Greenland melt drives continuous export of methane from the ice sheet bed
Ice sheets are currently ignored in global methane budgets1,2. Although ice sheets have been proposed to contain large reserves of methane that may contribute to a rise in atmospheric methane concentration if released during periods of rapid ice retreat3,4, no data exist on the current methane footp...
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ftunivbruxelles:oai:dipot.ulb.ac.be:2013/265994 2023-05-15T16:28:39+02:00 Greenland melt drives continuous export of methane from the ice sheet bed Lamarche-Gagnon, Guillaume Wadham, Jemma Louise Sherwood Lollar, Barbara Arndt, Sandra Fietzek, Peer Beaton, Alexander A.D. Tedstone, Andrew A.J. Telling, Jon Bagshaw, Elizabeth E.A. Hawkings, Jon J.R. Kohler, Tyler T.J. Zarsky, Jakub J.D. Mowlem, Matthew Charles Anesio, Alexandre Magno Stibal, Marek 2019-01-01 1 full-text file(s): application/pdf http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/265994 https://dipot.ulb.ac.be/dspace/bitstream/2013/265994/3/CH4_postprint.pdf en eng uri/info:doi/10.1038/s41586-018-0800-0 uri/info:pmid/30602750 uri/info:scp/85059502232 https://dipot.ulb.ac.be/dspace/bitstream/2013/265994/3/CH4_postprint.pdf http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/265994 1 full-text file(s): info:eu-repo/semantics/openAccess Nature (London), 565 (7737 Glaciologie info:eu-repo/semantics/article info:ulb-repo/semantics/articlePeerReview info:ulb-repo/semantics/openurl/article 2019 ftunivbruxelles 2022-06-12T22:07:59Z Ice sheets are currently ignored in global methane budgets1,2. Although ice sheets have been proposed to contain large reserves of methane that may contribute to a rise in atmospheric methane concentration if released during periods of rapid ice retreat3,4, no data exist on the current methane footprint of ice sheets. Here we find that subglacially produced methane is rapidly driven to the ice margin by the efficient drainage system of a subglacial catchment of the Greenland ice sheet. We report the continuous export of methane-supersaturated waters (CH4(aq)) from the ice-sheet bed during the melt season. Pulses of high CH4(aq) concentration coincide with supraglacially forced subglacial flushing events, confirming a subglacial source and highlighting the influence of melt on methane export. Sustained methane fluxes over the melt season are indicative of subglacial methane reserves that exceed methane export, with an estimated 6.3 tonnes (discharge-weighted mean; range from 2.4 to 11 tonnes) of CH4(aq) transported laterally from the ice-sheet bed. Stable-isotope analyses reveal a microbial origin for methane, probably from a mixture of inorganic and ancient organic carbon buried beneath the ice. We show that subglacial hydrology is crucial for controlling methane fluxes from the ice sheet, with efficient drainage limiting the extent of methane oxidation5 to about 17 per cent of methane exported. Atmospheric evasion is the main methane sink once runoff reaches the ice margin, with estimated diffusive fluxes (4.4 to 28 millimoles of CH4 per square metre per day) rivalling that of major world rivers6. Overall, our results indicate that ice sheets overlie extensive, biologically active methanogenic wetlands and that high rates of methane export to the atmosphere can occur via efficient subglacial drainage pathways. Our findings suggest that such environments have been previously underappreciated and should be considered in Earth’s methane budget. info:eu-repo/semantics/published Article in Journal/Newspaper Greenland Ice Sheet DI-fusion : dépôt institutionnel de l'Université libre de Bruxelles (ULB) Greenland |
institution |
Open Polar |
collection |
DI-fusion : dépôt institutionnel de l'Université libre de Bruxelles (ULB) |
op_collection_id |
ftunivbruxelles |
language |
English |
topic |
Glaciologie |
spellingShingle |
Glaciologie Lamarche-Gagnon, Guillaume Wadham, Jemma Louise Sherwood Lollar, Barbara Arndt, Sandra Fietzek, Peer Beaton, Alexander A.D. Tedstone, Andrew A.J. Telling, Jon Bagshaw, Elizabeth E.A. Hawkings, Jon J.R. Kohler, Tyler T.J. Zarsky, Jakub J.D. Mowlem, Matthew Charles Anesio, Alexandre Magno Stibal, Marek Greenland melt drives continuous export of methane from the ice sheet bed |
