you have it backwards. the sahara was green because the world in general was cooler back then, so the equator had weather more appropriate for the tropics. the world has gotten hotter since then, turning the region into a desert.
There’s a 10,000 year period from the exit of the last ice age to about the year 0 where global temperatures were at least as warm as the 1960-1990 average. For a maybe 6000 year period within that global temperatures were about a half a degree or a little less warmer than that 1960-1990 average.
You’re just wrong. Before greenhouse gas emissions took control there’s a well recognized pattern of slow global cooling over a few thousand years.
