We present the first evaluation of Greenland ice sheet (GrIS) and climate feedbacks with a CMIP model. Under 4×CO₂ forcing, lower elevations reduce GrIS summer blocking and incoming solar radiation and increase precipitation. Simulated increases of near-surface summer temperature are much lower than the 6 K km^-1 lapse rate that is commonly used in non-coupled simulations. CO₂ reduction to pre-industrial (PI) halts GrIS mass loss regardless of higher global warming and albedo than PI control.