An Exploratory Analysis of the Occurrence of Explosive Volcanism in the Northern Hemisphere, 1851-1985

Abstract Studies of regional climate following volcanic eruptions suggest that explosive volcanism exerts a short-term cooling effect. To understand the effects of explosive volcanism on historic temperatures, it is necessary to identify changes through time in the frequency of explosive eruptions. This article presents an exploratory analysis of a record of explosive eruptions in the Northern Hemisphere over the period 1851–1985. This record is modeled as a nonstationary Poisson process and the intensity function is estimated by kernel smoothing. Approximate confidence bands are constructed and diagnostics for checking the Poisson assumption are described. A comparison with a record of Northern Hemisphere temperatures indicates that part of the variability in temperature can be explained by variations in explosive volcanic activity.