Sláinte (a Gaelic toast) to the Irish monks! They not only preserved the knowledge of ancient Greece in western Europe after the fall of the Roman Empire, they also logged a 1200 year climate record of the Emerald Isle from 431 to 1649 CE in the Irish Annals. The writings of those meteorology-minded monks were recently used to correlate volcanic activity to intense cold snaps in Ireland.

The monks wrote the Irish Annals as a record of religious feast days and major events, but the clerics also noted extreme cold weather events, such as heavy snow or prolonged ice cover on lakes.

For example in the Annals of Connacht from 1465 CE: “Exceeding great frost and snow and stormy weather this year, so that no herb grew in the ground and no leaf budded on a tree until the feast of St. Brendan [May16].”

The monks kept up their observations through the Black Plague and Viking raids, but stopped after English invaders suppressed the traditional culture of Ireland during the Tudor conquest in the 1600s.

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“It’s clear that the scribes of the Irish Annals were diligent reporters of severe cold weather, most probably because of the negative impacts this had on society and the biosphere,” Francis Ludlow of Harvard University said in a press release.

Ludlow was lead author of a study that paired Irish weather observations with volcanic eruptions. The scientists dated historic volcanic activity using info from the Greenland Ice Sheet Project about volcanic residues trapped in Greenland’s glaciers. The study was published in Environmental Research Letters.

For example, Ludlow’s team found that the eruption of the Peruvian volcano, Huaynaputina, in 1600 was associated with a few years of hard winter in Ireland. Chinese records also showed a cold winter after than eruption, according to a study published in the International Journal of Climatology.

“The possibility that tropical eruptions may result in severe winter cooling for Ireland highlights the considerable complexity of the volcano-climate system in terms of the regional expression of the response of climate to volcanic disturbances,” said Ludlow.

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In total, Ludlow’s team observed 48 volcanic events between the years 431 and 1649. Of those, 38 correlated closely in time with 37 extreme Irish climate observations.

IMAGE: The huts of ancient Irish monks on Skellig Micheal island (Arian Zwegers, Wikimedia Commons)