Evidence item

The Miocene Climatic Optimum (MCO, ~ 15 Ma) offers insights into warm-climate dynamics and future climate change. However, its global warmth magnitude remains uncertain due to limitations in surface and benthic proxy records. Here, we develop long-run Miocene simulations featuring deep-ocean equilibration and water isotope capability, and present a probabilistic inference framework integrating them with a global compilation of benthic foraminiferal δ18O to better constrain the MCO warmth. Our approach yields a maximum likelihood estimate of MCO global mean surface temperature of 7.5 °C above preindustrial, significantly warmer than previous benthic δ18O-based reconstructions.