Arabia–Eurasia collision and the forcing of mid-Cenozoic global cooling

The end of the Eocene greenhouse world was the most dramatic phase in the long-term cooling trend of the Cenozoic Era. Here we show that the Arabia–Eurasia collision and the closure of the Tethys ocean gateway began in the Late Eocene at ~ 35 Ma, up to 25 million years earlier than in many reconstructions. We suggest that global cooling was forced by processes associated with the initial collision that reduced atmospheric CO2. These are: 1) waning volcanism across southwest Asia; 2) increased organic carbon storage in Paratethyan basins (e.g. Black Sea and South Caspian); 3) increased silicate weathering in the collision zone and, 4) a shift towards modern patterns of ocean currents, associated with increased vigour in circulation and organic productivity.