Comparison of equatorial Pacific sea surface temperature variability and trends with Sr/Ca records from multiple corals

Alpert, Alice E.; Cohen, Anne L.; Oppo, Delia W; DeCarlo, Thomas M.; Gove, Jamison M.; Young, Charles W.

doi:10.1002/2015pa002897

Cited by 46 publications

(56 citation statements)

References 63 publications

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“…The high spatial resolution of the laser ablation ICP‐MS makes this technique particularly sensitive to the sampling path selection. Suboptimal analysis paths near corallite fan margins or termination, both areas of low calcification rate, often display significant shifts of the Sr/Ca pattern, as reported before (Alibert & McCulloch, ; Alpert et al, , their Figures S2 and S3; DeLong et al, ). Resulting nonclimatic Sr/Ca variations can be a major hindrance to apply spectral analysis techniques or compare proxy reconstructions to climate model simulations (e.g., Ault et al, ).…”

Section: Resultssupporting

confidence: 69%

A Reconstruction of Subtropical Western North Pacific SST Variability Back to 1578, Based on a Porites Coral Sr/Ca Record from the Northern Ryukyus, Japan

2017

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We present a seasonal reconstruction of sea surface temperature (SST) from 1578 to 2008, based on a Porites coral Sr/Ca record from the northern Ryukyus, within the Kuroshio southern recirculation gyre. Interannual SST anomalies are generally ~0.5°C, making Sr/Ca‐derived SST reconstructions a challenging task. Replicate measurements along adjacent coral growth axes, enabled by the laser ablation inductively coupled plasma mass spectrometry technique used here, give evidence of rather large uncertainties. Nonetheless, derived winter SST anomalies are significantly correlated with the Western Pacific atmospheric pattern which has a dominant influence on winter temperature in East Asia. Annual mean SSTs show interdecadal variations, notably cold intervals between 1670 and 1700 during the Maunder Minimum (MM) and between 1766 and 1788 characterized by a negative phase of the North Atlantic Oscillation. Cold summers in 1783 and 1784 coincide with the long‐lasting Laki eruption that had a profound impact on the Northern Hemisphere climate, including the severe “Tenmei” famine in Japan. The decades between 1855 and 1900 are significantly cooler than the first half of the twentieth century, while those between 1700 and 1765, following the MM, are warmer than average. SST variability in the Ryukyus is only marginally influenced by the Pacific Decadal Oscillation, so that external forcing remains the main driver of low‐frequency temperature changes. However, the close connection between the Kuroshio extension (KE) and its recirculation gyre suggests that decadal SST anomalies associated with the KE front also impact the Ryukyus, and there is a possible additional role for feedback of the Kuroshio‐Oyashio variability to the large‐scale atmosphere at decadal timescale.

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Section: Resultssupporting

confidence: 69%

A Reconstruction of Subtropical Western North Pacific SST Variability Back to 1578, Based on a Porites Coral Sr/Ca Record from the Northern Ryukyus, Japan

2017

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“…Jarvis data are reported in Alpert et al . []. Element ratio measurements were standardized to the JCp‐1 coral standard [ Okai et al ., ], which has nominal Sr/Ca and U/Ca ratios of 8.838 ± 0.042 mmol mol −1 and 1.192 ± 0.045 µmol mol −1 , respectively [ Hathorne et al ., ].…”

Section: Methodsmentioning

confidence: 99%

“…As reported in Alpert et al . [], the batch of JCp‐1 used in this study was compared to High Purity Standards single element standards gravimetrically mixed to simulate coral skeleton (40 ppm Ca with variable concentrations of Mg, Sr, Ba, and U). Three aliquots of JCp‐1 powder were dissolved and each analyzed in duplicate with resulting mean ± 1 σ for Sr/Ca of 8.87 ± 0.03 mmol mol −1 and U/Ca of 1.23 ± 0.01 µmol mol −1 .…”

