ardon me if this has already been discussed.
http://en.wikipedia.org/wiki/Year_Without_A_Summer
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In May of 1816, however, frost killed off most of the crops that had been planted, and in June two large snowstorms resulted in many human deaths as well. In July and August, lake and river ice were observed as far south as Pennsylvania. Rapid, dramatic temperature swings were common, with temperatures sometimes reverting from normal or above-normal summer temperatures as high as 95 °F (35 °C) to near-freezing within hours. Even though farmers south of New England did succeed in bringing some crops to maturity, maize (corn) and other grain prices rose dramatically. Oats, for example, rose from 12¢ a bushel the previous year to 92¢ a bushel.
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Europe, still recuperating from the Napoleonic Wars, suffered from food shortages. Food riots broke out in Britain and France and grain warehouses were looted. The violence was worst in landlocked Switzerland, where famine caused the government to declare a national emergency.
If it is not one thing, it is another.