Source attribution of the changes in atmospheric methane for 2006–2008
Open Access
- 20 April 2011
- journal article
- research article
- Published by Copernicus GmbH in Atmospheric Chemistry and Physics
- Vol. 11 (8), 3689-3700
- https://doi.org/10.5194/acp-11-3689-2011
Abstract
The recent increase of atmospheric methane is investigated by using two atmospheric inversions to quantify the distribution of sources and sinks for the 2006–2008 period, and a process-based model of methane emissions by natural wetland ecosystems. Methane emissions derived from the two inversions are consistent at a global scale: emissions are decreased in 2006 (−7 Tg) and increased in 2007 (+21 Tg) and 2008 (+18 Tg), as compared to the 1999–2006 period. The agreement on the latitudinal partition of the flux anomalies for the two inversions is fair in 2006, good in 2007, and not good in 2008. In 2007, a positive anomaly of tropical emissions is found to be the main contributor to the global emission anomalies (~60–80%) for both inversions, with a dominant share attributed to natural wetlands (~2/3), and a significant contribution from high latitudes (~25%). The wetland ecosystem model produces smaller and more balanced positive emission anomalies between the tropics and the high latitudes for 2006, 2007 and 2008, mainly due to precipitation changes during these years. At a global scale, the agreement between the ecosystem model and the inversions is good in 2008 but not satisfying in 2006 and 2007. Tropical South America and Boreal Eurasia appear to be major contributors to variations in methane emissions consistently in the inversions and the ecosystem model. Finally, changes in OH radicals during 2006–2008 are found to be less than 1% in inversions, with only a small impact on the inferred methane emissions.Keywords
This publication has 43 references indexed in Scilit:
- Implementation and evaluation of a new methane model within a dynamic global vegetation model: LPJ-WHyMe v1.3.1Geoscientific Model Development, 2010
- An attempt to quantify the impact of changes in wetland extent on methane emissions on the seasonal and interannual time scalesGlobal Biogeochemical Cycles, 2010
- Renewed growth of atmospheric methaneGeophysical Research Letters, 2008
- Tropical methane emissions: A revised view from SCIAMACHY onboard ENVISATGeophysical Research Letters, 2008
- Evidence for variability of atmospheric hydroxyl radicals over the past quarter centuryGeophysical Research Letters, 2005
- Interannual variability and trend of CH4 lifetime as a measure for OH changes in the 1979–1993 time periodJournal of Geophysical Research: Solid Earth, 2003
- Influence of transport uncertainty on annual mean and seasonal inversions of atmospheric CO2 dataJournal of Geophysical Research: Solid Earth, 2002
- Interannual growth rate variations of atmospheric CO2 and its δ13C, H2, CH4, and CO between 1992 and 1999 linked to biomass burningGlobal Biogeochemical Cycles, 2002
- Inverse modeling of methane sources and sinks using the adjoint of a global transport modelJournal of Geophysical Research: Solid Earth, 1999
- An inverse modeling approach to investigate the global atmospheric methane cycleGlobal Biogeochemical Cycles, 1997