DOI: 10.25921/atbt-6k95
title: NOAA/WDS Paleoclimatology - Great Barrier Reef Fossil Coral Sr/Ca and d18O derived Sea Surface Temperature Anomalies since the Last Glacial Maximum (LGM)

description: The Great Barrier Reef (GBR) is a globally recognized and widely studied ecosystem, yet little is known about its sea surface temperature evolution since the Last Glacial Maximum (LGM) (~20 kyr BP). Here, we present the first paleo-application of Isopora coral-derived SST calibrations to a suite of 25 previously published fossil Isopora from the central GBR spanning ~25-11 kyr BP. The resultant multi-coral Sr/Ca- and d18O-derived sea surface temperature anomaly (SSTA) histories are placed within the context of published relative sea level, reef sequence and coralgal reef assemblage evolution. Our new calculations indicate SSTs were cooler on average by ~5-5.5°C at Noggin Pass (~17°S) and ~7-8°C at Hydrographer’s Passage (~20°S) (Sr/Ca-derived) during the LGM, in line with previous estimates (Felis et al., 2014). We focus on contextualizing the Younger Dryas Chronozone (YDC, 12.9-11.7 kyr BP), whose southern hemisphere expression, in particular in Australia, is elusive and poorly constrained. Our record does not indicate cooling during the YDC with near modern temperatures reached during this interval on the GBR, supporting an asymmetric hemispheric presentation of this climate event. Building on a previous study (Felis et al., 2014), these fossil Isopora SSTA data from the GBR provide new insights into the deglacial reef response, with near-modern warming during the YDC, since the LGM.
description: These data include geochemical data associated with fossil Isopora corals collected during IODP Exp 325 and calculated Sr/Ca or d18O derived Sea Surface Temperature Anomalies (SSTAs). Each Isopora coral yields one Sr/Ca and one d18O value representing the entire fossil coral. Each coral is U/Th dated and are stitched together for a discontinuous time series.  
Samples are from Hydrographers Passage (HYD) and Noggin Pass (NOG)
The geochemical data (Sr/Ca, d18O) was originally published by Felis et al., 2014 and can also be found at https://doi.pangaea.de/10.1594/PANGAEA.833407.
Here coral Sr/Ca and d18O were converted to SST using two different calibration equations. The Brenner et al. (2017) calibration is based on high-resolution sampled modern Isopora corals and the Felis et al. (2014) calibration is based on bulk sampled modern Isopora corals. 
Brenner et al. (2017): Sr/Ca×10^3=11.37(±0.02)-0.083(±0.007)×SST AND δ^18 O=0.65(±0.04)-0.185(±0.014)×SST
Felis et al. (2014): Sr/Ca×10^3=11.15(±0.09)-0.075(±0.011)×SST AND δ^18 O=1.6(±0.5)-0.218(±0.027)×SST
The SSTAs were calculated by subtracting the calculated SST values from modern SST Benchmarks (26.6°C for Noggin Pass and 26°C for Hydrographers Passage, based on the World Ocean Atlas 2009 long-term climatological mean (reference period: 1955-2006) (Locarnini et al., 2010)). 
Propagated error was calculated for each site- and calibration- specific SSTA. Detailed steps for error propagation can be found in Brenner et al. (In review) and the error components referred to in this data submission refer to the steps outlined in the supplementary material of the paper.
Locations of events:
325-M0031A (HYD): Latitude: -19.678950,  Longitude: 150.239610
325-M0033A (HYD): Latitude: -19.678830, Longitude: 150.239850
325-M0035A (HYD): Latitude: -19.67263, Longitude: 150.243830
325-M0036A (HYD): Latitude: -19.672390, Longitude: 150.243960
325-M0039A (HYD): Latitude: -19.671500, Longitude: 150.244880
325-M0053A (NOG): Latitude: -17.101170, Longitude: 146.576320
325-M0057A (NOG): Latitude: -17.105210,  Longitude: 146.563990
More detailed information on location, various core properties, and geochemical analyses can be found in Felis et al. (2014), Webster et al. (2018), Yokoyama et al. (2018), Humblet et al. (2019) amongst others
Additional References: 
Brenner, L. D., Linsley, B. K. and D. C. Potts (2017), A Modern Sr/Ca-δ18O- Sea Surface Temperature calibration for Isopora corals on the Great Barrier Reef, Paleoceanography, 32(2), 182-194, doi:10.1002/2016PA002973
Felis, T., McGregor, H. V., Linsley, B. K., Tudhope, A. W., Gagan, M. K., Suzuki, A., Inoue, M., Thomas, A. L., Esat, T. M., Thompson, W. G., Tiwari, M., Potts, D. C., Mudelsee, M., Yokoyama, Y., and J. M. Webster (2014), Intensification of the meridional temperature gradient in the Great Barrier Reef following the Last Glacial Maximum, Nature Communications, 5, 4102, doi:10.1038/ncomms5102.
Humblet, M., Potts, D. C., Webster, J. M., Braga, J .C., Iryu, Y., Yokoyama, Y., Bourillot, R., Séard, C., Droxler, A., Fujita, K., Gischler, E., and H. Kan (2019), Late glacial to deglacial variation of coralalgal assemblages in the Great Barrier Reef, Australia, Global and Planetary Change, 174, 70-91, doi: 10.1016/j.gloplacha.2018.12.014.
Locarnini, R. A., Mishonov, A. V., Antonov, J. I., Boyer, T. P., Garcia, H. E., Baranova, O. K., Zweng, M. M., and D. R. Johnson (2010), World Ocean Atlas 2009, Volume 1: Temperature, S. Levitus, Ed., NOAA Atlas NESDIS 68, U.S. Government Printing Office, Washington, D.C., 184 pp.
Webster, J.M., Braga, J.C., Humblet, M., Potts, D.C., Iryu, Y., Yokoyama, Y., Fujita, K., Bourillot, R., Esat, T.M., Fallon, S., Thompson, W.G., Thomas, A.L., Kan, H., McGregor, H.V., Hinestrosa, G., Obrochta, S.P., and B.C. Lougheed (2018), Response of the Great Barrier Reef to sea-level and environmental changes over the past 30,000 years, Nature Geoscience, 11, 426-432, doi: 10.1038/s41561-018-0127-3.
Yokoyama, Y., Esat, T.M., Thompson, W.G., Thomas, A.L., Webster, J.M., Miyairi, Y., Sawada, C., Aze, T., Matsuzaki, H., Okuno, J., Fallon, S., Braga, J.-C., Humblet, M., Iryu, Y., Potts, D.C., Fujita, K., Suzuki, A., and H. Kan (2018), Rapid glaciation and a two-step sea level plunge into the Last Glacial Maximum, Nature, 559, 603-607, doi: 10.1038:/s41586-018-0335-4.
Provided Keywords: Younger Dryas Chronozone, Great Barrier Reef, Last Glacial Maximum, coral, Sr/Ca