The change in the net, downward minus upward, radiative flux  at the tropopause or top of atmosphere due to a change in an  driver of climate change, such as a change in the concentration of carbon dioxide , the concentration of volcanic aerosols or the output of the Sun. The traditional radiative forcing is computed with all tropospheric properties held fixed at their unperturbed values, and after allowing for stratospheric temperatures, if perturbed, to readjust to radiative-dynamical equilibrium. Radiative forcing is called instantaneous if no change in stratospheric temperature is accounted for. The radiative forcing once rapid adjustments are accounted for is termed the effective radiative forcing. Radiative forcing is not to be confused with cloud radiative forcing, which describes an unrelated measure of the impact of clouds on the radiative flux at the top of the atmosphere.
IPCC
Climate Change 2022: Impacts, Adaptation and Vulnerability
IPCC Report