A holistic model of outlet calving, dynamic acceleration and drawdown for the Greenland Ice Sheet
Lead Research Organisation:
Aberystwyth University
Department Name: Inst of Geography and Earth Sciences
Abstract
The body of scientific evidence for significant anthropogenic impacts on the global climate is growing and public concern underscores a need for better assessments of contemporary environmental changes in polar regions. The greatest store of fresh water in the northern hemisphere - equivalent to 7m of eustatic sea level rise - is held within the Greenland Ice Sheet (GIS), and yet its present and future contribution to sea level is poorly constrained (IPCC, 2007). Recent observations suggest that mass loss near the margin of the GIS is accelerating through a combination of increased surface melting (e.g. Steffen et al, 2004) and dynamic thinning (e.g. Rignot and Kanagaratnam, 2006). However, the key processes controlling interior drawdown have yet to be fully identified, and in consequence, are not incorporated in the ice-sheet models which form the basis of the IPCC sea level projections. This in part reflects the fact that the satellite data that has revealed the widespread speed-up of glaciers cannot be acquired at the temporal resolution needed to resolve the causal mechanisms. This project focuses on second and third largest outlet glaciers of western GIS in order to help understand the processes by which these glaciers increase their speed and lose ice to the ocean by means of iceberg calving. Calving is the process of mechanical fracture where ice breaks off from the edge of glaciers and floating ice shelves. It accounts for the majority of loss from the Antarctic and over 50% of that from the GIS. Calving is a very efficient mass-loss mechanism which provides a rapid connection between the ice stored on land and the ocean where it is turned into sea level rise. Despite its fundamental importance, our understanding of the controls on iceberg calving and the associated process of dynamic drawdown are poorly understood and the present generation of coupled ice sheet models (ISMs) do not simulate these processes at all which severely handicaps their predictive ability. We aim to collect detailed oceanic, climatic, geodetic and geophysical datasets at two outlet glaciers which will enable us to: 1) investigate the main processes and linkages controlling iceberg calving and its effect on upstream glacier flow and thinning, and, 2) to use this data to refine a new process-based calving/flow dynamics criterion that can be easily included within models coupled to simulate the future climate and polar ice cover and its contribution on rising sea levels.
Publications
Doyle S
(2015)
Amplified melt and flow of the Greenland ice sheet driven by late-summer cyclonic rainfall
in Nature Geoscience
Jones G
(2017)
An automated approach to the location of icequakes using seismic waveform amplitudes
in Annals of Glaciology
Ryan J
(2016)
Attribution of Greenland's ablating ice surfaces on ice sheet albedo using unmanned aerial systems
in The Cryosphere Discussions
Christoffersen P
(2018)
Cascading lake drainage on the Greenland Ice Sheet triggered by tensile shock and fracture.
in Nature communications
Ryan JC
(2018)
Dark zone of the Greenland Ice Sheet controlled by distributed biologically-active impurities.
in Nature communications
Chandler D
(2013)
Evolution of the subglacial drainage system beneath the Greenland Ice Sheet revealed by tracers
in Nature Geoscience
Mikkelsen A
(2016)
Extraordinary runoff from the Greenland ice sheet in 2012 amplified by hypsometry and depleted firn retention
in The Cryosphere
Ryan JC
(2019)
Greenland Ice Sheet surface melt amplified by snowline migration and bare ice exposure.
in Science advances
Lindbäck K
(2014)
High-resolution ice thickness and bed topography of a land-terminating section of the Greenland Ice Sheet
in Earth System Science Data
Fitzpatrick A
(2017)
Ice flow dynamics and surface meltwater flux at a land-terminating sector of the Greenland ice sheet
in Journal of Glaciology
Doyle S
(2013)
Ice tectonic deformation during the rapid in situ drainage of a supraglacial lake on the Greenland Ice Sheet
in The Cryosphere
Chauché N
(2014)
Ice-ocean interaction and calving front morphology at two west Greenland tidewater outlet glaciers
in The Cryosphere
Doyle S
(2014)
Persistent flow acceleration within the interior of the Greenland ice sheet
in Geophysical Research Letters
Winsborrow M
(2016)
Regulation of ice stream flow through subglacial formation of gas hydrates
in Nature Geoscience
Dow C
(2017)
Seismic evidence of mechanically weak sediments underlying Russell Glacier, West Greenland
in Annals of Glaciology
Lindbäck K
(2015)
Subglacial water drainage, storage, and piracy beneath the Greenland ice sheet
in Geophysical Research Letters
Nick F
(2017)
The response of Petermann Glacier, Greenland, to large calving events, and its future stability in the context of atmospheric and oceanic warming
in Journal of Glaciology
Description | We have gleaned invaluable insight into the marine and mechanical processes operating across the calving fronts of major tidewater glaciers that drain the Greenland Ice Sheet. Characterised the main water masses that interact with the calving face. Derived submarine melt rate Derived ice front velocity & calving rate Developed a robotic boat to survey the glacier Developed a new technique for investigating submarine calving processes. |
Exploitation Route | Our field results on calving front processes have been used in numerical modelling & for the basis of further research funding. |
Sectors | Aerospace Defence and Marine Digital/Communication/Information Technologies (including Software) Environment |
URL | http://www.aber.ac.uk/greenland/uummannaq.shtml |
Description | Project research & findings at Store Glacier were used the basis for the BBC's "Operation Iceberg" - a gong winning doco that has met with wide acclaim & superb viewing figures. |
First Year Of Impact | 2012 |
Sector | Aerospace, Defence and Marine,Creative Economy,Environment |
Impact Types | Cultural Societal |
Description | Alfred Wagner Institute - Seismic reflection & Geochemistry |
Organisation | Alfred-Wegener Institute for Polar and Marine Research |
Country | Germany |
Sector | Private |
PI Contribution | AWI equipment & personnel have targeted & carried out extensive seismic profiling across three of my NERC Greenland targets. |
Collaborator Contribution | Full seismic & geochemical profiling, processing and analysis. |
Impact | Multi-disciplinary. An ERC proposal under review. A NERC Large grant submission in prep. Five outputs in prep. |
Start Year | 2013 |
Description | BBC "Frozen Planet II" - expertise for consulatany & consultant & expert advisor on Store Glacier calving sequence in Netflix "Our Planet" documentary series (April, 2019) |
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 | Public/other audiences |
Results and Impact | Our Planet (A WWF & Silverback Films collaborative documentary series commissioned by Netflix) is a 6 part flagship doco. Global viewing figures are 15M+. As part of Greenland outreach activity connected with NERC/RCUK research on the Greenland ice sheet, Alun Hubbard advised and consulted on many aspects of the Greenland sequences including expert advice on the Store Glacier calving sequence - considered the highlight of Epsiode 1. |
Year(s) Of Engagement Activity | 2016,2017,2018,2019 |
Description | JacksGAP |
Form Of Engagement Activity | A press release, press conference or response to a media enquiry/interview |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Public/other audiences |
Results and Impact | JacksGAP - a youtube channel/phenomena, covered in collaboration with myself & WWF, my two NERC Greenland ice sheet fieldsites with a short (12 min) film documenting climate change. see https://www.youtube.com/watch?v=gE7vkCz39eg This film has now been viewed over 700,000 times & targets a young (17 to 21 year old audience) & has been highly acclaimed by various pundits. |
Year(s) Of Engagement Activity | 2015 |
URL | https://www.youtube.com/watch?v=gE7vkCz39eg |