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Observational constraints on the distribution, seasonality, and environmental predictors of North American boreal methane emissions
Author(s) -
Miller Scot M.,
Worthy Doug E. J.,
Michalak Anna M.,
Wofsy Steven C.,
Kort Eric A.,
Havice Talya C.,
Andrews Arlyn E.,
Dlugokencky Edward J.,
Kaplan Jed O.,
Levi Patricia J.,
Tian Hanqin,
Zhang Bowen
Publication year - 2014
Publication title -
global biogeochemical cycles
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.512
H-Index - 187
eISSN - 1944-9224
pISSN - 0886-6236
DOI - 10.1002/2013gb004580
Subject(s) - atmospheric methane , methane , environmental science , biogeochemical cycle , wetland , flux (metallurgy) , atmospheric sciences , bay , climatology , oceanography , geology , ecology , environmental chemistry , chemistry , biology , organic chemistry
Wetlands comprise the single largest global source of atmospheric methane, but current flux estimates disagree in both magnitude and distribution at the continental scale. This study uses atmospheric methane observations over North America from 2007 to 2008 and a geostatistical inverse model to improve understanding of Canadian methane fluxes and associated biogeochemical models. The results bridge an existing gap between traditional top‐down, inversion studies, which typically emphasize total emission budgets, and biogeochemical models, which usually emphasize environmental processes. The conclusions of this study are threefold. First, the most complete process‐based methane models do not always describe available atmospheric methane observations better than simple models. In this study, a relatively simple model of wetland distribution, soil moisture, and soil temperature outperformed more complex model formulations. Second, we find that wetland methane fluxes have a broader spatial distribution across western Canada and into the northern U.S. than represented in existing flux models. Finally, we calculate total methane budgets for Canada and for the Hudson Bay Lowlands, a large wetland region (50–60°N, 75–96°W). Over these lowlands, we find total methane fluxes of 1.8±0.24 Tg C yr −1 , a number in the midrange of previous estimates. Our total Canadian methane budget of 16.0±1.2 Tg C yr −1 is larger than existing inventories, primarily due to high anthropogenic emissions in Alberta. However, methane observations are sparse in western Canada, and additional measurements over Alberta will constrain anthropogenic sources in that province with greater confidence.