The maunder minimum occurred at the same time as the and has been used by some to explain the cooling temperatures during that period.

The Maunder Minimum occurred at the same time as the  "Little Ice Age" and has been used by some to explain the cooling temperatures during that period. The Maunder Minimum is the name used for the period starting in about 1645 and continuing to about 1715 when sunspots became exceedingly rare.

Physical systems is the answer