The mystery of the end of the green Sahara

With the Earth System Model of the Max Planck Institute for Meteorology we have calculated the changes in the global climate system during the last 8000 years in a spatially detailed representation. This enabled us to solve part of the mystery about the end of the green Sahara. Reconstructions show a complex structure. In our simulation, the end of the humid phase is determined not only by the retreat of the monsoon but also by the change in the path of extratropical troughs. When their interplay broke up about 4000 years ago, the precipitation and vegetation in the Western Sahara rapidly decreased.