The ∼73 ka Toba super-eruption and its impact: History of a debate

Toba volcano in northern Sumatra is located at the intersection of two major tectonic lineaments in one of the most seismically active regions in the world, and its caldera is considered the largest Quaternary caldera on earth. The most recent Toba explosive eruption at ∼73 ka was an order of magnitude larger than that of Tambora in 1815, and has a Volcanic Explosivity Index of 8. The exceptional magnitude of this super-eruption and the widespread distribution of the Younger Toba Tuff (YTT) in marine cores in the Indian Ocean, the Arabian Sea and the South China Sea have prompted sustained debate as to its global and regional impact on climate, ecosystems and prehistoric human populations. However, despite climate modelling and appeals to a variety of proxy climatic data, including geochemistry, pollen analysis, archaeology, and stable isotopes, the extent of the impact remains unclear. In order to achieve better progress in the future, greater care is needed to obtain higher resolution and more precise chronologies from the marine and terrestrial proxy records used to test whether or not the ∼73 ka Toba super-eruption had a significant environmental impact. Records from speleothems and ice cores have much to offer in this regard.