Were the Dark Ages triggered by volcano-related climate changes in the 6th century?
Tree-ring data from Keith Briffa (CRU, Univ. of East Anglia), corroborated by European data compiled by Mike Baillie (Queen’s Univ., Belfast), shows clear evidence of a 535 AD climate perturbation, and it is now known worldwide. The origins of this event are likely to have been volcanic since ice core from Greenland and Antarctica show sulfuric acid spikes during this time interval, and for the Byrd core (Antarctica), it is the largest in the last 2000 years. David Keys and I worked with Claus Hammer (Niels Bohr Institute) to reinvestigate the GRIP core from Greenland that Clausen et al. (1997) had already identified. Although asteroid/comet impact remain as potential causes, I focus on a volcanic source located near the equator. Of over 100 potential equatorial volcanoes considered, I found best corroborating evidence in Indonesia, where 6th Century geo-political discontinuity is well documented. Tephra dates are very useful, but there can be pitfalls. For example, some published date
