Investigating meltwater flow beneath the Greenland Ice Sheet using a multi-tracer approach

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

Abstract

The Greenland Ice Sheet is the main reservoir of ice in the northern hemisphere capable of affecting sea level in the 21st Century. Measurements of the elevation of the ice sheet surface from aircraft now provide a much better picture of the whether the ice sheet is graining or losing mass. However, until there is a better understanding of how ice flows from the ice sheet interior to the ocean, models that aim to predict the response of the Greenland Ice Sheet to climate change and the impact on sea level are unlikely to produce accurate estimates. One of the least poorly understood aspects of ice flow is how meltwater lubrication at the ice sheet sole might affect the rate of ice discharge to the ocean. Recent research has shown that the input of surface meltwater to the ice sheet bed in summer causes considerable ice speed up. Exactly how meltwater flows at the bed (does it flow in discrete channels or does it spread out and flow in a more diffuse manner?) is crucial to understanding how the ice sheet might respond to increased melt inputs in a warming climate. Currently, little is known about basal meltwater routing because the vast amounts of meltwater prevent the use of traditional tracing techniques (e.g. dye tracing). This project aims to apply novel tracing methods which will survive large scale dilution, and which can be injected to holes (moulins) on the glacier surface and detected when the water emerges at the ice sheet front. Some of these techniques have been using widely in oceanography to trace currents across ocean basins. Our tracer experiments will provide new information regarding characteristics of meltwater flow paths and their temporal/spatial variations at the bed of the ice sheet and provide detailed measurements (e.g. pressure) of along-flow path characteristics. Comparison of our tracer results (e.g. water flow speeds, pressure conditions in channels) with ice velocity data from the same glacier will help identify linkages between meltwater routing and ice flow mechanisms, and will generate a unique dataset for future numerical modelling studies aimed at quantifying the future contribution of the Greenland Ice Sheet to global sea level rise.level rise.

Publications

10 25 50
 
Description We've found that the subglacial hydrological system beneath the GrIS evolves seasonally to effeciently encompass increased volume of melt-water. This result in a contrasting flow response of the ice sheet in marginal areas - where early summer acceleration is compensated by late summer/winter slow-down, whilst interior regions of the ice sheet (above the long-term ELA) appear to be undergoing long-term acceleration.
Exploitation Route The project developed a unique chemical tracing system for investigating subglacial environments.
Sectors Chemicals,Education,Environment,Other

 
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