Decadal-to-centennial increases of volcanic aerosols from Iceland challenge the concept of a Medieval Quiet Period

• Published in: Communications Earth & Environment
• Main Authors: Imogen Gabriel, Gill Plunkett, Peter M. Abbott, Melanie Behrens, Andrea Burke, Nathan Chellman, Eliza Cook, Dominik Fleitmann, Maria Hörhold, William Hutchison, Joseph R. McConnell, Bergrún A. Óladóttir, Johannes Preiser-Kapeller, Jakub T. Sliwinski, Patrick Sugden, Birthe Twarloh, Michael Sigl
• Format: Article in Journal/Newspaper
• Language: English
• Published: Nature Portfolio 2024
• Subjects: Geology; QE1-996.5; Environmental sciences; GE1-350; Greenland; Greenland ice core; Greenland ice cores; ice core; Iceland
• Online Access: https://doi.org/10.1038/s43247-024-01350-6; https://doaj.org/article/750ed64a8ae84a3f976472539469f84c

Abstract Existing global volcanic radiative aerosol forcing estimates portray the period 700 to 1000 as volcanically quiescent, void of major volcanic eruptions. However, this disagrees with proximal Icelandic geological records and regional Greenland ice-core records of sulfate. Here, we use cryptotephra analyses, high-resolution sulfur isotope analyses, and glaciochemical volcanic tracers on an array of Greenland ice cores to characterise volcanic activity and climatically important sulfuric aerosols across the period 700 to 1000. We identify a prolonged episode of volcanic sulfur dioxide emissions (751–940) dominated by Icelandic volcanism, that we term the Icelandic Active Period. This period commences with the Hrafnkatla episode (751–763), which coincided with strong winter cooling anomalies across Europe. This study reveals an important contribution of prolonged volcanic sulfate emissions to the pre-industrial atmospheric aerosol burden, currently not considered in existing forcing estimates, and highlights the need for further research to disentangle their associated climate feedbacks.