THE LAKI FISSURE ERUPTION AND UKMORTALITY CRISES OF 1783-1784

Abstract

The Lakigigar eruption 1783 – 1784 is known to be the largest air pollution incident in historic times; its effects were felt throughout Europe and beyond. In the UK, August temperatures in 1783 were 2.5oC to 3oC higher than the decadal average, causing the hottest summer on record for 200 years. A bitterly cold winter followed with temperatures 2oC below average. Contemporary observers noted the presence of an acid fog in much of Europe, which prevailed during the summer of 1783, coupled with an increase in sickness and ‘pestilential agues’. Coincidentally, in England, July 1783–June 1784 is classified as a mortality crisis (an annual mortality rate ~20% above the 51-year moving mean); the death rate doubled with 30,000 additional deaths recorded. The Laki fissure eruption has been put forward as the climatic and environmental forcing mechanism for this mortality crisis; whilst the broad impacts of the eruption on the environment are understood, less is known about the impact on mortality. The main aim of this research is to explore the role of the Laki fissure eruption and to test the null hypothesis that the eruption played no role in the mortality crises. An appraisal of British health in the latter half of the 18th Century is presented, specifically endemic diseases and the environmental forcing mechanisms which could make them epidemic. Particular attention is given to local weather patterns around Britain and the grain prices and social factors of influence, in four counties: Dorset, Cheshire, Yorkshire and Northumberland. The burial records for both small and large parishes in these counties and some major cities, are also investigated. The climatic and environmental effects were felt strongly across the UK, but with some geographical areas more sensitive than others. Grain prices, (as indicators of harvest yield) for the four counties, did not reveal a strong signal in their standard deviation for the decade 1780-89. Similarly, the burial data did not indicate crisis mortality, as strongly as in previously published work for other counties (notably, Bedfordshire). Whilst the null hypothesis for these four counties cannot be rejected, the findings highlight the differing levels of vulnerability within England and indicate that other counties would have been much worse affected. Given the growing risk to health from air pollution, climate change and volcanic eruptions, it is important that lessons from the vulnerabilities of the past can inform mitigation strategies for the future.