Airborne geophysical investigations of basal conditions at flow transitions of outlet glaciers on the Greenland Ice Sheet

Lead Research Organisation: University of Edinburgh
Department Name: Sch of Geosciences

Abstract

The 1.7 million km2 Greenland Ice Sheet is divided into a series of major drainage basins, each typically about 50-100,000 km2 in area. Most of these basins drain into the marine waters of fjord systems via relatively narrow and heavily crevassed outlet glaciers that dissect the mountains fringing the island. Over the past few years it has become clear that the Ice Sheet is losing mass and has become a significant contributor to global sea-level rise. This is related to, first, the doubling in speed of several outlet glaciers, increasing ice flux to the sea and, secondly, a major increase in the area affected by summer melting and runoff from the ice-sheet surface. Both of these changes have taken place in the past decade and have been linked with warmer air and water temperatures over and around Greenland. A major question for both scientists and policymakers is how the Greenland Ice Sheet will continue to react to the temperature rises that are predicted for the coming century by a suite of climate models, particularly in the context that the Arctic is likely to warm at a greater rate than the global average due to the continuing loss of its surrounding sea-ice cover and the changes in ocean albedo and, therefore, energy balance that will result. We will acquire geophysical data from a series of ten outlet glaciers of the Greenland Ice Sheet using airborne ice-penetrating radar, laser altimeter, gravimeter, and magnetometer and GPS instruments. These glacier systems have been selected because: (a) they are major drainage basins within the ice sheet which provide a high ice flux to the sea; and (b) they represent different sub-environments within the Greenland Ice Sheet and its related climate and ocean setting. We will focus our investigations on three key areas of each outlet glacier: first, the heavily crevassed fast-flowing outlet glaciers themselves, that flow in narrow channels through Greenland's fringing mountains; secondly, an upper transition zone between the ice-sheet interior and these narrow outlet glaciers; and thirdly, the grounding zone marking the transition of fast-flowing outlet glaciers to floating ice tongues that are present at the head of many Greenland fjords. Our scientific objectives are: 1. To determine ice surface elevation and subglacial bed elevation, including measurement beneath areas of heavy crevassing in fast-flowing outlet glaciers. 2. To characterize the substrate beneath the ice, in particular whether it is crystalline bedrock or deformable sediments. 3. To establish the distribution of subglacial melting and characterize the subglacial hydrological system where water is present. 4. To identify the transition zones between inland ice, outlet glaciers and the grounding zone and reveal basal character changes associated with them. 5. To describe the three-dimensional nature of internal ice layering within transition zone from inland ice to outlet glacier to measure the distribution of accumulation, strain, and basal melting. This information will make a fundamental contribution to the computer modelling of ice sheets, and how Greenland in particular may respond in future to changes in air and ocean temperate over the coming decades. This because these models require information, known as boundary conditions, on the shape of the bed and also the processes that are going on there in order to make useful predictions. To date, we know little about, for example, the distribution of water beneath these outlet glaciers. The changing amount of ice lost from the ice sheet by surface melting and iceberg production is important, in turn, for predictions on the future contributions of Greenland to sea-level rise in a warming Arctic. This is of significance beyond the academic community. In the UK and elsewhere, governments at national and regional level are requiring information about rates of sea-level rise and the remediation measures, such as sea defences, that are needed.

Related Projects

Project Reference Relationship Related To Start End Award Value
NE/H021078/1 01/10/2010 31/07/2012 £56,093
NE/H021078/2 Transfer NE/H021078/1 01/08/2012 30/09/2013 £21,814
 
Description We have built a new method for quantifying bed reflectivity as a means to show where basal water exists.

We have combined several independent datasets to build a new bed elevation model of Greenland.
Exploitation Route Our work is highly methodological, meaning it can be taken forward by future users. All data products are being made freely available.
Sectors Environment

 
Description Frontier Club Panel Discussion 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact A panel discussion on the Arctic and climate change, organised by the Scientific Expeditions Society. hosted by the Frontline Club, London.
Year(s) Of Engagement Activity 2015
URL http://www.ses-explore.org/news_detail.php?article=268
 
Description Inaugural Lecture 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? Yes
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact Lots of questions from the public

Emails and twitter questions
Year(s) Of Engagement Activity 2015
URL https://search.yahoo.com/search;_ylt=AwrBT.E48QNWo04AaNhXNyoA;_ylc=X1MDMjc2NjY3OQRfcgMyBGZyA3lzZXRfY...
 
Description Pint of Science 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? Yes
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact Many questions from the public about my talk

Emails, and social media contact, from the public about my talk
Year(s) Of Engagement Activity 2015
URL http://pintofscience.co.uk/event/undiscovered-origins/
 
Description Science Uncovered 2016 - exploration of East Antarctica 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact The ICECAP2 programme ran a exhibit at the Natural History Museum's Science Uncovered event, London, 30 September 2016. The audience was in the 1000s, and come from the public, academic, policy and businesses.
The exhibit demonstrated how polar exploration is undertaken, what the results are and how they are important for understanding sea level change.
Year(s) Of Engagement Activity 2016
URL http://www.nhm.ac.uk/visit/whats-on/programs/nhm/science_uncovered_2016.html?date=30.09.2016