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Flat meridional temperature gradient in the early Eocene in the subsurface rather than surface ocean

Nature Geoscience volume 9, pages 606–610 (2016)Cite this article

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Abstract

The early Eocene (49–55 million years ago) is a time interval characterized by elevated surface temperatures and atmospheric CO2 (refs 1,2), and a flatter-than-present latitudinal surface temperature gradient3,4. The multi-proxy-derived flat temperature gradient has been a challenge to reproduce in model simulations5,6,7, especially the subtropical warmth at the high-latitude surface oceans4,8, inferred from the archaeal lipid-based palaeothermometry, . Here we revisit the interpretation by analysing a global collection of multi-proxy temperature estimates from sediment cores spanning millennia to millions of years. Comparing the variability between proxy types, we demonstrate that the present interpretation9 overestimates the magnitude of past climate changes on all timescales. We attribute this to an inappropriate calibration, which reflects subsurface ocean but is calibrated to the sea surface, where the latitudinal temperature gradient is steeper. Recalibrating the proxy to the temperatures of subsurface ocean, where the signal is probably formed, yields colder -temperatures and latitudinal gradient consistent with standard climate model simulations of the Eocene climate10, invalidating the apparent, extremely warm polar sea surface temperatures. We conclude that there is a need to reinterpret -inferred marine temperature records in the literature, especially for reconstructions of past warm climates that rely heavily on this proxy as reflecting subsurface ocean.

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Figure 1: Spectral estimates of - and -inferred temperature variability.
Figure 2: Depth dependence of the global calibration.
Figure 3: Proxy–model comparison of early Eocene seawater temperatures.

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References

  1. Zachos, J., Pagani, M., Sloan, L., Thomas, E. & Billups, K. Trends, rhythms, and aberrations in global climate 65 Ma to present. Science 292, 686–693 (2001).

    Article  Google Scholar 

  2. Pagani, M., Zachos, J. C., Freeman, K. H., Tipple, B. & Bohaty, S. Marked decline in atmospheric carbon dioxide concentrations during the Paleogene. Science 309, 600–603 (2005).

    Article  Google Scholar 

  3. Greenwood, D. R. & Wing, S. L. Eocene continental climates and latitudinal temperature gradients. Geology 23, 1044–1048 (1995).

    Article  Google Scholar 

  4. Bijl, P. K. et al. Early Palaeogene temperature evolution of the southwest Pacific Ocean. Nature 461, 776–779 (2009).

    Article  Google Scholar 

  5. Lunt, D. J. et al. A model–data comparison for a multi-model ensemble of early Eocene atmosphere–ocean simulations: EoMIP. Clim. Past 8, 1717–1736 (2012).

    Article  Google Scholar 

  6. Huber, M. & Caballero, R. The early Eocene equable climate problem revisited. Clim. Past 7, 603–633 (2011).

    Article  Google Scholar 

  7. Sagoo, N., Valdes, P., Flecker, R. & Gregoire, L. J. The early Eocene equable climate problem: can perturbations of climate model parameters identify possible solutions? Phil. Trans. R. Soc. A 371, 20130123 (2013).

    Article  Google Scholar 

  8. Sluijs, A. et al. Subtropical Arctic Ocean temperatures during the Palaeocene/Eocene Thermal Maximum. Nature 441, 610–613 (2006).

    Article  Google Scholar 

  9. Kim, J.-H. et al. New indices and calibrations derived from the distribution of crenarchaeal isoprenoid tetraether lipids: implications for past sea surface temperature reconstructions. Geochim. Cosmochim. Acta 74, 4639–4654 (2010).

    Article  Google Scholar 

  10. Heinemann, M., Jungclaus, J. H. & Marotzke, J. Warm Paleocene/Eocene climate as simulated in ECHAM5/MPI-OM. Clim. Past 5, 785–802 (2009).

    Article  Google Scholar 

  11. Pearson, A. & Ingalls, A. E. Assessing the use of archaeal lipids as marine environmental proxies. Annu. Rev. Earth Planet. Sci. 41, 359–384 (2013).

