2.4 Data compilation
The Arctica islandica dataset was augmented with literature ∆47 values of aragonites with known calcification temperatures (see S3 ). The dataset includes samples from mollusks (Bernasconi et al., 2018; Caldarescu et al., 2021; this study), foraminifera (Piasecki et al., 2019), travertines (Kele et al., 2015; Bernasconi et al., 2018), cave deposits (Breitenbach et al., 2018), lab-grown aragonites (Kluge et al., 2015) and heated aragonites (Müller et al., 2017). Data from several older studies (e.g. Ghosh et al., 2006; 2007; Tripati et al., 2010; Wacker et al., 2013; 2014) was not included because they were not corrected for the pressure baseline (He et al., 2012; Bernasconi et al., 2013). Aragonite ∆47 data from other studies (e.g. Zhang et al., 2018; Zhai et al., 2019; Dong et al., 2021) were excluded because these lacked the standardization required to bring ∆47 values into the I-CDES scale (Bernasconi et al., 2021) or because the aragonite was precipitated out of equilibrium (e.g. Kimball et al., 2015; Chen et al., 2019; S3 ). Clumped isotope data from the literature was brought to the I-CDES reference frame using the multi-linear correction proposed in Appendix A of Bernasconi et al. (2021) using values of carbonate standards reported in the studies (see S1 ). The full dataset including ∆47 values and temperatures with their uncertainties used in this study is provided in S4 .
All data processing for this study is done in R (R Core Team, 2022) and scripts are provided in S5 and published on Github (https://github.com/nielsjdewinter/Aragonite_clumped). Details on data processing are provided in S1 . We compare our data with calibrations by Anderson et al., (2021) and Meinicke et al., (2020) as well as with temperature dependencies of aragonite and calcite clumped isotope compositions from ab initio modelling in Guo et al. (2009) brought into the I-CDES reference frame (see S1 ).