year(s) Of Engagement Activity 2013,2014
 
Description SERCE/POLENET GIA Summer School 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact Invited Lecturer at summer school on Glacial Isostatic Adjustment. Delivered lectures and one-to-one tutorials to PhD students, postdocs, and permanent academic staff from around the world, including online participants.
Year(s) Of Engagement Activity 2015
URL http://polenet.org/gia-training-school-application
 
Description School Visit (Durham) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact Delivered school assembly for ~200 primary school children (including ~30 deaf children) on Antarctica Day, 2017. Talked about living and working in Antarctica, held follow-up Q&A session with the whole school, and separately for Year 2 pupils. Also assisted with a science experiment for Year 4 in which they investigated the insulating properties of of different materials: activity involved measuring the rate at which beakers of hot water gradually cooled.

Separate school visit to county Durham primary school in spring 2018 - similar activities and similar size audience.
Year(s) Of Engagement Activity 2017,2018
 
Description Science talk at Rothera Field Station (Antarctica) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Other audiences
Results and Impact Whilst carrying out fieldwork in Antarctica I delivered a science talk on my research to other scientists and support staff working on the base. The audience comprised the widest mix of people you could think of - chefs, pilots, doctors, plumbers, mountaineers, engineers, divers, biologists, mechanics, as well as a few scientists from my field. These are the people who help deliver Antarctic Science, so I wanted them to understand the importance and the implications of this work. I aimed to pitch the talk at a level that everyone could relate to; it was clear that this aim was achieved as questions extended for over 20 minutes and continued informally for the rest of the evening.
Year(s) Of Engagement Activity 2016