How volcanoes could trigger a year without summer This month marks the 200th anniversary of the greatest known volcanic explosion in the historical record, and brings a warning that another huge blast could be imminent. In April 1815, the Tambora volcano, on the Indonesian island of Sumbawa, tore itself apart in a cataclysmic eruption that loaded the atmosphere with sun-shielding sulphur gases and brought bitterly cold weather to the UK and Europe, half a world away. Now scientists are keeping a careful eye on a clutch of long dormant but restless volcanoes across the planet that may present a similar threat, to provide us with advance warning of the next big bang. Most volcanologists would agree with the maxim “the longer the wait, the bigger the bang”. In other words, volcanoes that have been quiet for centuries, or even millennia, often announce their emergence from slumber with a huge explosion. Of the 20 biggest eruptions since 1800, half occurred at volcanoes that had lain dormant throughout the historical period. FULL REPORT