Variability and quasi-decadal changes in the methane budget over the period 2000–2012
Following the recent Global Carbon Project (GCP) synthesis of the decadal methane (CH₄) budget over 2000-2012 (Saunois et al., 2016), we analyse here the same dataset with a focus on quasi-decadal and inter-annual variability in CH₄ emissions. The GCP dataset integrates results from top-down studies...
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| Format: | Article |
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Copernicus Publications
2018
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| Online Access: | http://hdl.handle.net/1721.1/114970 https://orcid.org/0000-0001-5925-3801 |
| _version_ | 1811095448073535488 |
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| author | Saunois, Marielle Bousquet, Philippe Poulter, Ben Peregon, Anna Ciais, Philippe Canadell, Josep G. Dlugokencky, Edward J. Etiope, Giuseppe Bastviken, David Houweling, Sander Janssens-Maenhout, Greet Tubiello, Francesco N. Castaldi, Simona Jackson, Robert B. Alexe, Mihai Arora, Vivek K. Beerling, David J. Bergamaschi, Peter Blake, Donald R. Brailsford, Gordon Bruhwiler, Lori Crevoisier, Cyril Crill, Patrick Covey, Kristofer Frankenberg, Christian Gedney, Nicola Höglund-Isaksson, Lena Ishizawa, Misa Ito, Akihiko Joos, Fortunat Kim, Heon-Sook Kleinen, Thomas Krummel, Paul Lamarque, Jean-François Langenfelds, Ray Locatelli, Robin Machida, Toshinobu Maksyutov, Shamil Melton, Joe R. Morino, Isamu Naik, Vaishali O'Doherty, Simon Parmentier, Frans-Jan W. Patra, Prabir K. Peng, Changhui Peng, Shushi Peters, Glen P. Pison, Isabelle Ramonet, Michel Riley, William J. Saito, Makoto Santini, Monia Schroeder, Ronny Simpson, Isobel J. Spahni, Renato Takizawa, Atsushi Thornton, Brett F. Tian, Hanqin Tohjima, Yasunori Viovy, Nicolas Voulgarakis, Apostolos Weiss, Ray Wilton, David J. Wiltshire, Andy Worthy, Doug Wunch, Debra Xu, Xiyan Yoshida, Yukio Zhang, Bowen Zhang, Zhen Zhu, Qiuan Prinn, Ronald G |
| author2 | Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences |
| author_facet | Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Saunois, Marielle Bousquet, Philippe Poulter, Ben Peregon, Anna Ciais, Philippe Canadell, Josep G. Dlugokencky, Edward J. Etiope, Giuseppe Bastviken, David Houweling, Sander Janssens-Maenhout, Greet Tubiello, Francesco N. Castaldi, Simona Jackson, Robert B. Alexe, Mihai Arora, Vivek K. Beerling, David J. Bergamaschi, Peter Blake, Donald R. Brailsford, Gordon Bruhwiler, Lori Crevoisier, Cyril Crill, Patrick Covey, Kristofer Frankenberg, Christian Gedney, Nicola Höglund-Isaksson, Lena Ishizawa, Misa Ito, Akihiko Joos, Fortunat Kim, Heon-Sook Kleinen, Thomas Krummel, Paul Lamarque, Jean-François Langenfelds, Ray Locatelli, Robin Machida, Toshinobu Maksyutov, Shamil Melton, Joe R. Morino, Isamu Naik, Vaishali O'Doherty, Simon Parmentier, Frans-Jan W. Patra, Prabir K. Peng, Changhui Peng, Shushi Peters, Glen P. Pison, Isabelle Ramonet, Michel Riley, William J. Saito, Makoto Santini, Monia Schroeder, Ronny Simpson, Isobel J. Spahni, Renato Takizawa, Atsushi Thornton, Brett F. Tian, Hanqin Tohjima, Yasunori Viovy, Nicolas Voulgarakis, Apostolos Weiss, Ray Wilton, David J. Wiltshire, Andy Worthy, Doug Wunch, Debra Xu, Xiyan Yoshida, Yukio Zhang, Bowen Zhang, Zhen Zhu, Qiuan Prinn, Ronald G |
| author_sort | Saunois, Marielle |
| collection | MIT |
