Earth is heading towards a climate that last existed more than three million years ago (Ma) during the ‘mid-Pliocene warm period’1, when atmospheric carbon dioxide concentrations were about 400 parts per million, global sea level oscillated in response to orbital forcing2,3 and peak global-mean sea level (GMSL) may have reached about 20 metres above the present-day value4,5. For sea-level rise of this magnitude, extensive retreat or collapse of the Greenland, West Antarctic and marine-based sectors of the East Antarctic ice sheets is required. Yet the relative amplitude of sea-level variations within glacial–interglacial cycles remains poorly constrained. To address this, we calibrate a theoretical relationship between modern sediment transport by waves and water depth, and then apply the technique to grain size in a continuous 800-metre-thick Pliocene sequence of shallow-marine sediments from Whanganui Basin, New Zealand. Water-depth variations obtained in this way, after corrections for tectonic subsidence, yield cyclic relative sea-level (RSL) variations. Here we show that sea level varied on average by 13 ± 5 metres over glacial–interglacial cycles during the middle-to-late Pliocene (about 3.3–2.5 Ma). The resulting record is independent of the global ice volume proxy3 (as derived from the deep-ocean oxygen isotope record) and sea-level cycles are in phase with 20-thousand-year (kyr) periodic changes in insolation over Antarctica, paced by eccentricity-modulated orbital precession6 between 3.3 and 2.7 Ma. Thereafter, sea-level fluctuations are paced by the 41-kyr period of cycles in Earth’s axial tilt as ice sheets stabilize on Antarctica and intensify in the Northern Hemisphere3,6. Strictly, we provide the amplitude of RSL change, rather than absolute GMSL change. However, simulations of RSL change based on glacio-isostatic adjustment show that our record approximates eustatic sea level, defined here as GMSL unregistered to the centre of the Earth. Nonetheless, under conservative assumptions, our estimates limit maximum Pliocene sea-level rise to less than 25 metres and provide new constraints on polar ice-volume variability under the climate conditions predicted for this century.
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The code for the palaeobathymetry-grain size method is available from https://doi.org/10.1594/PANGAEA.902701.
Masson-Delmotte, V. et al. in Climate Change 2013: The Physical Science Basis. Contribution of Working Group 1 to the Fifth Assessment Report of Intergovernmental Panel on Climate Change (eds Stocker, T. F. et al.) Ch. 5 (Cambridge Univ. Press, 2013).
Naish, T. R. & Wilson, G. S. Constraints on the amplitude of Mid-Pliocene (3.6–2.4 Ma) eustatic sea-level fluctuations from the New Zealand shallow-marine sediment record. Phil. Trans. R. Soc. Lond. A 367, 169–187 (2009).
Lisiecki, L. E. & Raymo, M. E. A Pliocene-Pleistocene stack of 57 globally distributed benthic δ18O records. Paleoceanography 20, PA1003 https://doi.org/10.1029/2004PA001071 (2005).
Miller, K. G. et al. High tide of the warm Pliocene: implications of global sea level for Antarctic deglaciation. Geology 40, 407–410 (2012).
Dutton, A. et al. Sea-level rise due to polar ice-sheet mass loss during past warm periods. Science 349, aaa4019 (2015).
Grant, G. et al. Mid- to late Pliocene (3.3–2.6 Ma) global sea-level fluctuations recorded on a continental shelf transect, Whanganui Basin, New Zealand. Quat. Sci. Rev. 201, 241–260 (2018).
Pollard, D., DeConto, R. M. & Alley, R. B. Potential Antarctic Ice Sheet retreat driven by hydrofracturing and ice cliff failure. Earth Planet. Sci. Lett. 412, 112–121 (2015).
Rohling, E. J. et al. Sea-level and deep-sea-temperature variability over the past 5.3 million years. Nature 508, 477–482 (2014); erratum 510, 432 (2014).
Rovere, A. et al. The Mid-Pliocene sea-level conundrum: glacial isostasy, eustasy and dynamic topography. Earth Planet. Sci. Lett. 387, 27–33 (2014).
Raymo, M. E., Mitrovica, J. X., O’Leary, M. J., DeConto, R. M. & Hearty, P. J. Departures from eustasy in Pliocene sea-level records. Nat. Geosci. 4, 328–332 (2011).
