We already know that the Maunder [sunspot] minimum overlapped the Little Ice Age of the 1600's to early 1800's.
However, correlation is not causation.
It makes sense that less solar activity would mean a cooler earth, just as the greater sunspot activity of the 1850 to 2000 period could explain the warming of the earth during the same period.
The nice part of this is that there is a definite prediction that can be made: Lower sunspot/solar activity between 2020-2030 (even between now and 2030) should be associated with a cooler earth.
The early results, from 1996 to the present tend to support the hypothesis.