1816: The year without a summer

Dear Tom,
The year 1816 is known as “The year without a summer.” What would cause a global event like that?
Stephen Brown, LaPorte, Ind.

Dear Stephen,
Global temperatures decreased by 0.7 to 1.3 degrees in 1816, the result of a massive eruption on April 5-15, 1815, of Mount Tambora in the Dutch East Indies (now Indonesia). That volcanic eruption was the greatest in 1,300 years and it threw 24 cubic miles of material into the atmosphere. A vast cloud of stratospheric sulfate affected the Northern Hemisphere, dimming sunlight and causing global temperature reductions. It was a “volcanic winter.” Reduced summer temperatures resulted in an agricultural disaster across much of the Northern Hemisphere. Canada, the eastern United States, Europe and Asia were all affected. Food shortages and much higher food prices resulted, and starvation was a problem in some areas.

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