Reducing the uncertainty in estimates of the sea level contribution from the westernmost part of the East Antarctic Ice Sheet

Lead Research Organisation: British Antarctic Survey


This proposal aims to improve estimates of Antarctica's contribution to sea level.

Sea level is currently rising at approximately 3mm/yr. If we are to understand why it is rising and how future sea-level rise will continue - perhaps accelerate - and lead to a wide range of societal impacts then we need to understand the different contributions to sea level. Some of the largest contributions come from the great ice sheets in Antarctica and Greenland but the amount of ice being lost from Antarctica is particularly difficult to establish. There are three main ways to measure the amount of ice being lost or gained from Antarctica - its 'mass balance'. These are (i) satellite altimetery (measuring very precisely how the ice sheet surface is going up or down through time); (ii) the input-output method (calculating the difference between estimates of how much snow falls on Antarctica, and how much ice breaks off at the coast or is lost by melting); (iii) satellite gravimetry (measuring minute changes in Earth's gravitational field caused by loss or gain of ice in Antarctica through time).

Ideally, these three techniques would provide similar answers but they currently do not. All the techniques have problems or drawbacks and all are the subject of ongoing research. In this proposal we focus on the satellite gravimetry method. Mass balance from gravimetry is particularly tricky to calculate because the changes to the gravitational field are not only affected by ice loss/gain but also by mass moving around beneath the Earth's crust. At the end of the last ice age, a large thickness of ice in Antarctica melted and the rocks deep within the Earth are still responding to this change 1000s of years later. The consequence of this response - which scientists call glacial-isostatic adjustment or 'GIA' - is that the satellite measurements have to be corrected by a very large amount that accounts for movements of the rocky material and thus to provide the 'real' figure for ice mass loss/gain. It is getting this correction right that has been so problematic because it requires us to know the history of the ice sheet (including past snow accumulation) for over 10,000 years and also to know the structure of the Earth underneath Antarctica. Recent projects including a previous one by our group that was funded by NERC have made substantial improvements in determining this correction but our recently published work has shown very clearly that we still lack data to pin down the GIA correction tightly enough in parts of East Antarctica. In other words there is still an unacceptable level of uncertainty in East Antarctica, which leads directly to uncertainty in sea-level contribution.

In this proposal we have identified a region called Coats Land, in East Antarctica, which accounts for the greatest remaining uncertainty in the GIA correction but where we have managed to identify suitable sites where we can obtain the necessary ice history information, new seismic measurements of crustal structure, and GPS measurements of crustal uplift (a key part of testing GIA models). By visiting these sites and undertaking some world-leading modelling using our field data and a synthesis of existing snow accumulation data we will provide a new and much improved GIA correction for Antarctica. Whilst our data collection focus will be on Coats Land our subsequent modelling effort will encompass all of Antarctica. The data will be used to develop an improved model of GIA in Antarctica in order to correct the GRACE dataset. We conservatively estimate that with the measurements and modelling that we propose to carry out then we can at least halve the total uncertainty in satellite gravimetry measurements of Antarctic mass balance, and probably do substantially better than this. This proposal raises the prospect of getting an improved estimate of the Antarctic contribution to present-day global sea level rise.

Planned Impact

See Lead Proposal
Title Ice Floor by Wayne Binitie, Royal College of Arts. Art installation British Antarctic Survey and Arup Architects 
Description Arup presents Ice Floor, a new Phase 2 commission about climate change that has been developed by UK born artist Wayne Binitie in collaboration with the British Antarctic Survey, a world leading centre for polar science. Since 1979 summer sea-ice extent in the Arctic has reduced at 10% per decade. Some major glaciers that drain the Antarctic and Greenland ice sheets have accelerated by as much as 50%, adding to sea level rise. The installation explores the vulnerability of these regions to global warming and how they are subject to conditions like 'calving' (large chunks of ice breaking away at random moments). Deep ice cores from the polar regions have revealed more about the link between climate change and the atmosphere than any other scientific technique. In a cold room, specially created for the exhibition, slices taken from Antarctic ice cores appear to float on a solid ice floor. The exhibition has been made possible through collaboration with the British Antarctic Survey and the kind support of ISOVER. 
Type Of Art Artwork 
Year Produced 2019 
Impact The Ice Floor art installation comprised 360 discs, each 100 mm diameter and 20mm thick, of ancient Antarctic ice cores placed on a 2 meter diameter slab of frozen water in a dark and sound-proofed room, kept at -5 degrees Celsius, situated in the reception area of Arup Architects in London. The slab of ice was lit from below to cast an eerie light into the darkened room. Speakers set into the concrete floor projected the sounds of pre-industrial air being released from ice cores, which tell us the levels of greenhouse gases in the past. The exhibition was open to the public, with free access. Many thousands of visitors were entranced by the sight of the ice samples from Antarctica, slowly subliming away, evoking the fragility of the Antarctic ice landscape, yet providing mankind with the fundamental knowledge of the history of climate and the composition of the atmosphere. 
Title Solid Liquid Gas 
Description Audio visual field recording of Antarctic ice core air bubbles. 1, 500 years old. Glass sculpture. V&A Museum 
Type Of Art Artwork 
Year Produced 2018 
Impact Exhibition of glass sculptures, set to the sound of air bubbles being released from deep ice cores. Set in the courtyard of the V&A museum, it was visited by many thousands of visitors. Sculptures evoked natural polar ice. Artist provided narrative linking sculptures and sound of ancient air to modern anthropogenic changes in the climate and atmosphere. 
Description The project is still in the early field studies of the region. Other collaborators are responsible for field geomorphology, cosmogenic dating of deposits, and installation/uplift of GPS stations. At this stage, our contribution is limited to the field acquisition and subsequent analysis of 'mumiyo' deposits for radiocarbon dating to assess aspects such as first occupation of the nest sites which indicates an earliest age of deglaciation of the site (allowing access to the birds to nest).

