1645-———Remember that a journalism major wrote that.
Go read up on the "Maunder Minimum" and the "Little Ice Age".
Low sunspots = less solar wind.
Less solar wind = more high-energy radiation from space reaching the upper atmosphere, which acts to increase certain types of clouds.
These clouds lower the amount of the Sun's radiation reaching the earth, resulting in cooling trends.
The correlation between changes in sunspots and temperature, has been pretty well measured going back several hundred years.
The *other* factor has to do with the mechanism inside the Sun which produces sunspots in the first place: there are articles which show a drop in the sun's magnetic field, to the point that within a couple of years, the Sun might stop producing sunspots altogether.
https://www.newscientist.com/article/mg20627640-800-whats-wrong-with-the-sun/
https://www.newscientist.com/article/mg20627640-800-whats-wrong-with-the-sun/#bx276408B1
http://www.mrctv.org/blog/new-study-warns-ice-age-way