Reports
/ http://www.sciencemag.org/content/early/recent / 23 October 2014 / Page 1 / 10.1126/science.1255586
Downloaded from www.sciencemag.org on October 23, 2014
Antarctic role in Northern Hemisphere
glaciation
and fig. S3).
Spectral analysis shows that preNHG, our δ18Obf record is dominated
by 41 kyr pacing consistent with a
strong response to obliquity variations,
which is attributed to ice sheet dynamics (3). In contrast, Pacific BWT and
Stella C. Woodard,1* Yair Rosenthal,1,2 Kenneth G. Miller,2 James D. Wright,2
2
3
benthic δ13C exhibit strong 100 kyr
Beverly K. Chiu, Kira T. Lawrence
periodicity during that interval (fig. S4),
1
Rutgers University, Institute of Marine and Coastal Sciences, 71 Dudley Rd, New Brunswick, NJ 08901,
suggesting that BWT and circulation
2
USA. Rutgers University, Department of Earth and Planetary Sciences, 610 Taylor Rd, Piscataway, NJ
responded differently to orbital forcing
3
08845, USA. Lafayette College, Department of Geology and Environmental Geosciences, 730 High St,
than ice. The appearance of a secondary
Easton, PA 18042, USA.
100 kyr beat in the latter part of our
*Corresponding author. E-mail: [email protected]
δ18Obf record provides evidence for
stronger synchronization in the reEarth’s climate underwent a major transition from the warmth of the late Pliocene,
sponse of these climate-system compowhen global surface temperatures were ~2-3°C higher than today, to extensive
nents to orbital forcing as NHG
Northern Hemisphere glaciation (NHG) at ~2.73 Ma. We show that North Pacific deep
intensified (12).
waters were significantly colder (4°C) and likely fresher than North Atlantic deep
Site 1208 BWTs show no signifiwater prior to the intensification of NHG. At ~2.73 Ma, the Atlantic-Pacific
cant long-term trend over the 400 kyr
temperature gradient was reduced to <1°C suggesting the initiation of stronger heat
pre-NHG interval (Fig. 2). Therefore,
transfer from the North Atlantic to the deep Pacific. We posit that increased
we interpret the significant δ18Obf inglaciation of Antarctica, deduced from the 21 ± 10 m sea-level fall from 3.15-2.75 Ma,
crease, 0.21 ± 0.04‰ (1 S.E.), at Site
and the development of a strong polar halocline, fundamentally altered deep ocean
1208 over this interval (Fig. 2) to pricirculation, which enhanced inter-hemispheric heat and salt transport thereby
marily reflect an increase in the extent
contributing to the NHG.
of continental ice (12). Assuming an
average 0.1 ± 0.02‰ Δδ18O/10 m sealevel
(15), we estimate 21 ± 10 m (2
Benthic foraminiferal oxygen isotope (δ18Obf) records trend toward highS.E.) sea-level equivalent of “permanent” ice growth (12) pre-NHG.
er values throughout the late Pliocene warm period (1), culminating in
Because seawater Mg/Ca was likely ~20 ± 10% lower than modern durhigher amplitude of glacial-interglacial (G-IG) δ18O variability (Fig. 1)
ing the Pliocene, e.g., (16), BWTs at Site 1208 might have been higher
associated with a dramatic increase of Ice Rafted Debris (IRD) in sedithan present by ~1°C (12) (fig. S3). However, this uncertainty has a
ments around the Arctic at ~2.73 Ma [Marine Isotope Stage (MIS) G6],
negligible effect on our estimates of sea-level change and the G-IG variand signaling a major intensification of Northern Hemisphere glaciation
ability of BWT and δ18Osw during the late Pliocene interval leading to
(NHG) (2–4). During the same period, proxy records indicate a longthe NHG intensification (12) (fig. S5). Using the long-term trends also
term sea surface temperature (SST) cooling in most regions (5–8), which
minimizes uncertainties due to inaccurate temperature corrections or
is mimicked in bottom water temperature (BWT) records from the deep
differences in the primary orbital beats of the isotope and temperature
North Atlantic (9–11). Here, we reconstruct the BWT history of the deep
records. Thus, our reconstruction of continental ice provides only inforPacific at 2-5 kyr resolution from ODP Site 1208 (36.13°N, 158.20°W,
mation regarding mean sea-level position and does not reflect glacial
3350m water depth, fig. S1) on Shatsky Rise in the northwest Pacific
lowstands or interglacial highstands, which presumably occurred at orOcean (12), and determine ice volume changes during the 400 kyr interbital frequencies over this 400kyr interval (12).
val preceding the NHG intensification (3.15-2.75 Ma, henceforth preWe compare the Pacific with North Atlantic DSDP Site 607 (41°N,
NHG).
32°W, 3427 m water depth) records (9) and find pre-NHG Atlantic
18
The Pliocene δ Obf record at Site 1208 is consistent with the global
BWTs, generated using C. wuellerstorfi, are on average 4 ± 1.4°C
δ18Obf stack (LR04) (3) (Fig. 1). Beginning at glacial MIS G6, the ampliwarmer than at Site 1208 (9) (Fig. 2). New discrete measurements of
tude of G-IG δ18Obf variability (Δδ18OG-IG) increases from ~0.5‰ to
Uvigerina Mg/Ca from Site 607 range from 1.1-1.6 mmol/mol, well
>0.8‰ with more extreme glacial maxima and interglacial minima (fig.
above values recorded by Uvigerina in the Pacific at the same time (fig.
S2).
