EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Subglacial methane cycling under the Greenland Ice Sheet 

Jade Hatton1, Anna Polášková1, Mark Garnett2, Jakub Trubac1, Jesper Christiansen3, Christian Jørgensen4, Sarah Sapper3, Petra Vinšová1, Thomas Blunier5, Jakub Zarsky1, Michael Dyonisius5, Matěj Znamínko1, and Marek Stibal1
Jade Hatton et al.
  • 1Department of Ecology, Faculty of Science, Charles University, Prague, Czech Republic
  • 2Scottish Universities Environmental Research Centre, NEIF Radiocarbon Laboratory, East Kilbride, United Kingdom
  • 3Department of Geoscience and Natural Resource Management, University of Copenhagen, Copenhagen, Denmark
  • 4Department of Bioscience, Arctic Environment, Aarhus University, Roskilde, Denmark
  • 5Physics of Ice, Climate and Earth, Niels Bohr Institute, Univbersity of Copenhagen, Denmark

Glaciers and ice sheets cover around 10% of the Earth’s surface and the Greenland Ice Sheet (GrIS) is the largest ice mass in the Northern hemisphere, but is melting at an increasing rate, losing ~400 km3 annually. There have been recent studies linking subglacial environments of the GrIS with methane (CH4) production and release, presenting a possible positive climate feedback. Previous work has linked organic carbon in subglacial environments with significant CH4 export via methanogenesis. It has been hypothesised that the GrIS overlies a methanogenically active wetland environment, and thus needs to be included in the global CH4 budget.

However, the subglacial system of the GrIS is complex and highly heterogenous, hosting oxic and anoxic ecosystems, which have developed over a range of timescales. There are still questions outstanding surrounding the ubiquity of CH4 release from the GrIS, mainly because of the limited understanding of subglacial carbon cycling and the potential sources of CH4 in these environments.  

We present the first data from two new, complimentary projects investigating CH4 release from the GrIS margin, where we aim to quantify the production and release of CH4 into the atmosphere from the GrIS. We have developed an ambitious temporal and spatial sampling regime to evaluate the CH4 release along the western margin of the GrIS. We present the first radiocarbon (14C) dated CH4 samples from Greenland, helping to shed light on the carbon cycling processes occurring under the ice sheet. We analyse a mixture of atmospheric CH4 exported from subglacial ice caves and dissolved CH4 from proglacial rivers draining subglacial portals to explore the age of subglacially sourced CH4.

We can combine the carbon age of exported CH4 with microbial analysis and stable isotope data to improve our understanding of the environmental controls on and microbial sources of subglacial CH4 production and export. Understanding the mechanisms behind subglacial CH4 export is crucial when attempting to upscale the point source data that is available currently and we consider whether the GrIS could be a potentially important source of CH4, leading to a substantial, yet currently understudied climatic feedback.

How to cite: Hatton, J., Polášková, A., Garnett, M., Trubac, J., Christiansen, J., Jørgensen, C., Sapper, S., Vinšová, P., Blunier, T., Zarsky, J., Dyonisius, M., Znamínko, M., and Stibal, M.: Subglacial methane cycling under the Greenland Ice Sheet , EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4202,, 2022.