Abstract
The prevailing mid-latitude westerly winds, known as the westerlies, are a fundamental component of the climate system because they have a crucial role in driving surface ocean circulation1 and modulating airâsea heat, momentum and carbon exchange1,2,3. Recent work suggests that westerly wind belts are migrating polewards in response to anthropogenic forcing4,5. Reconstructing the westerlies during past warm periods such as the Pliocene epoch, in which atmospheric carbon dioxide (CO2) was about 350 to 450 parts per million6 and temperatures were about 2 to 4 degrees Celsius higher than today7, can improve our understanding of changes in the position and strength of these wind systems as the climate continues to warm. Here we show that the westerlies were weaker and more poleward during the warm Pliocene than during glacial periods after the intensification of Northern Hemisphere glaciation (iNHG), which occurred around 2.73 million years ago8. Our results, which are based on dust and export productivity reconstructions, indicate that major ice sheet development during the iNHG was accompanied by substantial increases in dust fluxes in the mid-latitude North Pacific Ocean, especially compared to those in the subarctic North Pacific. Following this shift, changes in dust and productivity largely track the glacialâinterglacial cycles of the late Pliocene and early Pleistocene epochs. On the basis of this pattern, we infer that shifts in the westerlies were primarily driven by variations in Plio-Pleistocene thermal gradients and ice volume. By combining this relationship with other dust records9,10,11 and climate modelling results12, we find that the proposed changes in the westerlies were globally synchronous. If the Pliocene is predictive of future warming, we posit that continued poleward movement and weakening of the present-day westerlies in both hemispheres can be expected.
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Data availability
All data produced for this study are available at https://doi.org/10.6084/m9.figshare.12472646.v6. Source data are provided with this paper.
Code availability
The code used in this study to produce all figures is available at https://doi.org/10.6084/m9.figshare.12472676.v5.
References
Russell, J. L., Dixon, K. W., Gnanadesikan, A., Stouffer, R. J. & Toggweiler, J. The Southern Hemisphere westerlies in a warming world: propping open the door to the deep ocean. J. Clim. 19, 6382â6390 (2006).
Toggweiler, J. R., Russell, J. L. & Carson, S. R. Midlatitude westerlies, atmospheric CO2, and climate change during the ice ages. Paleoceanography 21, PA2005 (2006).
Anderson, R. et al. Wind-driven upwelling in the Southern Ocean and the deglacial rise in atmospheric CO2. Science 323, 1443â1448 (2009).
Chen, G. & Held, I. M. Phase speed spectra and the recent poleward shift of Southern Hemisphere surface westerlies. Geophys. Res. Lett. 34, L21805 (2007).
Yang, H. et al. Poleward shift of the major ocean gyres detected in a warming climate. Geophys. Res. Lett. 47, e2019GL085868 (2020).
MartÃnez-BotÃ, M. et al. Plio-Pleistocene climate sensitivity evaluated using high-resolution CO2 records. Nature 518, 49â54 (2015); addendum 526, 458 (2015).
Haywood, A. M. et al. A return to large-scale features of Pliocene climate: the Pliocene Model Intercomparison Project Phase 2. Clim. Past 16, 2095â2123 (2020).
Haug, G. H., Sigman, D. M., Tiedemann, R., Pedersen, T. F. & Sarnthein, M. Onset of permanent stratification in the subarctic Pacific Ocean. Nature 401, 779â782 (1999).
Sun, Y. & An, Z. Late PlioceneâPleistocene changes in mass accumulation rates of eolian deposits on the central Chinese Loess Plateau. J. Geophys. Res. D 110, D23101 (2005).
Naafs, B. D. A. et al. Strengthening of North American dust sources during the late Pliocene (2.7 Ma). Earth Planet. Sci. Lett. 317â318, 8â19 (2012).
MartÃnez-Garcia, A. et al. Southern Ocean dustâclimate coupling over the past four million years. Nature 476, 312â315 (2011).