S6), supporting the interpretation of warm North Atlantic BWTs during
The BWT record at Site 1208 was reconstructed from Mg/Ca measthe Pliocene (12). Over the pre-NHG interval, Site 607 δ18Obf records a
urements of the infaunal foraminifera, Uvigerina spp. We determined a
0.48 ± 0.04‰ increase, more than double that observed at Site 1208, and
Mg/Ca-temperature sensitivity, 0.067 ±0.016 mmol/mol/°C, for this
BWTs cool by ~1.3 ± 0.4°C (Fig. 2). After accounting for BWT cooling,
18
species by calibrating the Holocene-LGM Δ(Mg/Ca) to the Δδ Obf at
we estimate ~15 ± 14 m (1 S.E.) sea-level equivalent of “permanent” ice
Site 1208 (12, 13). Note that, unlike epifaunal species, Cibicidoides
growth from the residual Δδ18Obf at Site 607 (12), consistent with the
wuellerstorfi, used to generate a North Atlantic BWT record (9), Uvigerestimate from Site 1208. As the uncertainty in the Pacific sea-level recina is apparently not affected by seawater carbonate ion saturation,
ord is less than the Atlantic estimate due to lack of temperature correcwhich can alter Mg/Ca independently of temperature (12, 14). Pacific
tion, we conclude that it is very likely (>95% confidence) that baseline
BWTs exhibit an average Pliocene G-IG range of ~2.1 ± 0.8°C, (1 S.D.),
sea-level fall exceeded 11 m and possibly reached 31 m pre-NHG.
similar to the average Holocene-LGM range of 2.6°C (12) in contrast
The gradual increase in Pliocene δ18Obf records has previously been
18
with oscillations of δ Obf (Fig. 1), suggesting the orbital-scale temperaattributed to a prolonged onset of NHG (17, 18). Ice-rafted debris proture variability of the Pliocene Pacific was somewhat decoupled from
vides evidence of ice on Greenland since the Miocene and an augmented
the ice volume. A notable change occurred at ~2.73 Ma, when following
ice sheet extent ~3.3 Ma (19). Although tectonic uplift in high northern
~4°C deglacial warming, average Pacific BWT became ~1.5°C warmer
latitudes surrounding the Barents Sea likely promoted regional ice
and G-IG temperature changes exhibit slightly lower amplitude (Fig. 1
growth as early as 4 Ma (20), the alpine glaciers were not large enough
to reach sea-level until MIS G6 (20), and so probably account for negligible sea-level equivalent ice pre-NHG (12). In light of the little evidence for widespread glaciers in the Northern Hemisphere until ~2.73
Ma (4, 19, 20), we suggest that at least half of the 21 ± 10 m sea-level
fall pre-NHG was due to ice added to Antarctica. Furthermore, because
the Greenland Ice Sheet (GIS) and West Antarctic Ice Sheet (WAIS) can
accommodate at most ~12 m ice equivalent of sea-level (21, 22), it’s
likely that the extent of the East Antarctic Ice Sheet (EAIS) was less than
modern during the late Pliocene, consistent with records of a dynamic
Antarctic margin (23–26).
The expansion of Antarctic ice sheets during the late Pliocene appears to surpass an important climatological threshold, which contributed to the intensification of NHG. The present deep Pacific δ18Osw value,
~-0.15‰, reflects the mixture of NADW (δ18Osw ~0.2‰) and AABW
(δ18Osw ~-0.5 to -0.3‰) forming circumpolar deep water (CDW) (27).
The pre-NHG deep Pacific δ18Osw was similar to modern AABW, averaging -0.43‰ and fluctuating by as much as 0.4-0.8‰ on G-IG timescales (Fig. 3). During this interval Pacific δ18Osw reached near modern
values only during glacial periods with much lower values during interglacials. The δ18Osw reconstruction at Site 607 shows no significant longterm change over the entire interval for which there is data overlapping
with our Pacific record (9) (Fig. 3). Although the Site 607 Pliocene G-IG
amplitude of Δδ18Osw was similar to the Pacific, average δ18Osw was
higher (0.28‰), with interglacial values not much different from the
modern North Atlantic. Thus, the low Pacific δ18Osw cannot be attributed
to lower continental ice volume but must reflect a hydrographic difference.
The persistence of an average ~0.7 ‰ δ18Osw gradient between Site
607 and Site 1208 (Fig. 3B), suggests the two sites were not ventilated
by the same water mass pre-NHG. During the same interval, Pacific
δ18Obf and BWTs were offset from the North Atlantic (Fig. 2). The relatively faster long-term δ18Obf increase at Site 607 compared with Site
1208 brings the records together by MIS G6 (Fig. 2A), and the AtlanticPacific BWT gradient was reduced from ~4°C to <1°C over one IG-G
cycle, MIS G6-MIS G5 (Fig. 2B), by cooling at Site 607and subsequent
warming at Site 1208. We interpret these data to reflect hydrographic
changes, which initiated stronger heat and salt transfer from the North
Atlantic to the Pacific due to a change in deep ocean circulation, perhaps
setting up a CDW mixing pattern similar to modern.
Today most AABW production occurs in the Weddell Sea (28), increasing opportunities for mixing between northern and southern
sourced deep-water masses due to its location in the Atlantic sector of
the Southern Ocean. If the formation regions for Pliocene southern
sourced deep water were different, an entirely different pattern of mixing
and CDW formation was possible. Detailed reconstructions of the late
Pliocene from the proximal ANDRILL AND-1B core indicate numerous
episodes of near total WAIS collapse (25), and diatom assemblages suggest open marine conditions were accompanied by deep-mixing in the
Ross Sea (26). Increased Pliocene deep-water production in the Pacific/Indian sector of the Southern Ocean (e.g., Prydz Bay, Ross Sea,
Amundsen Sea), potentially allowed AABW to influence the deep Pacific more directly, consistent with recent model results (29).
