This is the first continuous record of hydrographic variability (SST; δ18Osw) from the Agulhas Current core region spanning the past 270,000 years. Gordon, A. L. Interocean Exchange of Thermocline Water. Historically, the cape has been known to sailors as a major hazard on the traditional clipper route. Schouten, S. et al. Geophysical Research Letters 41, 2014GL059278, https://doi.org/10.1002/2014GL059278 (2014). Geochimica et Cosmochimica Acta 67, 2157–2171, https://doi.org/10.1016/S0016-7037(03)00168-6 (2003). Taken together, we hence recommend that future users apply calibration equations that include a correction for the dissolution effect on Mg/Ca in foraminiferal calcite such as presented in Dekens, et al.64 and Regenberg, et al.65 in addition to the standard calibrations for SST referred to above. Here we present a new continuous 270-kyr data set consisting of Agulhas Current near-surface temperature and inferred salinity based on surface-dwelling foraminiferal Mg/Ca and δ18O records from site CD154 10-06 P (31°10.36’S, 32°08.91’E, 3076 m water depth, Fig. Rapid coupling between ice volume and polar temperature over the past 150,000 years. Franzese, A. M., Hemming, S. R., Goldstein, S. L. & Anderson, R. F. Reduced Agulhas Leakage during the Last Glacial Maximum inferred from an integrated provenance and flux study. Therefore, all data is shown here as ice volume corrected δ18Osw (δ18Osw-ivc) values only. Credit: Jonathan Durgadoo, GEOMAR. 6, Q09P02, https://doi.org/10.1029/2005gc000930 (2005). 4, orange) were identical, despite that the record of Grant, et al.76 was used for sea level estimates and an average age model uncertainty of 2.5 kyr was applied downcore. and JavaScript. Clim. Ziegler, M. et al. Today Agulhas leakage of ~5–15 Sverdrup (Sv) is one of the dominant sources of the upper branch of the Atlantic Meridional Overturning Circulation (AMOC), connecting the warm route around the southern tip of Africa with the North Atlantic3,4. & de Ruijter, W. P. M. A weaker Agulhas Current leads to more Agulhas leakage. Additionally, the multi-proxy SST compilation over the last deglaciation can serve in future regional data compilations established around South Africa as well as in global temperature compilations. 2d–f) (Table 2). Contrasting multiproxy reconstructions of surface ocean hydrography in the Agulhas Corridor and implications for the Agulhas Leakage during the last 345,000 years. Nature 491, 744–747, https://doi.org/10.1038/nature11593 (2012). Weijer, W., De Ruijter, W. P. M., Sterl, A. first Agulhas Current Time-series (ACT) cruise in April 2010. the Bayesian BAYSPAR calibration by Tierney and Tingley73 and Ho and Laepple72. Paleoceanography and Paleoclimatology 33, 281–301, https://doi.org/10.1002/2017pa003201 (2018). To obtain lead the writing of the manuscript. The separation was achieved on an Alltech Prevail Cyano column (2.1 mm × 150 mm, 3 μm), maintained at 30 °C. Night Morning Day Afternoon Evening. By measuring the temperature, conductivity, and velocity of the current, we will quantify the variability in Agulhas Current heat and freshwater transport and learn more about the links between the Agulhas Current and the climate system. The TEXH86 SST calibration model by Kim et al.51 (SSTH = 68.4*LOG (TEXH86) + 38.6) was used to transfer TEX86 values to absolute SST. Simon, M. H. et al. Global and Planetary Change 34, 293–311, https://doi.org/10.1016/S0921-8181(02)00121-2 (2002). Machine-accessible metadata file describing the reported data: https://doi.org/10.6084/m9.figshare.13019678. and M.Z. Clim. Only 60 miles (100 km) wide, the Agulhas Current is estimated to flow at an average rate of 0.5 to 1.4 miles (0.8 to 2.2 km) per hour. Mariners Weather Log, January 1976.) Millennial- and orbital-scale changes in the East Asian monsoon over the past 224,000 years. Paleoceanography 28, 426–439, https://doi.org/10.1002/palo.20041 (2013). They measure current speed, direction and temperature at extremely high temporal resolutions. Below the transfer functions and error inputs used for the datasets in this study (CD154 10-06 P/ CD154 17-17 K) are listed: Number of Monte Carlo Simulations mc = 1000: δ18Osw-salinity relationship for the regional southern tropical Indian Ocean (24°S-44°S) of Tiwari, et al.75: δ18O–SSS slope of 0.44 ± 0.03; r2 = 0.69; n = 115; significant at p = 0.99, δ18Oc paleotemperature equation of Bemis, et al.44: T = 14.9-4.8(δ18O-δ18Osw), Mg/Ca-temperature-salinity equation of Tierney, et al.42: Mg/Ca = exp (0.084*T + 0.051*S - 2.54), sea level estimates: Spratt & Lisiecki et al. Regenberg, M., Regenberg, A., Garbe-Schönberg, D. & Lea, D. W. Global dissolution effects on planktonic foraminiferal Mg/Ca ratios controlled by the calcite-saturation state of bottom waters. Pena, L. D., Calvo, E., Cacho, I., Eggins, S. & Pelejero, C. Identification and removal of Mn-Mg-rich contaminant phases on foraminiferal tests: Implications for Mg/Ca past temperature reconstructions. Scussolini, P., Marino, G., Brummer, G.