Food Crisis and Famines.
The 18.6 years cycle of the seed viability is correlated with the frequency of scarsity of food and of famines, due to low seed viability.
Correlation with the famine years.
A non exhaustive analysis of the famine years, on the basis of data published on Wikipedia, shows a correlation with the long viability cycle in seeds of about 18,6 years long, and the canonical seven years of lean times, when the range of the Moon declination, relative to the Equator, exceeds +/- 26 degrees.
A good correlation if you do not consider the famines due to wars, to inefficient income distribution, to exports from regions affected by food scarsity. As well to nonsensical policies, for instance those leading to the famine of 1961 in China, in a period which should have been of plenty.
I will mention a few examples periods, when there were short episodes of cumulative interaction, aggravated by low temperature, so that also the dissipative processes were incomplete.
Starting from the great famine of 1315-1322. When the range of the Moon declination kept itself above +/-26 degrees from october 1314 to september 1321.
In good correlation, for the same reasons, also the famines occurred in France, when Louis xiv was king (little glaciation).
Closer to our times, less severe, but in a context of globalisation and speculation, one can mention the food scarsity, in particular during the years 2007 and 2008, if one refers to the prices. And whose end result was the so called arab spring, triggered by an event on december 2010, in a context of circumstances, gathered up during the preceding years.
Considering the future, the range of variation of the Moon configuration will be more than +/-26 degrees, from september 2021 until april 2028.
All this will occur in a context of huge migratory movements, wars, crazy weather, sea levels rising, population explosion, the natural desire of men of improving their conditions. By contrast, the limits are not taken into account, until the moment everything bursts.