Permaculture and Seven Years of Famine
The Earth has burst forth. The sky is filled with darkness. Starvation, disease and death stalks the land. Mount Tarawera, in present day New Zealand, has erupted, spewing forth enough ash to obscure the sun for at least a year... maybe two. Germany is already feeling the pinch. The eruption will cause "widespread crop failures" for 1316 and 1317 in a land already strained to the breaking point. The European population has tripled in the last century and the farmers are already having crop yield problems due to heavier rains and cooler weather. In years to come this disaster will be known as "The Great Famine" and like the biblical seven year famine, many people will wonder if God was unhappy about something.
My Take by Alex Shrugged
There is a permaculture connection to this event and to the rise of population in the 13th century. As we found in the story of the Pied Piper of Hamlin, many villages became overpopulated, forcing them to move into uncultivated forest lands. The book, "The Great Famine" by William Jordon suggests that these forest plots were "super-fertile" assarts, like "bites" out of the forest that sustained the sudden increase in population. Yet even permaculture-like plots could not survive a growing season without sun and the farmers did very little fertilizing so their crop yields were heavily dependent on the natural soil conditions and weather more than the modern farmer would. The difference between then and now is that modern methods of canning allow us to save enough of the yield in the "seven fat years" to sustain us through any "lean years" if we are prepared. 
Update [2014-March-6]: Texas A&M Atmospheric Science Department
responded (actually... one guy in the department so don't hold them to it
): "This sounds very good. It is not unusual for a violent eruption to inject aerosols into the stratosphere. There is very little exchange of air between the stratosphere and troposphere, so once an aerosol is injected into the stratosphere, it can remain there for quite a while circling the globe. Depending on the aerosol, it can have a net cooling effect on the earth. The aerosols can reflect or absorb solar radiation which then doesn't make it to the surface. Less solar radiation reaching the surface means a cooler global temperature and depending on where you are, it could mean shorter growing periods or none at all. We only have direct observations of sulfate aerosols going back to the 70s so the other way to find these concentrations is using ice cores. I looked and found a paper that saw a small peak in sulfate concentrations in the Southern Hemisphere in 1316. I'm not sure of the reliability of the data however. Your description does sound plausible."
An Economic Invitation Extended
With the passing of King Philip the Fair of France in a hunting accident, his son, King Louis "the Headstrong" takes the throne and immediately invites the Jews back to France. This is strictly business and the people will appreciate it. The French bureaucracy didn't seem to know how to handle money customers. The King will also free the slaves and allow the serfs to buy their freedom... much to the displeasure of the King's fellow noblemen. Unfortunately the King Louis will die rather suddenly in a tennis accident. After a vigorous workout he will drink some cooled wine, fall into a swoon and die.
My Take by Alex Shrugged
Well... remember that the Grand Master of the Templars cursed King Philip's family when he died. It seems like this curse is really working. :-) But all joking aside, it is probable that the King was poisoned. He was taking the first steps in dismantling the Medieval system of serfdom. It was a system that was economically flawed but as we learned from slavery in the United States, even if everyone agrees that a system is economically flawed, there is strong resistance to the pain of changing it nevertheless.
- ↑ Jordan, William Chester, The Great Famine: Northern Europe in the Early Fourteenth Century, Princeton University Press, December 15, 1997. (BOOK)
- ↑ Cantor, Norman F., In the Wake of the Plague: The Black Death and the World It Made, Harper Perennial, 2001. p. 74. (BOOK)
- ↑ Edwards, Anthony. Edward's Cork Remembrancer or Tablet of Memory, Castle-Street, Cork: Anthony Edwards, printer. March 1792. p. 43. (BOOK)
- ↑ Great Famine of 1315-17, Wikipedia
- ↑ Mount Tarawera - Wikipedia, 2014 [last update]
- ↑ 1314-1317 AD Great European Famine, from History Central, Multieducator Inc.
- ↑ Assarting - Wikipedia, 2014 [last update]
- ↑ Joseph and the Seven Years of Plenty - Wikipedia, 2014 [last update]
- ↑ 1315 Louis X (France), from Jewish History
- ↑ Louis X of France: Readmittance of Jews and the Reform of Serfdom - Wikipedia, 2014 [last update]