Uncertainties in marine boundary layer clouds arise in the presence of biomass burning aerosol, as is the case over the southeast Atlantic Ocean. Heating due to this aerosol has the potential to alter the thermodynamic profile as the aerosol is transported across the Atlantic Ocean. Radiation transfer experiments indicate local shortwave aerosol heating is ~2–8 K d⁻¹; however uncertainties in this quantity exist due to the single-scattering albedo and back trajectories of the aerosol plume.