Observations show that marine clouds enhance the surface warming over the Southeast Pacific due to the aerosol–cloud interaction. The anthropogenic aerosols emitted from South America change cloud macro- and microphysical properties that lead to stronger cloud top cooling and larger absorption of solar radiation within clouds. The increased heating above the marine boundary layer enhances the subsidence, reducing low-level clouds and leading to less shortwave reflection at the surface over the Southeast Pacific. The positive radiative forcing can further modulate the circulation and generate an anomalous anticyclone west of South America, facilitating more aerosols transported over the eastern Pacific that reinforces surface warming. This study not only highlights the significant modification of marine clouds and associated energy budget induced by anthropogenic aerosols during the industrial period but also unravels physical links between remote sources and regional climate variability over the southern subtropical Pacific.