Mid‐Holocene, Coral‐Based Sea Surface Temperatures in the Western Tropical Atlantic

Rodriguez, Luis Genaro; Cohen, Anne L.; Ramirez, Wilson R.; Oppo, Delia W; Pourmand, A.; Alpert, Alice E.; Mollica, Nathaniel R.

doi:10.1029/2019pa003571

Cited by 12 publications

(15 citation statements)

References 42 publications

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“…Furthermore, the relationship between Sr-U and satellite SST is consistent between both colonies (Fig. 4.6), a result expected given the premise of the Sr-U thermometer and the results of bulk analyses (Alpert et al 2017;Rodriguez et al 2019). However, the observed deviations in the Sr-U record may be a result of this imperfect control on measured SST.…”

Section: Discussionsupporting

confidence: 62%

“…4.10C). This result indicates the potential for a universal Sr-U SST calibration for Porites similar to that observed in bulk analyses of Atlantic coral species (Rodriguez et al, 2019). The calibration we derive from these results is as follows:…”

Section: Regression Of Laser Sr-u and Sr/ca On Sstsupporting

confidence: 62%

“…Previous work has shown that these inconsistencies can be resolved by incorporating additional geochemical information (i.e., the skeletal U/Ca ratio) in an improvement to the Sr/Ca proxy called Sr-U Alpert et al 2017;Rodriguez et al 2019). Here, we demonstrate that Sr-U can be used to reconstruct monthly SSTs when paired with laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS).…”

Section: Coral Proxy Recordsmentioning

confidence: 76%

“…The new coral thermometer Sr-U shows great potential in resolving this conundrum by accurately resolving not only long-term mean SST and SST trends, but also the magnitude of interannual variability. Annual Sr-U has been shown to capture long term trends and decadal variability in the western tropical Atlantic (Alpert et al 2017) and has been applied to generate SST records from fossil corals during key periods in Earth's climate history (Alpert et al 2017;Rodriguez et al 2019). In this paper we show the Sr-U proxy's ability to capture seasonal variations in SST when sampled monthly via LA-ICPMS.…”

Section: Discussionmentioning

confidence: 96%

“…and Risk 2006) we previously developed a new coral-based paleo-thermometer, Sr-U, that uses U/Ca to deconvolve the influence of Rayleigh fractionation from that of seawater temperature on coral Sr/CaAlpert et al 2017). U/Ca is used because it covaries with the carbonate ion concentration of the calcifying fluid(DeCarlo et al 2015) and is thus a proxy for the mass fraction of aragonite precipitated by the coral.Previous Sr-U studies(Alpert et al 2017;Rodriguez et al 2019) utilize multiple paired Sr/Ca and U/Ca values generated over two to three years of coral growth to calculate a single Sr-U value. By overlapping consecutive years, Sr-U values were generated at nominally annual resolution.…”

mentioning

confidence: 99%

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Coral reefs in the Anthropocene Ocean: novel insights from skeletal proxies of climate change, impacts, and resilience

Mollica¹

2021

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Section: Discussionsupporting

confidence: 62%

Section: Regression Of Laser Sr-u and Sr/ca On Sstsupporting

confidence: 62%

Section: Coral Proxy Recordsmentioning

confidence: 76%

Section: Discussionmentioning

confidence: 96%

mentioning

confidence: 99%

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Coral reefs in the Anthropocene Ocean: novel insights from skeletal proxies of climate change, impacts, and resilience

Mollica¹

2021

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Accuracy and Reproducibility of Coral Sr/Ca SIMS Timeseries in Modern and Fossil Corals

