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

10 25 50
 
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 Public 
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