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Spatial and Temporal Robustness of Sr/Ca‐SST Calibrations in Red Sea Corals: Evidence for Influence of Mean Annual Temperature on Calibration Slopes
Author(s) -
Murty S. A.,
Bernstein W. N.,
Ossolinski J. E.,
Davis R. S.,
Goodkin N. F.,
Hughen K. A.
Publication year - 2018
Publication title -
paleoceanography and paleoclimatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.927
H-Index - 127
eISSN - 2572-4525
pISSN - 2572-4517
DOI - 10.1029/2017pa003276
Subject(s) - porites , coral , sea surface temperature , climatology , environmental science , latitude , oceanography , geology , atmospheric sciences , geodesy
Sr/Ca ratios recorded in the aragonite skeleton of massive coral colonies are commonly used to reconstruct seasonal‐ to centennial‐scale variability in sea surface temperature (SST). While the Sr/Ca paleothermometer is robust in individual colonies, Sr/Ca‐SST relationships between colonies vary, leading to questions regarding the utility of the proxy. We present biweekly‐resolution calibrations of Sr/Ca from five Porites spp. corals to satellite SST across 10° of latitude in the Red Sea to evaluate the Sr/Ca proxy across both spatial and temporal scales. SST is significantly correlated with coral Sr/Ca at each site, accounting for 69–84% of Sr/Ca variability ( P ≪ 0.01). Intercolony variability in Sr/Ca‐SST sensitivities reveals a latitudinal trend, where calibration slopes become shallower with increasing mean annual temperature. Mean annual temperature is strongly correlated with the biweekly‐resolution calibration slopes across five Red Sea sites ( r 2 = 0.88, P = 0.05), while also correlating significantly to Sr/Ca‐SST slopes for 33 Porites corals from across the entire Indo‐Pacific region ( r 2 = 0.26, P < 0.01). Although interannual summer, winter, and mean annual calibrations for individual Red Sea colonies are inconsistently robust, combined multicoral calibrations are significant at summer ( r 2 = 0.53, P ≪ 0.01), winter ( r 2 = 0.62, P ≪ 0.01), and mean annual time scales ( r 2 = 0.79, P ≪ 0.01). Our multicoral, multisite study indicates that the Sr/Ca paleothermometer is accurate across both temporal and spatial scales in the Red Sea and also potentially explains for the first time variability in Sr/Ca‐SST calibration slopes across the Indo‐Pacific region. Our study provides strong evidence supporting the robustness of the coral Sr/Ca proxy for examining seasonal to multicentury variability in global climate phenomena.