Community Research and Development Information Service - CORDIS

Final Report Summary - HEEEME (The historical evidence for European environmental and meteorological extremes AD 400 – 1000.)

The main challenge of this project was in assembling a sufficient body of historical evidence that analysis could take place of the relationship between severe weather and societal stress in the period 400 – 1000 CE. Although the term ‘Dark Ages’ is no longer applied to this era, which saw a continued economic and agricultural advance, it has to be recognised that there was a collapse in the production of written works, one that did not see a significant revival until after 1000 CE. Therefore it was a success for this project that the PI was able to identify and translate (or have translated) over 1,300 relevant references from Latin, Greek, Syriac or Arabic sources. With the removal of duplicates and the categorising of the data in terms of the type of event it described and the reliability of the source, this led to project creating a body of evidence with 884 entries at the time that the investigation ceased.

This is sufficient a data set that it has proven valuable in a number of contexts. When, for example, researchers wanting to investigate whether reports of ‘blood rain’ could be connected to deposits of Saharan sand in Europe approached the PI, twenty-four reports of ‘blood rain’ could be identified within minutes. More importantly, this was the dataset that assisted a group of ice-core researchers to revolutionise our chronology of volcanic activity in the past. By calibrating their findings against the historical information provided by this project, researchers have significantly revised the pattern of historic volcanic eruptions. The consequences of this are still to be fully realised, but already new patterns of cause and effect in regard to eruptions and human society can be identified. The importance of the establishment of this new ice-core chronology was recognised in a publication in Nature (see section 2).

The other successful outcomes of this project derived from a multi-disciplinary synthesis of the historical data with that from natural proxy sources, in particular, with tree-ring and ice-core sequences. This involved a collaboration with Dr Francis Ludlow (Harvard, Yale and now Trinity College Dublin). Posing the question of whether there are long-term patterns over the six centuries in regard to extreme weather and societal stress (such as famines and epidemics) Monte Carlo tests were carried out to calculate the probabilities of persistent associations. A whole range of discoveries arose on the basis of this methodologies that highlight the potency of combining human and natural archives in efforts environment.

Perhaps the most significant findings of the analyses, is that drought is a recurring societal stressor in both early medieval Europe and the Near East regarding subsistence crises, and for Europe regarding mass mortality and epidemic disease. Here, the timing of scarcity and famine versus the peak incidence of mortality and disease suggests an interesting temporal dynamic in social response and vulnerability to drought-promoted subsistence crises. Regional disparities in the timing, presence and absence of given stress responses also suggest apparently pronounced regional differences in resilience and vulnerability that mediate the efficacy of drought in promoting mortality and disease via scarcity and famine (or other mechanisms). The character and role of the disease regimes operating in each region looms large as an additional consideration.

Other results from this project include:

• A demonstration of the considerable potential of medieval chronicles to characterize the varied early medieval responses to extreme climatic events.
• Complex social responses to extreme weather events, including: societal robustness (not all extreme events are associated with societal stresses).
• Lags between extreme events and societal stresses, e.g. where societal coping mechanisms may stave off scarcity during the year of an extreme event.
• The occurrence of previous weather extremes may heighten sensitivity to subsequent extremes.
• The need to consider “interaction effects”, e.g. where different kinds of weather extremes co-occurring closely in time combine to promote different societal stresses.
• Tree-rings are a valuable independent source of evidence, but the complex growth responses to extremes necessitates their careful interpretation.
• The potential to examine societal sensitivity to extremes through time, e.g. how sensitivity to different extremes varies per century in response to evolving socioeconomic circumstances, such as levels of conflict, balance between pastoral and arable agriculture, etc.

For policy makers:

This project indicates the need for a contingency plan for the challenges faced following a 7 VEI volcanic eruption (those we’ve experienced since 1815 have been 1000 times weaker): the serious potential impact on human health; the agricultural implications of a frost lasting until May; the folly of geoengineering by mimicking eruptions.

Reported by

United Kingdom


Life Sciences
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