Evans, D., Brierley, C., Raymo, M. E., Erez, J. & Müller, W. Planktic foraminifera shell chemistry response to seawater chemistry: Pliocene–Pleistocene seawater Mg/Ca, temperature and sea level change. Earth Planet. Sci. Lett. 438, 139–148 (2016).
Gasson, E., DeConto, R. M. & Pollard, D. Modeling the oxygen isotope composition of the Antarctic ice sheet and its significance to Pliocene sea level. Geology 44, 827–830 (2016).
Tapia, C. A. et al. High-resolution magnetostratigraphy of mid-Pliocene (3.3–3.0 Ma) shallow-marine sediments, Whanganui Basin, New Zealand. Geophys. J. Int. 217, 41–57 (2019).
van Rijn, L. C. Unified view of sediment transport by currents and waves. I: Initiation of motion, bed roughness, and bed-load transport. J. Hydraul. Eng. 133, 649–667 (2007).
Trewick, S. A. & Bland, K. J. Fire and slice: palaeogeography for biogeography at New Zealand’s North Island/South Island juncture. J. R. Soc. NZ 42, 153–183 (2012).
Kominz, M. & Pekar, S. Oligocene eustasy from two-dimensional sequence stratigraphic back-stripping. Bull. Geol. Soc. Am. 113, 291–304 (2001).
Lourens, L. J. et al. Evaluation of the Plio-Pleistocene astronomical timescale. Paleoceanogr. Paleoclim. 11, 391–413 (1996).
Laskar, J. et al. A long-term numerical solution for the insolation quantities of the Earth. Astron. Astrophys. 428, 261–285 (2004).
de Boer, B., Haywood, A. M., Dolan, A. M., Hunter, S. J. & Prescott, C. L. The transient response of ice volume to orbital forcing during the warm Late Pliocene. Geophys. Res. Lett. 44, 10486–10494 (2017).
Golledge, N. et al. Antarctic climate and ice sheet configuration during the early Pliocene interglacial 4.23 Ma. Clim. Past 13, 959–975 (2017).
Patterson, M. et al. Orbital forcing of the East Antarctic Ice Sheet during the Pliocene and Early Pleistocene. Nat. Geosci. 7, 841–847 (2014).
Jansen, E., Fronval, T., Rack, F. & Channell, J. E. Pliocene-Pleistocene ice rafting history and cyclicity in the Nordic Seas during the last 3.5 Myr. Paleoceanography 15, 709–721 (2000).
Bailey, I. et al. An alternative suggestion for the Pliocene onset of major northern hemisphere glaciation based on the geochemical provenance of North Atlantic Ocean ice-rafted debris. Quat. Sci. Rev. 75, 181–194 (2013).
Lawrence, K. T., Herbert, T. D., Brown, C. M., Raymo, M. E. & Haywood, A. M. High-amplitude variations in North Atlantic sea surface temperature during the early Pliocene warm period. Paleoceanogr. Paleoclim. 24, https://doi.org/10.1029/2008PA001669 (2009).
Herbert, T. D., Peterson, L. C., Lawrence, K. T. & Liu, Z. Tropical ocean temperatures over the past 3.5 million years. Science 328, 1530–1534 (2010).
Martínez-Garcia, A. et al. Southern Ocean dust-climate coupling over the past four million years. Nature 476, 312–315 (2011).
Shackleton, N. J. et al. Oxygen isotope calibration of the onset of ice-rafting and history of glaciation in the North Atlantic region. Nature 307, 620 (1984).
Fretwell, P. et al. Bedmap2: Improved ice bed, surface and thickness datasets for Antarctica. Cryosphere 7, 375–393 (2013).
Naish, T. et al. Obliquity-paced Pliocene West Antarctic ice sheet oscillations. Nature 458, 322 (2009).
Spada, G. et al. Modeling Earth’s post-glacial rebound. Eos 85, 62–64 (2004).
Journeaux, T. D., Kamp, P. J. J. & Naish, T. R. Middle Pliocene cyclothems, Mangaweka Region, Wanganui Basin, New Zealand: a lithostratigraphic framework. NZ J. Geol. Geophys. 39, 135–149 (1996).
