While understanding of the climate forcing associated with large volcanic eruptions has advanced greatly since the 1991 Mount Pinatubo eruption, the wider environmental impacts and consequences of volcanism on the trajectories of human societies remain only partially explored, especially for the early and high medieval periods ( c. Dendroclimatology and historical documentation both attest, moreover, to severe climatic anomalies following the proposed eruptions, likely providing the environmental preconditions for subsistence crises experienced in Western Europe between 11 CE. Asama, whose largest Holocene eruption occurred in August 1108 CE and is credibly documented by a contemporary Japanese observer, is a plausible contributor to the elevated sulfate in Greenland. The sources of these eruptions remain unknown, but we propose that Mt. Furthermore, careful evaluation of ice core records points to the occurrence of several closely spaced volcanic eruptions between 11 CE. Here we show that a unique medieval observation of a “dark” total lunar eclipse attests to a dust veil over Europe in May 1110 CE, corroborating the revised ice-core chronologies. This newly recognized bipolar deposition episode has consequently been deemed to reveal a previously unknown major tropical eruption in 1108 CE. Long considered the product of the 1104 CE Hekla (Iceland) eruption, this event can now be associated with substantial deposition seen in Antarctica under a similarly revised chronology. Recently revised ice core chronologies for Greenland have newly identified one of the largest sulfate deposition signals of the last millennium as occurring between 11 CE.

Seven ice extreme v2