| description | Following the recent Global Carbon Project (GCP) synthesis of the decadal methane (CH₄) budget over 2000-2012 (Saunois et al., 2016), we analyse here the same dataset with a focus on quasi-decadal and inter-annual variability in CH₄ emissions. The GCP dataset integrates results from top-down studies (exploiting atmospheric observations within an atmospheric inverse-modelling framework) and bottom-up models (including process-based models for estimating land surface emissions and atmospheric chemistry), inventories of anthropogenic emissions, and data-driven approaches. The annual global methane emissions from top-down studies, which by construction match the observed methane growth rate within their uncertainties, all show an increase in total methane emissions over the period 2000-2012, but this increase is not linear over the 13 years. Despite differences between individual studies, the mean emission anomaly of the top-down ensemble shows no significant trend in total methane emissions over the period 2000-2006, during the plateau of atmospheric methane mole fractions, and also over the period 2008-2012, during the renewed atmospheric methane increase. However, the top-down ensemble mean produces an emission shift between 2006 and 2008, leading to 22 [16-32]Tg CH₄ yr⁻¹ higher methane emissions over the period 2008-2012 compared to 2002-2006. This emission increase mostly originated from the tropics, with a smaller contribution from mid-latitudes and no significant change from boreal regions. The regional contributions remain uncertain in top-down studies. Tropical South America and South and East Asia seem to contribute the most to the emission increase in the tropics. However, these two regions have only limited atmospheric measurements and remain therefore poorly constrained. The sectorial partitioning of this emission increase between the periods 2002-2006 and 2008-2012 differs from one atmospheric inversion study to another. However, all top-down studies suggest smaller changes in fossil fuel emissions (from oil, gas, and coal industries) compared to the mean of the bottom-up inventories included in this study. This difference is partly driven by a smaller emission change in China from the top-down studies compared to the estimate in the Emission Database for Global Atmospheric Research (EDGARv4.2) inventory, which should be revised to smaller values in a near future. We apply isotopic signatures to the emission changes estimated for individual studies based on five emission sectors and find that for six individual top-down studies (out of eight) the average isotopic signature of the emission changes is not consistent with the observed change in atmospheric ¹³CH₄. However, the partitioning in emission change derived from the ensemble mean is consistent with this isotopic constraint. At the global scale, the top-down ensemble mean suggests that the dominant contribution to the resumed atmospheric CH₄ growth after 2006 comes from microbial sources (more from agriculture and waste sectors than from natural wetlands), with an uncertain but smaller contribution from fossil CH₄ emissions. In addition, a decrease in biomass burning emissions (in agreement with the biomass burning emission databases) makes the balance of sources consistent with atmospheric 13 CH₄ observations. In most of the top-down studies included here, OH concentrations are considered constant over the years (seasonal variations but without any inter-annual variability). As a result, the methane loss (in particular through OH oxidation) varies mainly through the change in methane concentrations and not its oxidants. For these reasons, changes in the methane loss could not be properly investigated in this study, although it may play a significant role in the recent atmospheric methane changes as briefly discussed at the end of the paper. |
| first_indexed | 2024-09-23T16:16:56Z |
| format | Article |
| id | mit-1721.1/114970 |
| institution | Massachusetts Institute of Technology |
| last_indexed | 2024-09-23T16:16:56Z |
| publishDate | 2018 |
| publisher | Copernicus Publications |
| record_format | dspace |
