Two volcanoes trigger crises of the late antiquity
As they write in the international journal Climatic Change, the impact of the volcanic double event of 536/540 on Northern Hemisphere climate was stronger than any other documented or reconstructed event of the past 1200 years. "One of the eruptions would have led to a significant cooling of the Earth's surface. Two of them, so close in time, caused what is probably the coldest decade of the past 2000 years," says Dr. Matthew Toohey from GEOMAR, lead author of the study today at a press conference at the annual EGU Meeting in Vienna where he presented the results.
To simulate the impact of the 536 and 540 eruptions, the scientists used the available data from ice cores and the descriptions of the solar dimming from contemporary scholars. With this data they estimated the magnitude of the eruptions and their approximate locations on Earth, and then simulated the spread and impacts of the aerosol clouds resulting from the volcanic injection of sulfur into the stratosphere. This revealed that following the eruptions, the solar radiation at the Earth's surface was strongly reduced over the Northern Hemisphere for several years, and caused decreases in the hemispheric average temperature of up to 2 degrees Celsius.
|The 1815 Mount Tambora eruption. The red areas are maps of the thickness |
of volcanic ashfall [Credit: WikiCommons]
Toohey and his colleagues used their climate model simulations to directly estimate the impact of the eruptions on agriculture in Europe, and identified Northern Europe and in particular Scandinavia as the most likely locations to have suffered under the cold conditions after the eruptions. This result supports the theory of a connection between the eruptions and archaeological evidence of a large-scale societal crisis in Scandinavia in the 6th century. "Each one of the eruptions of 536/540 would have strongly impacted societies, and it happened twice within four years," says co-author Prof. Dr. Kirstin Kruger from the University of Oslo.
Which volcanoes exactly were responsible for these aerosols clouds is still enigmatic. "Several candidates are being discussed, including volcanoes in Central America, Indonesia and North America. Future studies will be necessary to show the exact source of the aerosol clouds of 536/540," says Dr. Toohey.
Source: Helmholtz Centre for Ocean Research Kiel (GEOMAR) [April 19, 2016]
Labels Ancient Environment, ArchaeoHeritage, Archaeology, Breakingnews, Climate Change, Earth Science, Palaeontology, Scandinavia