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

DOI
Publisher DOI
Abstract
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.
Date Issued
2020-06-21
Publication Type
Article
Subject(s)
Subjects
ice core
volcano
Okmok
Rome
climate forcing
Language(s)
en
Author(s)
McConnell, Joseph R.
Plunkett, Gill
Burke, Andrea
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
Steffensen, Jørgen Peder
Additional Credits
Journal
Proceedings of the National Academy of Sciences of the United States of America - PNAS
Publisher
National Academy of Sciences NAS
ISSN
0027-8424
Project(s)
Access(Rights)
restricted
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