Historical Pattern and Future Trajectories of Terrestrial N2O Emission driven by Multi-factor Global Changes

Abstract:

Nitrous oxide (N₂O) is among the most important greenhouse gases only next to carbon dioxide (CO₂) and methane (CH₄) due to its long life time and high radiative forcing (with a global warming potential 265 times as much as CO₂ at 100-year time horizon). The Atmospheric concentration of N₂O has increased by 20% since pre-industrial era, and this increase plays a significant role in shaping anthropogenic climate change. However, compared to CO₂- and CH₄-related research, fewer studies have been performed in assessing and predicting the spatiotemporal patterns of N₂O emission from natural and agricultural soils. Here we used a coupled biogeochemical model, DLEM, to quantify the historical and future changes in global terrestrial N₂O emissions resulting from natural and anthropogenic perturbations including climate variability, atmospheric CO₂ concentration, nitrogen deposition, land use and land cover changes, and agricultural land management practices (i.e., synthetic nitrogen fertilizer use, manure application, and irrigation etc.) over the period 1900-2099.

We focused on inter-annual variation and long-term trend of terrestrial N₂O emission driven by individual and combined environmental changes during historical and future periods. The sensitivity of N₂O emission to climate, atmospheric composition, and human activities has been examined at biome-, latitudinal, continental and global scales. Future projections were conducted to identify the hot spots and hot time periods of global N₂O emission under two emission scenarios (RCP2.6 and RCP8.5). It provides a modeling perspective for understanding human-induced N₂O emission growth and developing potential management strategies to mitigate further atmospheric N₂O increase and climate warming.