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

Lead Research Organisation: University of Exeter
Department Name: Engineering Computer Science and Maths

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 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 Hadley Centre 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

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