D. Variability in Sun’s Radiation Intensity Changes Black Body Temperatures.
The output of the sun varies daily, weekly, monthly and yearly. A sample plot by NASA from 1980 to 2018 is illustrative. [https://science.nasa.gov/science-news/science-at-nasa/2013/08jan_sunclimate]
The top curve shows a variation of up to 5 w/m2 (1360 to 1365 w/m2) between 1980-1985, 1988-1993, and 2000-2005. This represents a percentage change of 0.36%.
Between 2007 and 2018 the variation was about 1.5 w/m2 (1361 to 1362.5 w/m2) or 0.1% as used by the IPCC. The amount the IPCC attributes to the Greenhouse Effect is 2.3 to 2.9 w/m2. Hence, the normal variability depends on which time period is selected. The 5 w/m2 is twice the amount attributed to the CO2 Greenhouse Effect whereas the 1.5 W/m2 is about half of the Greenhouse effect. Using the weighted average reveals a normal variability in the Sun’s output at 3.8 w/m2. This is 30% more that for the Greenhouse Effect. There is no scientifically supported method to determine which is causing the warming influence between “normal variances in the Sun’s output” verses the “Greenhouse Effect.”