The Partisan Divide on Issues

[pbrower2a]

(04-22-2020, 10:39 PM)Bob Butler 54 Wrote:

(04-22-2020, 04:53 PM)pbrower2a Wrote: You have your times mixed up; the Ice Age is well attested; the "Green Sahara" is shown to have happened when the sun reached its most northerly point on the ecliptic was closer to the perigee (summers were hotter and shorter in the northern hemisphere, so the summer rains got farther north, but winters were colder and longer, so Mediterranean storms dipped further south in the winter). During the coldest parts of the Ice Age, sea levels were lower -- but there were no large cities.

I have also heard that that the time when the Sahara went from green lands to desert also coincided with the wide spread use of slash and burn agriculture by the humans.  Yep.  More greenhouse gasses.  Less land dedicated to forests.  The Sahara may have been the first casualty of human climate change.  

One temple of ancient Egypt shows palm trees, abundant greenery, abundant African wildlife, all growing within close proximity of the core Nile civilization.  Some are saying this was literal, was not any kind of fantasy.  The fall of the first wave of civilizations in the core of the Middle East corresponds to this period, when some of the best land for the development of human civilization went dry, when the action shifted to the north side of the Mediterranean.

Interesting connection. I've never seen that, but it makes some sense.

Arnold Toynbee tells us that when the Sahara was green, the Nile Valley was practically uninhabited. It was simply too difficult for people to exploit because it was thick in reeds when much of the rest of North Africa was highly habitable. But as the Sahara desiccated people got desperate and found their way to the Nile Valley, chopped the reeds and channeled the river into small plots of land, and survived. Others went south into African savannas and would be lost to history or north to the Mediterranean zone of climate in the Maghreb and some coastal zones of Libya. People who failed to move starved.

The first settlers of the Nile Valley probably remembered the verdant Sahara. The Egyptians are not known for fantasy except in their religion.   But the Egyptians developed irrigation, large-scale building, and sailing... As Toynbee said, the optimum for human settlement is the environment that requires much sophistication to allow people to adapt, but not so much as to waste most such effort. The savannas of central Africa are fine for hunter-gatherers, and the desert is livable only for people who keep moving from one place of forage to the next -- if not completely barren.