-J. Overall, to better constrain the various sources of uncertainty that arise from calculating temperature and δ18Osw-ivc for our data set (Fig. & Lea, D. W. Reevaluation of the oxygen isotopic composition of planktonic foraminifera: Experimental results and revised paleotemperature equations. Nature 429, 623–628, https://doi.org/10.1038/nature02599 (2004). A late Pleistocene dataset of Agulhas Current variability. 2) of the core as the event caused sediment erosion in that interval, which is evident through the absence of half a precession cycle in the Fe/K record during MIS 5 c/d (Fig. The age model making use of the alignment of the Fe/K ratio of core CD 154 10-06 P to the δ18O splice from Chinese speleothems36,37,38 has been validated by comparing the radiocarbon-dated upper portion of the marine core with the U-Th dated speleothem signal (Fig. McKay, N. P. & Emile-Geay, J. 2) (Table 2). Core top calibration of Mg/Ca in tropical foraminifera: Refining paleotemperature estimation. Thank you for visiting nature.com. Geochimica et Cosmochimica Acta 47, 1815–1819, https://doi.org/10.1016/0016-7037(83)90029-7 (1983). Updates? The analytical error associated with this method is ±0.3 °C (standard error)52. Mg/Ca ratios of G. ruber converted to calcification temperature using the sediment trap calibration of Anand, et al.54 (previously published29) are shown in comparison with applying a Mg/Ca-temperature-salinity equation42 to the same data set. 15, 489–512, https://doi.org/10.5194/os-15-489-2019 (2019). Assessing the effect of dissolution on planktonic foraminiferal Mg/Ca ratios: Evidence from Caribbean core tops. The Agulhas is noted as a major western boundary current in the Southern Hemisphere. Mg/Ca ratios were run every 1 cm in the upper part of the record (Holocene-LGM) and the data set is published in Simon, et al.29. A flexible approach to assessing synchroneity of past events using Bayesian reconstructions of sedimentation history. van Sebille, E., Beal, L. M. & Johns, W. E. Advective Time Scales of Agulhas Leakage to the North Atlantic in Surface Drifter Observations and the 3D OFES Model. Tiwari, M. et al. In the meantime, to ensure continued support, we are displaying the site without styles Internet Explorer). It is the geographic southern tip of the African continent and the beginning of the dividing line between the Atlantic and Indian Oceans according to the International Hydrographic Organization. PubMed Google Scholar. Low-latitude control on seasonal and interannual changes in planktonic foraminiferal flux and shell geochemistry off south Java: A sediment trap study. PSU Solver requires the user to specify a set of input conditions which include (1) the number of total Monte Carlo simulations to be performed, (2) a choice of sea‐level curve (or the option to not correct for ice volume), and (3) the desired set of climate‐geochemistry relationships. One of the fastest-flowing currents in any ocean, it reaches an estimated top speed of 5.8 miles (9.3 km) per hour off the southeast coast of South Africa. & Penven, P. Decoupling of the Agulhas Leakage from the Agulhas Current. We thank Rainer Zahn, the captain, officers, and crew of RRS Charles Darwin cruise number 154, for which I.H. ADS  Various models have been put forward determining the modern connection between the two. It can be noted that absolute SST biomarker-based estimates are higher and the pattern over the deglaciation differs from the inorganic based values. The comparison shows that, despite the different tuning approach, a high level of synchronicity between the benthic δ18O record of core CD154 10-06 P and the LR04 record is achieved (Pearson T = 0.919; CL 95% (0.86; 0.95)). Bemis, B. E., Spero, H. J., Bijma, J. The reason for these discordant results among the different paleothermometers might be manifold. The results show that, on