Investigating the Dynamic Response of the Greenland Ice Sheet to Climate Forcing using a Geophysical, Remote-Sensing and Numerical Modelling Framework

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

Abstract

An increasing number of scientific studies show that human activities, e.g. burning of fossil fuels, have increased the concentration of heat-trapping gasses in the atmosphere. It is estimated that global temperatures will increase by 2-5 degrees C during this century if we continue to add carbon dioxide and other 'greenhouse' gasses to the atmosphere. In the Arctic, warming is expected to be even faster and mean annual temperature may increase by 4-7 degrees C. The implications of global warming are of immense proportions because glaciers and ice sheets will melt faster and become increasingly prone to collapse. In Greenland, discharge from outlet glaciers is responsible for about half the annual loss of ice. The other lost half is due to runoff of surface meltwater. The combined effect of iceberg discharge and surface melt are currently greater than the total amount of snowfall falling onto the Greenland Ice Sheet. This ice sheet is therefore shrinking while releasing freshwater into the Atlantic Ocean. The imbalance amounted to -90 cubic km per year for 1996 and increased to -140 cubic km per year by 2000. In 2005, this imbalance may have increased to as much as -220 cubic km per year. The size of the Greenland Ice Sheet is thus diminishing at what appears to be a growing rate. Worldwide concern is associated with this trend because ice-sheet decay results in global sea-level rise and possibly even an obstruction of oceanic circulation, which in key places - such as the North Atlantic - is sensitive to freshwater released from melting ice masses. The Greenland Ice Sheet rests on bedrock above or close to sea level. Glaciologists have for years assumed that such position would be stable and that demise of the ice sheet would require thousands of years even under extreme global warming scenarios. This assumption may need revision. It was shown recently that surface meltwater could penetrate through over 1km of ice to the base of the Greenland Ice Sheet and cause ice-flow speed-up due to faster basal sliding. This mechanism is potentially dangerous because accelerated ice flow leads to thinning, which in turn leads to an increase in surface melt since a larger part of the ice sheet moves into lower and warmer elevations. The Greenland Ice Sheet may therefore be far more prone to decay than it was assumed in earlier projections of global warming. However, up until now the mechanisms by which this dynamic response between surface melt and ice flow have only been generally understood and the present generation of climate-ice sheet models which are used to forecast future sea-level change do not include them in any rigorous manner. This is particularly true in respect of: 1) the extent to which the surface, interior and basal water-plumbing and ice flow systems can moderate, amplify and transmit the dynamic response away into the interior of the ice sheet thereby drawing the inland ice reservoir down and, 2) the extent to which future changes in Greenland temperatures may increase both the area and length of time of which the ice sheet directly experiences these effects. This project directly addresses both of these shortcomings in current models and will implement a set of fieldwork, satellite remote-sensing and comprehensive Greenland Ice Sheet modelling simulations that will fully assess and implement those 'dynamical processes related to ice flow not included in current models... (which) could increase the vulnerability of the ice sheets to warming, increasing future sea-level rise.' (IPCC, WG1 - 2007).

Publications

10 25 50
 
Description That the flow of the Greenland Ice Sheet has a complex response to future climate change. The lower melt zone appears to self-regulate whilst the upper melt/lower accumulation appears to show a long-term flow acceleration - thereby increasing the vulnerability of the ice sheet to future climate. Key outcomes:
That the GrIS is partially underlain by deforming sediments
That we have imaged hydrofracture to the base of the ice sheet.
That surface meltwater impacts the basal environment and ice dynamics in a variety of ways.
That supraglacial melt lakes are increasing in extent & volume
That the ice sheet experiences major tectonic failure on supraglacial lake drainage.
Exploitation Route Our findings have been used to dictate policy via the IPCC.
The hydrofracture imaging algorithm has been used in the gas/oil exploration industry.
Basis as BBC Frozen Planet documentary
Sectors Creative Economy,Digital/Communication/Information Technologies (including Software),Education,Energy,Environment

URL http://www.aber.ac.uk/greenland/
 
Description Basis for BBC's gong-winning - Frozen Planet - Greenland episode & footage.
First Year Of Impact 2011
Sector Creative Economy,Education,Other
Impact Types 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