Can the carbon isotopic composition of methane be reconstructed from multi-site firn air measurements?
International audience Methane is a strong greenhouse gas and large uncertainties exist concerning the future evolution of its atmospheric abundance. Analyzing methane atmospheric mixing and stable isotope ratios in air trapped in polar ice sheets helps in reconstructing the evolution of its sources...
Published in: | Atmospheric Chemistry and Physics |
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Main Authors: | , , , , , , , , , , , , |
Other Authors: | , , , , , , , , , , , , , , , , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
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HAL CCSD
2013
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Subjects: | |
Online Access: | https://hal.science/hal-00931580 https://hal.science/hal-00931580/document https://hal.science/hal-00931580/file/acp-13-6993-2013.pdf https://doi.org/10.5194/acp-13-6993-2013 |
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Open Polar |
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Institut National de la Recherche Agronomique: ProdINRA |
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ftinraparis |
language |
English |
topic |
[SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere |
spellingShingle |
[SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere J. Sapart, C. Martinerie, P. Witrant, Emmanuel Chappellaz, J. S. W. van de Wal, R. Sperlich, P. van Der Veen, C. Bernard, Serge Sturges, W.T. Blunier, T. Schwander, J. Etheridge, D. Röckmann, T. Can the carbon isotopic composition of methane be reconstructed from multi-site firn air measurements? |
topic_facet |
[SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere |
description |
International audience Methane is a strong greenhouse gas and large uncertainties exist concerning the future evolution of its atmospheric abundance. Analyzing methane atmospheric mixing and stable isotope ratios in air trapped in polar ice sheets helps in reconstructing the evolution of its sources and sinks in the past. This is important to improve predictions of atmospheric CH4 mixing ratios in the future under the influence of a changing climate. The aim of this study is to assess whether past atmospheric δ13C(CH4) variations can be reliably reconstructed from firn air measurements. Isotope reconstructions obtained with a state of the art firn model from different individual sites show unexpectedly large discrepancies and are mutually inconsistent. We show that small changes in the diffusivity profiles at individual sites lead to strong differences in the firn fractionation, which can explain a large part of these discrepancies. Using slightly modified diffusivities for some sites, and neglecting samples for which the firn fractionation signals are strongest, a combined multi-site inversion can be performed, which returns an isotope reconstruction that is consistent with firn data. However, the isotope trends are lower than what has been concluded from Southern Hemisphere (SH) archived air samples and high-accumulation ice core data. We conclude that with the current datasets and understanding of firn air transport, a high precision reconstruction of δ13C of CH4 from firn air samples is not possible, because reconstructed atmospheric trends over the last 50 yr of 0.3-1.5 ‰ are of the same magnitude as inherent uncertainties in the method, which are the firn fractionation correction (up to ~2 ‰ at individual sites), the Kr isobaric interference (up to ~0.8 ‰, system dependent), inter-laboratory calibration offsets (~0.2 ‰) and uncertainties in past CH4 levels (~0.5 ‰). |
author2 |