Li, X. et al. Mid-Pliocene westerlies from PlioMIP simulations. Adv. Atmos. Sci. 32, 909â923 (2015).
Gillett, N. P. & Thompson, D. W. Simulation of recent Southern Hemisphere climate change. Science 302, 273â275 (2003).
Shindell, D. T., Miller, R. L., Schmidt, G. A. & Pandolfo, L. Simulation of recent northern winter climate trends by greenhouse-gas forcing. Nature 399, 452â455 (1999).
Chavaillaz, Y., Codron, F. & Kageyama, M. Southern westerlies in LGM and future (RCP4. 5) climates. Clim. Past Discuss. 8, 3693â3717 (2012).
Gray, W. R. et al. Windâdriven evolution of the North Pacific subpolar gyre over the last deglaciation. Geophys. Res. Lett. 47, e2019GL086328 (2020).
Nagashima, K. et al. Orbital-and millennial-scale variations in Asian dust transport path to the Japan Sea. Palaeogeogr. Palaeoclimatol. Palaeoecol. 247, 144â161 (2007).
Sime, L. C. et al. Southern Hemisphere westerly wind changes during the Last Glacial Maximum: modelâdata comparison. Quat. Sci. Rev. 64, 104â120 (2013).
Lora, J. M., Mitchell, J. L., Risi, C. & Tripati, A. E. North Pacific atmospheric rivers and their influence on western North America at the Last Glacial Maximum. Geophys. Res. Lett. 44, 1051â1059 (2017).
Burke, K. et al. Pliocene and Eocene provide best analogs for near-future climates. Proc. Natl Acad. Sci. USA 115, 13288â13293 (2018).
Lisiecki, L. E. & Raymo, M. E. A PlioceneâPleistocene stack of 57 globally distributed benthic δ18O records. Paleoceanography 20, PA1003 (2005).
Raymo, M. E. The initiation of Northern Hemisphere glaciation. Annu. Rev. Earth Planet. Sci. 22, 353â383 (1994).
Lawrence, K. T. et al. Timeâtransgressive North Atlantic productivity changes upon Northern Hemisphere glaciation. Paleoceanography 28, 740â751 (2013).
Tanaka, T. Y. & Chiba, M. A numerical study of the contributions of dust source regions to the global dust budget. Glob. Planet. Change 52, 88â104 (2006).
Heermance, R. V. et al. Erg deposition and development of the ancestral Taklimakan Desert (western China) between 12.2 and 7.0 Ma. Geology 46, 919â922 (2018).
Lang, D. C. et al. The transition on North America from the warm humid Pliocene to the glaciated Quaternary traced by eolian dust deposition at a benchmark North Atlantic Ocean drill site. Quat. Sci. Rev. 93, 125â141 (2014).
Janecek, T. R. & Rea, D. K. Eolian deposition in the northeast Pacific Ocean: Cenozoic history of atmospheric circulation. Geol. Soc. Am. Bull. 94, 730â738 (1983).
Rea, D. K., Snoeckx, H. & Joseph, L. H. Late Cenozoic eolian deposition in the North Pacific: Asian drying, Tibetan uplift, and cooling of the northern hemisphere. Paleoceanography 13, 215â224 (1998).
Zhang, W., Chen, J., Ji, J. & Li, G. Evolving flux of Asian dust in the North Pacific Ocean since the late Oligocene. Aeolian Res. 23, 11â20 (2016).
McGee, D. & Mukhopadhyay, S. in The Noble Gases as Geochemical Tracers 155â176 (Springer, 2013).
Dickens, G., Snoeckx, H., Arnold, E., Morley, J. & Owen, R. Composite depth scale and stratigraphy for Sites 885/886. In Proc. ODP Sci. Res. Vol. 145, 205â217 (Ocean Drilling Program, 1995).
McGee, D., Broecker, W. S. & Winckler, G. Gustiness: the driver of glacial dustiness? Quat. Sci. Rev. 29, 2340â2350 (2010).
