Recent Efforts to Improve the Accuracy and Precision of Carbonate Clumped-Isotope Analysis

The carbonate clumped-isotope thermometer, a relatively recent innovation, is based on the strong relationship between ¹³C-¹⁸O bond abundance in carbonates and their formation temperature. It can measure temperatures solely based on the CO₂ extracted from carbonates and has attracted attention as it accurately reconstructs surface water temperatures on a geological timescale. However, at the time of development, there were many limitations in its application to paleoenvironmental reconstruction such as the large sample size (10 mg), the complicated organic contaminant removal process, and the lack of internationally recognized carbonate standards, and improvements in the measurement method were required. Here, we review the studies conducted since the thermometer development to improve the accuracy and precision of carbonate clumped-isotope analysis. Finally, we discuss advanced carbonate clumped-isotope analysis methods, including laser spectroscopy.