Institute for Marine and Atmospheric Research Utrecht (IMAU) Universiteit Utrecht / Utrecht University Utrecht Laboratoire de glaciologie et géophysique de l'environnement (LGGE) Observatoire des Sciences de l'Univers de Grenoble (OSUG) Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS) GIPSA - Systèmes linéaires et robustesse (GIPSA-SLR) Département Automatique (GIPSA-DA) Grenoble Images Parole Signal Automatique (GIPSA-lab) Université Pierre Mendès France - Grenoble 2 (UPMF)-Université Stendhal - Grenoble 3-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Pierre Mendès France - Grenoble 2 (UPMF)-Université Stendhal - Grenoble 3-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Grenoble Images Parole Signal Automatique (GIPSA-lab) Université Pierre Mendès France - Grenoble 2 (UPMF)-Université Stendhal - Grenoble 3-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Pierre Mendès France - Grenoble 2 (UPMF)-Université Stendhal - Grenoble 3-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS) Centre for Ice and Climate Copenhagen Niels Bohr Institute Copenhagen (NBI) Faculty of Science Copenhagen University of Copenhagen = Københavns Universitet (UCPH)-University of Copenhagen = Københavns Universitet (UCPH)-Faculty of Science Copenhagen University of Copenhagen = Københavns Universitet (UCPH)-University of Copenhagen = Københavns Universitet (UCPH) School of Environmental Sciences Norwich University of East Anglia Norwich (UEA) Physics Institute Bern Universität Bern = University of Bern = Université de Berne (UNIBE) Centre for Australian Weather and Climate Research (CAWCR) |
format |
Article in Journal/Newspaper |
author |
J. Sapart, C. Martinerie, P. Witrant, Emmanuel Chappellaz, J. S. W. van de Wal, R. Sperlich, P. van Der Veen, C. Bernard, Serge Sturges, W.T. Blunier, T. Schwander, J. Etheridge, D. Röckmann, T. |
author_facet |
J. Sapart, C. Martinerie, P. Witrant, Emmanuel Chappellaz, J. S. W. van de Wal, R. Sperlich, P. van Der Veen, C. Bernard, Serge Sturges, W.T. Blunier, T. Schwander, J. Etheridge, D. Röckmann, T. |
author_sort |
J. Sapart, C. |
title |
Can the carbon isotopic composition of methane be reconstructed from multi-site firn air measurements? |
title_short |
Can the carbon isotopic composition of methane be reconstructed from multi-site firn air measurements? |
title_full |
Can the carbon isotopic composition of methane be reconstructed from multi-site firn air measurements? |
title_fullStr |
Can the carbon isotopic composition of methane be reconstructed from multi-site firn air measurements? |
title_full_unstemmed |
Can the carbon isotopic composition of methane be reconstructed from multi-site firn air measurements? |
title_sort |
can the carbon isotopic composition of methane be reconstructed from multi-site firn air measurements? |
publisher |
HAL CCSD |
publishDate |
2013 |
url |
https://hal.science/hal-00931580 https://hal.science/hal-00931580/document https://hal.science/hal-00931580/file/acp-13-6993-2013.pdf https://doi.org/10.5194/acp-13-6993-2013 |
genre |
ice core |
genre_facet |
ice core |
op_source |
ISSN: 1680-7316 EISSN: 1680-7324 Atmospheric Chemistry and Physics https://hal.science/hal-00931580 Atmospheric Chemistry and Physics, 2013, 13 (14), pp.6993-7005. ⟨10.5194/acp-13-6993-2013⟩ |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.5194/acp-13-6993-2013 hal-00931580 https://hal.science/hal-00931580 https://hal.science/hal-00931580/document https://hal.science/hal-00931580/file/acp-13-6993-2013.pdf doi:10.5194/acp-13-6993-2013 |
op_rights |
http://creativecommons.org/licenses/by-nd/ info:eu-repo/semantics/OpenAccess |
op_doi |
https://doi.org/10.5194/acp-13-6993-2013 |
container_title |
Atmospheric Chemistry and Physics |
container_volume |
13 |
container_issue |
14 |
container_start_page |
6993 |
op_container_end_page |
7005 |
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1809914617920487424 |
spelling |
ftinraparis:oai:HAL:hal-00931580v1 2024-09-09T19:44:58+00:00 Can the carbon isotopic composition of methane be reconstructed from multi-site firn air measurements? J. Sapart, C. Martinerie, P. Witrant, Emmanuel Chappellaz, J. S. W. van de Wal, R. Sperlich, P. van Der Veen, C. Bernard, Serge Sturges, W.T. Blunier, T. Schwander, J. Etheridge, D. Röckmann, T. Institute for Marine and Atmospheric Research Utrecht (IMAU) Universiteit Utrecht / Utrecht University Utrecht Laboratoire de glaciologie et géophysique de l'environnement (LGGE) Observatoire des Sciences de l'Univers de Grenoble (OSUG) Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS) GIPSA - Systèmes linéaires et robustesse (GIPSA-SLR) Département Automatique (GIPSA-DA) Grenoble