Mahowald, N. M. et al. Change in atmospheric mineral aerosols in response to climate: Last glacial period, preindustrial, modern, and doubled carbon dioxide climates. J. Geophys. Res. D 111, D10202 (2006).
Albani, S. et al. Improved dust representation in the Community Atmosphere Model. J. Adv. Model. Earth Syst. 6, 541â570 (2014).
Uno, I. et al. Asian dust transported one full circuit around the globe. Nat. Geosci. 2, 557â560 (2009).
Jia, Y. et al. Cenozoic aridification in Northwest China evidenced by paleovegetation evolution. Palaeogeogr. Palaeoclimatol. Palaeoecol. 557, 109907 (2020).
Herbert, T. D., Peterson, L. C., Lawrence, K. T. & Liu, Z. Tropical ocean temperatures over the past 3.5 million years. Science 328, 1530â1534 (2010).
Bauer, E. & Ganopolski, A. Aeolian dust modeling over the past four glacial cycles with CLIMBER-2. Global Planet. Change 74, 49â60 (2010).
Li, X., Liu, X. & Zhou, H. Joint influence of surface erosion and high-latitude ice-sheet extent on Asian dust cycle during the last glacial maximum. Geol. Mag. 157, 777â789 (2020).
Lorenz, S., Grieger, B., Helbig, P. & Herterich, K. Investigating the sensitivity of the atmospheric general circulation model ECHAM 3 to paleoclimatic boundary conditions. Geol. Rundsch. 85, 513â524 (1996).
Kienast, S. S., Winckler, G., Lippold, J., Albani, S. & Mahowald, N. M. Tracing dust input to the global ocean using thorium isotopes in marine sediments: ThoroMap. Glob. Biogeochem. Cycles 30, 1526â1541 (2016).
Serno, S. et al. Eolian dust input to the Subarctic North Pacific. Earth Planet. Sci. Lett. 387, 252â263 (2014).
Costa, K. M. Geochemical Fingerprints of Paleoceanographic Variability in the Subarctic Pacific over the Last 500,000 Years. PhD thesis, Columbia Univ. (2006).
Maeda, L., Kawahata, H. & Nohara, M. Fluctuation of biogenic and abiogenic sedimentation on the Shatsky Rise in the western North Pacific during the late Quaternary. Mar. Geol. 189, 197â214 (2002).
Venti, N. L., Billups, K. & Herbert, T. D. Increased sensitivity of the Plio-Pleistocene northwest Pacific to obliquity forcing. Earth Planet. Sci. Lett. 384, 121â131 (2013).
Venti, N. L., Billups, K. & Herbert, T. D. Paleoproductivity in the northwestern Pacific Ocean during the PlioceneâPleistocene climate transition (3.0â1.8 Ma). Paleoceanography 32, 92â103 (2017).
Brierley, C. M. et al. Greatly expanded tropical warm pool and weakened Hadley circulation in the early Pliocene. Science 323, 1714â1718 (2009).
Benxing, Z. & Rutter, N. On the problem of Quaternary glaciations, and the extent and patterns of Pleistocene ice cover in the Qinghai-Xizang (Tibet) Plateau. Quat. Int. 45â46, 109â122 (1998).
Bolton, C. T., Lawrence, K. T., Gibbs, S. J., Wilson, P. A. & Herbert, T. D. Biotic and geochemical evidence for a global latitudinal shift in ocean biogeochemistry and export productivity during the late Pliocene. Earth Planet. Sci. Lett. 308, 200â210 (2011).
Venti, N. L. & Billups, K. Stable-isotope stratigraphy of the PlioceneâPleistocene climate transition in the northwestern subtropical Pacific. Palaeogeogr. Palaeoclimatol. Palaeoecol. 326â328, 54â65 (2012).
Shipboard Scientific Party. Site 1208. In Proc. ODP Init. Rep. Vol. 198 (eds Bralower, T. J. et al.) 1â93 (Ocean Drilling Program, 2002).