Past studies, which attribute Pliocene warmth to increased oceanic
heat transport via the thermohaline conveyor (30–32), cite weak meridional δ13C gradients (30, 31) and increased North Atlantic sediment drift
accumulation (32) as evidence of enhanced NADW production. However, their interpretation of ocean circulation based upon δ13C hinges on
the use of modern NADW and AABW end-members that are related to
surface nutrient content and atmospheric exchange, and thus may not
reflect Pliocene values. Evidence for poorly stratified (33, 34) and more
productive (24, 25) Southern Ocean surface waters with less sea ice
during the Pliocene, makes a higher preformed δ13C AABW endmember plausible (35). While there is evidence for NADW production
during the late Pliocene based on drift deposits (32), we have no direct
way to quantify deep-water formation relative to the modern or to
AABW. Both AABW and NADW production may have increased simultaneously, as suggested by modeling (29), with the end result of lower
contribution of NADW to CDW.
Regardless, the absence of a long-term temperature trend in our Pacific BWT record over the period when NADW cooled by ~1.3°C attests
to inefficient heat transport from the North Atlantic to the deep Pacific
via the Southern Ocean before 2.73 Ma. We contend that NADW was
not a major contributor to CDW and that deep water formed in the
Southern Ocean was the primary source of deep water to the Pacific preNHG. This interpretation is also supported by a ~0.6‰ increase in Site
1208 δ18Osw, which effectively eliminates the Pacific-Atlantic δ18Osw
gradient by ~2.7 Ma (Fig. 3). The proposed change in deep ocean circulation was almost certainly tied to high latitude processes which altered
the temperature or salinity of either the northern or southern deep water
mass or both. Presumably, high latitude cooling steepened equator-topole temperature gradients throughout the Pliocene (6, 7) and triggered
the expansion Antarctic glaciation in the Southern Hemisphere (26), as
supported by our sea-level estimates from Site 1208. Dust records suggest a northward shift in southern hemisphere wind belts about the time
of NHG intensification (36), which would have allowed expansion of sea
ice and promoted the development of a stronger halocline (34), reducing
deep water ventilation around Antarctica (26, 35).
Stronger and more permanent stratification of Southern Ocean surface waters is indicated by decreased opal accumulation beginning
around 2.73 Ma (33) (Fig. 3C). Such stratification probably reduced heat
exchange between the atmosphere and upwelling Southern Ocean waters
[e.g., (37)], trapping heat transported via NADW in the subsurface and
causing the warming observed in our Pacific BWT record. A decreasing
SST gradient between the North and South Atlantic (Fig. 3D) further
signifies the transfer of heat from the high northern latitudes. Thus, we
argue that the expanded glaciation of Antarctica during the late Pliocene
culminated in a fundamental change in deep-water circulation, which
contributed to the intensification of NHG by facilitating the redistribution of heat at Earth’s surface.
References and Notes
1. H. J. Dowsett, K. M. Foley, D. K. Stoll, M. A. Chandler, L. E. Sohl, M.
Bentsen, B. L. Otto-Bliesner, F. J. Bragg, W.-L. Chan, C. Contoux, A. M.
Dolan, A. M. Haywood, J. A. Jonas, A. Jost, Y. Kamae, G. Lohmann, D. J.
Lunt, K. H. Nisancioglu, A. Abe-Ouchi, G. Ramstein, C. R. Riesselman, M.
M. Robinson, N. A. Rosenbloom, U. Salzmann, C. Stepanek, S. L. Strother,
H. Ueda, Q. Yan, Z. Zhang, Sea surface temperature of the mid-Piacenzian
ocean: A data-model comparison. Sci. Rep. 3, 2013 (2013). Medline
doi:10.1038/srep02013
2. N. J. Shackleton, A new late Neogene timescale: Application to Leg 138 Sites,
in Proc. ODP, Sci. Results. (College Station, TX, Ocean Drilling Program,
1995), vol. 138, pp. 337–355.
3. L. E. Lisiecki, M. E. Raymo, A Pliocene‐Pleistocene stack of 57 globally
distributed benthic δ18O records. Paleoceanography 20, PA1003 (2005).
4. M. A. Maslin, G. H. Haug, M. Sarnthein, R. Tiedemann, The progressive
intensification of northern hemisphere glaciation as seen from the North
Pacific. Geol. Rundsch. 85, 452–465 (1996). doi:10.1007/BF02369002
5. S. Steph, R. Tiedemann, M. Prange, J. Groeneveld, D. Nürnberg, L. Reuning,
M. Schulz, G. H. Haug, Changes in Caribbean surface hydrography during the
Pliocene shoaling of the Central American Seaway. Paleoceanography 21, 1–
25 (2006). doi:10.1029/2004PA001092
6. T. D. Herbert, L. C. Peterson, K. T. Lawrence, Z. Liu, Tropical ocean
temperatures over the past 3.5 million years. Science 328, 1530–1534 (2010).
Medline doi:10.1126/science.1185435
7. K. T. Lawrence, S. Sosdian, H. E. White, Y. Rosenthal, North Atlantic climate
evolution through the Plio-Pleistocene climate transitions. Earth Planet. Sci.
Lett. 300, 329–342 (2010). doi:10.1016/j.epsl.2010.10.013
8. A. Martínez-Garcia, A. Rosell-Melé, E. L. McClymont, R. Gersonde, G. H.
/ http://www.sciencemag.org/content/early/recent / 23 October 2014 / Page 2 / 10.1126/science.1255586
Haug, Subpolar link to the emergence of the modern equatorial Pacific cold
tongue.
Science
328,
1550–1553
(2010).
Medline
doi:10.1126/science.1184480
9. S. Sosdian, Y. Rosenthal, Deep-sea temperature and ice volume changes across
the Pliocene-Pleistocene climate transitions. Science 325, 306–310 (2009).
