Xudong Zhu Yujie He Catherine Prigent Jerry M. Melillo A. David McGuire Ronald G. Prinn David W. Kicklighter Qianlai Zhuang 2015 <p>Estimates of the seasonal and interannual exchanges of carbon dioxide (CO₂) and methane (CH₄) between land ecosystems north of 45&deg;N and the atmosphere are poorly constrained, in part, because of uncertainty in the temporal variability of water-inundated land area. Here we apply a process-based biogeochemistry model to evaluate how interannual changes in wetland inundation extent might have influenced the overall carbon dynamics of the region during the time period 1993&ndash;2004. We find that consideration by our model of these interannual variations between 1993 and 2004, on average, results in regional estimates of net methane sources of 67.8 &plusmn; 6.2 Tg CH₄ yr^&minus;1, which is intermediate to model estimates that use two static inundation extent datasets (51.3 &plusmn; 2.6 and 73.0 &plusmn; 3.6 Tg CH₄ yr^&minus;1). In contrast, consideration of interannual changes of wetland inundation extent result in regional estimates of the net CO₂ sink of &minus;1.28 &plusmn; 0.03 Pg C yr^&minus;1 with a persistent wetland carbon sink from &minus;0.38 to &minus;0.41 Pg C yr^&minus;1 and a upland sink from &minus;0.82 to &minus;0.98 Pg C yr^&minus;1. Taken together, despite the large methane emissions from wetlands, the region is a consistent greenhouse gas sink per global warming potential (GWP) calculations irrespective of the type of wetland datasets being used. However, the use of satellite-detected wetland inundation extent estimates a smaller regional GWP sink than that estimated using static wetland datasets. Our sensitivity analysis indicates that if wetland inundation extent increases or decreases by 10% in each wetland grid cell, the regional source of methane increases 13% or decreases 12%, respectively. In contrast, the regional CO₂ sink responds with only 7&ndash;9% changes to the changes in wetland inundation extent. Seasonally, the inundated area changes result in higher summer CH₄ emissions, but lower summer CO₂ sinks, leading to lower summer negative greenhouse gas forcing. Our analysis further indicates that wetlands play a disproportionally important role in affecting regional greenhouse gas budgets given that they only occupy approximately 10% of the total land area in the region.</p> application/pdf 10.1088/1748-9326/10/9/095009 en Institute of Physics Publishing Influence of changes in wetland inundation extent on net fluxes of carbon dioxide and methane in northern high latitudes from 1993 to 2004 article