The Wetting and the Drying out of the Sahara

8 Apr 2013

Prior to 3000BC the Sahara was a verdant landscape, a rich grassland with a typical African fauna - see http://phys.org/print284364895.html ... and went back through the early Holocene to the end of the Younger Dryas event.

Research on the abrupt climate change at around 3000BC found it widespread across N Africa. We might add to that the climate of northern Europe was remarkably more agreeable than it was after 3000BC - and this is why climate models have such a problem in integrating such a rapid change into their models. Sediment cores from the Atlantic, to the west of N Africa, figured highly in the research, on the basis that when it was dry there was a greater amount of dust, and very little evidence of dust when the Sahara was wet and humid. The findings seem to show a far greater change at 3000BC than previously allowed, as climate change in mainstream is usually attributed to a migrating monsoon rain band at a Milankovitch time scale. The sediments show it was rapid - and this is perhaps self evident on the ground where Pre-dynastic sites were abandoned and the Nile Valley became the centre of settlement in the Old Kingdom..

The paper is published by Earth and Planetary Science Letters and makes the point that climate models are unable to reproduce the magnitude of wet conditions in the Sahara in the early Holocene - so what else was going on?

Not only that but a dusty episode appears to coincide with the Younger Dryas episode but what of the Late Pleistocene as a whole - as there were distinct wet periods there too. The sediments are said to go back 30,000 years.