Thanks, Roswell--that Guijohn seems to be an arrogant s.o.b., and needn't expect to be taken seriously if he won't present evidence. I named the events to which i referred.
I have a problem with the chart you present, though, and that's that it doesn't seem to indicate the Toba eruption event, which took place about 70,000 years ago, and which plunged the earth back into an "ice age" (a silly term, really) at a time when it ws coming out of one. Toba was a stratovolcano in what is now called Indonesia. There may have been a spate of eruptions which lead the the sudden and drastic cooling. The Toba Catastrophe Hypothesis proposes that the seeming human evolutionary bottleneck which dates to about that period has gotten more and more evidentiary confirmation over the years, and is now pretty well established. It can't ever be more than an hypothesis, because it can't be tested or falsified. However, in 1815, there was a prolonged period of volcanic eruptions in the southwest quadrant of the ring of fire (i.e., present day Indonesia) capped by the eruption of the stratovolcano Tambora, east of Java and Bali. The period of eruption had already caused poor harvests in the waning years of the Napoleonic Wars, which of course, caused their own disruptions.
The eruption of Tambora lead to what became known as the year without a summer in 1816. Crops failed in New England and Canada, where, because of stockpiles, famine was not a problem, but food prices shot up, and no surpluses were available to ship to Europe. Crops failed in Ireland, Wales and England, and some researchers put the death toll in Ireland at 100,000 (for much the same reasons that the crop failures of the 1840s were a disaster). Starving Welsh families took to the roads and flooded England, already barely able to cope with their own shortages--and no help to be expected from North American imports. Crop failures were general in Germany and Switzerland, and Swiss researchers have estimated that 200,000 people starved or died of famine diseases in central Europe. In Italy and Hungary, they had crop failures two years in a row--the immediate consequence of the Tambora eruption being brown or red snow, and temperatures low enough that most winter wheat plantings failed. The harvests in Switzerland and Germany failed in 1817, as well, leading to rioting and looting as the people became convinced that speculators were hoarding grain to drive up the prices, as had been the case in France in 1788, leading to the events which ended in the French revolution.
There were the same problems in China, and there, as in North America, snow fell in the fields in June of 1816. Snow fell on the island of Formosa (now called Taiwan), which at only 30 degrees north, is subtropical. Livestock all over the world died of starvation and famine diseases, too, as insufficient new grass grew in 1816 and 1817. Not only were grain prices elevated (goddamned capitalist!), but also the price of meat, butter and cheese.
The Toba event roughly 70,000 years ago was severe enough that there was an evolutionary bottleneck, and some scientists are now looking for evidence of volcanic activity about 30,000 to 35,000 years ago, when h. Neanderthalis disappeared and h.s.s. was reduced to a world-wide population of no more than 10,000 and possible as low as 1000 individuals, according to genetic studies by Durbin and Li at Harvard.
Maybe it's just that the resolution of that graph is not sufficient to show such events as Tamora, but i would think that an event like Toba would show up there.