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Methane is an important greenhouse gas, and its atmospheric concentration has nearly tripled since pre-industrial times. The growth rate of atmospheric methane is determined by the balance between surface emissions and photochemical destruction by the hydroxyl radical, the major atmospheric oxidant. Remarkably, this growth rate has decreased markedly since(More)
[1] The dynamics of forest-atmosphere CO 2 carbon isotope exchange were examined in a coniferous forest in Colorado, United States. Tunable diode laser absorption spectrometry provided extensive characterization of the carbon isotope content (d 13 C) of CO 2. Observed patterns in d 13 C of forest air were associated with photosynthesis, respiration, and(More)
[1] Estimating discrimination against 13 C during photosynthesis at landscape, regional, and biome scales is difficult because of large-scale variability in plant stress, vegetation composition, and photosynthetic pathway. Here we present estimates of 13 C discrimination for northern biomes based on a biosphere-atmosphere model and on National Oceanic and(More)
[1] Previous studies suggest that a large part of the variability in the atmospheric ratio of 13 CO 2 / 12 CO 2 originates from carbon exchange with the terrestrial biosphere rather than with the oceans. Since this variability is used to quantitatively partition the total carbon sink, we here investigate the contribution of interannual variability (IAV) in(More)
Despite rapid melting in the coastal regions of the Greenland Ice Sheet, a significant area (~40%) of the ice sheet rarely experiences surface melting. In these regions, the controls on annual accumulation are poorly constrained owing to surface conditions (for example, surface clouds, blowing snow, and surface inversions), which render moisture flux(More)
The isotope • SO in CO2 is of particular interest in studying the global carbon cycle because it is sensitive to the processes by which the global land biosphere absorbs and respires CO2. Carbon dioxide and water exchange isotopically both in leaves and in soils, and the • SO character of atmospheric CO2 is strongly influenced by the land biota, which(More)
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