Medline doi:10.1126/science.1169938
10. T. M. Cronin, H. J. Dowsett, G. S. Dwyer, P. A. Baker, M. A. Chandler, MidPliocene deep-sea bottom-water temperatures based on ostracode Mg/Ca
ratios.
Mar.
Micropaleontol.
54,
249–261
(2005).
doi:10.1016/j.marmicro.2004.12.003
11. G. Bartoli, M. Sarnthein, M. Weinelt, H. Erlenkeuser, D. Garbe-Schönberg,
D. W. Lea, Final closure of Panama and the onset of northern hemisphere
glaciation.
Earth
Planet.
Sci.
Lett.
237,
33–44
(2005).
doi:10.1016/j.epsl.2005.06.020
12. Supplementary materials, analytical methods, supporting text, and
supplementary figures are available on Science Online. Original data is
archived as a paleoclimate dataset with the National Oceanic and Atmopheric
Administration’s National Climatic Data Center, available online at:
www.ncdc.noaa.gov/data-access/paleoclimatology-data/datasets.
13. H. Elderfield, M. Greaves, S. Barker, I. R. Hall, A. Tripati, P. Ferretti, S.
Crowhurst, L. Booth, C. Daunt, A record of bottom water temperature and
seawater δ18O for the Southern Ocean over the past 440kyr based on Mg/Ca of
benthic foraminiferal Uvigerina spp. Quat. Sci. Rev. 29, 160–169 (2010).
doi:10.1016/j.quascirev.2009.07.013
14. H. Elderfield, J. Yu, P. Anand, T. Kiefer, B. Nyland, Calibrations for benthic
foraminiferal Mg/Ca paleothermometry and the carbonate ion hypothesis.
Earth Planet. Sci. Lett. 250, 633–649 (2006). doi:10.1016/j.epsl.2006.07.041
15. R. G. Fairbanks, R. K. Matthews, The marine oxygen isotope record in
Pleistocene coral, Barbados, West Indies. Quat. Res. 10, 181–196 (1978).
doi:10.1016/0033-5894(78)90100-X
16. M. S. Fantle, D. J. DePaolo, Sr isotopes and pore fluid chemistry in carbonate
sediment of the Ontong Java Plateau: Calcite recrystallization rates and
evidence for a rapid rise in seawater Mg over the last 10 million years.
Geochim.
Cosmochim.
Acta
70,
3883–3904
(2006).
doi:10.1016/j.gca.2006.06.009
17. M. Mudelsee, M. E. Raymo, Slow dynamics of the Northern Hemisphere
glaciation.
Paleoceanography
20,
PA4022
(2005).
doi:10.1029/2005PA001153
18. H. Flesche Kleiven, E. Jansen, T. Fronval, T. M. Smith, Intensification of
Northern Hemisphere glaciations in the circum Atlantic region (3.5–2.4 Ma)–
ice-rafted detritus evidence. Palaeogeogr. Palaeoclimatol. Palaeoecol. 184,
213–223 (2002). doi:10.1016/S0031-0182(01)00407-2
19. E. Jansen, T. Fronval, F. Rack, J. E. T. Channell, Pliocene‐Pleistocene ice
rafting history and cyclicity in the Nordic Seas during the last 3.5 Myr.
Paleoceanography 15, 709–721 (2000). doi:10.1029/1999PA000435
20. J. Knies, R. Mattingsdal, K. Fabian, K. Grøsfjeld, S. Baranwal, K. Husum, S.
De Schepper, C. Vogt, N. Andersen, J. Matthiessen, K. Andreassen, W. Jokat,
S.-I. Nam, C. Gaina, Effect of early Pliocene uplift on late Pliocene cooling in
the Arctic–Atlantic gateway. Earth Planet. Sci. Lett. 387, 132–144 (2014).
doi:10.1016/j.epsl.2013.11.007
21. P. Fretwell, H. D. Pritchard, D. G. Vaughan, J. L. Bamber, N. E. Barrand, R.
Bell, C. Bianchi, R. G. Bingham, D. D. Blankenship, G. Casassa, G. Catania,
D. Callens, H. Conway, A. J. Cook, H. F. J. Corr, D. Damaske, V. Damm, F.
Ferraccioli, R. Forsberg, S. Fujita, Y. Gim, P. Gogineni, J. A. Griggs, R. C. A.
Hindmarsh, P. Holmlund, J. W. Holt, R. W. Jacobel, A. Jenkins, W. Jokat, T.
Jordan, E. C. King, J. Kohler, W. Krabill, M. Riger-Kusk, K. A. Langley, G.
Leitchenkov, C. Leuschen, B. P. Luyendyk, K. Matsuoka, J. Mouginot, F. O.
Nitsche, Y. Nogi, O. A. Nost, S. V. Popov, E. Rignot, D. M. Rippin, A.
Rivera, J. Roberts, N. Ross, M. J. Siegert, A. M. Smith, D. Steinhage, M.
Studinger, B. Sun, B. K. Tinto, B. C. Welch, D. Wilson, D. A. Young, C.
Xiangbin, A. Zirizzotti, Bedmap2: Improved ice bed, surface and thickness
datasets for Antarctica. The Cryosphere 7, 375–393 (2013). doi:10.5194/tc-7375-2013
22. J. L. Bamber, J. A. Griggs, R. Hurkmans, J. A. Dowdeswell, S. P. Gogineni, I.
Howat, J. Mouginot, J. Paden, S. Palmer, E. Rignot, D. Steinhage, A new bed
elevation dataset for Greenland. The Cryosphere 7, 499–510 (2013).
doi:10.5194/tc-7-499-2013
23. S. Passchier, Linkages between East Antarctic Ice Sheet extent and Southern
Ocean temperatures based on a Pliocene high‐resolution record of ice‐rafted
debris off Prydz Bay, East Antarctica. Paleoceanography 26, PA4204 (2011).
doi:10.1029/2010PA002061
24. C. P. Cook, T. van de Flierdt, T. Williams, S. R. Hemming, M. Iwai, M.
Kobayashi, F. J. Jimenez-Espejo, C. Escutia, J. J. González, B.-K. Khim, R.
