Explosive Super-Eruptions and Potential Global Impacts

Rare, but extremely large, explosive super-eruptions lead to the catastrophic formation of huge calderas, devastation of substantial regions by pyroclastic density currents or flows and their deposits, and ashfalls that cover continent-sized areas. The effects of future super-eruptions will be felt globally or at least by a whole hemisphere. The most widespread effects are likely to derive from the volcanic gases released, particularly sulfur gases that are converted into sulfuric acid aerosols in the stratosphere. These will remain for several years, promoting changes in atmospheric circulation, causing surface temperatures to fall in many regions, leading to short-term, temporary reductions in light levels, and severe and unseasonable weather ("volcanic winter"), but are not expected to be severe enough to cause major climatic changes. Major disruptions to global societal infrastructure can be expected for periods of months to years, and the cost to global financial markets will be high and sustained.