When the volcano Tambora erupted in Indonesia in 1815, as many as 100,000 people perished as a result of the blast and an ensuing famine caused by the destruction of rice fields on Sumbawa and neighboring islands. Gases and dust particles ejected into the atmosphere changed weather patterns around the world, resulting in the infamous ''year without a summer'' in North America, food riots in Europe, and a widespread cholera epidemic. And the gloomy...