The explosive volcanic eruption signal in northern hemisphere continental temperature records

Several catalogs of explosive volcanic eruptions are reviewed and their limitations assessed. A new, homogeneous set of high quality gridded temperature data for continental regions of the northern hemisphere is then examined in relation to the timing of major explosive eruptions. Several of the largest eruptions are associated with significant drops in summer and fall temperatures, whereas pronounced negative anomalies in winter and spring temperatures are generally unrelated to volcanic activity. The effect of explosive eruptions on temperature decreases latitudinally away from the location of the eruption. High latitude eruptions have the greatest impact on high and mid latitudes; low latitude eruptions mainly influence low and mid latitudes. Temperature depressions following major eruptions are very abrupt but short-lived (1 to 3 months) decreasing in magnitude over the course of the subsequent 1 to 3 years. Generally any signal is indistinguishable from noise after 12 months but a small recurrent drop in temperature is evident about 12 to 24 months after the initial anomaly. Considering all known eruptions which injected material into the stratosphere over the last 100 years (except the 5 largest eruptions) a significant temperature depression is observed over the continents only in the month immediately following the eruption. There is no evidence that large eruptions over the last 100 years have had a significant effect on low frequency temperature changes.