Shipboard Scientific Party. Sites 885/886. In Proc. ODP Init. Rep. Vol. 145 (eds Rea, D. K. et al.) 303â334 (Ocean Drilling Program, 1993).
Evans, H. F. Magnetic Stratigraphy and Environmental Magnetism of Oceanic Sediments. PhD thesis, Univ. of Florida (2006).
Gradstein, F. M., Ogg, J. G., Schmitz, M. B. & Ogg, G. M. The Geologic Time Scale 2012 (Elsevier, 2012).
Winckler, G., Anderson, R. F. & Schlosser, P. Equatorial Pacific productivity and dust flux during the midâPleistocene climate transition. Paleoceanography 20, PA4025 (2005).
Clarke, W. B., Jenkins, W. & Top, Z. Determination of tritium by mass spectrometric measurement of 3He. Int. J. Appl. Radiat. Isot. 27, 515â522 (1976).
Welhan, J. A. Carbon and Hydrogen Gases in Hydrothermal Systems: the Search for a Mantle Source. PhD thesis, Univ. of California, San Diego (1981).
Mamyrin, B. A. & Tolstikhin, I. N. Helium Isotopes in Nature (Elsevier, 1984).
McGee, D. et al. Tracking eolian dust with helium and thorium: impacts of grain size and provenance. Geochim. Cosmochim. Acta 175, 47â67 (2016).
Patterson, D. B., Farley, K. & Norman, M. 4He as a tracer of continental dust: a 1.9 million year record of aeolian flux to the west equatorial Pacific Ocean. Geochim. Cosmochim. Acta 63, 615â625 (1999).
Mukhopadhyay, S., Farley, K. & Montanari, A. A. 35 Myr record of helium in pelagic limestones from Italy: implications for interplanetary dust accretion from the early Maastrichtian to the middle Eocene. Geochim. Cosmochim. Acta 65, 653â669 (2001).
Farley, K. A. Cenozoic variations in the flux of interplanetary dust recorded by 3He in a deep-sea sediment. Nature 376, 153â156 (1995).
Farley, K., Love, S. & Patterson, D. B. Atmospheric entry heating and helium retentivity of interplanetary dust particles. Geochim. Cosmochim. Acta 61, 2309â2316 (1997).
Farley, K. & Mukhopadhyay, S. An extraterrestrial impact at the Permian-Triassic boundary? Science 293, 2343 (2001).
Nier, A. & Schlutter, D. Extraction of helium from individual interplanetary dust particles by stepâheating. Meteoritics 27, 166â173 (1992).
Ozima, M. & Podosek, F. A. Noble Gas Geochemistry (Cambridge Univ. Press, 1983).
Farley, K. & Patterson, D. A 100-kyr periodicity in the flux of extraterrestrial 3 He to the sea floor. Nature 378, 600â603 (1995).
Marcantonio, F. et al. A comparative study of accumulation rates derived by He and Th isotope analysis of marine sediments. Earth Planet. Sci. Lett. 133, 549â555 (1995).
Patterson, D. B. & Farley, K. Extraterrestrial 3He in seafloor sediments: evidence for correlated 100 kyr periodicity in the accretion rate of interplanetary dust, orbital parameters, and Quaternary climate. Geochim. Cosmochim. Acta 62, 3669â3682 (1998).
Middleton, J. L., Langmuir, C. H., Mukhopadhyay, S., McManus, J. F. & Mitrovica, J. X. Hydrothermal iron flux variability following rapid sea level changes. Geophys. Res. Lett. 43, 3848â3856 (2016).
Middleton, J. L., Mukhopadhyay, S., Langmuir, C. H., McManus, J. F. & Huybers, P. J. Millennial-scale variations in dustiness recorded in Mid-Atlantic sediments from 0 to 70 ka. Earth Planet. Sci. Lett. 482, 12â22 (2018).
