Observational constraints on recent increases in the atmospheric CH4 burden

摘要: [1] Measurements of atmospheric CH4 from air samples collected weekly at 46 remote surface sites show that, after a decade near-zero growth, globally averaged methane increased during 2007 and 2008. During 2007, by 8.3 ± 0.6 ppb. mole fractions over polar northern latitudes the Southern Hemisphere more than other zonally regions. In 2008, 4.4 ppb; largest increase was in tropics, while did not increase. Satellite situ CO observations suggest only minor contribution to biomass burning. The most likely drivers anomalies observed 2008 are anomalously high temperatures Arctic greater average precipitation tropics. Near-zero growth suggests we have yet activated strong climate feedbacks permafrost hydrates.