The Ostracod Clumped‐Isotope Thermometer: A Novel Tool to Accurately Quantify Continental Climate Changes

Abstract This study presents a methodological advancement in the field of clumped‐isotope (∆ 47 ) thermometry, specifically tailored for application to freshwater ostracods. The novel ostracod clumped isotope approach enables quantitative temperature and hydrological reconstruction in lacustrine records. The relationship between ∆ 47 and the temperature at which ostracod shell mineralized is determined by measuring ∆ 47 on different species grown under controlled temperatures, ranging from 4 ± 0.8 to 23 ± 0.5ºC. The excellent agreement between the presented ∆ 47 ostracod data and the monitored temperatures confirms that ∆ 47 can be applied to ostracod shells and that a vital effect is absent outside the uncertainty of measurements. Results are consistent with the carbonate clumped‐isotope unified calibration (Anderson et al., 2021, https://doi.org/10.1029/2020gl092069 ), therefore, an ostracod‐specific calibration is not needed. The ostracod clumped‐isotope thermometer represents a powerful tool for terrestrial paleoclimate studies all around the world, as lakes and ostracods are found in all climatic belts.