There are currently many uncertainties surrounding the accuracy of TSI (total solar irradiance) in modern times, in fact my own research over the last 20+ yrs has found values of 1365-1361-1362 with a varience of .9 Wm2. If we go back to Maunder period mid 17th Century the value was 1365 Wm2.
As you can see the period registered 1363.5 Wm2 a drop of 1.6 Wm2. Not a great number is it yet it brought about serious hardship Globally, remember the food chain is mainly grown in the NH, decrease in growing seasons Would effect distribution.
We then look at NASA GISS.
Here again we see a different value of 1366Wm2.
Reason- In CMIP5, TSI/SSI was based on Lean (2009) and Wang et al. (2005) (1850 to 2000) with extensions back to 850 CE based on reconstructions from Delaygue and Bard (as discussed in Schmidt et al., 2011).
Let us now look at SORCE TIM TSI.
Low and behold another value is given of 1361Wm2 with a varience of 1Wm2 over Maunder period!
I will now leave you with a paper from the Astrophysical journal volume 830 (accepted and published) that gives the mean value of TSI of 1362.9Wm2 based on DIARAD/SOVIM absolute level, and ask the Question "what value" are we working from here? This is a critical index in understanding irradiance received at Earth without a "correct" index could cause misconceptions within the field of "Climate Science.
https://iopscience.iop.org/article/10.3847/0004-637X/830/1/25
Once again- Thanks for dropping by.
Regards
DIBirch