Extreme climate after massive eruption of Alaska’s Okmok volcano in 43 BCE and effects on the late Roman Republic and Ptolemaic Kingdom

McConnell, Joseph R.; Sigl, Michael; Plunkett, Gill; Burke, Andrea; Kim, Woon Mi; Raible, Christoph C.; Wilson, Andrew I.; Manning, Joseph G.; Ludlow, Francis; Chellman, Nathan J.; Innes, Helen M.; Yang, Zhen; Larsen, Jessica F.; Schaefer, Janet R.; Kipfstuhl, Sepp; Mojtabavi, Seyedhamidreza; Wilhelms, Frank; Opel, Thomas; Meyer, Hanno and Steffensen, Jørgen Peder (2020). Extreme climate after massive eruption of Alaska’s Okmok volcano in 43 BCE and effects on the late Roman Republic and Ptolemaic Kingdom. Proceedings of the National Academy of Sciences of the United States of America - PNAS, 117(27), pp. 15443-15449. National Academy of Sciences NAS 10.1073/pnas.2002722117

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The assassination of Julius Caesar in 44 BCE triggered a power struggle that ultimately ended the Roman Republic and, eventually, the Ptolemaic Kingdom, leading to the rise of the Roman Empire. Climate proxies and written documents indicate that this struggle occurred during a period of unusually inclement weather, famine, and disease in the Mediterranean region; historians have previously speculated that a large volcanic eruption of unknown origin was the most likely cause. Here we show using well-dated volcanic fallout records in six Arctic ice cores that one of the largest volcanic eruptions of the past 2,500 y occurred in early 43 BCE, with distinct geochemistry of tephra deposited during the event identifying the Okmok volcano in Alaska as the source. Climate proxy records show that 43 and 42 BCE were among the coldest years of recent millennia in the Northern Hemisphere at the start of one of the coldest decades. Earth system modeling suggests that radiative forcing from this massive, high-latitude eruption led to pronounced changes in hydroclimate, including seasonal temperatures in specific Mediterranean regions as much as 7 °C below normal during the 2 y period following the eruption and unusually wet conditions. While it
is difficult to establish direct causal linkages to thinly documented historical events, the wet and very cold conditions from this massive eruption on the opposite side of Earth probably resulted in crop failures, famine, and disease, exacerbating social unrest and contributing to political realignments throughout the Mediterranean region at this critical juncture of Western civilization.

Item Type:

Journal Article (Original Article)

Division/Institute:

10 Strategic Research Centers > Oeschger Centre for Climate Change Research (OCCR)
08 Faculty of Science > Physics Institute > Climate and Environmental Physics

Graduate School:

Graduate School of Climate Sciences

UniBE Contributor:

Sigl, Michael; Kim, Woon Mi and Raible, Christoph

Subjects:

500 Science > 550 Earth sciences & geology
500 Science > 530 Physics

ISSN:

0027-8424

Publisher:

National Academy of Sciences NAS

Funders:

[18] European Research Council

Projects:

[1314] Timing of Holocene volcanic eruptions and their radiative aerosol forcing

Language:

English

Submitter:

Michael Sigl

Date Deposited:

07 Jul 2020 10:13

Last Modified:

30 Jul 2020 02:12

Publisher DOI:

10.1073/pnas.2002722117

Uncontrolled Keywords:

ice core volcano Okmok Rome climate forcing

BORIS DOI:

10.7892/boris.145066

URI:

https://boris.unibe.ch/id/eprint/145066

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