chapter  17
28 Pages

Volcanoes and climate: an updated assessment

A symposium was held at the Hamburg 1983 Congress of the International Union of Geodesy and Geophysics to mark the hundredth anniversary of the great eruption of Krakatoa in the Sunda Straits in the East Indies (about 60 S 105 SE) on 26-27 August 1883 and review present knowledge of the effects of volcanic explosions on the atmosphere and on the development of climate. * Much of the island of Krakatoa and its mountains, together with other small nearby islands in the Strait, disappeared into the atmosphere or fell as 'bombs' into the sea. Estimates of the amount of solid matter blown up range from 6-18 km3 • The column of finer debris, lumped together as 'dust' or 'ash' - though we now know that the gaseous products, particularly sulphur oxides, which form aerosol in the stratosphere, may be more important as regards climatic effect - rose to an observed height of 27 km. Batavia, now known as Jakarta, 160 km from the volcano, was in darkness for 4-5 h in the middle of the day (and there was much rain there, presumably from thunderclouds formed in the rising air column).