Edge is holding a forum on the question. John Tooby’s contribution:
The average G-type star shows a variability in energy output of around 4%. Our sun is a typical G-type star, yet its observed variability in our brief historical sample is only 1/40th of this. When or if the Sun returns to more typical variation in energy output, this will dwarf any other climate concerns.
(Hat tip: Arnold Kling)