Contemporary and projected biogenic fluxes of methane and nitrous oxide in North American terrestrial ecosystems

Accurately estimating biogenic methane (CH₄) and nitrous oxide (N₂O) fluxes in terrestrial ecosystems is critical for resolving global budgets of these greenhouse gases (GHGs) and continuing to mitigate climate warming. Here, we assess contemporary biogenic CH₄ and N₂O budgets and probable climate-change-related impacts on CH₄ and N₂O emissions in terrestrial North America. Multi-approach estimations show that, during 1990-2010, biogenic CH₄ emissions ranged from 0.159 to 0.502 petagrams of carbon dioxide (CO₂) equivalents per year (Pg CO₂eq yr⁻¹, where 1 Pg = 1 × 10¹⁵ g) and N₂O emissions ranged from 0.802 to 1.016 Pg CO₂ eq yr⁻¹, which offset 47-166% of terrestrial CO₂ sequestration (0.915-2.040 Pg CO₂ eq yr⁻¹, as indicated elsewhere in this Special Issue). According to two future climate scenarios, CH₄ and N₂O emissions are projected to continue increasing by 137-151% and 157-227%, respectively, by the end of this century, as compared with levels during 2000-2010. Strategies to mitigate climate change must account for non-CO₂ GHG emissions, given their substantial warming potentials.