Ogg, J. G. Geomagnetic polarity time scale. In The Geologic Time Scale 2012 (eds Gradstein, F. M., Ogg, J. G., Schmitz, M. & Ogg, G.) 85–113 (Elsevier, 2012).
Turner, G. M. et al. A coherent middle Pliocene magnetostratigraphy, Wanganui Basin, New Zealand. J. R. Soc. NZ 35, 197–227 (2005).
Swift, D. J. Quaternary shelves and the return to grade. Mar. Geol. 8, 5–30 (1970).
Wright, J., Colling, A. & Park, D. (eds) Waves, Tides, and Shallow-Water Processes Vol. 4 (Gulf Professional Publishing, 1999).
Dunbar, G. B. & Barrett, P. J. Estimating paleobathymetry of wave-graded continental shelves from sediment texture. Sedimentology 52, 253–269 (2005).
Komar, P. D. & Miller, M. C. On the comparison between the threshold of sediment motion under waves and unidirectional currents with a discussion of the practical evaluation of the threshold: Reply. J. Sedim. Res. 45, 362–367 (1975).
Grant, G. R. et al. A Pliocene relative sea level record from New Zealand calculated from grain size. https://doi.pangaea.de/10.1594/PANGAEA.902701 (PANGAEA, 2019).
Chin, J. L. Late Quaternary Coastal Sedimentation and Depositional History, South-Central Monterey Bay, California. Ph.D. thesis, San Jose State Univ. (1984).
Beaumont, J., Anderson, T. J. & MacDiarmid, A. B. Benthic Flora and Fauna of the Patea Shoals Region, South Taranaki Bight. NIWA Client Report No. WLG2012-55 (NIWA, 2013).
Hume, T., Gorman, R., Green, M. & MacDonald, I. Coastal Stability in the South Taranaki Bight – Phase 2: Potential Effects of Offshore Sand Extraction on Physical Drivers and Coastal Stability. NIWA Client Report No. HAM2013-082 (NIWA, 2013).
Scripps Institution of Oceanography. CDIP: Coastal Data Information Program. http://cdip.ucsd.edu/themes/cdip?d2=p70&u3=dt:201101:p_id:p70:ibf:1:mode:all:s:156:st:1:t:data (2018).
MetOcean View. MetOcean View Hindcast. https://hindcast.metoceanview.com/ (2017).
McCave, I. N. Wave effectiveness at the sea bed and its relationship to bed-forms and deposition of mud. J. Sedim. Res. 41, 89–96 (1971).
Coastal Engineering Research Centre. Shore Protection Manual Vols I and II (US Army Corps of Engineers, Washington DC, 1984).
Li, X. et al. Mid-Pliocene westerlies from PlioMIP simulations. Adv. Atmos. Sci. 32, 909–923 (2015).
Meyers, S. R. Astrochron: An R Package for Astrochronology. https://cran.r-project.org/package=astrochron (2014).
Kominz, M. A. Late Cretaceous to Miocene sea-level estimates from the New Jersey and Delaware coastal plain coreholes: an error analysis. Basin Res. 20, 211–226 (2008).
Farrell, W. E. & Clark, J. A. On postglacial sea-level. Geophys. J. R. Astron. Soc. 46, 647–667 (1976).
Spada, G. & Stocchi, P. SELEN: A Fortran 90 program for solving the “sea-level equation”. Comput. Geosci. 33, 538–562 (2007).
Stocchi, P. et al. MIS 5e relative sea-level changes in the Mediterranean Sea: contribution of isostatic disequilibrium. Quat. Sci. Rev. 185, 122–134 (2018).
Mitrovica, J. X. & Peltier, W. R. On postglacial geoid subsidence over the equatorial oceans. J. Geophys. Res. B 96, 20053–20071 (1991).
Dziewonski, A. M. & Anderson, D. L. Preliminary reference Earth model. Phys. Earth Planet. Inter. 25, 297–356 (1981).
Peltier, W. R. Global glacial isostasy and the surface of the ice-age Earth: the ICE-5G (VM2) model and GRACE. Annu. Rev. Earth Planet. Sci. 32, 111–149 (2004).
de Boer, B., Stocchi, P. & Van De Wal, R. A fully coupled 3-D ice-sheet-sea-level model: algorithm and applications. Geosci. Model Dev. 7, 2141–2156 (2014).
