Simulation of an abrupt change in Saharan vegetation in the Mid‐Holocene

TLDR

During the Holocene, climate was generally stable but experienced abrupt events such as the 4–6 ka Saharan desertification, which likely influenced the rise of Nile, Euphrates, and Tigris civilizations and was governed by global atmospheric, oceanic, sea‑ice, and vegetation interactions. The study proposes that subtle orbital variations, amplified by subtropical atmosphere‑vegetation feedbacks, triggered Saharan and Arabian desertification. Orbital changes were amplified by subtropical atmosphere‑vegetation feedbacks, driving the desertification process.

Abstract

Climate variability during the present interglacial, the Holocene, has been rather smooth in comparison with the last glacial. Nevertheless, there were some rather abrupt climate changes. One of these changes, the desertification of the Saharan and Arabian region some 4–6 thousand years ago, was presumably quite important for human society. It could have been the stimulus leading to the foundation of civilizations along the Nile, Euphrat and Tigris rivers. Here we argue that Saharan and Arabian desertification was triggered by subtle variations in the Earth's orbit which were strongly amplified by atmosphere‐ vegetation feedbacks in the subtropics. The timing of this transition, however, was mainly governed by a global interplay between atmosphere, ocean, sea ice, and vegetation.