Scientists have found an explanation for the periods of extreme cold described in the writings of Irish monks: volcanic eruptions, some very far away.
About 1,582 years ago, some Irish scribes sat down to write about how very, very cold it was. This was the Dark Ages, after all.
In 2013, scientists also sat down to read those same 40,000 tales of woe — now collected in the Irish Annals, written from 431 to 1649 — and compared them with measurements taken from ice cores dating from the same 1,200-year period. What they found was an explanation for the punishing Irish winters through which the poor scribes shivered: volcanic eruptions, often thousands of miles away.
Their results, published in Environmental Research Letters, showed that out of 48 explosive volcanic eruptions identified in the Greenland Ice Sheet Project (GISP2) ice-core – which records deposits of volcanic sulfate in annual layers of ice – 38 were associated with 37 extreme cold events in Ireland described in the scribes’ writings and identified using modern Irish meteorological data.
At times, the ancient Irish had events far from their homeland to blame for the bad weather. In one instance, the 1600 eruption Huaynaputina, in Peru, resulted in extreme cold winter weather to Ireland for several years following.