    Article  Google Scholar 

  12. Schouten, S., Hopmans, E. C. & Sinninghe Damsté, J. S. The organic geochemistry of glycerol dialkyl glycerol tetraether lipids: a review. Org. Geochem. 54, 19–61 (2013).

    Article  Google Scholar 

  13. Sluijs, A. et al. Southern ocean warming, sea level and hydrological change during the Paleocene–Eocene thermal maximum. Clim. Past 7, 47–61 (2011).

    Article  Google Scholar 

  14. Pross, J. et al. Persistent near-tropical warmth on the Antarctic continent during the early Eocene epoch. Nature 488, 73–77 (2012).

    Article  Google Scholar 

  15. Schouten, S., Hopmans, E. C., Schefuß, E. & Sinninghe Damsté, J. S. Distributional variations in marine crenarchaeotal membrane lipids: a new tool for reconstructing ancient sea water temperatures? Earth Planet. Sci. Lett. 204, 265–274 (2002).

    Article  Google Scholar 

  16. Schouten, S., Forster, A., Panoto, F. E. & Sinninghe Damsté, J. S. Towards calibration of the TEX86 palaeothermometer for tropical sea surface temperatures in ancient greenhouse worlds. Org. Geochem. 38, 1537–1546 (2007).

    Article  Google Scholar 

  17. O’ Brien, C. L. et al. High sea surface temperatures in tropical warm pools during the Pliocene. Nature Geosci. 7, 606–611 (2014).

    Article  Google Scholar 

  18. Ho, S. L. & Laepple, T. Glacial cooling as inferred from marine temperature proxies and . Earth Planet. Sci. Lett. 409, 15–22 (2015).

    Article  Google Scholar 

  19. Seki, O. et al. Assessment and calibration of TEX86 paleothermometry in the Sea of Okhotsk and sub-polar North Pacific region: implications for paleoceanography. Prog. Oceanogr. 126, 254–266 (2014).

    Article  Google Scholar 

  20. Kim, J.-H. et al. Pronounced subsurface cooling of North Atlantic waters off northwest Africa during Dansgaard–Oeschger interstadials. Earth Planet. Sci. Lett. 339–340, 95–102 (2012).

    Article  Google Scholar 

  21. Ohkouchi, N., Eglinton, T. I., Keigwin, L. D. & Hayes, J. M. Spatial and temporal offsets between proxy records in a sediment drift. Science 298, 1224–1227 (2002).

    Article  Google Scholar 

  22. Rhines, A. & Huybers, P. Estimation of spectral power laws in time uncertain series of data with application to the Greenland Ice Sheet Project 2 δ18O record. J. Geophys. Res. Atmos. 116, D01103 (2011).

    Article  Google Scholar 

  23. Laepple, T. & Huybers, P. Reconciling discrepancies between Uk37 and Mg/Ca reconstructions of Holocene marine temperature variability. Earth Planet. Sci. Lett. 375, 418–429 (2013).

    Article  Google Scholar 

  24. Laepple, T. & Huybers, P. Ocean surface temperature variability: large model–data differences at decadal and longer periods. Proc. Natl Acad. Sci. USA 111, 16682–16687 (2014).

    Article  Google Scholar 

  25. Qin, W. et al. Confounding effects of oxygen and temperature on the TEX86 signature of marine Thaumarchaeota. Proc. Natl Acad. Sci. USA 112, 10979–10984 (2015).

    Article  Google Scholar 

  26. Conte, M. H. et al. Global temperature calibration of the alkenone unsaturation index ( ) in surface waters and comparison with surface sediments. Geochem. Geophys. Geosyst. 7, Q02005 (2006).

    Article  Google Scholar 

  27. Karner, M. B., DeLong, E. F. & Karl, D. M. Archaeal dominance in the mesopelagic zone of the Pacific Ocean. Nature 409, 507–510 (2001).

