Concepedia

Tectonic Uplift and Eastern Africa Aridification

Pierre Sepulchre, Gilles Ramstein, Frédéric Fluteau, Mathieu Schuster, Jean‐Jacques Tiercelin, Michel Brunet

Science · 2006 · 487 citations · 27 references

TL;DR

Eastern African hominids evolved alongside a gradual expansion of open grassland over the past 8 million years, a trend driven by global climate but not explained by the massive tectonic uplift that occurred during that period, which previously lowered topographic barriers and allowed zonal circulation with moisture transport and strong precipitation. The study uses coupled atmosphere–biosphere simulations to quantify how tectonic uplift influenced climate. The authors performed these simulations to assess the impact of uplift on atmospheric circulation patterns. The results show that uplift reorganized atmospheric circulation, driving strong aridification and the paleoenvironmental changes inferred from the data.

Abstract

The history of Eastern African hominids has been linked to a progressive increase of open grassland during the past 8 million years. This trend was explained by global climatic processes, which do not account for the massive uplift of eastern African topography that occurred during this period. Atmosphere and biosphere simulations quantify the role played by these tectonic events. The reduced topographic barrier before 8 million years ago permitted a zonal circulation with associated moisture transport and strong precipitation. Our results suggest that the uplift itself led to a drastic reorganization of atmospheric circulation, engendering the strong aridification and paleoenvironmental changes suggested by the data.