Publication details

Global wood anatomical perspective on the onset of the Late Antique Little Ice Age (LALIA) in the mid-6th century CE

Authors	BÜNTGEN Ulf CRIVELLARO Alan ARSENEAULT Dominique BAILLIE Mike BARCLAY David BERNABEI Mauro BONTADI Jarno BOSWIJK Gretel BROWN David CHRISTIE Duncan A CHURAKOVA Olga V. COOK Edward R ARRIGO Rosanne DAVI Nicole ESPER Jan FONTI Patrick GREAVES Ciara HANTEMIROV Rashit M. HUGHES Malcolm K. KIRDYANOV Alexander V. KRUSIC Paul J. CARLOS Le Quesne LJUNGQVIST Fredrik C. MCCORMICK Michael MYGLAN Vladimir S. NICOLUSSI Kurt OPPENHEIMER Clive PALMER Jonathan QIN Chun REINIG Frederick SALZER Matthew STOFFEL Markus TORBENSON Max TRNKA Mirek VILLALBA Ricardo WIESENBERG Nick WILES Greg YANG Bao PIERMATTEI Alma
Year of publication	2022
Type	Article in Periodical
Magazine / Source	Science Bulletin
MU Faculty or unit	Faculty of Science
Citation
Web	https://doi.org/10.1016/j.scib.2022.10.019
Doi	http://dx.doi.org/10.1016/j.scib.2022.10.019
Keywords	Blue Rings; Climate extremes; Dendrochronology; Late Antiquity; Tree rings; Volcanic eruptions
Description	Linked to major volcanic eruptions around 536 and 540 CE, the onset of the Late Antique Little Ice Age has been described as the coldest period of the past two millennia. The exact timing and spatial extent of this exceptional cold phase are, however, still under debate because of the limited resolution and geographical distribution of the available proxy archives. Here, we use 106 wood anatomical thin sections from 23 forest sites and 20 tree species in both hemispheres to search for cell-level fingerprints of ephemeral summer cooling between 530 and 550 CE. After cross-dating and double-staining, we identified 89 Blue Rings (lack of cell wall lignification), nine Frost Rings (cell deformation and collapse), and 93 Light Rings (reduced cell wall thickening) in the Northern Hemisphere. Our network reveals evidence for the strongest temperature depression between mid-July and early-August 536 CE across North America and Eurasia, whereas more localised cold spells occurred in the summers of 532, 540–43, and 548 CE. The lack of anatomical signatures in the austral trees suggests limited incursion of stratospheric volcanic aerosol into the Southern Hemisphere extra-tropics, that any forcing was mitigated by atmosphere-ocean dynamical responses and/or concentrated outside the growing season, or a combination of factors. Our findings demonstrate the advantage of wood anatomical investigations over traditional dendrochronological measurements, provide a benchmark for Earth system models, support cross-disciplinary studies into the entanglements of climate and history, and question the relevance of global climate averages.