Magnitude and Uncertainty of Nitrous Oxide Emissions From North America Based on Bottom-Up and Top-Down Approaches: Informing Future Research and National Inventories

We synthesized N2O emissions over North America using 17 bottom-up (BU) estimates from 19802016 and five top-down (TD) estimates from 19982016. The BU-based total emission shows a slight increase owing to U.S. agriculture, while no consistent trend is shown in TD estimates. During 20072016, North American N2O emissions are estimated at 1.7 (1.03.0) Tg N yr-1 (BU) and 1.3 (0.91.5) Tg N yr-1 (TD). Anthropogenic emissions were twice as large as natural fluxes from soil and water. Direct agricultural and industrial activities accounted for 68% of total anthropogenic emissions, 71% of which was contributed by the U.S. Our estimates of U.S. agricultural emissions are comparable to the EPA greenhouse gas (GHG) inventory, which includes estimates from IPCC tier 1 (emission factor) and tier 3 (process-based modeling) approaches. Conversely, our estimated agricultural emissions for Canada and Mexico are twice as large as the respective national GHG inventories.

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Recommended citation: Xu, R., Tian, H., Pan, N., Thompson, R. L., Canadell, J. G., Davidson, E. A., … & Zhou, F. (2021). Magnitude and uncertainty of nitrous oxide emissions from North America based on bottom‐up and top‐down approaches: Informing future research and national inventories. Geophysical Research Letters, e2021GL095264.