    Article  Google Scholar 

  28. Merbt, S. N. et al. Differential photoinhibition of bacterial and archaeal ammonia oxidation. FEMS Microbiol. Lett. 327, 41–46 (2012).

    Article  Google Scholar 

  29. Taylor, K. W. R., Huber, M., Hollis, C. J., Hernandez-Sanchez, M. T. & Pancost, R. D. Re-evaluating modern and Palaeogene GDGT distributions: implications for SST reconstructions. Glob. Planet. Change 108, 158–174 (2013).

    Article  Google Scholar 

  30. Thomas, D. J., Bralower, T. J. & Jones, C. E. Neodymium isotopic reconstruction of late Paleocene–early Eocene thermohaline circulation. Earth Planet. Sci. Lett. 209, 309–322 (2003).

    Article  Google Scholar 

  31. Müller, P. J., Kirst, G., Ruhland, G., von Storch, I. & Rosell-Melé, A. Calibration of the alkenone paleotemperature index based on core-tops from the eastern South Atlantic and the global ocean (60° N–60° S). Geochim. Cosmochim. Acta 62, 1757–1772 (1998).

    Article  Google Scholar 

  32. Percival, D. B. & Walden, A. T. Spectral Analysis for Physical Applications: Multitaper and Conventional Univariate Techniques (Cambridge Univ. Press, 1993).

    Book  Google Scholar 

  33. McClymont, E. L. et al. Sea-surface temperature records of Termination 1 in the Gulf of California: challenges for seasonal and interannual analogues of tropical Pacific climate change. Paleoceanography 27, PA2202 (2012).

    Article  Google Scholar 

  34. Richey, J. N., Hollander, D. J., Flower, B. P. & Eglinton, T. I. Merging late Holocene molecular organic and foraminiferal-based geochemical records of sea surface temperature in the Gulf of Mexico. Paleoceanography 26, PA1209 (2011).

    Article  Google Scholar 

  35. Prahl, F. G., Muehlhausen, L. A. & Zahnle, D. L. Further evaluation of long-chain alkenones as indicators of paleoceanographic conditions. Geochim. Cosmochim. Acta 52, 2303–2310 (1988).

    Article  Google Scholar 

  36. Tierney, J. E. & Tingley, M. P. A Bayesian, spatially-varying calibration model for the TEX86 proxy. Geochim. Cosmochim. Acta 127, 83–106 (2014).

    Article  Google Scholar 

  37. Locarnini, R. A. et al. NOAA Atlas NESDIS 68 184 (US Government Printing Office, 2010).

    Google Scholar 

  38. Steiger, J. H. Test for comparing elements of a correlation matrix. Psychol. Bull. 87, 245–251 (1980).

    Article  Google Scholar 

  39. Bijl, P. K. et al. Eocene cooling linked to early flow across the Tasmanian Gateway. Proc. Natl Acad. Sci. USA 110, 9645–9650 (2013).

    Article  Google Scholar 

  40. Frieling, J. et al. Paleocene–Eocene warming and biotic response in the epicontinental West Siberian Sea. Geology 42, 767–770 (2014).

    Article  Google Scholar 

  41. van Hinsbergen, D. J. J. et al. A paleolatitude calculator for paleoclimate studies. PLoS ONE 10, e0126946 (2015).

    Article  Google Scholar 

  42. Torsvik, T. H. et al. Phanerozoic polar wander, palaeogeography and dynamics. Earth-Sci. Rev. 114, 325–368 (2012).

    Article  Google Scholar 

  43. Bemis, B. E., Spero, H. J., Bijma, J. & Lea, D. W. Reevaluation of the oxygen isotopic composition of planktonic foraminifera: experimental results and revised paleotemperature equations. Paleoceanography 13, 150–160 (1998).

    Article  Google Scholar 

  44. Anand, P., Elderfield, H. & Conte, M. H. Calibration of Mg/Ca thermometry in planktonic foraminifera from a sediment trap time series. Paleoceanography 18, 1050 (2003).