Milne, G. A. & Mitrovica, J. X. Searching for eustasy in deglacial sea-level histories. Quat. Sci. Rev. 27, 2292–2302 (2008).
Milne, G. A., Gehrels, W. R., Hughes, C. W. & Tamisiea, M. E. Identifying the causes of sea-level change. Nat. Geosci. 2, 471–478 (2009).
Mitrovica, J. X. et al. On the robustness of predictions of sea level fingerprints. Geophys. J. Int. 187, 729–742 (2011).
Yamane, M. et al. Exposure age and ice-sheet model constraints on Pliocene East Antarctic ice sheet dynamics. Nat. Commun. 6, 7016 (2015).
Dolan, A. M., de Boer, B., Bernales, J., Hill, D. J. & Haywood, A. M. High climate model dependency of Pliocene Antarctic ice-sheet predictions. Nat. Commun. 9, 2799 (2018).
Shakun, J. D. et al. Minimal East Antarctic Ice Sheet retreat onto land during the past eight million years. Nature 558, 284 (2018).
Hay, C. et al. The sea-level fingerprints of ice-sheet collapse during interglacial periods. Quat. Sci. Rev. 87, 60–69 (2014).
Kopp, R. E. et al. Temperature-driven global sea-level variability in the common era. Proc. Natl Acad. Sci. USA 113, E1434–E1441 (2016); correction. 113, E5694–E5696 (2016).
Bamber, J. L., Riva, R. E., Vermeersen, B. L. & LeBrocq, A. M. Reassessment of the potential sea-level rise from a collapse of the West Antarctic Ice Sheet. Science 324, 901–903 (2009).
We thank L. van Rijn for comments on the grain size–water depth methodology. This research was primarily funded by The Royal Society of New Zealand, Marsden Grant 13 VUW 112, with additional support from the New Zealand Ministry of Business Innovation and Employment contract C05X1001. Technical drilling expertise was provided by D. Mandeno and A. Pyne of the Science Drilling Office, Antarctic Research Centre, Victoria University of Wellington and Webster Drilling and Exploration Ltd.
The authors declare no competing interests.
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Peer review information Nature thanks Natasha Barlow and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.
Extended data figures and tables
a, Observations (dots) and model values (shaded bands represent the maximum and minimum ranges from the average bold lines) for sand (∑V>63) and water depth for three different modern shelf transects (Manawatu, NZ, green36; Monterey Bay, USA, blue39; Whanganui Bight, NZ, grey40). Wave parameters used are as follows: for Manawatu, Hs = 1.2 m and Tp = 20 s (ref. 41); for Monterey, Hs = 1.8 m and Tp = 20 s (ref. 42); and for Whanganui Bight, Hs = 2.2 m and Tp = 20 s (ref. 43). See Methods for nomenclature. Model error is described by equation (8). The red shaded band for ∑V>63 = 95%–100% represents the limit of the method, where all water depths contain 100% ∑V>63. The modern Whanganui Bight is selected as the most appropriate modern analogue to determine water depth from ∑V>63 recorded in both core and outcrop in this study. b, Derivatives of water depth–grain size models, for an average sediment cycle amplitude of 30% ∑V>63, for peak wave period Tp = 20 s and significant wave height Hs = 2.0 m (dark grey) and Hs = 2.5 m (light grey) and the difference (dashed light grey). c, Calibration of ΣV>63 from maximum grain size in distribution and measured D90 from core samples (blue circles) described by a linear relationship (dotted dark blue line; equation (5)) and the deviation (grey) of the model from observations. d, Calibration of peak wave period (Tp) exponent for the critical required velocity (Ucr,w; equation (1))14. Observations for Manawatu (most extensively sampled; green circles) are used for comparison between peak wave period exponents 0.33 (solid dark green line), 0.43 (dashed dark green line) and 0.5 (dotted light green line), with the deviations between models and observations shown by the respective patterned thinner black lines.
The figure shows a semi-enclosed broad embayment open to the dominant westerly wind, with an arcuate shoreline and a westward-deepening shelf15. The location of the Siberia-1 core (red circle) and the Rangitikei River Section (dotted red line) are noted.
