A Song of Neither Ice nor Fire: Temperature Extremes had No Impact on Violent Conflict Among European Societies During the 2nd Millennium CE

W Christopher Carleton,Huw S Groucutt,Mathew Stewart,Mark Collard

doi:10.3389/feart.2021.769107

Abstract

The second millennium CE in Europe is known for both climatic extremes and bloody conflict. Europeans experienced the Medieval Warm Period and the Little Ice Age, and they suffered history-defining violence like the Wars of the Roses, Hundred Years War, and both World Wars. In this paper, we describe a quantitative study in which we sought to determine whether the climatic extremes affected conflict levels in Europe between 1,005 and 1980 CE. The study involved comparing a well-known annual historical conflict record to four published temperature reconstructions for Central and Western Europe. We developed a Bayesian regression model that allows for potential threshold effects in the climate–conflict relationship and then tested it with simulated data to confirm its efficacy. Next, we ran four analyses, each one involving the historical conflict record as the dependent variable and one of the four temperature reconstructions as the sole covariate. Our results indicated that none of the temperature reconstructions could be used to explain variation in conflict levels. It seems that shifts to extreme climate conditions may have been largely irrelevant to the conflict generating process in Europe during the second millennium CE.

Highlights

“Winter is coming”, the motto of House Stark in George R.R
The novels were inspired by the historical events of the Wars of the Roses (DiPaolo, 2018), a series of conflicts in Late Medieval England that began in 1455 CE (Hicks, 2012)
The conflict records include events ranging in scale and intensity from cattle raids to political uprisings and civil wars that occurred during various sub-intervals of the 20th and early 21st centuries CE

Summary

Introduction

“Winter is coming”, the motto of House Stark in George R.R. Martin’s A Song of Ice and Fire series of epic fantasy novels, is an ominous metaphorical portent of difficult times to come. The novels were inspired by the historical events of the Wars of the Roses (DiPaolo, 2018), a series of conflicts in Late Medieval England that began in 1455 CE (Hicks, 2012) These conflicts erupted shortly after the onset of the Little Ice Age, a period during which average temperatures in the Northern Hemisphere dropped by around 0.5°C in a few decades and remained low for centuries (Mann et al, 2009). The temperature or precipitation in one interval is usually correlated with the temperature or precipitation in previous intervals—i.e., there tends to be autocorrelation in climatolological processes, too These common features of conflict and climate processes create challenges for seeing meaningful persistent signals in short runs of observations because the records can be noisy and explained by previous observations alone. It can be difficult to detect persistent and significant covariation between conflict records and climate change if only short intervals are considered

Methods

Results

Conclusion