Impact of surface melt and ponding on ice shelf dynamics and stability

Lead Research Organisation: Aberystwyth University
Department Name: Inst of Geography and Earth Sciences

Abstract

Ice shelves fringe around half of the Antarctic coastline and exert a fundamental control on the discharge of ice from the Antarctic ice sheets. They can gain and lose mass through interactions with both the ocean and the atmosphere. In the long term their evolution and impact on the ice sheets is controlled by the ocean, but the effect of a warming atmosphere may dominate in the shorter term by providing the conditions and mechanisms for abrupt ice shelf collapse. The atmosphere on the Antarctic Peninsula, where ice shelves have recently undergone most change, is warming faster than anywhere else on Earth.

Atmospheric warming leading to surface melt and ponding has already been implicated in the collapse of ice shelves of the Antarctic Peninsula - the loss of the Larsen B ice shelf in 2002 led to significant and ongoing glacier acceleration, draw-down of grounded ice from the interior, and contribution to sea level rise. There is no doubt that climate warming will lead to more ice shelves being subject to temperatures above freezing for significant periods. The much larger southerly neighbour of the Larsen B ice shelf, Larsen C, annually experiences periods of surface melt and ponding, and appears in parts to be approaching the level of firn densification that preceded the Larsen B collapse. Very little is known, however, about the spatial and temporal pattern of melt and firn densification, the distribution and size of ponds, or the impact of these factors on flow and fracture. A key control on ice sheet mass balance is therefore inadequately understood.

Our project will address this issue through a combined program of fieldwork, remote sensing and numerical modelling. We will focus on the Larsen C Ice Shelf as an ideal example of a large ice shelf experiencing a wide variety of surface melt and ponding conditions, and which is readily accessible for field measurements. Using borehole camera survey and monitoring instrumentation, and surface geophysics, we will acquire much needed new data about the density and temperature across the ice shelf in the upper half of the ice column. We will probe layers of ice going back hundreds of years to understand the history of melt and ponding on Larsen C Ice Shelf. To understand the impact on the ice shelf of past and future melt and ponding, we will develop a coupled simulation which will use a regional climate model to predict surface melt and ponding and an ice shelf numerical model to test the impact of this meltwater on flow and fracture. These models will be optimised by data from fieldwork and remote sensing that we will collect. The outcome will be the most accurate model of an ice shelf to date which will allow us fully understand impact of melt and ponding on ice shelves and to predict the future evolution of Larsen C Ice Shelf over the next century.

Planned Impact

We focus our impact efforts on education and outreach, aiming for a better public understanding of processes and risks associated with ice shelves. The general public and policy makers will benefit from this project through a better understanding of the impact of climate change on ice shelves, a key part of the cryosphere which encompasses potential climate tipping points.

Our impact activities will include a daily blog from our fieldwork location designed to engage school age children and students from our home departments, a website dedicated to ice shelf research and featuring project progress and Google Earth downloads, and general outreach activities at venues such as the National Eisteddfod.

We recognise that the most effective public message is one that originates from an agreed view of an appropriate section of the academic community, rather than simply the outcomes of one project. Consequently, as a means of seeking common ground in related international research, we include a science workshop in the pathways to impact as a step on the critical path to better public understanding of ice shelf issues.

Publications

10 25 50
 
Description Larsen C ice shelf is partly composed of a massive internal ice layer formed as a result of intensive surface melting and the refreezing of that melt and of intermittent surface melt ponds.

Internal structure of ice shelf has been mapped at both the local and regional scale and published in two papers in 2017.

Rift propagation across Larsen C has been tracked and media updated regularly, along with scientific publication. History of melt over past 300 years has been reconstructed - indicating that melt is not new, but that there has been two phases of intense melt - and published in 2017.
Exploitation Route Numerical modelers of ice shelf behaviour and response to climate change can improve 3-D temperature and density fields.

