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.