Modelling the impact of Icelandic volcanic eruptions upon the prehistoric societies and environment of northern and western Britain

This paper is part of the special publication No.161, Volcanoes in the Quaternary (eds: C.R. Firth and W.J. McGuire). Many studies now address the impact of Icelandic volcanic eruptions upon the societies and environment of Britain and Ireland. It has become apparent that the assumptions of the magnitude of volcanic impact inherent in these studies are open to question. The scale of climatic change following many eruptions has been observed to be ephemeral or non-existent, whilst the impact of toxic volatile gases and aerosols is dependent, to a large degree, on the vulnerability of the receptor rather than the scale of deposition. The scale and extent of volcanic climatic-forcing mechanisms are examined and the popular perception of the effectiveness of these is challenged. In particular, the concepts of harsh volcanic winters and cool volcanic summers is examined via case studies of the impacts of the three largest eruptions of recent and historical times, i.e. those of the Laki fissure, Tambora and Mount Pinatubo. Alternative volcanic forcing mechanisms for environmental change are considered, principally those concerned with the transport and deposition of toxic volatile material. The need for caution in the adoption of these models is also urged. It is suggested that workers in this field need to adopt a clearer theoretical framework when contemplating the association of palaeoenvironmental data and volcanic events. Such a framework is proposed.