Top panel shows the impact of the alteration of the carbon cycle alone on radiative forcing. The bottom panel shows the impacts of the alteration of carbon, nitrogen, and sulfur cycles on radiative forcing. SO2 and NH3 increase aerosols and decrease radiative forcing. NH3 is likely to increase plant biomass, and consequently decrease forcing. NOx is likely to increase the formation of tropospheric ozone (O3) and increase radiative forcing. Ozone has a negative effect on plant growth/biomass, which might increase radiative forcing. CO2 and NH3 act synergistically to increase plant growth, and therefore decrease radiative forcing. SO2 is likely to reduce plant growth, perhaps through the leaching of soil nutrients, and consequently increase radiative forcing. NOx is likely to reduce plant growth directly and through the leaching of soil nutrients, therefore increasing radiative forcing. However, it could act as a fertilizer that would have the opposite effect.