Costa, K. M. et al. 230Th normalization: New insights on an essential tool for quantifying sedimentary fluxes in the modern and Quaternary ocean. Paleoceanogr. Paleoclimatol. 35, e2019PA003820 (2020).
Burls, N. J. et al. Active Pacific meridional overturning circulation (PMOC) during the warm Pliocene. Sci. Adv. 3, e1700156 (2017).
Fleisher, M. & Anderson, R. Assessing the collection efficiency of Ross Sea sediment traps using 230Th and 231Pa. Deep Sea Res. Part IIÂ 50, 693â712 (2003).
Taylor, S. R. & McLennan, S. M. The geochemical evolution of the continental crust. Rev. Geophys. 33, 241â265 (1995).
Mortlock, R. A. & Froelich, P. N. A simple method for the rapid determination of biogenic opal in pelagic marine sediments. Deep-Sea Res. A 36, 1415â1426 (1989).
Müller, P. J., Kirst, G., Ruhland, G., Von Storch, I. & Rosell-Melé, A. Calibration of the alkenone paleotemperature index U37Kâ² based on core-tops from the eastern South Atlantic and the global ocean (60°N-60°S). Geochim. Cosmochim. Acta 62, 1757â1772 (1998).
Haug, G., Maslin, M., Sarnthein, M., Stax, R. & Tiedemann, R. Evolution of northwest Pacific sedimentation patterns since 6 Ma (Site 882). In Proc. ODP Sci. Res. Vol. 293 (Ocean Drilling Program, 1995).
Zhang, Q. et al. Mechanism for enhanced eolian dust flux recorded in North Pacific Ocean sediments since 4.0 Ma: aridity or humidity at dust source areas in the Asian interior? Geology 48, 77â81 (2020).
Bailey, I. et al. Iron fertilisation and biogeochemical cycles in the sub-Arctic northwest Pacific during the late Pliocene intensification of northern hemisphere glaciation. Earth Planet. Sci. Lett. 307, 253â265 (2011).
Andrews, J. T. Icebergs and iceberg rafted detritus (IRD) in the North Atlantic: facts and assumptions. Oceanography 13, 100â108 (2000).
Weber, E. T. et al. Quantitative resolution of eolian continental crustal material and volcanic detritus in North Pacific surface sediment. Paleoceanography 11, 115â127 (1996).
Lam, P. J. & Bishop, J. K. The continental margin is a key source of iron to the HNLC North Pacific Ocean. Geophys. Res. Lett. 35, L07608 (2008).
Bigg, G., Clark, C. & Hughes, A. A last glacial ice sheet on the Pacific Russian coast and catastrophic change arising from coupled iceâvolcanic interaction. Earth Planet. Sci. Lett. 265, 559â570 (2008).
Caves, J. K., Sjostrom, D. J., Mix, H. T., Winnick, M. J. & Chamberlain, C. P. Aridification of Central Asia and uplift of the Altai and Hangay Mountains, Mongolia: stable isotope evidence. Am. J. Sci. 314, 1171â1201 (2014).
Caves, J. K. et al. Late Miocene uplift of the Tian Shan and Altai and reorganization of Central Asia climate. GSA Today 27, 20â26 (2017).
Guo, Z. et al. Onset of Asian desertification by 22 Myr ago inferred from loess deposits in China. Nature 416, 159â163 (2002).
Zan, J., Fang, X., Zhang, W., Yan, M. & Zhang, D. A new record of late Pliocene-early Pleistocene aeolian loessâred clay deposits from the western Chinese Loess Plateau and its palaeoenvironmental implications. Quat. Sci. Rev. 186, 17â26 (2018).
Che, X. & Li, G. Binary sources of loess on the Chinese Loess Plateau revealed by UâPb ages of zircon. Quat. Res. 80, 545â551 (2013).
Bird, A. et al. Quaternary dust source variation across the Chinese Loess Plateau. Palaeogeogr. Palaeoclimatol. Palaeoecol. 435, 254â264 (2015).
