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Link to original content: https://pubmed.ncbi.nlm.nih.gov/30413774
First observation of direct methane emission to the atmosphere from the subglacial domain of the Greenland Ice Sheet - PubMed Skip to main page content
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. 2018 Nov 9;8(1):16623.
doi: 10.1038/s41598-018-35054-7.

First observation of direct methane emission to the atmosphere from the subglacial domain of the Greenland Ice Sheet

Jesper Riis Christiansen  1 , Christian Juncher Jørgensen  2   3
Affiliations

First observation of direct methane emission to the atmosphere from the subglacial domain of the Greenland Ice Sheet

Jesper Riis Christiansen et al. Sci Rep. .

Abstract

During a 2016 field expedition to the West Greenland Ice Sheet, a striking observation of significantly elevated CH4 concentrations of up to 15 times the background atmospheric concentration were measured directly in the air expelled with meltwater at a subglacial discharge point from the Greenland Ice Sheet. The range of hourly subglacial CH4 flux rate through the discharge point was estimated to be 3.1 to 134 g CH4 hr-1. These measurements are the first observations of direct emissions of CH4 from the subglacial environment under the Greenlandic Ice Sheet to the atmosphere and indicate a novel emission pathway of CH4 that is currently a non-quantified component of the Arctic CH4 budget.

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Conflict of interest statement

The authors declare no competing interests.

Figures

Figure 1
Figure 1
Measurements of CH4 (black) and CO2 (green) concentrations in subglacial air expelled from one lateral subglacial meltwater discharge point at the Isunnguata Sermia glacier, West Greenland on (A) August 23rd, (B) August 24th, (C) August 25th and (D) August 26th 2016. Blue and red triangles mark the start and end of CH4 and CO2 measurements in the subglacial cave, respectively. For (B) is also shown timeseries of CH4 concentrations measured in the air flowing through cracks in the ice next to the main lateral outlet. (see Fig. 3C for details). The red asterisk in (B) represent a closed chamber measurement (Fig. 3B) of the CH4 exchange between meltwater and the atmosphere (insert graph). The CO2 concentrations in the air is not shown due to contamination with human breadth resulting in highly fluctuating measurements of CO2 in the air outside the cave. This was not the case for CH4.
Figure 2
Figure 2
Location and detailed view of study site in Western Greenland. Source of satellite images: Google Earth (accessed 05–05–2017), Google Inc. 2017. Attribution to map providers: (A) IBCAO, U.S. Geological Survey, Landsat/Copernicus, (B) IBCAO, U.S. Geological Survey, (C) DigitalGlobe 2017, U.S. Geological Survey, (D) DigitalGlobe 2017. (E) Panoramic view of the margin of the Isunnguata Sermia Glacier. Letters A to D refer to the location of the four different modes of CH4 and CO2 exchange performed at the site (see Fig. 3 for details).
Figure 3
Figure 3
Modes of CH4 and CO2 measurements at the subglacial discharge point. (A) Open chamber inside the subglacial cave, (B) Closed chamber placed in a pool of subglacial meltwater, (C) open chamber placed in front of an ice crack connected to the subglacial discharge point and (D) Closed chamber placed on sediment beneath the ice edge. For (B,D) the chamber was connected to the analyzer forming a closed recirculation system for the measurement of the meltwater/sediment atmosphere exchange of gases, respectively. The mobile CH4 and CO2 analyzer (G4301, Picarro Inc.) can be seen in (B–D).
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