<p>Aerosols can enhance ecosystem productivity by increasing diffuse radiation. Such diffuse fertilization effects (DFEs) vary among different aerosol compositions and sky conditions. Here, we apply a suite of chemical, radiation, and vegetation models in combination with ground- and satellite-based measurements to assess the impacts of natural and anthropogenic aerosol species on gross primary productivity (GPP) through DFE during 2001–2014. Globally, aerosols increase GPP by 8.9 Pg C yr<sup>-1</sup> at clear skies but only 0.95 Pg C yr<sup>-1</sup> at all skies. Anthropogenic aerosols account for 41% of the total GPP enhancement though they contribute only 25% to the increment of diffuse radiation. Sulfate/nitrate aerosols from anthropogenic sources make dominant contributions of 33% (36%) to aerosol DFE at all (clear) skies, followed by the ratio of 18% (22%) by organic carbon aerosols from natural sources. In contrast to other species, black carbon aerosols decrease global GPP by 0.28 (0.12) Pg C yr<sup>-1</sup> at all (clear) skies. Long-term simulations show that aerosol DFE is increasing 2.9% yr<sup>-1</sup> at all skies mainly because of a downward trend in cloud amount. This study suggests that the impacts of aerosols and cloud should be considered in projecting future changes of ecosystem productivity under varied emission scenarios.</p>