M. McKay, S. Passchier, S. M. Bohaty, C. R. Riesselman, L. Tauxe, S.
Sugisaki, A. L. Galindo, M. O. Patterson, F. Sangiorgi, E. L. Pierce, H.
Brinkhuis, A. Klaus, A. Fehr, J. A. P. Bendle, P. K. Bijl, S. A. Carr, R. B.
Dunbar, J. A. Flores, T. G. Hayden, K. Katsuki, G. S. Kong, M. Nakai, M. P.
Olney, S. F. Pekar, J. Pross, U. Röhl, T. Sakai, P. K. Shrivastava, C. E.
Stickley, S. Tuo, K. Welsh, M. Yamane, Dynamic behaviour of the East
Antarctic ice sheet during Pliocene warmth. Nat. Geosci. 6, 765–769 (2013).
doi:10.1038/ngeo1889
25. T. Naish, R. Powell, R. Levy, G. Wilson, R. Scherer, F. Talarico, L. Krissek,
F. Niessen, M. Pompilio, T. Wilson, L. Carter, R. DeConto, P. Huybers, R.
McKay, D. Pollard, J. Ross, D. Winter, P. Barrett, G. Browne, R. Cody, E.
Cowan, J. Crampton, G. Dunbar, N. Dunbar, F. Florindo, C. Gebhardt, I.
Graham, M. Hannah, D. Hansaraj, D. Harwood, D. Helling, S. Henrys, L.
Hinnov, G. Kuhn, P. Kyle, A. Läufer, P. Maffioli, D. Magens, K.
Mandernack, W. McIntosh, C. Millan, R. Morin, C. Ohneiser, T. Paulsen, D.
Persico, I. Raine, J. Reed, C. Riesselman, L. Sagnotti, D. Schmitt, C.
Sjunneskog, P. Strong, M. Taviani, S. Vogel, T. Wilch, T. Williams,
Obliquity-paced Pliocene West Antarctic ice sheet oscillations. Nature 458,
322–328 (2009). Medline doi:10.1038/nature07867
26. R. McKay, T. Naish, L. Carter, C. Riesselman, R. Dunbar, C. Sjunneskog, D.
Winter, F. Sangiorgi, C. Warren, M. Pagani, S. Schouten, V. Willmott, R.
Levy, R. DeConto, R. D. Powell, Antarctic and Southern Ocean influences on
Late Pliocene global cooling. Proc. Natl. Acad. Sci. U.S.A. 109, 6423–6428
(2012). Medline doi:10.1073/pnas.1112248109
27. A. N. LeGrande, G. A. Schmidt, Global gridded data set of the oxygen
isotopic composition in seawater. Geophys. Res. Lett. 33, L12604 (2006).
doi:10.1029/2006GL026011
28. A. H. Orsi, G. C. Johnson, J. L. Bullister, Circulation, mixing, and production
of Antarctic Bottom Water. Prog. Oceanogr. 43, 55–109 (1999).
doi:10.1016/S0079-6611(99)00004-X
29. Z. Zhang, K. H. Nisancioglu, U. S. Ninnemann, Increased ventilation of
Antarctic deep water during the warm mid-Pliocene. Nat. Commun. 4, 1499
(2013). Medline doi:10.1038/ncomms2521
30. M. E. Raymo, B. Grant, M. Horowitz, G. H. Rau, Mid-Pliocene warmth:
Stronger greenhouse and stronger conveyor. Mar. Micropaleontol. 27, 313–
326 (1996). doi:10.1016/0377-8398(95)00048-8
31. A. C. Ravelo, D. H. Andreasen, Enhanced circulation during a warm period.
Geophys. Res. Lett. 27, 1001–1004 (2000). doi:10.1029/1999GL007000
32. J. D. Wright, K. G. Miller, Control of North Atlantic deep water circulation by
the Greenland-scotland Ridge. Paleoceanography 11, 157–170 (1996).
doi:10.1029/95PA03696
33. C. D. Hillenbrand, D. Fütterer, Neogene to Quaternary deposition of opal on
the continental rise west of the Antarctic Peninsula, ODP Leg 178, Sites 1095,
1096, and 1101. Barker, PF, Camerlenghi, A., Acton, GD, and Ramsay, ATS
(Eds.), Proc. ODP, Sci. Results, 178 [Online]. Available from World Wide
Web:
wwwodp.tamu.edu/publications/178_SR/VOLUME/CHAPTERS/SR178_23.PDF
1, (2001).
