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Climate, disease and society in late-medieval Ireland

13 October 2021

In today's blog on Climate and Society in Ireland, Bruce Campbell and Francis Ludlow reflect on climate change as a major but neglected grand theme of late medieval Irish history. 

Climate and Society in Ireland is a collection of essays, commissioned by the Royal Irish Academy, that provides a multi-period, interdisciplinary perspective on one of the most important challenges currently facing humanity. In Chapter 7, Bruce Campbell (Queen's University Belfast) and Francis Ludlow (Trinity College Dublin) consider the effects that climate had on the lives and livelihoods of ordinary people in late medieval Ireland.

Ireland ‘more than any other [country] suffers from storms of wind and rain’: thus wrote Gerald of Wales in his History and topography of Ireland, based upon firsthand observations from his two extended Irish visits in 1183 and 1185. It constitutes what is probably the first reasonably detailed extant account of Ireland’s climate. As a Welshman he does not appear to have been unduly perturbed by these now well-known characteristics of the Irish weather, rather, he comments favourably on the generally temperate nature of the climate and absence of extremes of either summer heat or winter cold. He was struck by the fact that the grass remained green throughout the winter, so that haymaking and the winter housing of livestock were not practised, and noted that snow was seldom seen and rarely lasted long. In his experience, thunder and lightning were equally rare, partly because ‘you will scarcely see even in summer three consecutive days of really fine weather’. Hence his stress upon the windiness of the Irish weather (‘a north-west wind, along with the west wind to its south, prevails here, and is more frequent and violent than any other’) combined with its cloudiness and ‘plentiful supply of rain’. These natural attributes meant that the island was ‘richer in pastures than in crops, and in grass than in grain’, with obvious influences on the agrarian economy and the composition of diets. He also considered the air ‘so healthy’ that ‘you will not find many sick men, except those that are actually at the point of death’. On his testimony, fevers, apart from the ague, were comparative strangers to Ireland, whose insularity partially shielded it from the germs which circulated more readily on the continent.

These observations about the Irish weather at the end of the twelfth century accord with what palaeoclimatic reconstructions are revealing about the distinctive climatic conditions prevailing at that time when the atmospheric circulation patterns characteristic of the Medieval Climate Anomaly (formerly the Medieval Warm Period) were firmly in the ascendant. For Ireland that meant a dominant Atlantic airstream, especially in the winter when a characteristically steep pressure gradient between the Azores and Iceland ensured that the North Atlantic Oscillation (NAO) was typically strongly positive. When the NAO was in positive mode Irish winters were usually mild, windy and wet, while incursions of cold, dry Arctic or continental air masses were kept at bay. One recent reconstruction suggests that these conditions prevailed in four out of five years during the second half of the twelfth century and were the established norm from 1183 to 1200, at the time when Gerald of Wales was in Ireland. The comparative stability of the NAO at this time is consistent with the unusually settled state of the weather during this benign climatic interlude and which not even a notable northern hemisphere volcanic eruption in c.1182 was able to disturb. At this time Atlantic storms were to be expected but not, as Gerald says, extremes of cold, heat or drought. In these respects, the findings of climate science broadly corroborate his qualitative account.

Yet the climate would not remain so temperate, nor had it always been so, as Gerald, a learned man, could have discovered for himself by consulting the Gaelic Irish Annals (hereafter Annals) which, by the late-twelfth century, already spanned more than 600 years. Within living memory, in 1156, these recorded that Ireland had endured ‘great snow and intense frost…so that the lakes and rivers of Ireland were frozen over’ and ‘most of the birds of Ireland perished’ (Annals of the Four Masters). Lightning strikes (either because they damaged ecclesiastical buildings or were interpreted as acts of God) were regularly reported in the Annals, as in 1135 when the Chronicon Scotorum reported: ‘Lighting took the roof from the tower of Clonmacnoise and made a hole in the tower of Roscrea’. A few years earlier, in 1129, the Annals of Inisfallen noted a hot summer and drought so severe that ‘the waters of Ireland dried up, and there was a great mortality of beasts and cattle’. And the previous century, in 1095, ‘a great sickness’ was widely reported ‘that killed many people, [lasting] from the first of August until the following May Day—i.e. the year of the mortality’ (Annals of Ulster). Evidently, Ireland was less immune to epidemics than Gerald supposed and once the Black Death arrived in 1348 plague mortality would weigh heavily upon Ireland’s then-shrinking population.

In fact, as the Annals make clear, natural hazards—both physical and biological—posed a recurrent threat to Irish society throughout the late-medieval centuries, as the Irish climate was itself subject to change. Thus, in 1050, at the climax of the Oort Solar Minimum when very different patterns of atmospheric circulation prevailed, ‘Much inclement weather happened in the land of Ireland, which carried away corn, milk, fruit, and fish, from the people, so that there grew up dishonesty among all, that no protection was extended to church or fortress, gossipred or mutual oath, until the clergy and laity of Munster assembled, with their chieftains, under Donnchadh, son of Brian, i.e. the son of the King of Ireland, at Cill-Dalua [Killaloe], where they enacted a law and a restraint upon every injustice, from small to great’ (Annals of the Four Masters). While this account has a clear subtext in the fraught politics of the high kingship of the period,12 it also bears out the self-evident point that this economically under-developed society was heavily dependent for its subsistence upon the annual harvests of grain, grass, fruit and nuts, milk, meat, wool and hides. When production fell short poverty almost invariably increased and famine not unusually resulted. Scarcity, in turn, might prompt the needy to resort to crime and the powerful to violence. Such circumstances were the breeding ground of disease, as in 1189 when the Annals of Inisfallen noted ‘Great warfare and sickness and much bad weather this year’. The weather was not, of course, the sole cause of violence and plague, rather it was the catalyst that often triggered and magnified them and to a degree shaped their courses. As yet there has been little systematic investigation of these interactions, which often weighed more heavily upon the poor than the privileged, partly because they have been eclipsed by the traditionally dominant historiographic grand themes of Church reform, the emergence of a high kingship, English invasion, conquest and colonisation, and the Gaelic revival. Relevant palaeoclimatic information has also been wanting. That has now changed and it is at last possible to place Gerald of Wales’s description and the many environmental observations of the annalists in a proper scientific context.

Recent advances in palaeoclimatology have equipped historians with an array of high-resolution datasets constructed from a variety of natural and historical archives and now frequently spanning the entirety of the medieval period. These datasets have continued to clarify the geographical and temporal character of the often profound changes in climate that occurred over the course of the late-medieval centuries as temperatures and atmospheric circulation patterns transitioned from the relative warmth and stability of the Medieval Climate Anomaly to the cooler and more unsettled conditions of the Little Ice Age, with the critical tipping point from one global climate regime to the other occurring during the first half of the fourteenth century. At the same time, a conjuncture of demographic, economic, commercial, political, military, religious and epidemiological developments was variously placing societies from Iceland to China under increasing stress. Climate change thus emerges as an additional grand theme of late-medieval history and one of overarching global significance. What ecological, epidemiological and societal relevance it may have had for late-medieval Ireland remains to be established.

To continue reading, purchase Climate and Society in Ireland.

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