1815: http://en.wikipedia.org/wiki/Year_without_a_summer http://en.wikipedia.org/wiki/Year_without_a_summer Not sure about the joy bit since large SO2 emission

1815: http://en.wikipedia.org/wiki/Year_without_a_summer http://en.wikipedia.org/wiki/Year_without_a_summer Not sure about the joy bit since large SO2 emissions have a catastrophic effect on agriculture as you noted, but do not have effects lasting more than a few years. CO2 lasts a good bit longer than that.