A. Alpert, A. Cohen, D. Oppo, T. DeCarlo, G. Gaetani, E. Hernández-Delgado, A. Winter, M. Gonneea
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引用次数: 11
Abstract
Coral skeletons are valuable archives of past ocean conditions. However, interpretation of coral paleotemperature records is confounded by uncertainties associated with single element-ratio thermometers, including Sr/Ca. A new approach, Sr-U, uses U/Ca to constrain the influence of Rayleigh fractionation on Sr/Ca [DeCarlo et al., 2016]. Here, we build on the initial Pacific Porites Sr-U calibration to include multiple Atlantic and Pacific coral genera from multiple coral reef locations spanning a temperature range of 23.15-30.12 °C. Accounting for the wintertime growth cessation of one Bermuda coral, we show that Sr-U is strongly correlated with the average water temperature at each location (r2 = 0.91, P < 0.001, n = 19). We applied the multi-species spatial calibration between Sr-U and temperature to reconstruct a 96-year long temperature record at Mona Island, Puerto Rico using a coral not included in the calibration. Average Sr-U derived temperature for the period 1900-1996 is within 0.12 °C of the average instrumental temperature at this site and captures the 20th century warming trend of 0.06 °C per decade. Sr-U also captures the timing of multi-year variability but with higher amplitude than implied by the instrumental data. Mean Sr-U temperatures and patterns of multi-year variability were replicated in a second coral in the same grid box. Conversely, Sr/Ca records from the same two corals were inconsistent with each other and failed to capture absolute sea temperatures, timing of multi-year variability or the 20th century warming trend. Our results suggest that coral Sr-U paleothermometry is a promising new tool for reconstruction of past ocean temperatures.