Southern and Northern hemisphere high-latitude summer insolation18 (65° S, 1 January, solid line; 65° N, 1 July, dashed line) Pearson correlation coefficient with the PlioSeaNZ record between 3.3 and 3.0 Ma, using the ‘slideCor’ function from the R – Astrochron package47. Here a 0-kyr lag period denotes no temporal shift in the untuned PlioSeaNZ age model, and ±10-kyr lag periods signify correlation with a positive or negative shift of the PlioSeaNZ age model with respect to the astronomical record.
Extended Data Fig. 4 Assessment of RSL predicted at Whanganui, New Zealand, for pre-determined ESL scenarios.
a–c, RSL calculated for 20-kyr glacial–interglacial polar ice-sheet variability for three values of ESL (a, 15 m; b, 20 m; and c, 25 m) and three scenarios of polar ice-sheet contribution. Scenario 1 represents an Antarctic-only contribution, scenario 2 represents a Greenland Ice Sheet (GIS) contribution (of 5 m) in phase with a 15-m Antarctic contribution, and scenario 3 has a 30-m AIS contribution in anti-phase with 5 m of GIS accumulation. For each ESL value, all scenarios are indistinguishable as RSL at the Whanganui, New Zealand, site. d–f, RSL calculated for 20-kyr Antarctic variability and 40-kyr Northern Hemisphere variability, with 10 m from AIS and three different contributions from Northern Hemisphere ice sheets (NHIS); d, 10 m; e, 20 m; and f, 30 m.
Modelled RSL at Whanganui, New Zealand, for comparison of symmetrical glacial–interglacial cyclicity (bold lines) and extended glacials and interglacials (dashed lines) using the ANICE-SELEN ice-sheet model. a, Modelled RSL for a 15-m ESL fluctuation as a symmetrical waveform (bold black line) and with extended glacials and interglacials (dashed grey line); b, the residuals of RSL curves from a with respect to ESL (symmetrical, bold black; and extended, dashed grey). c, As a but for a 10-m ESL fluctuation of a linear 20-kyr chronology (bold dark blue line) and a longer period cyclicity from cumulative extended glacial and interglacials (dashed blue line); d, as b showing the residuals from c but repeated using the ICE-5G model54 (symmetrical bold, yellow; and extended, dashed yellow). The differences between the ANICE-SELEN and ICE-5G models in d are evident but are of the order of tens of centimetres. Interestingly, longer periodicity and extended glacials/interglacials yield larger RSL excursions with respect to ESL (positive values).
Shown is the predicted RSL rise for a 15-m ESL change, after 10 kyr of linear melting between glacial and interglacial for scenarios described in Extended Data Fig 4 (namely, scenarios 1 (short-dashed line), 2 (dashed line) and 3 (solid grey line)), for the four Earth models (a, b, c, d; Extended Data Table 2). Higher contrast between lower and upper mantle results in lower values for the predicted RSL rise. A thicker lithosphere (120 km) results in a slightly higher than eustatic peak for scenario 1.
Extended Data Fig. 7 Calculated global RSL change produced by instantaneous ice-sheet melting of 15-m ESL.
Shown is RSL (normalized with respect to ESL) according to scenario 1 (AIS only) after 10 kyr of viscous relaxation (mantle viscosity profile a; Extended Data Table 2) following an instantaneous melting. The white band denotes RSL from 0.8 to 1.2 of the ESL signal. The GIA-driven RSL fingerprints are more evident if compared to Fig. 4a (10-kyr-long linear melting). The Whanganui site is highlighted by the red and white bullseye.
This file contains geological data (Supplementary Figs 1 & 2) that provides the basis for environmental interpretation of the stratigraphy. Location figures of the modern grain size transects and wave data referred to in the manuscript are shown in Supplementary Figs 3 & 4. The sample sites are correlated and backstripped using stratigraphic thicknesses shown in the cross-section (Supplementary Fig. 5).
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Grant, G.R., Naish, T.R., Dunbar, G.B. et al. The amplitude and origin of sea-level variability during the Pliocene epoch. Nature 574, 237–241 (2019). https://doi.org/10.1038/s41586-019-1619-z
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