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

By Gabriel I, Plunkett G, Abbott PM, Behrens M, Burke A, Chellman N, Cook E, Fleitmann D, Hörhold M, Hutchison W, McConnell JR, Óladóttir BA, Preiser-Kapeller J, Sliwinski JT, Sugden P, Twarloh B and Sigl M.

A new paper has been published by Gabriel I et al. in Communications Earth & Environment on a long-lasting flare-up of volcanism in early medieval Iceland that caused climate shocks throughout Europe.

Contrary to previous estimates of global volcanic activity which suggested minimal eruptions between 700 and 1000 AD, the authors present evidence for increased volcanic activity. Through the analysis of Icelandic geological and Greenland ice-core records using diverse geochemical methods, including the detection of volcanic metals and volatiles, prolonged activity such as the Icelandic Active Period (751–940 CE) and shorter bursts like the Hrafnkatla episode (751–763 CE) were revealed.

In their discussion, amongst other points, the authors state that their "revised estimates across this 300-year period, with the inclusion of a long-lasting tropospheric S contribution, have important implications for climate model simulations, such as those from PMIP3 and PMIP4, which use the year 850 CE as the start of the past1000 simulations covering the pre-industrial millennium (850–1849 CE)3,4. These models use only stratospheric volcanic forcing where the tropospheric aerosols are not included, in contrast to historic climate simulations (starting in 1850 CE), which also include tropospheric aerosol forcing."

The authors conclude that their findings challenge the notion of volcanic quiescence during this period and highlight significant volcanic events, emphasizing the need for a reevaluation of historical volcanic activity.

This research benefited from the participation of the authors in the Volcanic Impacts on Climate and Society (VICS) working group of the Past Global Changes (PAGES) project.

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