As our dataset is an extension of the original Antarctic, sub-Antarctic and Chilean dataset from Pearson et al. (2011), we applied the global brGDGT–temperature calibration to the Antarctic dataset to evaluate its performance (Table 2; Supplementary Table S2). Previous applications of the global brGDGT–temperature calibration to lakes in Minnesota and Iowa, USA (Schoon et al., 2013), Switzerland (Naeher et al., 2014) and the Canadian and Siberian Arctic (Peterse et al., 2014) produced reconstructed temperatures that UNC3866 were comparable with either summer lake or air temperatures. When applying the Pearson et al. (2011) global brGDGT–temperature calibration to our Antarctic dataset the model errors were similar to bladder of the original global dataset (RMSE=2.3 °CRMSE=2.3 °C; Table 2) although the r2r2 values dropped to 0.54. The Pearson et al. (2011) global model reconstructed temperatures showed a warm bias when compared to MSAT temperatures with an overestimation of temperatures at all sites apart from our warmest site (Lago Bulnes, Chile at 53°S latitude). The average overestimation of the global model in the Antarctic dataset was 6.0 °C with a standard deviation of 2.4 °C.
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