To assess impacts of solar geoengineering, the GeoMIP G1 experiment forces Earth System Models with prescribed reductions in solar radiation to balance increases in atmospheric CO₂. One key source of uncertainty is the magnitude of solar constant reduction required to offset a CO₂ quadrupling. Here, we decompose the G1 experiment in the Community Earth System Model with solar only and CO₂ only forcing experiments to quantify single forcing rapid radiative adjustments. We find that radiative adjustments to both single forcings have a net positive effect on top of atmosphere energy balance such that they both increase the net G1 forcing. Stratospheric temperature and shortwave cloud adjustments are the main sources of positive adjustment in both Solar and CO₂ scenarios. We also show that net G1 radiative adjustment cannot be represented linearly with CO2 and solar forcing adjustments, which is primarily traced to further reductions in boundary layer clouds.