Humans Extinct by 1900!

County Cork, Ireland, 1847, in a time of climate change:  Several wet summers in succession have allowed a blight, Phytophthora infestans, to ravage the Irish potato crop. These potatoes, propagated asexually, have low resistance to the blight since they have almost no genetic diversity.  Even though Ireland has continued to export meat, grain, and dairy products, the peasants live almost exclusively on potatoes.  Now that crop is failing and the peasants are starving.
This is just as the Rev Thomas Malthus predicted forty years ago in 1800.  The Irish, ignorant Roman Catholics, multiplied faster than their food supply.   As Malthus commented, “The population should be swept from the soil.”
There could be more far reaching effects.  As plague jumped from rats to people, P. infestans could affect other members of the Solanaceae family: eggplants, tomatoes, and tobacco.  Not only that, in half a century, it could affect all agricultural crops. We just don’t know what kind of Black Swan event might occur.   When world agriculture fails, so will humanity. Human extinction is possible by 1900!

Well, all that could have happened, but how much to worry about something depends on the probability of it happening. An asteroid could fall on my house, my house could burn down, or a tree could fall on it.  I get homeowner’s insurance, but not asteroid insurance, since there’s only an asteroid landing big enough to create a crater only every five thousand years or so.
Be reasonable!