The possible effects of large 19th and 20th century volcanic eruptions on zonal and hemispheric surface temperatures

The contribution of volcanic material to the stratosphere from major eruptions within the last two centuries has been estimated using volcanological criteria, including eruption type, eruption column height, volume and duration of eruption, and composition and degree of fragmentation of magma. The chronology of major explosive volcanic eruptions is compared with a record of mean surface-temperature deviation (ΔT) for the same interval constructed from all available temperature data. The temperature records are divided into 6 latitudinal zones, allowing analysis for individual zones where temperature changes induced by aerosol perturbation might be intensified. We focus on the explosive volcanic events which by our estimates injected the most material into the stratosphere. These include Tambora 1815, Krakatau 1883, Santa Maria 1902, Katmai 1912 and Quizapu 1932. Such eruptions appear to have produced a consistent but small temperature decrease on the order of 0.2° to 0.5°C on a hemispheric scale for periods ranging from one to five years, although these changes are similar to background temperature variations. The maximum change in ΔT after some of these explosions appears to lag by up to three years in going from equatorial to polar latitudes. Somewhat smaller eruptions, e.g. Agung 1963 and possibly Cosiguina 1835, seem to have produced about the same perturbation in ΔT as the larger eruptions. This suggests either a limiting mechanism on loading of the aerosol layer after a volcanic eruption or, that the composition of injected material (i.e., the ratio of silicate "dust" to volatiles, and composition of the volatiles) may significantly effect stratospheric optical depth perturbation. Temperatures do not remain depressed for a longer period after a series of closely timed eruptions (e.g., the 1881-1889 or the 1902-1903 sequences) than after single events.