10,000 years of the same boring weather

Iraq, the cradle of civilization, 10,000 years ago.  Domestication of grasses into wheat, and barley.  Domestication of cattle, sheep, goats, camels, horses, dogs, geese (dogs may have been earlier).  Establishment of cities with public and private structures, institutions, written language.
For the exact same length of time we have had civilization which to this day are still dependent upon the crops and animals listed above, the temperature of the earth has averaged ±1°c.  In other words we have lived comfortably within a little over a 4°f band.  That is just amazing isn't it?
If you are a subject to depression, stop reading now, google apricots or something. Bye bye!
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Currently it looks like we are on track for 4°C rise in 40 years or so which will also mean 3 feet or more of sea level, and 5 or 6 by 2100.  If you have young kids, maybe they will see this.  At 6°C rise, thats about 12° fahrenheit all but the northern tier of states in the US will not be farmable.  We have many days now in the central plains states that are 100, and the odd 110°.  Wheat, corn, and cattle cannot spend the summer in 112° and the odd 122° no matter how much water you throw at them.  Homes and factories cannot afford 9 months of air conditioning.  Water sources will dry up.
Move farming north some will say, even into Canada. (Canada already uses everything they can farm.  Farming takes more than the right temperature. The soil types do not exist in abundance to move much of our current farming, almost all the worlds farmable land is already in use.  The only solution, kill all the poor people to reduce the demand, let the wealthy live on the few remaining nice places.  The rich can inherit the earth, after all they schemed for control all 10,000 years.