This may also explain why Egypt, in the time of the Pharoahs, about a 3100+ year period, may not just have been hotter, but wetter as well as far more agriculturally productive.
To explain, Egypt is very unusual because it typically has only one farm season, that begins with the flooding of the Nile River. Importantly, global cooling or global warming, the Nile is pretty constant in its water level through history.
However, if it was much hotter, it could have also brought more rain, enough for a smaller second farming season. And thus, more abundance.
Uh, no. For quite some time the Nile even flowed west to the Atlantic out the mouth of what is now the Niger (ground penetrating radar from the Shuttle exposed the connecting channel McCauley, 1982). At that time, Lake Chad was the size of the Caspian Sea.
There was a time earlier in its history that what is now the Nile had a canyon deeper than the Grand Canyon. When the Mediterranean flooded, that canyon became a sea inlet (from fossil remains drilled in the current channel). There may have been a geophysical volcanic event near the Bayuda Volcanic Field that diverted it back into where it runs today.
Unfortunately, the paper I'm citing is on JSTOR, so there's no copy directly available online.