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

Lead Research Organisation: Durham University
Department Name: Geography

Abstract

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 altimetry (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

We are planning impact activities focussed on Public Audiences, and in particular UK schools. Antarctica and ice sheet change/sea-level rise are topics that speak to the public imagination, and in different ways. However, the scientific message about polar change can sometimes come across rather 'dry' or even 'preaching', whereas discussions of Antarctica as a place often focus only on the wilderness quality. We propose to combine these two elements into a series of activities that will allow us to have two-way interaction with a broad range of school pupils and teachers, particularly focussed on Key Stage 2 (KS2; ages 7-11) and KS5 (A-level; 16-18). These activities are aimed specifically at embedding Antarctica and global change into a range of schools, initially in the North-East of England but subsequently with a view to delivering materials nationally. We will carry out these activities in conjunction with an education partner, the Climate Change for Schools Project (CCSP). This is a non-profit organisation, operating since 2007, and hosted by the Science Learning Centre North East www.climatechangeschools.org.uk. The CCSP puts climate change at the heart of the national curriculum, brings climate change to life for young people and makes schools 'beacons' for positive action in their local communities. It empowers young people through teachers and schools to become 'everyday experts' on climate change. The CCSP has won national awards, including The Observer Ethical Awards 'Grassroots Community Challenge' 2012 and National Climate Week's inaugural 'Best Educational Initiative'. It has been remarkably successful and so for example, since 2008, 100s of schools and 1000s of young people have led 50,000+ hours of climate related activity, in and around their local communities. We share the goal to bring climate change to life for young people and will collaboratively develop a series of activities focused on Antarctica and climate change that can be used in schools.

Our schools work will encompass four areas of activity:
(i) Development of schemes of work for topic-based modules in KS2 and KS5.

(ii) Continuing Professional Development days for teachers where we can work interactively with cohorts of KS2 and KS5 teachers to find the best ways to embed the schemes of work into practice and long-term lesson planning.

(iii) Polar Day - as part of the Durham Science Festival (Oct each year) we will run a 'Polar Day' that exposes a broad audience of schoolchildren and beyond, to Polar Science, living and working in Antarctica, 'meet the scientist', and hands-on activities (tents, clothing, melting ice and sea-level rise etc).

(iv) A field blog. During the fieldwork (2014/15) we propose to run a field blog. This will be written by Bentley and Hodgson for a very specific schools audience - we can give impressions of Antarctica but interwoven with explanations of the science we are undertaking, its background, and its direct relevance to young people.

Our eventual aim is that at the end of the grant we and our education partners have managed to embed Antarctica and global change (and especially sea-level) into the curriculum and teaching practice fro two Key Stage age ranges, and that this is being delivered to a broad network of schools.

Publications

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Bentley M (2015) Exploring the Last Continent

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Jamieson S (2014) The glacial geomorphology of the Antarctic ice sheet bed in Antarctic Science

 
Description Antarctic Exhibition 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Schools
Results and Impact Antarctic Exhibiton with several 1000 visitors. and accompanying primary and secondary education programme focussed on ice sheets and sea level.

Teachers reported changes in way they teach Geography and Science curricula (esp ice sheets and sea level )
Year(s) Of Engagement Activity 2015