Estimation of pre-industrial nitrous oxide emissions from the land biosphere

Other literature type English OPEN
Xu, Rongting ; Tian, Hanqin ; Lu, Chaoqun ; Pan, Shufen ; Chen, Jian ; Yang, Jia ; Zhang, Bowen (2016)

To accurately assess how increased global nitrous oxide (N<sub>2</sub>O) emission has affected the climate system requires a robust estimation of the pre-industrial N<sub>2</sub>O emissions since only the difference between current and pre-industrial emissions represents net drivers of anthropogenic climate change. However, large uncertainty exists in previous estimates of pre-industrial N<sub>2</sub>O emissions from the land biosphere, while pre-industrial N<sub>2</sub>O emissions at the finer scales such as regional, biome, or sector have not yet well quantified. In this study, we applied a process-based Dynamic Land Ecosystem Model (DLEM) to estimate the magnitude and spatial patterns of pre-industrial N<sub>2</sub>O fluxes at the biome-, continental-, and global-level as driven by multiple environmental factors. Uncertainties associated with key parameters were also evaluated. Our study indicates that the mean of the pre-industrial N<sub>2</sub>O emission was approximately 6.20&thinsp;Tg&thinsp;N&thinsp;yr<sup>&minus;1</sup>, with an uncertainty range of 4.76 to 8.13&thinsp;Tg&thinsp;N&thinsp;yr<sup>&minus;1</sup>. The estimated N<sub>2</sub>O emission varied significantly at spatial- and biome-levels. South America, Africa, and Southern Asia accounted for 34.12&thinsp;%, 23.85&thinsp;%, 18.93&thinsp;%, respectively, together contributing of 76.90&thinsp;% of global total emission. The tropics were identified as the major source of N<sub>2</sub>O released into the atmosphere, accounting for 64.66&thinsp;% of the total emission. Our multi-scale estimates with a reasonable uncertainty range provides a robust reference for assessing the climate forcing of anthropogenic N<sub>2</sub>O emission from the land biosphere.
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