3D Simulations of the Archean Earth Including Photochemical Haze Profiles

Abstract We present results from 3D simulations of the Archean Earth including a prescribed (non‐interactive) spherical haze generated through a 1D photochemical model. Our simulations suggest that a thin haze layer, formed when CH 4 /CO 2 = 0.1, leads to global warming of ∼10.6 K due to the change of water vapor and cloud feedback, compared to the simulation without any haze. However, a thicker haze layer, formed when CH 4 /CO 2 > 0.1, leads to global cooling of up to ∼65 K as the scattering and absorption of shortwave radiation from the haze reduces the radiation from reaching the planetary surface. A thermal inversion is formed with a lower tropopause as the CH 4 /CO 2 ratio increases. The haze reaches an optical threshold thickness when CH 4 /CO 2 ∼ 0.175 beyond which the atmospheric structure and the global surface temperature do not vary much.