The Miocene (∼24 to ∼5 million years ago) was a period of relative global warmth compared to the Quaternary (∼2 million years ago to present; e.g. Zachos et al., 2001) and was characterised by the intermittent glaciation of Antarctica only. Paradoxically, the majority of available proxy data suggest that during the Miocene, pCO2 was similar, or even lower, than the pre-industrial levels (280 pp...