Multi-trace-element sea surface temperature coral reconstruction for the southern Mozambique Channel reveals teleconnections with the tropical Atlantic

• Published in: Biogeosciences
• Main Authors: Zinke, J, D'Olivo, JP, Gey, CJ, McCulloch, MT, Bruggemann, JH, Lough, JM, Guillaume, MMM
• Format: Article in Journal/Newspaper
• Language: English
• Published: European Geosciences Union (EGU), Copernicus Publications 2019
• Subjects: Science & Technology; Life Sciences & Biomedicine; Physical Sciences; Ecology; Geosciences; Multidisciplinary; Environmental Sciences & Ecology; Geology; BLENDED SATELLITE; CLIMATE; SR/CA; CIRCULATION; CALIBRATION; ISLANDS; PERIOD; OSCILLATION; ARAGONITE; IMPACTS; Pacific; Indian; Guillaume; Antarc*; Antarctique*; North Atlantic
• Online Access: https://www.biogeosciences.net/16/695/2019/; http://hdl.handle.net/2381/44182; https://doi.org/10.5194/bg-16-695-2019

Trace element data will be made publicly available on the NOAA WDC paleoclimate data server at https://www. ncdc.noaa.gov/data-access/paleoclimatology-data/datasets (last access: 20 December 2018, NOAA, 2018). Supplement. The supplement related to this article is available online at: https://doi.org/10.5194/bg-16-695-2019-supplement. Here we report seasonally resolved sea surface temperatures for the southern Mozambique Channel in the SW Indian Ocean based on multi-trace-element temperature proxy records preserved in two Porites sp. coral cores. Particularly, we assess the suitability of both separate and combined Sr∕Ca and Li∕Mg proxies for improved multielement SST reconstructions. Overall, geochemical records from Europa Island Porites sp. highlight the potential of Sr∕Ca and Li∕Mg ratios as high-resolution climate proxies but also show significant differences in their response at this Indian Ocean subtropical reef site. Our reconstruction from 1970 to 2013 using the Sr∕Ca SST proxy reveals a warming trend of 0.58±0.1 ∘C in close agreement with instrumental data (0.47±0.07 ∘C) over the last 42 years (1970–2013). In contrast, the Li∕Mg showed unrealistically large warming trends, most probably caused by uncertainties around different uptake mechanisms of the trace elements Li and Mg and uncertainties in their temperature calibration. In our study, Sr∕Ca is superior to Li∕Mg to quantify absolute SST and relative changes in SST. However, spatial correlations between the combined detrended Sr∕Ca and Li∕Mg proxies compared to instrumental SST at Europa revealed robust correlations with local climate variability in the Mozambique Channel and teleconnections to regions in the Indian Ocean and southeastern Pacific where surface wind variability appeared to dominate the underlying pattern of SST variability. The strongest correlation was found between our Europa SST reconstruction and instrumental SST records from the northern tropical Atlantic. Only a weak correlation was found with ENSO, with recent warm anomalies in the geochemical proxies coinciding with strong El Niño or La Niña. We identified the Pacific–North American (PNA) atmospheric pattern, which develops in the Pacific in response to ENSO, and the tropical North Atlantic SST as the most likely causes of the observed teleconnections with the Mozambique Channel SST at Europa. The scientific expedition ORCIE 2013 conducted by Mireille M. M. Guillaume benefited from financial support from CNRS-INEE for the inter-organism program îles Éparses and from the Association Française des Plongeurs Scientifiques (COLIMPHA). Authorizations for diving around Europa and a CITES export permit (no. FR1398400001-E) were provided by the Terres australes et antarctiques françaises (TAAF) administration. The Forces Armées de la Zone Sud de l'Océan Indien (FAZSOI) and the gendarme were very helpful. The assistance of photographer Steven Weinberg, skipper Jean-Bernard Galves, and the crew of the vessel Inventive is gratefully acknowledged. We further thank the professional divers Jean-Patrick Rousse and Erwan Meyer for their efficient help in coring the coral colonies and the Division Technique from CNRS-INSU, especially Michel Calzas, Christine Drezen, and Christophe Guillerm, for sharing the temperature records of the RBR gauges that were deployed and retrieved by Jean-Patrick Rousse. Météo-France is acknowledged for the use of meteorological data from Europa. We thank Vanessa E. Skiba from FU Berlin for composing the map in Fig. 1. Mireille M. M. Guillaume also received funds from the MNHN/UMR BOrEA for geochemical analysis and support from the ANR-STORISK project (no. ANR-15-CE03-0003) for conducting research at Europa. We thank Kai Rankenburg from the University of Western Australia Advanced Geochemical Facility for Indian Ocean Research for support in trace element measurements. Research conducted at UWA was supported by the Australian Research Council through the Centre of Excellence for Coral Reef Studies (CE140100020) and a Laureate Fellowship awarded to Malcolm McCulloch (FL120100049). We acknowledge support from the Open Access Publication Initiative of Freie Universität Berlin. Peer-reviewed Publisher Version