Estimation of pre-industrial nitrous oxide emissions from the land biosphere
Rongting Xu1, Hanqin Tian1, Chaoqun Lu2,1, Shufen Pan1, Jian Chen3,1, Jia Yang1, and Bowen Zhang11International Center for Climate and Global Change Research and School of Forestry and Wildlife Sciences, Auburn University, Auburn, AL 36849, USA 2Department of Ecology, Evolution, & Organismal Biology, Iowa State University, Ames, IA 50011, USA 3College of Sciences and Mathematics, Auburn University, Auburn, AL 36849, USA
Received: 08 Oct 2016 – Accepted for review: 22 Oct 2016 – Discussion started: 24 Oct 2016
Abstract. To accurately assess how increased global nitrous oxide (N2O) emission has affected the climate system requires a robust estimation of the pre-industrial N2O 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 N2O emissions from the land biosphere, while pre-industrial N2O 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 N2O 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 N2O emission was approximately 6.20 Tg N yr−1, with an uncertainty range of 4.76 to 8.13 Tg N yr−1. The estimated N2O emission varied significantly at spatial- and biome-levels. South America, Africa, and Southern Asia accounted for 34.12 %, 23.85 %, 18.93 %, respectively, together contributing of 76.90 % of global total emission. The tropics were identified as the major source of N2O released into the atmosphere, accounting for 64.66 % of the total emission. Our multi-scale estimates with a reasonable uncertainty range provides a robust reference for assessing the climate forcing of anthropogenic N2O emission from the land biosphere.
Xu, R., Tian, H., Lu, C., Pan, S., Chen, J., Yang, J., and Zhang, B.: Estimation of pre-industrial nitrous oxide emissions from the land biosphere, Clim. Past Discuss., doi:10.5194/cp-2016-103, in review, 2016.