34. D. M. Sigman, S. L. Jaccard, G. H. Haug, Polar ocean stratification in a cold
climate. Nature 428, 59–63 (2004). Medline doi:10.1038/nature02357
35. D. A. Hodell, K. A. Venz‐Curtis, Late Neogene history of deepwater
ventilation in the Southern Ocean. Geochem. Geophys. Geosyst. 7, Q09001
(2006). doi:10.1029/2005GC001211
36. A. Martínez-Garcia, A. Rosell-Melé, S. L. Jaccard, W. Geibert, D. M.
Sigman, G. H. Haug, Southern Ocean dust-climate coupling over the past four
million years. Nature 476, 312–315 (2011). Medline doi:10.1038/nature10310
37. L. Menviel, A. Timmermann, O. E. Timm, A. Mouchet, Climate and
biogeochemical response to a rapid melting of the West Antarctic Ice Sheet
during interglacials and implications for future climate. Paleoceanography 25,
PA4231 (2010). doi:10.1029/2009PA001892
38. N. J. Shackleton, J. Imbrie, M. A. Hall, Oxygen and carbon isotope record of
East Pacific coreV19-30: Implications for the formation of deep water in the
late Pleistocene North Atlantic. Earth Planet. Sci. Lett. 65, 233–244 (1983).
doi:10.1016/0012-821X(83)90162-0
39. L. E. Lisiecki, M. E. Raymo, Diachronous benthic δ18O responses during late
/ http://www.sciencemag.org/content/early/recent / 23 October 2014 / Page 3 / 10.1126/science.1255586
Pleistocene terminations. Paleoceanography 24, PA3210 (2009).
doi:10.1029/2009PA001732
40. M. E. Raymo, W. F. Ruddiman, J. Backman, B. M. Clement, D. G. Martinson,
Late Pliocene variation in Northern Hemisphere ice sheets and North Atlantic
Deep Water circulation. Paleoceanography 4, 413–446 (1989).
doi:10.1029/PA004i004p00413
41. P. B. Kwiek, A. C. Ravelo, Pacific Ocean intermediate and deep water
circulation during the Pliocene. Palaeogeogr. Palaeoclimatol. Palaeoecol.
154, 191–217 (1999). doi:10.1016/S0031-0182(99)00111-X
42. A. Gordon, in Ocean Currents: A Derivative of the Encyclopedia of Ocean
Sciences, J. H. Steele, S. A. Thorpe, K. K. Turekian, Eds. (Academic Press,
2009), pp. 263–269.
43. A. Govin, E. Michel, L. Labeyrie, C. Waelbroeck, F. Dewilde, E. Jansen,
Evidence for northward expansion of Antarctic Bottom Water mass in the
Southern Ocean during the last glacial inception. Paleoceanography 24,
PA1202 (2009). doi:10.1029/2008PA001603
44. E. A. Boyle, L. D. Keigwin, Comparison of Atlantic and Pacific
paleochemical records for the last 250,000 years: Changes in deep ocean
circulation and chemical inventories. Earth Planet. Sci. Lett. 76, 135–150
(1985). doi:10.1016/0012-821X(85)90154-2
45. Y. Rosenthal, M. P. Field, R. M. Sherrell, Precise determination of
element/calcium ratios in calcareous samples using sector field inductively
coupled plasma mass spectrometry. Anal. Chem. 71, 3248–3253 (1999).
Medline doi:10.1021/ac981410x
46. N. L. Venti, K. Billups, Stable-isotope stratigraphy of the Pliocene–
Pleistocene climate transition in the northwestern subtropical Pacific.
Palaeogeogr.
Palaeoclimatol.
Palaeoecol.
326,
54–65
(2012).
doi:10.1016/j.palaeo.2012.02.001
47. M. Medina-Elizalde, D. W. Lea, Late Pliocene equatorial Pacific.
Paleoceanography 25, PA2208 (2010). doi:10.1029/2009PA001780
48. A. Holbourn, W. Kuhnt, M. Schulz, J.-A. Flores, N. Andersen, Orbitallypaced climate evolution during the middle Miocene “Monterey” carbonisotope excursion. Earth Planet. Sci. Lett. 261, 534–550 (2007).
doi:10.1016/j.epsl.2007.07.026
49. T. D. Herbert, R. F. Stallard, A. G. Fischer, Anoxic events, productivity
rhythms, and the orbital signature in a Mid‐Cretaceous deep‐sea sequence
from
central
Italy.
Paleoceanography
1,
495–506
(1986).
doi:10.1029/PA001i004p00495
50. T. D. Herbert, Orbital chronology of Cretaceous-Paleocene marine sediments.
(1995).
51. J. Zachos, M. Pagani, L. Sloan, E. Thomas, K. Billups, Trends, rhythms, and
aberrations in global climate 65 Ma to present. Science 292, 686–693 (2001).
Medline doi:10.1126/science.1059412
52. T. Westerhold, U. Röhl, B. Donner, H. K. McCarren, J. C. Zachos, A
complete high‐resolution Paleocene benthic stable isotope record for the
central Pacific (ODP Site 1209). Paleoceanography 26, PA2216 (2011).
doi:10.1029/2010PA002092
53. C. H. Lear, Y. Rosenthal, N. Slowey, S. N., Benthic foraminiferal Mg/Capaleothermometry: A revised core-top calibration. Geochim. Cosmochim.
Acta 66, 3375–3387 (2002). doi:10.1016/S0016-7037(02)00941-9
54. P. A. Martin, D. W. Lea, Y. Rosenthal, T. P. Papenfuss, M. Sarnthein, Late
Quaternary deep-sea temperatures inferred from benthic foraminiferal
magnesium. Earth Planet. Sci. Lett. 198, 193–209 (2002). doi:10.1016/S0012821X(02)00472-7
55. S. P. Bryan, T. M. Marchitto, Mg/Ca–temperature proxy in benthic
foraminifera: New calibrations from the Florida Straits and a hypothesis
regarding
Mg/Li.
Paleoceanography
23,
PA2220
(2008).
doi:10.1029/2007PA001553
56. J. Yu, H. Elderfield, Mg/Ca in the benthic foraminifera Cibicidoides
wuellerstorfi and Cibicidoides mundulus: Temperature versus carbonate ion
saturation.
Earth
Planet.
Sci.
Lett.
