The cooling occurring during the lower Palaeozoic explained by the paleogeography

The Lower Palaeozoic climate was commonly assumed to be a long greenhouse period, the Late Ordovician glaciation taking place in a CO2 enriched atmosphere. Recent oxygen isotopic records in apatite revealed a cooling trend through the Ordovician, a climate change associated to a major radiation in the Earth Life history. If the cooling trend is established, the explanation for such a climatic change did not exist yet. By performing simulations with a climate model coupled to a geochemical model (GEOCLIM), we demonstrate that past changes in geography associated to the sea-level rise were important in bringing about cooling.