Because carbon in the air is absorbed by trees, carbon - 14 levels in tree rings actually reflect solar activity and unusual solar events in the past. (sciencedaily.com)
Another hypothesis as to what could be causing periodic rapid changes to the planet's climate is that there are periodic solar events which affect cloud formation. (realclimate.org)
During solar events as a child I remember hearing, «Don't look at it! (mindbodygreen.com)