Sub-permafrost methane seepage from open-system pingos in Svalbard
Methane release from beneath lowland permafrost represents an important uncertainty in the Arctic greenhouse gas budget. Our current knowledge is arguably best developed in settings where permafrost is being inundated by rising sea level, which means much of the methane is oxidised in the water colu...
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Online Access: | https://doi.org/10.5194/tc-14-3829-2020 https://tc.copernicus.org/articles/14/3829/2020/ |
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ftcopernicus:oai:publications.copernicus.org:tc82899 2023-05-15T13:05:42+02:00 Sub-permafrost methane seepage from open-system pingos in Svalbard Hodson, Andrew J. Nowak, Aga Hornum, Mikkel T. Senger, Kim Redeker, Kelly Christiansen, Hanne H. Jessen, Søren Betlem, Peter Thornton, Steve F. Turchyn, Alexandra V. Olaussen, Snorre Marca, Alina 2020-11-09 application/pdf https://doi.org/10.5194/tc-14-3829-2020 https://tc.copernicus.org/articles/14/3829/2020/ eng eng doi:10.5194/tc-14-3829-2020 https://tc.copernicus.org/articles/14/3829/2020/ eISSN: 1994-0424 Text 2020 ftcopernicus https://doi.org/10.5194/tc-14-3829-2020 2020-11-16T17:22:15Z Methane release from beneath lowland permafrost represents an important uncertainty in the Arctic greenhouse gas budget. Our current knowledge is arguably best developed in settings where permafrost is being inundated by rising sea level, which means much of the methane is oxidised in the water column before it reaches the atmosphere. Here we provide a different process perspective that is appropriate for Arctic fjord valleys where local deglaciation causes isostatic uplift to out pace rising sea level. We describe how the uplift induces permafrost aggradation in former marine sediments, whose pressurisation results in methane escape directly to the atmosphere via groundwater springs. In Adventdalen, central Spitsbergen, we show how the springs are historic features responsible for the formation of open-system pingos and capable of discharging brackish waters enriched with high concentrations of mostly biogenic methane (average 18 mg L −1 ). Thermodynamic calculations show that the methane concentrations sometimes marginally exceed the solubility limit for methane in water at 0 ∘ C (41 mg L −1 ). Year-round emissions from the pingos are described. During winter, rapid methane loss to the atmosphere occurs following outburst events from beneath an ice blister. During summer, highly variable emissions occur due to complex surface processes at the seepage point and its inundation by surface runoff. In spite of this complexity, our observations confirm that sub-permafrost methane migration deserves more attention for the improved forecasting of Arctic greenhouse gas emissions. Text Adventdalen Arctic Ice permafrost Svalbard Spitsbergen Copernicus Publications: E-Journals Adventdalen ENVELOPE(16.264,16.264,78.181,78.181) Arctic Svalbard The Cryosphere 14 11 3829 3842 |
institution |
Open Polar |
collection |
Copernicus Publications: E-Journals |
op_collection_id |
ftcopernicus |
language |
English |
description |
Methane release from beneath lowland permafrost represents an important uncertainty in the Arctic greenhouse gas budget. Our current knowledge is arguably best developed in settings where permafrost is being inundated by rising sea level, which means much of the methane is oxidised in the water column before it reaches the atmosphere. Here we provide a different process perspective that is appropriate for Arctic fjord valleys where local deglaciation causes isostatic uplift to out pace rising sea level. We describe how the uplift induces permafrost aggradation in former marine sediments, whose pressurisation results in methane escape directly to the atmosphere via groundwater springs. In Adventdalen, central Spitsbergen, we show how the springs are historic features responsible for the formation of open-system pingos and capable of discharging brackish waters enriched with high concentrations of mostly biogenic methane (average 18 mg L −1 ). Thermodynamic calculations show that the methane concentrations sometimes marginally exceed the solubility limit for methane in water at 0 ∘ C (41 mg L −1 ). Year-round emissions from the pingos are described. During winter, rapid methane loss to the atmosphere occurs following outburst events from beneath an ice blister. During summer, highly variable emissions occur due to complex surface processes at the seepage point and its inundation by surface runoff. In spite of this complexity, our observations confirm that sub-permafrost methane migration deserves more attention for the improved forecasting of Arctic greenhouse gas emissions. |
format |
Text |
author |
Hodson, Andrew J. Nowak, Aga Hornum, Mikkel T. Senger, Kim Redeker, Kelly Christiansen, Hanne H. Jessen, Søren Betlem, Peter Thornton, Steve F. Turchyn, Alexandra V. Olaussen, Snorre Marca, Alina |
spellingShingle |
Hodson, Andrew J. Nowak, Aga Hornum, Mikkel T. Senger, Kim Redeker, Kelly Christiansen, Hanne H. Jessen, Søren Betlem, Peter Thornton, Steve F. Turchyn, Alexandra V. Olaussen, Snorre Marca, Alina Sub-permafrost methane seepage from open-system pingos in Svalbard |
author_facet |
Hodson, Andrew J. Nowak, Aga Hornum, Mikkel T. Senger, Kim Redeker, Kelly Christiansen, Hanne H. Jessen, Søren Betlem, Peter Thornton, Steve F. Turchyn, Alexandra V. Olaussen, Snorre Marca, Alina |
author_sort |
Hodson, Andrew J. |
title |
Sub-permafrost methane seepage from open-system pingos in Svalbard |
title_short |
Sub-permafrost methane seepage from open-system pingos in Svalbard |
title_full |
Sub-permafrost methane seepage from open-system pingos in Svalbard |
title_fullStr |
Sub-permafrost methane seepage from open-system pingos in Svalbard |
title_full_unstemmed |
Sub-permafrost methane seepage from open-system pingos in Svalbard |
title_sort |
sub-permafrost methane seepage from open-system pingos in svalbard |
publishDate |
2020 |
url |
https://doi.org/10.5194/tc-14-3829-2020 https://tc.copernicus.org/articles/14/3829/2020/ |
long_lat |
ENVELOPE(16.264,16.264,78.181,78.181) |
geographic |
Adventdalen Arctic Svalbard |
geographic_facet |
Adventdalen Arctic Svalbard |
genre |
Adventdalen Arctic Ice permafrost Svalbard Spitsbergen |
genre_facet |
Adventdalen Arctic Ice permafrost Svalbard Spitsbergen |
op_source |
eISSN: 1994-0424 |
op_relation |
doi:10.5194/tc-14-3829-2020 https://tc.copernicus.org/articles/14/3829/2020/ |
op_doi |
https://doi.org/10.5194/tc-14-3829-2020 |
container_title |
The Cryosphere |
container_volume |
14 |
container_issue |
11 |
container_start_page |
3829 |
op_container_end_page |
3842 |
_version_ |
1766391693262716928 |