Hey guys, you're preaching to the choir. Okay here goes.
The tree rings have recorded major worldwide affecting events at the following times: 3195BC, 2354BC, 1628BC, 1159BC and 540AD. There were also two smaller events at 207BC and 44BC. (Many, Clube, Napier, Bailey, Baillie believe the 540AD event (Start of Dark Ages) was caused by a comet fragment or comet swarm.)