Policy on use of Larsen C ice shelf and surrounding ocean in relation to propagating rift and likelihood of imminent large iceberg calving event
Sectors Aerospace, Defence and Marine,Education,Environment

URL http://www.projectmidas.org/
 
Description Numerous media reports, ongoing, relating to the structure and stability of Larsen C Ice Shelf. This includes monitoring of major rift propagating across the ice shelf through 2015 tp present (2017)
First Year Of Impact 2015
Sector Education,Environment
Impact Types Cultural,Societal

 
Description Research Grant
Amount € 824,645 (EUR)
Funding ID ERC-2015-CoG-683043 
Organisation European Research Council (ERC) 
Sector Public
Country Belgium
Start 09/2016 
End 09/2021
 
Description Research Grant
Amount £122,746 (GBP)
Funding ID NE/P002021/1 
Organisation Natural Environment Research Council 
Sector Public
Country United Kingdom
Start 09/2016 
End 03/2019
 
Title Borehole density profiles reconstructed from calibrated optical televiewer (OPTV) logs from the northern sector of Larsen C Ice Shelf, Antarctica 
Description These are vertical density profiles of snow, firn and ice reconstructed from the vertical luminosity trace of digital optical televiewer (OPTV) logs of five boreholes drilled by hot water to ~100 m depth in Larsen C Ice Shelf, Antarctica. Boreholes were drilled in austral summers of 2014 and 2015 in order to investigate the internal properties of the ice shelf, and specifically the influence of surface melting and melt pond formation on those properties, as part of the NERC-funded MIDAS ("Impact of surface melt and ponding on ice shelf dynamics and stability") research project. The associated borehole OPTV logs are also available, as are more general data including borehole temperature profiles, surface radar profiles, flow-line model code, AWS data and SMB data. 
Type Of Material Database/Collection of data 
Year Produced 2018 
Provided To Others? Yes  
 
Title Borehole optical televiewer (OPTV) logs from the northern sector of Larsen C Ice Shelf, Antarctica 
Description These are digital optical televiewer (OPTV) logs of five boreholes drilled by hot water to ~100 m depth in Larsen C Ice Shelf, Antarctica. Boreholes were drilled in austral summers of 2014 and 2015 in order to investigate the internal properties of the ice shelf, and specifically the influence of surface melting and melt pond formation on those properties, as part of the NERC-funded MIDAS ("Impact of surface melt and ponding on ice shelf dynamics and stability") research project. These data are part of a larger project. Borehole density and temperature profiles are also available, as are more general data including surface radar profiles, flow-line model code, AWS data and SMB data. 
Type Of Material Database/Collection of data 
Year Produced 2018 
Provided To Others? Yes  
 
Title Englacial temperature time-series from the northern sector of Larsen C Ice Shelf, Antarctica 
Description The datasets are temperature time series from strings of thermistors, each located at a discrete depth within one of six boreholes drilled to a depth of ~100 m in the northern sector of Larsen C Ice Shelf, Antarctica. Supporting borehole information is presented by Ashmore and others (2017). As part of the broader MIDAS project, associated (near-surface) borehole temperature records, OPTV logs and density records are also available, as are more general data including surface radar profiles, flow-line model code, AWS data and SMB data. 
Type Of Material Database/Collection of data 
Year Produced 2018 
Provided To Others? Yes  
 
Title Ground penetrating radar data from the Larsen C Ice Shelf, 2014 and 2015 
Description This archive is a suite of ground penetrating radar (GPR) data acquired by Project MIDAS during field campaigns on Larsen C, in 2014 and 2015. All data were acquired with a Sensors & Software pulsEKKO PRO GPR system, fitted with antennas of 200 MHz centre-frequency. The system was towed behind a snowmobile, with distances recorded with GPS. These data are part of the NERC-funded MIDAS ('Impact of surface melt and ponding on ice shelf dynamics and stability') research project, with grant references NE/L006707/1 and NE/L005409/1. Other MIDAS data are available. 
Type Of Material Database/Collection of data 
Year Produced 2018 
Provided To Others? Yes  
 
Title Near-surface temperature time-series from the northern sector of Larsen C Ice Shelf, Antarctic 
Description The datasets are temperature time series from thermistor strings installed into two boreholes drilled to a depth of ~7 m in the northern sector of Larsen C Ice Shelf, Antarctica. Supporting borehole information is presented by Ashmore and others (2017). As part of the broader MIDAS project, associated (longer) borehole temperature records, OPTV logs and density records are also available, as are more general data including surface radar profiles, flow-line model code, AWS data and SMB data. 
Type Of Material Database/Collection of data 
Year Produced 2018 
Provided To Others? Yes  
 
Description Research collaboration 
Organisation Utrecht University
Country Netherlands 
Sector Academic/University 
PI Contribution New links made with firn and snow climate modelers based at IMAU, University of Utrecht: Dr P Kuipers Munneke Dr J Linearts
Collaborator Contribution Our field data have been conmbined with outputs from climate models to shed new light on firn densification processes in Antarctica
Impact Publications attributed to this grant include contributions from Kuipers Munneke
Start Year 2015