The IPCC establishment denied the sun for too long. Now, the biggest factor of all is being included in their analysis. Finally we’re past the Stone Age of Climate Science!
The solar forcing is provided for radiative properties, namely total solar irradiance (TSI), solar spectral irradiance (SSI), and the F10.7 index as well as particle forcing, including geomagnetic indices Ap and Kp, and ionization rates to account for effects of solar protons, electrons, and galactic cosmic rays. This is the first time that a recommendation for solar-driven particle forcing has been provided for a CMIP exercise.
"Solar forcing for CMIP6 (v3.2) (Coupled Model Intercomparison Project)
The quantitative assessment of radiative solar forcing has been systematically hampered so far by the large uncertainties and the instrumental artifacts that plague SSI(solar spectral irradiance) observations, and to a lesser degree TSI (total solar irradiance) observations (e.g., Ermolli et al., 2013; Solanki et al., 2013). Another problem is the sparsity of the observations, which only started in the late 1970s with the satellite era. These problems have deprived us of the hindsight that is needed to properly assess variations on timescales that are relevant for climate studies. Another issue is the uncertainty regarding their absolute level. Since CMIP5, the nominal TSI has been reduced to 1361.0 ± 0.5 W m−2 (see Prša et al., 2016, and also Kopp and Lean, 2011). This adjustment has inevitable implications for understanding the Earth’s radiation budget."
As one can see by the graph below, if IPCC models used CMIP6, CO2's so-called climate forcing would be gone.