Volcanic Eruptions can Cause Volcanic Winters

April 10, 1815: Tambora Eruption Triggers ‘Volcanic Winter.’

The big show began April 10. Three columns of fire were seen towering into the sky. By the next day Tambora had ejected about 12 cubic miles of magma into the air.

It propelled enough pulverized rock into the atmosphere to disrupt weather around the globe for more than a year. Average temperatures dropped as much as 5 degrees Fahrenheit over the next year … and beyond.

Many Europeans and North Americans called 1816 the “year without a summer.”

“Snow fell in New England and Eastern Canada in June. (Quebec City got a foot of the stuff.) Frost was recorded in each of the summer months. Drought struck in July and August, and the sunlight was weak. Crops were stunted or failed entirely. Much of what survived and looked near to harvest was killed off by a September frost.”

“The only silver lining to this dark and lethal cloud: The failure of the oat crop in Germany made maintaining horses expensive … and led to invention of the bicycle.”

Note that this occurred during the Dalton Minimum, which was similar to the sunspot minimum that we now appear to be headed into. It looks to me as if sunspot minimums can trigger civilization-changing volcanic activity.

http://www.wired.com/science/discoveries/news/2009/04/dayintech_0410

Thanks to Ann Morrison for this link