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Impact of meteorology and emissions on methane trends, 1990–2004
Author(s) -
Fiore Arlene M.,
Horowitz Larry W.,
Dlugokencky Edward J.,
West J. Jason
Publication year - 2006
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2006gl026199
Subject(s) - environmental science , atmospheric sciences , methane , climatology , troposphere , limiting , atmospheric chemistry , meteorology , lightning (connector) , climate change , ozone , geography , chemistry , physics , geology , oceanography , mechanical engineering , power (physics) , organic chemistry , quantum mechanics , engineering
Over the past century, atmospheric methane (CH 4 ) rose dramatically before leveling off in the late 1990s. The processes controlling this trend are poorly understood, limiting confidence in projections of future CH 4 . The MOZART‐2 global tropospheric chemistry model qualitatively captures the observed CH 4 trend (increasing in the early 1990s and then leveling off) with constant emissions. From 1991–1995 to 2000–2004, the CH 4 lifetime versus tropospheric OH decreases by 1.6%, reflecting increases in OH and temperature. The rise in OH stems from an increase in lightning NO x as parameterized in the model. A simulation including annually varying anthropogenic and wetland CH 4 emissions, as well as the changes in meteorology, best reproduces the observed CH 4 distribution, trend, and seasonal cycles. Projections of future CH 4 abundances should consider climate‐driven changes in CH 4 sources and sinks.