Impacts of Permafrost Degradation on N2O Emissions From Natural Terrestrial Ecosystems in Northern High Latitudes: A Process-Based Biogeochemistry Model Analysis

Abstract

Nitrous oxide (N₂O) is a potent greenhouse gas with its radiative forcing 265–298 times stronger than that of carbon dioxide (CO₂). Recent field studies show N₂O emissions from northern high latitude (north of 45°N) ecosystems have increased due to warming. However, spatiotemporal quantification of N₂O emissions remains inadequate in this region. Here we revise the Terrestrial Ecosystem Model to incorporate more detailed processes of soil nitrogen (N) biogeochemical cycling, permafrost thawing effects, and atmospheric N deposition. Terrestrial Ecosystem Model is then used to analyze N₂O emissions from natural terrestrial ecosystems in the region. Our study reveals that regional N₂O production and net emissions increased from 1969 to 2019. Production rose from 1.12 (0.82–1.46) to 1.18 (0.84–1.51) Tg N yr⁻¹, while net emissions increased from 0.98 (0.7–1.34) to 1.05 (0.72–1.39) Tg N yr⁻¹, considering permafrost thawing. Emissions from permafrost regions grew from 0.37 (0.2–0.57) to 0.41 (0.21–0.6) Tg N yr⁻¹. Soil N₂O uptake from the atmosphere remained relatively stable at 0.12 (0.1–0.15) Tg N yr ⁻¹. Atmospheric N deposition significantly increased N₂O emission by 37.2 ± 2.9%. Spatially, natural terrestrial ecosystems act as net sources or sinks of −12 to 900 mg N m⁻² yr⁻¹ depending on changing temperature, precipitation, soil characteristics, and vegetation types. Our findings underscore the critical need for more observational studies to reduce the uncertainty in N₂O budget.