The climate impacts of carbon fertilization of the terrestrial biosphere include cooling associated with the biogeochemical effects of enhanced land carbon storage, whereas the non-carbon-cycle biogeophysical effects associated with changes in surface energy and turbulent heat fluxes may warm or cool the climate system. Both of these effects may be dependent on the background climate. Here, I analyze state-of-the-art CMIP6 Earth system models that conducted simulations driven by 1 % yr⁻¹ increases in atmospheric carbon dioxide (CO₂) concentration that isolate the carbon fertilization effect (i.e., CO₂ radiative effects are not active) relative to a preindustrial background climate. At the time of CO₂ quadrupling, the biogeophysical effects yield multimodel global mean near-surface warming of 0.16±0.09 K, with 13 of the 15 models yielding warming. Using a Surface Energy Balance decomposition, most of this warming is associated with decreases in surface latent heat flux associated with reduced canopy transpiration. Decreases in surface albedo and increases in downwelling shortwave and longwave radiation – both of which are modulated by cloud reductions – are also associated with the warming. Overall, however, the biogeophysical warming is about an order of magnitude smaller than the corresponding cooling associated with enhanced land carbon storage at −1.38 K (−1.92 to −0.84 K). Simulations that isolate the carbon fertilization effect relative to a warmer, higher CO₂ background climate yield similar overall results. However, some nuances exist including stronger biogeophysical warming of the extratropics and weaker but nonsignificant biogeophysical warming of the tropics.