average, the Agulhas follows the continental slope with a side-ways meandering displacement of … Empirically, TEX86 correlates best to SST or temperatures between 0 and 100 m51,70, yet Thaumarchaeota typically reside deeper within the water column. Technical note: The Linked Paleo Data framework – a common tongue for paleoclimatology. The Creative Commons Public Domain Dedication waiver http://creativecommons.org/publicdomain/zero/1.0/ applies to the metadata files associated with this article. In the depth interval 76.5–918.5 cm which is the focus of this study, 3 more samples have been identified and were removed. & Zahn, R. On the role of the Agulhas system in ocean circulation and climate. The samples were analyzed using a Thermo Element XR High inductively coupled plasma-mass spectrometry with a long-term precision of element ratios, determined by replicate analyses of standard solutions containing Mg/Ca = 1.15 mmol mol-1 and Mg/Ca = 6.9 mmol mol-1 of ±1.25% relative standard deviation (RSD) and ±0.52% RSD, respectively. Franzese, A. M., Hemming, S. R. & Goldstein, S. L. Use of strontium isotopes in detrital sediments to constrain the glacial position of the Agulhas Retroflection. The sources of the Agulhas Current are the East Madagascar Current (25 Sv), the Mozambique Current (5 Sv) and a recirculated part of the south-west Indian subgyre south of Madagascar (35 Sv). Geochimica et Cosmochimica Acta 74, 4639–4654, https://doi.org/10.1016/j.gca.2010.05.027 (2010). Paleoceanography 24, PA1201, https://doi.org/10.1029/2008pa001636 (2009). Stable isotopes were measured at Cardiff University, School of Earth and Environmental Sciences using a ThermoFinnigan MAT 253 mass spectrometer linked online to a Carbo Kiel-II carbonate preparation device (long-term external precision is 0.06‰ for δ18O and 0.02‰ for δ13C). Quaternary Science Reviews 30, 2948–2960, https://doi.org/10.1016/j.quascirev.2011.07.024 (2011). Beal, L. M., De Ruijter, W. P. M., Biastoch, A. Article, Scientific Reports | Caley, T. et al. Variability in the Agulhas Current regime is key in shaping hydroclimate on the adjacent coastal areas of the African continent today as well as during past climates. Ring in the new year with a Britannica Membership, This article was most recently revised and updated by, https://www.britannica.com/place/Agulhas-Current, The Cooperative Institute for Marine and Atmospheric Studies - The Agulhas Current. Location map of Site CD154 10-06 P (this study) and CD154 17-17 K23 with main surface currents (arrows) in the southwest Indian Ocean and atmospheric circulation over southern Africa during austral summer (December, January, February) with the approximate position of the Congo Air Boundary (CAB) (dashed lines; adapted from Reason et al., 200677). It is sometimes regarded as one of the great capes. The error associated with this calibration is ±1.5 °C on the SST estimates. A late Pleistocene dataset of Agulhas Current variability. NORCE Norwegian Research Centre, Bjerknes Centre for Climate Research, Jahnebakken 5, 5007, Bergen, Norway, Centre for Early Sapiens Behaviour (SapienCE), AHKR Institute, University of Bergen, Bergen, Norway, Department of Earth Sciences, Utrecht University, 3584, CD, Utrecht, Netherlands, School of Earth and Environmental Sciences, Cardiff University, Cardiff, CF10 3AT, United Kingdom, Department of Marine Organic Biogeochemistry, NIOZ Royal Netherlands Institute for Sea Research, Den Burg, Netherlands, Marcel T. J. van der Meer & Stefan Schouten, You can also search for this author in The average ship-drift derived surface velocity plot shows two major source regions for the Agulhas current: (1) from the Mozambique channel to the north and along the coast; and (2) from the east including a major contribution from the Madagascar current. L'Agulhas weather in March. Knorr, G. & Lohmann, G. Rapid transitions in the Atlantic thermohaline circulation triggered by global warming and meltwater during the last deglaciation. Knorr, G. & Lohmann, G. Southern Ocean origin for the resumption of Atlantic thermohaline circulation during deglaciation. I.R.H, S.B. Google Scholar. Additionally, we demonstrate in Fig. Rühs, S., Durgadoo, J. V., Behrens, E. & Biastoch, A. Advective timescales and pathways of Agulhas leakage. Paleoceanography and Paleoclimatology 34, 306–315, https://doi.org/10.1029/2018pa003517 (2019).

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