liu.seSearch for publications in DiVA
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Variability and quasi-decadal changes in the methane budget over the period 2000-2012
University of Paris Saclay, France.
University of Paris Saclay, France.
NASA, MD 20771 USA.
University of Paris Saclay, France.
Show others and affiliations
2017 (English)In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 17, no 18, 11135-11161 p.Article in journal (Refereed) Published
Abstract [en]

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 (CH4)-C-13. 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 (CH4)-C-13 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.

Place, publisher, year, edition, pages
COPERNICUS GESELLSCHAFT MBH , 2017. Vol. 17, no 18, 11135-11161 p.
National Category
Physical Geography
Identifiers
URN: urn:nbn:se:liu:diva-141711DOI: 10.5194/acp-17-11135-2017ISI: 000411253700003OAI: oai:DiVA.org:liu-141711DiVA: diva2:1147322
Note

Funding Agencies|EU FP7 GEOCARBON project; National Environmental Science Program - Earth Systems and Climate Change Hub; NASA [NNX07AK10G]; Swiss National Science Foundation; National Science and Engineering Research Council of Canada (NSERC) discovery grant; Chinas QianRen Program; Research Council of Norway project [209701]; Swedish Research Council VR; ERC [725546]; Environment Research and Technology Development Fund of the Ministry of the Environment, Japan [A2-1502]; Office of Science, Office of Biological and Environmental Research of the US Department of Energy as part of the RGCM BGC-Climate Feedbacks SFA [DE-AC02-05CH11231]; European Commission Seventh Framework Programme (FP7) project MACCII [283576]; European Commission Horizon Programme project MACC-III [633080]; ESA Climate Change Initiative Greenhouse Gases Phase 2 project; NASA Carbon Monitoring Program [NNX12AP84G, NNX14AO73G]; Joint DECC/Defra Met Office Hadley Centre Climate Programme [GA01101]; ERC Advanced grant (CDREG) [322998]; NERC [NE/J00748X/1]; CSIRO Australia; Australian Bureau of Meteorology; Australian Institute of Marine Science; Australian Antarctic Division; NOAA USA; Meteorological Service of Canada; National Aeronautic and Space Administration (NASA) [NAG5-12669, NNX07AE89G, NNX11AF17G, NNX07AE87G, NNX07AF09G, NNX11AF15G, NNX11AF16G]; Department of Energy and Climate Change (DECC, UK) [GA01081]; Commonwealth Scientific and Industrial Research Organisation (CSIRO Australia); Bureau of Meteorology (Australia)

Available from: 2017-10-05 Created: 2017-10-05 Last updated: 2017-10-05

Open Access in DiVA

No full text

Other links

Publisher's full text

Search in DiVA

By author/editor
Bastviken, David
By organisation
Tema Environmental ChangeFaculty of Arts and Sciences
In the same journal
Atmospheric Chemistry And Physics
Physical Geography

Search outside of DiVA

GoogleGoogle Scholar

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 60 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf