The impact of a six-year climate anomaly on the ‘Spanish Flu’ Pandemic and WWI

Abstract The H1N1 ?Spanish Influenza? pandemic of 1918-1919 caused the highest known number of deaths recorded for a single pandemic in human history Several theories have been offered to explain the virulence and spread of the disease, but the environmental context remains underexamined In this study we present a new environmental record from a European, Alpine ice core, showing a significant climate anomaly that affected the continent from 1914 to 1919 Incessant torrential rain and declining temperatures increased casualties in the battlefields of WWI, setting the stage for the spread of the pandemic at the end of the conflict Multiple independent records of temperature, precipitation and mortality corroborate these findings