Fig. 1.

Terrestrial ecosystem emissions of reactive trace gases in the Eocene and Cretaceous. Simulated equilibrium global-scale (A) reactive biogenic trace gas emissions to the atmosphere for the 2 × CO₂ (560 ppm) and 4 × CO₂ (1,120 ppm) Eocene, and 4 × CO₂ Cretaceous climates, relative to the preindustrial (PI) era. Panels B, C, and D, respectively, show zonal total fluxes for methane (CH₄) from all biogenic sources (wetlands, biomass burning, oceans, and termites), isoprene released from forested regions, and oxides of nitrogen (NO_x = NO + NO₂) released from soils, and generated by biomass burning and lightning (see SI Text, SI Methods).