Section: Methodsmentioning

confidence: 99%

Coral Sr‐U thermometry

et al. 2016

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Coral skeletons archive past climate variability with unrivaled temporal resolution. However, extraction of accurate temperature information from coral skeletons has been limited by "vital effects," which confound, and sometimes override, the temperature dependence of geochemical proxies. We present a new approach to coral paleothermometry based on results of abiogenic precipitation experiments interpreted within a framework provided by a quantitative model of the coral biomineralization process. DeCarlo et al. (2015a) investigated temperature and carbonate chemistry controls on abiogenic partitioning of Sr/Ca and U/Ca between aragonite and seawater and modeled the sensitivity of skeletal composition to processes occurring at the site of calcification. The model predicts that temperature can be accurately reconstructed from coral skeleton by combining Sr/Ca and U/Ca ratios into a new proxy, which we refer to hereafter as the Sr-U thermometer. Here we test the model predictions with measured Sr/Ca and U/Ca ratios of 14 Porites sp. corals collected from the tropical Pacific Ocean and the Red Sea, with a subset also analyzed using the boron isotope (δ 11 B) pH proxy. Observed relationships among Sr/Ca, U/Ca, and δ 11 B agree with model predictions, indicating that the model accounts for the key features of the coral biomineralization process. By calibrating to instrumental temperature records, we show that Sr-U captures 93% of mean annual temperature variability (26-30°C) and has a standard deviation of prediction of 0.5°C, compared to 1°C using Sr/Ca alone. The Sr-U thermometer may offer significantly improved reliability for reconstructing past ocean temperatures from coral skeletons.

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“…Recent work, however, has highlighted the benefit of using both intracolony and intercolony replication to capture the local or regional SST signal (DeLong et al, ). Alpert et al () suggested that in tropical regions, Sr/Ca‐SST relationships based on a single Porites lobata colony have uncertainties exceeding 4 °C (the standard error [1σ]). Lough () also found discrepancies when comparing geochemical records from 20 coral colonies growing in the Pacific Ocean, suggesting that single core analyses may reflect colony‐specific, nontemperature‐based influences in addition to the regional SST signal.…”

Section: Introductionmentioning

confidence: 99%

Quantifying Uncertainty in Sr/Ca‐Based Estimates of SST From the Coral Orbicella faveolata

Flannery

Richey

Toth

et al. 2018

Paleoceanog and Paleoclimatol

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The strontium to calcium ratio (Sr/Ca) in aragonitic skeletons of massive corals provides a proxy for sea surface temperature (SST) that can be used to reconstruct paleoclimates across decades, centuries, and, potentially, millennia. Determining the reproducibility of Sr/Ca records among contemporaneous coral colonies from the same region is critical to quantifying uncertainties associated with the Sr/Ca‐SST proxy. We evaluated both intracolony and intercolony variability in Sr/Ca using five modern colonies of Orbicella faveolata collected live from the Dry Tortugas National Park, FL. We regressed all available Sr/Ca‐SST data pairs from the five O. faveolata colonies against the Advanced Very High Resolution Radiometer gridded SST data set to produce a new Sr/Ca‐SST calibration equation (Sr/Ca = −0.049 × SST + 10.460), which we suggest can be applied to O. faveolata colonies collected throughout the Gulf of Mexico/Caribbean region. We estimated total uncertainty by calculating the root‐mean‐square of the intracolony, intercolony, and analytical error terms. Our (1σ) uncertainty estimates of 0.082 mmol/mol (1.66 °C) for subannual Sr/Ca‐SST and 0.070 mmol/mol (1.43 °C) for mean annual Sr/Ca‐SST represent conservative error terms that can be applied to individual data points in single‐colony Sr/Ca‐SST reconstructions. We illustrate how these uncertainties can be significantly reduced by generating multicolony reconstructions and/or through replication of sampling within individual coral colonies. Although the uncertainties on absolute Sr/Ca‐based SST are likely too large to allow researchers to evaluate subdecadal temperature variability, we show that the O. faveolata paleothermometer can reliably detect changes of ~2 °C across decadal timescales and ~1 °C over multidecadal timescales.

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Comparison of equatorial Pacific sea surface temperature variability and trends with Sr/Ca records from multiple corals

Cited by 46 publications

References 63 publications

A Reconstruction of Subtropical Western North Pacific SST Variability Back to 1578, Based on a Porites Coral Sr/Ca Record from the Northern Ryukyus, Japan

A Reconstruction of Subtropical Western North Pacific SST Variability Back to 1578, Based on a Porites Coral Sr/Ca Record from the Northern Ryukyus, Japan

Coral Sr‐U thermometry

Quantifying Uncertainty in Sr/Ca‐Based Estimates of SST From the Coral Orbicella faveolata

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