276,
129–139
(2008).
doi:10.1016/j.epsl.2008.09.015
57. A. A. Tisserand, T. M. Dokken, C. Waelbroeck, J. M. Gherardi, V. Scao, C.
Fontanier, F. Jorissen, Refining benthic foraminiferal Mg/Ca‐temperature
calibrations using core‐tops from the western tropical Atlantic: Implication for
paleotemperature estimation. Geochem. Geophys. Geosyst. 14, 929–946
(2013).
58. J. Yu, W. S. Broecker, Comment on “Deep-sea temperature and ice volume
changes across the Pliocene-Pleistocene climate transitions”. Science 328,
1480
(2010);
10.1126/science.1186544.
Medline
doi:10.1126/science.1186544
59. S. Sosdian, Y. Rosenthal, Response to comment on “Deep-sea temperature
and ice volume changes across the Pliocene-Pleistocene climate transitions”.
Science
328,
1480
(2010);
10.1126/science.1186768.
Medline
doi:10.1126/science.1186544
60. J. F. Adkins, K. McIntyre, D. P. Schrag, The salinity, temperature, and δ18O of
the glacial deep ocean. Science 298, 1769–1773 (2002). Medline
doi:10.1126/science.1076252
61. N. J. Shackleton, Attainment of isotopic equilibrium between ocean water and
the benthonic foraminifera genus Uvigerina: Isotopic changes in the ocean
during the last glacial. Colloques Internationaux du C.N.R.S. 219, (1974).
62. R. Schlitzer, Electronic atlas of WOCE hydrographic and tracer data now
available. Eos Trans. AGU 81, 45 (2000). doi:10.1029/00EO00028
63. J. Horita, H. Zimmermann, H. D. Holland, Chemical evolution of seawater
during the Phanerozoic: Implications from the record of marine evaporites.
Geochim. Cosmochim. Acta 66, 3733–3756 (2002). doi:10.1016/S00167037(01)00884-5
64. T. K. Lowenstein, M. N. Timofeeff, S. T. Brennan, L. A. Hardie, R. V.
Demicco, Oscillations in Phanerozoic seawater chemistry: Evidence from
fluid
inclusions.
Science
294,
1086–1088
(2001).
Medline
doi:10.1126/science.1064280
65. D. Evans, W. Müller, Deep time foraminifera Mg/Ca paleothermometry:
Nonlinear correction for secular change in seawater Mg/Ca.
Paleoceanography 27, PA4205 (2012). doi:10.1029/2012PA002315
66. A. Mucci, J. W. Morse, The incorporation of Mg2+ and Sr2+ into calcite
overgrowths: Influences of growth rate and solution composition. Geochim.
Cosmochim. Acta 47, 217–233 (1983). doi:10.1016/0016-7037(83)90135-7
67. F. J. Hasiuk, K. C. Lohmann, Application of calcite Mg partitioning functions
to the reconstruction of paleocean Mg/Ca. Geochim. Cosmochim. Acta 74,
6751–6763 (2010). doi:10.1016/j.gca.2010.07.030
68. M. Raitzsch, A. Dueñas-Bohórquez, G. J. Reichart, L. J. de Nooijer, T.
Bickert, Incorporation of Mg and Sr in calcite of cultured benthic
foraminifera: Impact of calcium concentration and associated calcite
saturation state. Biogeosciences 7, 869–881 (2010). doi:10.5194/bg-7-8692010
69. E. Segev, J. Erez, Effect of Mg/Ca ratio in seawater on shell composition in
shallow benthic foraminifera. Geochem. Geophys. Geosyst. 7, Q02P09 (2006).
doi:10.1029/2005GC000969
70. M. L. Delaney, A. W. H. Bé, E. A. Boyle, Li, Sr, Mg, and Na in foraminiferal
calcite shells from laboratory culture, sediment traps, and sediment cores.
Geochim. Cosmochim. Acta 49, 1327–1341 (1985). doi:10.1016/00167037(85)90284-4
71. H. J. Dowsett, M. A. Chandler, M. M. Robinson, Surface temperatures of the
Mid-Pliocene North Atlantic Ocean: Implications for future climate. Philos.
Trans. R. Soc. London Ser. A 367, 69–84 (2009). Medline
doi:10.1098/rsta.2008.0213
72. E. Grossman, Stable isotopes in modern benthic foraminifera: A study of vital
effect. J. Foraminiferal Res. 17, 48–61 (1987). doi:10.2113/gsjfr.17.1.48
73. B. E. Bemis, H. J. Spero, D. W. Lea, Reevaluation of the oxygen isotopic
composition of planktonic foraminifera: Experimental results and revosed
paleotemperature equations. Paleoceanography 13, 150–160 (1998).
doi:10.1029/98PA00070
74. T. M. Marchitto, W. B. Curry, J. Lynch-Stieglitz, S. P. Bryan, K. M. Cobb, D.
C. Lund, Improved oxygen isotope temperature calibrations for cosmopolitan
benthic foraminifera. Geochim. Cosmochim. Acta 130, 1–11 (2014).
doi:10.1016/j.gca.2013.12.034
75. D. P. Schrag, J. F. Adkins, K. McIntyre, J. L. Alexander, D. A. Hodell, C. D.
Charles, J. F. McManus, The oxygen isotopic composition of seawater during
the Last Glacial Maximum. Quat. Sci. Rev. 21, 331–342 (2002).
doi:10.1016/S0277-3791(01)00110-X
76. C. Waelbroeck, L. Labeyrie, E. Michel, J. C. Duplessy, J. F. McManus, K.
Lambeck, E. Balbon, M. Labracherie, Sea-level and deep water temperature
changes derived from benthic foraminifera isotopic records. Quat. Sci. Rev.