Sayani

Cobb

Monteleone

et al. 2022

Geochem Geophys Geosyst

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Coral strontium‐to‐calcium ratios (Sr/Ca) provide quantitative estimates of past sea surface temperatures (SST) that allow for the reconstruction of changes in the mean state and climate variations, such as the El Nino‐Southern Oscillation, through time. However, coral Sr/Ca ratios are highly susceptible to diagenesis, which can impart artifacts of 1–2°C that are typically on par with the tropical climate signals of interest. Microscale sampling via Secondary Ion Mass Spectrometry (SIMS) for the sampling of primary skeletal material in altered fossil corals, providing much‐needed checks on fossil coral Sr/Ca‐based paleotemperature estimates. In this study, we employ a set modern and fossil corals from Palmyra Atoll, in the central tropical Pacific, to quantify the accuracy and reproducibility of SIMS Sr/Ca analyses relative to bulk Sr/Ca analyses. In three overlapping modern coral samples, we reproduce bulk Sr/Ca estimates within ±0.3% (1σ). We demonstrate high fidelity between 3‐month smoothed SIMS coral Sr/Ca timeseries and SST (R = −0.5 to −0.8; p < 0.5). For lightly‐altered sections of a young fossil coral from the early‐20th century, SIMS Sr/Ca timeseries reproduce bulk Sr/Ca timeseries, in line with our results from modern corals. Across a moderately‐altered section of the same fossil coral, where diagenesis yields bulk Sr/Ca estimates that are 0.6 mmol too high (roughly equivalent to −6°C artifacts in SST), SIMS Sr/Ca timeseries track instrumental SST timeseries. We conclude that 3–4 SIMS analyses per month of coral growth can provide a much‐needed quantitative check on the accuracy of fossil coral Sr/Ca‐derived estimates of paleotemperature, even in moderately altered samples.

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Capturing Equatorial Pacific Variability With Multivariate Sr‐U Coral Thermometry

Mollica,

Cohen,

Horton

et al. 2023

Paleoceanog and Paleoclimatol

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Sr‐U, a coral‐based paleothermometer, corrects for the effects of Rayleigh Fractionation on Sr/Ca by regressing multiple, paired U/Ca and Sr/Ca values. Prior applications of Sr‐U captured mean annual sea surface temperatures (SST), inter‐annual variability, and long‐term trends. However, because many Sr/Ca‐U/Ca pairs are needed for a single Sr‐U value as originally formulated, the temporal resolution of the proxy is typically limited to one year. Here, we address this limitation by applying laser ablation inductively coupled plasma mass spectrometry (LA‐ICPMS) to 3 Porites colonies from Jarvis and Nikumaroro Islands in the central equatorial Pacific (CEP), generating ∼25 Sr/Ca‐U/Ca pairs per month of skeletal growth. Both Sr/Ca and U/Ca vary significantly over small (sub‐mm) length scales and support calculation of Sr‐U values using the original regression method. Over the represented temperature range of 24 °C to 31 °C, the Sr/Ca‐U/Ca‐SST relationships are non‐linear, a finding consistent with predictions of the Rayleigh model. To reflect this non‐linearity, we developed a calibration using multivariate nonlinear regression. The multivariate, 3‐coral calibration was applied to 20‐years of monthly resolved Sr/Ca and U/Ca of a coral interval not included in the calibration, yielding RMSE = 0.73 °C and r2 = 0.85 (p < 0.05; df = 256). The multivariate calibration performed significantly better than Sr/Ca alone (r2 = 0.28). Application of the new calibration to a sub‐fossil Porites from Kiritimati Atoll, CEP (2200 Before Present) yields equivalent phase and amplitude of interannual variability but water temperatures ∼1.6 °C cooler than they are in this region today.This article is protected by copyright. All rights reserved.

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Mid‐Holocene, Coral‐Based Sea Surface Temperatures in the Western Tropical Atlantic

Cited by 12 publications

References 42 publications

Coral reefs in the Anthropocene Ocean: novel insights from skeletal proxies of climate change, impacts, and resilience

Coral reefs in the Anthropocene Ocean: novel insights from skeletal proxies of climate change, impacts, and resilience

Accuracy and Reproducibility of Coral Sr/Ca SIMS Timeseries in Modern and Fossil Corals

Capturing Equatorial Pacific Variability With Multivariate Sr‐U Coral Thermometry

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