Proposed re‐dating of the European ice core chronology by seven years prior to the 7th century AD

Progress in the study of past climate change requires integration of historical documentation, tree‐ring data and ice‐core chemistry. Larsen et al. (2008) re‐evaluate volcanic acid signals in the Dye‐3, GRIP and NGRIP ice cores and identify large eruptions at 529 ± 2 and 533–534 ± 2; the latter claimed to cause the ‘dry fog’ of 536–537 and environmental consequences to 550; this conflicts with previous suggestions of a two stage environmental event; one in 536, the second c.540. Understanding the full range of natural hazards requires critical evaluation of the happenings in the mid‐6th century. This paper will show that 4 spaced tree‐ring responses to extreme environmental conditions in the 6th century can be used to re‐locate 4 key ice‐acid dates. Moving the ice‐core chronology forward 7 years places two large volcanoes in 536 and 541 explaining the extended duration of the 536–550 effects and anchoring the ice chronology.