Maunder minimum
The cause of the Little Ice Age is unknown, but many people have pointed at the coincidence in low sunspot activity and the timing of the Little Ice. This so called
Maunder Minimum[SUP]2[/SUP] coincided with the coldest part of the Little Ice Age, in particular during the period roughly from 1645 to 1715, when sunspots were a rare occurrence, as noted by solar observers such as Cassini and Flamsteed
[SUP]3[/SUP]. A minimum in sunspots, indicates an much less active and possibly colder sun and consequently less energy output to warm the earth.
http://www.eh-resources.org/timeline/timeline_lia.html