topic_facet |
Glaciologie |
description |
Ice sheets are currently ignored in global methane budgets1,2. Although ice sheets have been proposed to contain large reserves of methane that may contribute to a rise in atmospheric methane concentration if released during periods of rapid ice retreat3,4, no data exist on the current methane footprint of ice sheets. Here we find that subglacially produced methane is rapidly driven to the ice margin by the efficient drainage system of a subglacial catchment of the Greenland ice sheet. We report the continuous export of methane-supersaturated waters (CH4(aq)) from the ice-sheet bed during the melt season. Pulses of high CH4(aq) concentration coincide with supraglacially forced subglacial flushing events, confirming a subglacial source and highlighting the influence of melt on methane export. Sustained methane fluxes over the melt season are indicative of subglacial methane reserves that exceed methane export, with an estimated 6.3 tonnes (discharge-weighted mean; range from 2.4 to 11 tonnes) of CH4(aq) transported laterally from the ice-sheet bed. Stable-isotope analyses reveal a microbial origin for methane, probably from a mixture of inorganic and ancient organic carbon buried beneath the ice. We show that subglacial hydrology is crucial for controlling methane fluxes from the ice sheet, with efficient drainage limiting the extent of methane oxidation5 to about 17 per cent of methane exported. Atmospheric evasion is the main methane sink once runoff reaches the ice margin, with estimated diffusive fluxes (4.4 to 28 millimoles of CH4 per square metre per day) rivalling that of major world rivers6. Overall, our results indicate that ice sheets overlie extensive, biologically active methanogenic wetlands and that high rates of methane export to the atmosphere can occur via efficient subglacial drainage pathways. Our findings suggest that such environments have been previously underappreciated and should be considered in Earth’s methane budget. info:eu-repo/semantics/published |
format |
Article in Journal/Newspaper |
author |
Lamarche-Gagnon, Guillaume Wadham, Jemma Louise Sherwood Lollar, Barbara Arndt, Sandra Fietzek, Peer Beaton, Alexander A.D. Tedstone, Andrew A.J. Telling, Jon Bagshaw, Elizabeth E.A. Hawkings, Jon J.R. Kohler, Tyler T.J. Zarsky, Jakub J.D. Mowlem, Matthew Charles Anesio, Alexandre Magno Stibal, Marek |
author_facet |
Lamarche-Gagnon, Guillaume Wadham, Jemma Louise Sherwood Lollar, Barbara Arndt, Sandra Fietzek, Peer Beaton, Alexander A.D. Tedstone, Andrew A.J. Telling, Jon Bagshaw, Elizabeth E.A. Hawkings, Jon J.R. Kohler, Tyler T.J. Zarsky, Jakub J.D. Mowlem, Matthew Charles Anesio, Alexandre Magno Stibal, Marek |
author_sort |
Lamarche-Gagnon, Guillaume |
title |
Greenland melt drives continuous export of methane from the ice sheet bed |
title_short |
Greenland melt drives continuous export of methane from the ice sheet bed |
title_full |
Greenland melt drives continuous export of methane from the ice sheet bed |
title_fullStr |
Greenland melt drives continuous export of methane from the ice sheet bed |
title_full_unstemmed |
Greenland melt drives continuous export of methane from the ice sheet bed |
title_sort |
greenland melt drives continuous export of methane from the ice sheet bed |
publishDate |
2019 |
url |
http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/265994 https://dipot.ulb.ac.be/dspace/bitstream/2013/265994/3/CH4_postprint.pdf |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Greenland Ice Sheet |
genre_facet |
Greenland Ice Sheet |
op_source |
Nature (London), 565 (7737 |
op_relation |
uri/info:doi/10.1038/s41586-018-0800-0 uri/info:pmid/30602750 uri/info:scp/85059502232 https://dipot.ulb.ac.be/dspace/bitstream/2013/265994/3/CH4_postprint.pdf http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/265994 |
op_rights |
1 full-text file(s): info:eu-repo/semantics/openAccess |
_version_ |
1766018328747311104 |