| spelling | mit-1721.1/1149702022-09-29T19:22:38Z Variability and quasi-decadal changes in the methane budget over the period 2000–2012 Saunois, Marielle Bousquet, Philippe Poulter, Ben Peregon, Anna Ciais, Philippe Canadell, Josep G. Dlugokencky, Edward J. Etiope, Giuseppe Bastviken, David Houweling, Sander Janssens-Maenhout, Greet Tubiello, Francesco N. Castaldi, Simona Jackson, Robert B. Alexe, Mihai Arora, Vivek K. Beerling, David J. Bergamaschi, Peter Blake, Donald R. Brailsford, Gordon Bruhwiler, Lori Crevoisier, Cyril Crill, Patrick Covey, Kristofer Frankenberg, Christian Gedney, Nicola Höglund-Isaksson, Lena Ishizawa, Misa Ito, Akihiko Joos, Fortunat Kim, Heon-Sook Kleinen, Thomas Krummel, Paul Lamarque, Jean-François Langenfelds, Ray Locatelli, Robin Machida, Toshinobu Maksyutov, Shamil Melton, Joe R. Morino, Isamu Naik, Vaishali O'Doherty, Simon Parmentier, Frans-Jan W. Patra, Prabir K. Peng, Changhui Peng, Shushi Peters, Glen P. Pison, Isabelle Ramonet, Michel Riley, William J. Saito, Makoto Santini, Monia Schroeder, Ronny Simpson, Isobel J. Spahni, Renato Takizawa, Atsushi Thornton, Brett F. Tian, Hanqin Tohjima, Yasunori Viovy, Nicolas Voulgarakis, Apostolos Weiss, Ray Wilton, David J. Wiltshire, Andy Worthy, Doug Wunch, Debra Xu, Xiyan Yoshida, Yukio Zhang, Bowen Zhang, Zhen Zhu, Qiuan Prinn, Ronald G Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Prinn, Ronald G Following the recent Global Carbon Project (GCP) synthesis of the decadal methane (CH₄) budget over 2000-2012 (Saunois et al., 2016), we analyse here the same dataset with a focus on quasi-decadal and inter-annual variability in CH₄ emissions. The GCP dataset integrates results from top-down studies (exploiting atmospheric observations within an atmospheric inverse-modelling framework) and bottom-up models (including process-based models for estimating land surface emissions and atmospheric chemistry), inventories of anthropogenic emissions, and data-driven approaches. The annual global methane emissions from top-down studies, which by construction match the observed methane growth rate within their uncertainties, all show an increase in total methane emissions over the period 2000-2012, but this increase is not linear over the 13 years. Despite differences between individual studies, the mean emission anomaly of the top-down ensemble shows no significant trend in total methane emissions over the period 2000-2006, during the plateau of atmospheric methane mole fractions, and also over the period 2008-2012, during the renewed atmospheric methane increase. However, the top-down ensemble mean produces an emission shift between 2006 and 2008, leading to 22 [16-32]Tg CH₄ yr⁻¹ higher methane emissions over the period 2008-2012 compared to 2002-2006. This emission increase mostly originated from the tropics, with a smaller contribution from mid-latitudes and no significant change from boreal regions. The regional contributions remain uncertain in top-down studies. Tropical South America and South and East Asia seem to contribute the most to the emission increase in the tropics. However, these two regions have only limited atmospheric measurements and remain therefore poorly constrained. The sectorial partitioning of this emission increase between the periods 2002-2006 and 2008-2012 differs from one atmospheric inversion study to another. However, all top-down studies suggest smaller changes in fossil fuel emissions (from oil, gas, and coal industries) compared to the mean of the bottom-up inventories included in this study. This difference is partly driven by a smaller emission change in China from the top-down studies compared to the estimate in the Emission Database for Global Atmospheric Research (EDGARv4.2) inventory, which should be revised to smaller values in a near future. We apply isotopic signatures to the emission changes estimated for individual studies based on five emission sectors and find that for six individual top-down studies (out of eight) the average isotopic signature of the emission changes is not consistent with the observed change in atmospheric ¹³CH₄. However, the partitioning in emission change derived from the ensemble mean is consistent with this isotopic constraint. At the global scale, the top-down ensemble mean suggests that the dominant contribution to the resumed atmospheric CH₄ growth after 2006 comes from microbial sources (more from agriculture and waste sectors than from natural wetlands), with an uncertain but smaller contribution from fossil CH₄ emissions. In addition, a decrease in biomass burning emissions (in agreement with the biomass burning emission databases) makes the balance of sources consistent with atmospheric 13 CH₄ observations. In most of the top-down studies included here, OH concentrations are considered constant over the years (seasonal variations but without any inter-annual variability). As a result, the methane loss (in particular through OH oxidation) varies mainly through the change in methane concentrations and not its oxidants. For these reasons, changes in the methane loss could not be properly investigated in this study, although it may play a significant role in the recent atmospheric methane changes as briefly discussed at the end of the paper. 2018-04-26T19:20:19Z 2018-04-26T19:20:19Z 2017-09 2017-07 2018-04-24T14:04:53Z Article http://purl.org/eprint/type/JournalArticle 1680-7324 1680-7316 http://hdl.handle.net/1721.1/114970 Saunois, Marielle et al. “Variability and Quasi-Decadal Changes in the Methane Budget over the Period 2000–2012.” Atmospheric Chemistry and Physics 17, 18 (September 2017): 11135–11161 © 2017 Author(s) https://orcid.org/0000-0001-5925-3801 http://dx.doi.org/10.5194/ACP-17-11135-2017 Atmospheric Chemistry and Physics Creative Commons Attribution 3.0 Unported license http://creativecommons.org/licenses/by/3.0/ application/pdf Copernicus Publications Copernicus Publications |
| spellingShingle | Saunois, Marielle Bousquet, Philippe Poulter, Ben Peregon, Anna Ciais, Philippe Canadell, Josep G. Dlugokencky, Edward J. Etiope, Giuseppe Bastviken, David Houweling, Sander Janssens-Maenhout, Greet Tubiello, Francesco N. Castaldi, Simona Jackson, Robert B. Alexe, Mihai Arora, Vivek K. Beerling, David J. Bergamaschi, Peter Blake, Donald R. Brailsford, Gordon Bruhwiler, Lori Crevoisier, Cyril Crill, Patrick Covey, Kristofer Frankenberg, Christian Gedney, Nicola Höglund-Isaksson, Lena Ishizawa, Misa Ito, Akihiko Joos, Fortunat Kim, Heon-Sook Kleinen, Thomas Krummel, Paul Lamarque, Jean-François Langenfelds, Ray Locatelli, Robin Machida, Toshinobu Maksyutov, Shamil Melton, Joe R. Morino, Isamu Naik, Vaishali O'Doherty, Simon Parmentier, Frans-Jan W. Patra, Prabir K. Peng, Changhui Peng, Shushi Peters, Glen P. Pison, Isabelle Ramonet, Michel Riley, William J. Saito, Makoto Santini, Monia Schroeder, Ronny Simpson, Isobel J. Spahni, Renato Takizawa, Atsushi Thornton, Brett F. Tian, Hanqin Tohjima, Yasunori Viovy, Nicolas Voulgarakis, Apostolos Weiss, Ray Wilton, David J. Wiltshire, Andy Worthy, Doug Wunch, Debra Xu, Xiyan Yoshida, Yukio Zhang, Bowen Zhang, Zhen Zhu, Qiuan Prinn, Ronald G Variability and quasi-decadal changes in the methane budget over the period 2000–2012 |
| title | Variability and quasi-decadal changes in the methane budget over the period 2000–2012 |
| title_full | Variability and quasi-decadal changes in the methane budget over the period 2000–2012 |
| title_fullStr | Variability and quasi-decadal changes in the methane budget over the period 2000–2012 |
| title_full_unstemmed | Variability and quasi-decadal changes in the methane budget over the period 2000–2012 |
| title_short | Variability and quasi-decadal changes in the methane budget over the period 2000–2012 |
| title_sort | variability and quasi decadal changes in the methane budget over the period 2000 2012 |
| url | http://hdl.handle.net/1721.1/114970 https://orcid.org/0000-0001-5925-3801 |
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