The beautiful thing about climate change is not just in devastation but also in proliferation.
In the time period around 10,500 BC, a shift in weather patterns meant northern Egypt began to experience better rainfall, and this lasted some two thousand years.
On the one hand, and considering the good possibility that there is more to the planning of the Giza pyramids - and for one theory, the arrangement of the chambers and passages of the Great Pyramid being aligned to astronomical positions - having 10,500 BC as a model could be better suited, not circa. 2,200 BC, which is about 400 years after the pyramid was supposedly built.
Yes, they could prepare for a time of trouble...but what about celebrating a time of prosperity?