Large-Scale Controls of Methanogenesis Inferred from Methane and Gravity Spaceborne Data

• Published in: Science
• Main Authors: Bloom, A. Anthony, Palmer, Paul I., Fraser, Annemarie, Reay, David S., Frankenberg, Christian
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Association for the Advancement of Science 2010
• Subjects: Arctic
• Online Access: https://authors.library.caltech.edu/57435/; https://authors.library.caltech.edu/57435/2/Bloom.SOM.pdf; https://resolver.caltech.edu/CaltechAUTHORS:20150512-091007483

Wetlands are the largest individual source of methane (CH_4), but the magnitude and distribution of this source are poorly understood on continental scales. We isolated the wetland and rice paddy contributions to spaceborne CH_4 measurements over 2003–2005 using satellite observations of gravity anomalies, a proxy for water-table depth Γ, and surface temperature analyses T_S. We find that tropical and higher-latitude CH_4 variations are largely described by Γ and T_S variations, respectively. Our work suggests that tropical wetlands contribute 52 to 58% of global emissions, with the remainder coming from the extra-tropics, 2% of which is from Arctic latitudes. We estimate a 7% rise in wetland CH_4 emissions over 2003–2007, due to warming of mid-latitude and Arctic wetland regions, which we find is consistent with recent changes in atmospheric CH_4.