Images Parole Signal Automatique (GIPSA-lab) Université Pierre Mendès France - Grenoble 2 (UPMF)-Université Stendhal - Grenoble 3-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Pierre Mendès France - Grenoble 2 (UPMF)-Université Stendhal - Grenoble 3-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Grenoble Images Parole Signal Automatique (GIPSA-lab) Université Pierre Mendès France - Grenoble 2 (UPMF)-Université Stendhal - Grenoble 3-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Pierre Mendès France - Grenoble 2 (UPMF)-Université Stendhal - Grenoble 3-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS) Centre for Ice and Climate Copenhagen Niels Bohr Institute Copenhagen (NBI) Faculty of Science Copenhagen University of Copenhagen = Københavns Universitet (UCPH)-University of Copenhagen = Københavns Universitet (UCPH)-Faculty of Science Copenhagen University of Copenhagen = Københavns Universitet (UCPH)-University of Copenhagen = Københavns Universitet (UCPH) School of Environmental Sciences Norwich University of East Anglia Norwich (UEA) Physics Institute Bern Universität Bern = University of Bern = Université de Berne (UNIBE) Centre for Australian Weather and Climate Research (CAWCR) 2013 https://hal.science/hal-00931580 https://hal.science/hal-00931580/document https://hal.science/hal-00931580/file/acp-13-6993-2013.pdf https://doi.org/10.5194/acp-13-6993-2013 en eng HAL CCSD European Geosciences Union info:eu-repo/semantics/altIdentifier/doi/10.5194/acp-13-6993-2013 hal-00931580 https://hal.science/hal-00931580 https://hal.science/hal-00931580/document https://hal.science/hal-00931580/file/acp-13-6993-2013.pdf doi:10.5194/acp-13-6993-2013 http://creativecommons.org/licenses/by-nd/ info:eu-repo/semantics/OpenAccess ISSN: 1680-7316 EISSN: 1680-7324 Atmospheric Chemistry and Physics https://hal.science/hal-00931580 Atmospheric Chemistry and Physics, 2013, 13 (14), pp.6993-7005. ⟨10.5194/acp-13-6993-2013⟩ [SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere info:eu-repo/semantics/article Journal articles 2013 ftinraparis https://doi.org/10.5194/acp-13-6993-2013 2024-07-30T14:12:32Z International audience Methane is a strong greenhouse gas and large uncertainties exist concerning the future evolution of its atmospheric abundance. Analyzing methane atmospheric mixing and stable isotope ratios in air trapped in polar ice sheets helps in reconstructing the evolution of its sources and sinks in the past. This is important to improve predictions of atmospheric CH4 mixing ratios in the future under the influence of a changing climate. The aim of this study is to assess whether past atmospheric δ13C(CH4) variations can be reliably reconstructed from firn air measurements. Isotope reconstructions obtained with a state of the art firn model from different individual sites show unexpectedly large discrepancies and are mutually inconsistent. We show that small changes in the diffusivity profiles at individual sites lead to strong differences in the firn fractionation, which can explain a large part of these discrepancies. Using slightly modified diffusivities for some sites, and neglecting samples for which the firn fractionation signals are strongest, a combined multi-site inversion can be performed, which returns an isotope reconstruction that is consistent with firn data. However, the isotope trends are lower than what has been concluded from Southern Hemisphere (SH) archived air samples and high-accumulation ice core data. We conclude that with the current datasets and understanding of firn air transport, a high precision reconstruction of δ13C of CH4 from firn air samples is not possible, because reconstructed atmospheric trends over the last 50 yr of 0.3-1.5 ‰ are of the same magnitude as inherent uncertainties in the method, which are the firn fractionation correction (up to ~2 ‰ at individual sites), the Kr isobaric interference (up to ~0.8 ‰, system dependent), inter-laboratory calibration offsets (~0.2 ‰) and uncertainties in past CH4 levels (~0.5 ‰). Article in Journal/Newspaper ice core Institut National de la Recherche Agronomique: ProdINRA Atmospheric Chemistry and Physics 13 14 6993 7005 |