Pro-ventricular stomach oil (sometimes referred to as 'mumiyo') deposits were first reported in the Heimefrontfjella by Lewis Jukes (BAS) during an over snow traverse from Halley Bay in the mid 1960's. The deposits result from the defensive ejection of stomach oils at nest sites. The oils preserve well in the cold polar environment and can form accumulations up to 20-30 cm thick together with internal layering.

As with other organic deposits in Antarctica the oils can be dated (by radiocarbon) and together with information about their position, altitude and geomorphological context, can provide valuable constraints on ice sheet history. For example, dating the onset of deposition provides minimum age for deglaciation and by studying samples along altitude transects can constrain the extent of ice thickening at different sites. An additional advantage is that the stratigraphy of individual deposits can be dated at different levels, providing an occupation history that can be used to infer whether glaciers re-advanced over the site (discontinuous deposition) or if the sites have been continuously ice free since the initial deglaciation (continuous deposition).
We found snow petrel nests at al elevations from immediately beside ice margins right up to ridge crests, and it was notable that in areas of suitable boulders we found that virtually all suitable crevices were occupied by active nests or had been occupied at some point (mumiyo deposits). This might suggest that suitable areas are rapidly and intensively colonised once they are available to the birds; moreover the majority of suitable crevices were actively occupied suggesting that there is a reasonable degree of continuity of occupation.
Exploitation Route Timing the deglaciation history of Coats Land is of value to ice sheet modellers for contraining their models.

Deglaciation adds to sea level rise - the results are valuable to those studying earlier changes in sea level, and ultimately to policy makers taking decisions about defences against future sea level rise.
Sectors Education,Environment,Government, Democracy and Justice

Description Ad hoc climate and atmospheric change briefings 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Industry/Business
Results and Impact Briefings to visitors to BAS on climate and atmospheric change, and tours of the NERC/BAS ice core facilities.

Highest impact comes from allowing visitors to handle small samples of ice that originates from the pre-industrial period, and allow them to feel and hear the escape of pre-industrial air, with levels of carbon dioxide significantly lower than present day.
Year(s) Of Engagement Activity Pre-2006,2006,2007,2008,2009,2010,2011,2012,2013,2014,2015,2016,2017,2018,2019,2020
Description Antarctic ice core display - Science Museum, London 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact Display of an Antarctic ice core in the 'Atmospheres' gallery of the Science Museum in London, with a caption showing 800,000 years of climate change and atmospheric carbon dioxide levels, and explanation of the interaction between carbon dioxide and climate. Display has been in place for ten years, and has been renewed for another five years, and possibly longer., accessed 10th March 2021, records the following:

Step into a virtual world, with its own oceans, land and atmosphere, and go back in time to discover key moments in the Earth's multibillion-year climate history.

The Atmosphere gallery is an exciting place to make sense of the climate-the science of how it works, what it's doing now and what it might do next. Uncover the secrets of ice cores and stalagmites, then head for the future to wonder at the latest ideas for a low-carbon life.

Fascinating objects include a real Antarctic ice core, tree rings and scientists' instruments. Come to this gallery to get to grips with the latest climate news and investigate the important issue of climate change.

The Science Museum developed the content for this gallery through extensive research and engagement with scientists and experts, including expertise from the Met Office as principal content contributor.
Year(s) Of Engagement Activity 2021
Description Cambridge Institute for Sustainable Leadership 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Industry/Business
Results and Impact Regular (4 - 8 times per year) briefings on climate change, and the longer term changes over millennia of global climate and greenhouse gases, together with demonstrations of the NERC/BAS ice core facilities . Audiences range from Politicians/Ministers, to senior business leaders in sectors such as international banking (World Bank, IMF), insurance, motor industry, food industry, building industry. Politicians include those from the UK, and from overseas (particularly China).
Year(s) Of Engagement Activity 2010,2011,2012,2013,2014,2015,2016,2017,2018
Description Demonstration of climate research from ice cores to Duke and Duchess of Cambridge and Sir David Attenborough 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Policymakers/politicians
Results and Impact Demonstrated ice cores and discussed climate research with the Duke and Duchess of Cambridge and Sir David Attenborough. Discussion was filmed and aired on national TV as a news item, and then later included as a segment in a BBC programme presented by Sir David Attenborough. Reach is thought to have been global.
Year(s) Of Engagement Activity 2019
Description Documentary interview for television: global climate effects of super-eruptions 
Form Of Engagement Activity A broadcast e.g. TV/radio/film/podcast (other than news/press)
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Media (as a channel to the public)
Results and Impact Documentary interview for television programme on the climate effects of a volcano super eruption. Supplied both face to face interview, and high quality footage of drilling ice cores in Antarctica from personal video assets. UK programme maker commissioned by US channel. Likely to be sold on and screened globally.
Year(s) Of Engagement Activity 2020
Description Prince's Teaching Institute 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact Teaching climate change science to GCSE and A-Level school science teachers.
Year(s) Of Engagement Activity 2010,2011,2013,2015,2016,2018