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Coupling of Nitrous Oxide and Methane by Global Atmospheric Chemistry
- Prather, Michael J., Hsu, Juno
- Science 2010 v.330 no.6006 pp. 952-954
- anthropogenic activities, atmospheric chemistry, greenhouse effect, greenhouse gas emissions, greenhouse gases, hydroxyl radicals, methane, nitrous oxide, ozone, stratosphere, troposphere, ultraviolet radiation
- Nitrous oxide (N₂O) and methane (CH₄) are chemically reactive greenhouse gases with well-documented atmospheric concentration increases that are attributable to anthropogenic activities. We quantified the link between N₂O and CH₄ emissions through the coupled chemistries of the stratosphere and troposphere. Specifically, we simulated the coupled perturbations of increased N₂O abundance, leading to stratospheric ozone (O₃) depletion, altered solar ultraviolet radiation, altered stratosphere-to-troposphere O₃ flux, increased tropospheric hydroxyl radical concentration, and finally lower concentrations of CH₄. The ratio of CH₄ per N₂O change, -36% by mole fraction, offsets a fraction of the greenhouse effect attributable to N₂O emissions. These CH₄ decreases are tied to the 108-year chemical mode of N₂O, which is nine times longer than the residence time of direct CH₄ emissions.