Can you imagine solar irradiance falling by 60% over 30 years?
Radiance is proportional to the fourth power of temperature. That's a huge dependence, so timothy and sycodon have got that going for them. Even so, we know the temperature of the photosphere is 5777 K. Since 5777 * (1 - sqrt(sqrt(1-0.6))) / (2030 - 2015) = 80, that implies an 80 degree drop every year across the entire sun, which would have been noticed a long time ago.
These two are skeptical that Earth's atmosphere might be several degrees warmer decades from now, and they're ready to back that up with a claim that the sun's entire atmosphere is cooling down 80 degrees every year.
And they cite a paper that didn't imply that at all. What are these guys smoking?