Volcanic eruptions dry fogs and the European palaeoenvironmental record: localised phenomena or hemispheric impacts?

This paper addresses the climatic and environmental significance of historical records of dry fogs, particularly from Mediterranean sources, which have previously been interpreted as indicating the occurrence of large scale volcanic eruptions. A consideration of material presented here suggests that such descriptions may not indicate the presence of stratospheric aerosols emitted in massive volcanic eruptions, which may be capable of affecting hemispheric climate for several years. Such descriptions may instead record the concentration of volcanic gases in the lower atmosphere from relatively minor, climatically ineffective but environmentally significant, volcanic eruptions. The ‘mystery dust veil of AD 536’ is discussed in the light of this debate and the need for caution when estimating the magnitude of a volcanic event from associated historical records is stressed.