“The bright sun was extinguish’d … and the icy earth swung blind and blackening in the moonless air.” These words from Lord Byron’s 1816 poem Darkness evoke a hellish apocalypse. But Byron may have been inspired by the fallout of a real cataclysm — one that happened half a world away.

Mount Tambora, in present-day Indonesia, blew its top in 1815. More than 71,000 people in the vicinity died. And climate-cooling aerosols from the eruption ushered in extreme weather the following years in far-flung places. Cold weather in the summer of 1816, sometimes with frosts and snow, destroyed corn in New England, rice and buckwheat in China and wheat, oats and potatoes in Ireland. In some places, the rising cost of bread sparked protests and riots. The circumstances may have helped spread typhus.…