Two hundred years ago, the greatest eruption in Earth’s recorded history took place. Mount Tambora—located on Sumbawa Island in the East Indies—blew itself up with apocalyptic force in April 1815.
 After perhaps 1,000 years’ dormancy, the devastating evacuation and collapse required only a few days. It was the concentrated energy of this event that was to have the greatest human impact. By shooting its contents into the stratosphere with biblical force, Tambora ensured its volcanic gases reached sufficient height to disable the seasonal rhythms of the global climate system, throwing human communities worldwide into chaos. The sun-dimming stratospheric aerosols produced...