Around five and half millenia ago, northern Africa went through a dramatic transformation. The Sahara desert expanded and grasslands, forests and lakes favoured by humans disappeared. Humans were forced to retreat to the mountains, the oases, and the Nile valley and delta.
As a relatively large and dispersed population was squeezed into smaller and more fertile areas, it needed to innovate new ways to produce food and organise society. Soon after, one of the world’s first great civilisations emerged – ancient Egypt.
This transition from the most recent “African humid period”, which lasted from 15,000 to 5,500 years ago, to the current dry conditions in northern Africa is the clearest example of a climate tipping point in recent geological history. Climate tipping points are thresholds that, once crossed, result in dramatic climate change to a new stable climate.