    Article  Google Scholar 

  45. Ghosh, P. et al. 13C–18O bonds in carbonate minerals: a new kind of paleothermometer. Geochim. Cosmochim. Acta 70, 1439–1456 (2006).

    Article  Google Scholar 

  46. Pearson, P. N. et al. Stable warm tropical climate through the Eocene epoch. Geology 35, 211–214 (2007).

    Article  Google Scholar 

  47. John, C. M. et al. North American continental margin records of the Paleocene–Eocene thermal maximum: implications for global carbon and hydrological cycling. Paleoceanography 23, PA2217 (2008).

    Article  Google Scholar 

  48. Zachos, J. C. et al. Extreme warming of mid-latitude coastal ocean during the Paleocene–Eocene Thermal Maximum: inferences from TEX86 and isotope data. Geology 34, 737–740 (2006).

    Article  Google Scholar 

  49. Zachos, J. C., Dickens, G. R. & Zeebe, R. E. An early Cenozoic perspective on greenhouse warming and carbon-cycle dynamics. Nature 451, 279–283 (2008).

    Article  Google Scholar 

  50. Dunkley Jones, T. et al. Climate model and proxy data constraints on ocean warming across the Paleocene–Eocene Thermal Maximum. Earth-Sci. Rev. 125, 123–145 (2013).

    Article  Google Scholar 

  51. Weijers, J. W. H., Schouten, S., Spaargaren, O. C. & Sinninghe Damsté, J. S. Occurrence and distribution of tetraether membrane lipids in soils: implications for the use of the TEX86 proxy and the BIT index. Org. Geochem. 37, 1680–1693 (2006).

    Article  Google Scholar 

  52. Liu, Z. et al. Global cooling during the Eocene–Oligocene climate transition. Science 323, 1187–1190 (2009).

    Article  Google Scholar 

  53. Kim, J.-H. et al. Holocene subsurface temperature variability in the eastern Antarctic continental margin. Geophys. Res. Lett. 39, L06705 (2012).

    Google Scholar 

  54. Bice, K. L. & Marotzke, J. Numerical evidence against reversed thermohaline circulation in the warm Paleocene/Eocene ocean. J. Geophys. Res. Oceans 106, 11529–11542 (2001).

    Article  Google Scholar 

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Acknowledgements

We thank M. Heinemann for providing the ECHAM5/MPI-OM Eocene simulation, and authors who shared their published data. We acknowledge the World Climate Research Programme’s Working Group on Coupled Modelling, which is responsible for CMIP, and we thank the climate modelling groups for producing and making available their model output. For CMIP, the US Department of Energy’s Program for Climate Model Diagnosis and Intercomparison provides coordinating support and led development of software infrastructure in partnership with the Global Organization for Earth System Science Portals. We thank D. Naafs, K. Rehfeld, P. Huybers, M. Heinemann, C. Huguet, G. Inglis and P. Bijl for fruitful discussions. J. Groeneveld, R. Tapia and G. Martinez-Mendez helped with the collection of Mg/Ca data. This work was supported by the Initiative and Networking Fund of the Helmholtz Association Grant VG-NH900.

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  1. Sze Ling Ho

    Present address: Present address: University of Bergen and Bjerknes Centre for Climate Research, Allegaten 41, 5007 Bergen, Norway.,

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  1. Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Telegrafenberg A43, D-14473 Potsdam, Germany

    Sze Ling Ho & Thomas Laepple

  2. University of Bergen and Bjerknes Centre for Climate Research, Allegaten 41, 5007 Bergen, Norway

    Sze Ling Ho

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S.L.H. and T.L. contributed equally to the study.

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Correspondence to Sze Ling Ho or Thomas Laepple.

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Ho, S., Laepple, T. Flat meridional temperature gradient in the early Eocene in the subsurface rather than surface ocean. Nature Geosci 9, 606–610 (2016). https://doi.org/10.1038/ngeo2763

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