|
Abstract
|
When Mount Tambora in the Lesser Sunda Islands, Indonesia, erupted in 1815, more than 100 km3 of volcanic pyroclasts and ash were discharged into the stratosphere up to altitudes of over 40 km (1). The volcanic gases and ash dispersed over the Northern Hemisphere, causing what was called “the year without a summer” in Europe, with severe starvation, famine, mass migrations, and an estimated several tens of thousands of casualties. By comparison, the 2010 Eyjafjallajökull eruption in Iceland discharged only about 0.3 km3—300 times less than Tambora—yet caused a week of air traffic shutdown and more than 100,000 flight cancellations over Northern and Central Europe, with an estimated economic loss of 3.3 billion euros (2). If an eruption of the scale of the Tambora eruption occurred today, its impacts would vastly exceed those of the 2010 Eyjafjallajökull eruption. Yet, global societies are essentially unprepared for such an event.
The 1815 Tambora eruption was large, but far from extreme. Its size is classified as 7 on the Volcanic Explosivity Index (VEI), which is a relative measure of the magnitude of volcanic eruptions. In the past 2 million years, there have been 27 so-called supereruptions (VEI 8, with an eruption volume >1000 km3) (3), the most recent of which occurred at Taupo volcano, New Zealand, about 27,000 years ago. Four VEI 8 eruptions occurred in the past 100,000 years. The Toba eruption, which occurred in Indonesia 74,000 years ago, has been linked to a catastrophic decrease in global human population (4). The theory, however, is controversial (5), mostly because of uncertainty in the amount of sulfur released and the consequent extent of aerosol production in the atmosphere.
Smaller eruptions can have substantial impacts as well. The 1991 eruption of Mount Pinatubo in the Philippines, classified as VEI 6, produced about 11 km3 of tephra, injecting ∼20 megatons of sulfur dioxide into the atmosphere and causing a years-long global cooling of up to 0.7°C. In historic times there has not been a supereruption, and humans therefore do not have direct knowledge of such extreme events. However, such an event would be likely to strongly affect global society. According to Sparks et al., a supereruption could devastate an area the size of North America and cause weather deterioration, loss of crops, and severe disruption of food supplies, resulting in mass starvation and threatening the fabric of civilization (6). Such a situation would constitute an existential risk to humanity. A VEI 8 eruption, and to a large extent, a VEI 7 eruption, would shut down air traffic for weeks, months, or years over an area as large as the hemisphere, disrupting world trading and economies. There are no other known natural phenomena of endogenous origin (apart from flood basalts, which are orders of magnitude less frequent) that could disrupt our entire civilization so deeply and abruptly ...
Language: en |