The oxygen‑isotope composition (δ18O) of well‑preserved planktonic foraminifera is a classic tool for reconstructing past ocean temperatures. It relies on the temperature‑dependent fractionation of oxygen isotopes during calcite formation, with warmer waters producing shells depleted in 18O. Because δ18O also reflects seawater composition and pH, the MioOcean compilation uses state‑of‑the‑art corrections to provide the most robust Miocene temperature reconstructions possible.