Figure 3: Top: Δ47-temperature relationship for all 108 freshwater carbonates included in this study. Black line represents a linear, ordinary least squares regression through the data and the gray shaded area represents the 95% confidence interval. We find a strong relationship between Δ47 and temperature(p <0.0001; r2 = 0.8959). Red diamonds represent low temperature and/or high pH lacustrine microbialites from Anderson et al. (2021) that have been excluded from the regression.Bottom: Comparison of our composite freshwater regression to previously published clumped isotope calibrations. ANCOVA results show that the slope derived for our calibration is statistically different from the acid corrected calibration of Petersen et al. (2019) and Anderson et al. (2021), with pslope values of 0.0036 and 0.0334, respectively (Table 3). Our calibration yields higher temperature estimates than Anderson et al. (2021) in the range of natural carbonate growth, but similar temperatures to Petersen et al. (2019) (Supplementary Table 3).