Climatic impact of the A.D. 1783 Asama (Japan) Eruption was minimal: Evidence from the GISP2 Ice Core

Abstract

Assessing the climatic impact of the A.D. 1783 eruption of Mt. Asama, Japan, is complicated by the concurrent eruption of Laki, Iceland. Estimates of the stratospheric loading of H 2 SO 4 for the A.D. 1108 eruption of Asama derived from the SO 4 2− time series in the GISP2 Greenland ice core indicate a loading of about 10.4 Tg H 2 SO 4 with a resulting stratospheric optical depth of 0.087. Assuming sulfur emissions from the 1783 eruption were only one‐third of the 1108 event yields a H 2 SO 4 loading value of 3.5 Tg and a stratospheric optical depth of only 0.029. These results suggest minimal climatic effects in the Northern Hemisphere from the 1783 Asama eruption, thus any volcanically‐induced cooling in the mid‐1780s is probably due to the Laki eruption.