Combustion-induced carbonaceous aerosols, particularly black carbon (BC) and brown carbon (BrC), have been largely considered as the only significant anthropogenic contributors to shortwave atmospheric heating. Natural iron oxide (FeO ) has been recognized as an important contributor, but the potential contribution of anthropogenic FeO is unknown. In this study, we quantify the abundance of FeO over East Asia through aircraft measurements using a modified single-particle soot photometer. The majority of airborne FeO particles in the continental outflows are of anthropogenic origin in the form of aggregated magnetite nanoparticles. The shortwave absorbing powers (P ) attributable to FeO and to BC are calculated on the basis of their size-resolved mass concentrations and the mean P (FeO )/P (BC) ratio in the continental outflows is estimated to be at least 4-7%. We demonstrate that in addition to carbonaceous aerosols the aggregate of magnetite nanoparticles is a significant anthropogenic contributor to shortwave atmospheric heating.