21, 295–305 (2002). doi:10.1016/S0277-3791(01)00101-9
77. N. Lhomme, G. K. C. Clarke, C. Ritz, Global budget of water isotopes
inferred from polar ice sheets. Geophys. Res. Lett. 32, L20502 (2005).
doi:10.1029/2005GL023774
78. R. S. Hill, D. M. Harwood, P. N. Webb, Nothofagus beardmorensis
/ http://www.sciencemag.org/content/early/recent / 23 October 2014 / Page 4 / 10.1126/science.1255586
(Nothofagaceae), a new species based on leaves from the Pliocene Sirius
Group, Transantarctic Mountains, Antarctica. Rev. Palaeobot. Palynol. 94,
11–24 (1996). doi:10.1016/S0034-6667(96)00003-6
79. A. C. Ashworth, D. J. Cantrill, Neogene vegetation of the Meyer Desert
Formation (Sirius Group) Transantarctic Mountains, Antarctica. Palaeogeogr.
Palaeoclimatol.
Palaeoecol.
213,
65–82
(2004).
doi:10.1016/j.palaeo.2004.07.002
80. D. R. Marchant, G. H. Denton, Miocene and Pliocene paleoclimate of the Dry
Valleys region, southern Victoria Land: A geomorphological approach. Mar.
Micropaleontol. 27, 253–271 (1996). doi:10.1016/0377-8398(95)00065-8
81. W. Dansgaard, Stable isotopes in precipitation. Tellus XVI 4, 436–468 (1964).
doi:10.1111/j.2153-3490.1964.tb00181.x
82. J. Jouzel, G. Hoffmann, R. D. Koster, V. Masson, Water isotopes in
precipitation: Data/model comparison for present-day and past climates. Quat.
Sci. Rev. 19, 363–379 (2000). doi:10.1016/S0277-3791(99)00069-4
83. J. Jouzel, R. D. Koster, R. J. Suozzo, G. L. Russell, Stable water isotope
behavior during the last glacial maximum: A general circulation model
analysis. J. Geophys. Res. 99, 25791–25801 (1994). doi:10.1029/94JD01819
84. R. Z. Poore, R. S. Williams Jr., C. Tracey, Sea level and climate. USGS Fact
Sheet 002 (2000).
Acknowledgments: The authors thank N. Venti and K. Billups for providing
samples, J. Crisicone, N. Abdul and R. Mortlock for lab assistance. Funding
was provided by NSF grants EAR-1052257 and OCE-1334691. B.K.C. thanks
Rutgers Aresty Undergraduate Research Fellowship for its support.
Supplementary Materials
www.sciencemag.org/cgi/content/full/science.1255586/DC1
Materials and Methods
Supplementary Text
Figs. S1 to S8
References (39–84)
5 May 2014; accepted 10 October 2014
Published online 23 October 2014
10.1126/science.1255586
/ http://www.sciencemag.org/content/early/recent / 23 October 2014 / Page 5 / 10.1126/science.1255586
Fig. 1. Stable isotope and Mg/Ca data for the deep Pacific Ocean, Site
1208, spanning the Holocene-LGM (0-25 ka, left) and late Pliocene
(3.3-2.5 Ma, right). Holocene-LGM data from V19-30 (eastern tropical
18
Pacific) (38) and the Pacific δ O benthic stack (39) are included for
13
comparison. (A) Uvigerina spp. δ C records from the Pacific Ocean. (B)
18
18
Global benthic δ O stack (LR04) (3). (C) Uvigerina spp. δ Obf record from
Site 1208. (D) Uvigerina spp. Mg/Ca record from Site 1208, temperature
scale is given for reference. Raw data (points) were smoothed using a 15
kyr low-pass filter (line); gray shading indicates 1 S.E. of temperature
estimate. The box identifies the pre-NHG interval and gray shaded box
highlights the period following NHG intensification. Important Pliocene
18
Marine Isotope Stages (MIS) are labeled on the LR04 benthic δ O stack.
/ http://www.sciencemag.org/content/early/recent / 23 October 2014 / Page 6 / 10.1126/science.1255586
Fig. 2. Benthic δ Obf (A) and BWTs (B) comparing Pacific
(blue, this study) with the North Atlantic [red, (9)] records.
Gray shading highlights the interval after Pacific and Atlantic
18
δ Obf and BWT records come together around MIS G6. Longterm trends spanning the 400 kyr pre-NHG interval (3.15-2.75 Ma)
are highlighted. Raw data (points) are smoothed by 15 kyr lowpass filter (line). Blue (Site 1208) and red (Site 607) shading gives
1 S.E. of filtered BWTs. Dashed lines are least squares
regressions. The slopes of significant trends are given in boxes.
Marine Isotope Stages (MIS) discussed in the text are labeled on
panel (A).
18
/ http://www.sciencemag.org/content/early/recent / 23 October 2014 / Page 7 / 10.1126/science.1255586
Fig. 3. (A) Calculated δ Osw for Pliocene deep Pacific Site 1208 (blue, this
study) and the North Atlantic Site 607 [red, (9)]. Shaded area indicates 1 S.E. of
18
18
filtered δ Osw. Dashed line indicates modern deep Pacific δ Osw, -0.15‰. (B)
18
Pacific minus Atlantic δ Osw showing a reduction in the inter-basinal gradient at
~2.7 Ma. (C) Southern Ocean opal mass accumulation rates (ODP Site 1096) (33).
(D) Evolution of North (DSDP Site 607 and ODP Site 982) (7) and South Atlantic
(ODP Site 1090) (8) high latitude SST gradients. Data were interpolated to even 2
kyr spacing before differencing (thin lines); thick lines are 50 kyr-smoothed curves.
18
/ http://www.sciencemag.org/content/early/recent / 23 October 2014 / Page 8 / 10.1126/science.1255586