Nie, J. et al. Loess plateau storage of northeastern Tibetan plateau-derived Yellow River sediment. Nat. Commun. 6, 8511 (2015); corrigendum 7, 10831 (2016).
Qian, W., Quan, L. & Shi, S. Variations of the dust storm in China and its climatic control. J. Clim. 15, 1216â1229 (2002).
Prospero, J. M., Ginoux, P., Torres, O., Nicholson, S. E. & Gill, T. E. Environmental characterization of global sources of atmospheric soil dust identified with the Nimbus 7 Total Ozone Mapping Spectrometer (TOMS) absorbing aerosol product. Rev. Geophys. 40, 1002 (2002).
Bory, A. J., Biscaye, P. E. & Grousset, F. E. Two distinct seasonal Asian source regions for mineral dust deposited in Greenland (NorthGRIP). Geophys. Res. Lett. 30, 1167 (2003).
Sun, Y. et al. Tracing the provenance of fineâgrained dust deposited on the central Chinese Loess Plateau. Geophys. Res. Lett. 35, L01804 (2008).
Kapp, P. et al. Wind erosion in the Qaidam basin, central Asia: implications for tectonics, paleoclimate, and the source of the Loess Plateau. GSA Today 21, 4â10 (2011).
Pullen, A. et al. Qaidam Basin and northern Tibetan Plateau as dust sources for the Chinese Loess Plateau and paleoclimatic implications. Geology 39, 1031â1034 (2011).
Licht, A., Pullen, A., Kapp, P., Abell, J. & Giesler, N. Eolian cannibalism: reworked loess and fluvial sediment as the main sources of the Chinese Loess Plateau. Geol. Soc. Am. Bull. 128, 944â956 (2016).
Sun, J., Zhang, Z. & Zhang, L. New evidence on the age of the Taklimakan Desert. Geology 37, 159â162 (2009).
Zheng, H. et al. Late oligoceneâearly miocene birth of the Taklimakan Desert. Proc. Natl Acad. Sci. USA 112, 7662â7667 (2015).
Heermance, R. V. et al. Climatic and tectonic controls on sedimentation and erosion during the PlioceneâQuaternary in the Qaidam Basin (China). Geol. Soc. Am. Bull. 125, 833â856 (2013).
Luo, Z. et al. Orbital forcing of Plio-Pleistocene climate variation in a Qaidam Basin lake based on paleomagnetic and evaporite mineralogic analysis. Palaeogeogr. Palaeoclimatol. Palaeoecol. 510, 31â39 (2018).
Jijun, L. et al. Geomorphological and environmental evolution in the upper reaches of the Yellow River during the late Cenozoic. Sci. China Ser. D 39, 380â390 (1996).
Teng, Z. & Li, L. Loess stratum and an analysis on the environment of Pleistocene in south bank of the Yellow River between Zhengzhou and Luoyang. J. Northw. Univ. 28, 153â156 (1997).
Yue, L. P., Lei, X. Y. & Qu, H. J. The age of terrace development in the middle reaches of the Yellow River. Geol. Rev. 43, 186â192 (1997).
Craddock, W. H. et al. Rapid fluvial incision along the Yellow River during headward basin integration. Nat. Geosci. 3, 209â213 (2010).
Molnar, P., England, P. & Martinod, J. Mantle dynamics, uplift of the Tibetan Plateau, and the Indian monsoon. Rev. Geophys. 31, 357â396 (1993).
Bird, A. et al. A constant Chinese Loess Plateau dust source since the late Miocene. Quat. Sci. Rev. 227, 106042 (2020).
Li, Z. et al. Chronology studies of a drill core in the central Tengger Desert of China and its implication for Asian desertification. Quat. Sci. Rev. 85, 85â98 (2014).
Wang, F. et al. Formation and evolution of the Badain Jaran Desert, North China, as revealed by a drill core from the desert centre and by geological survey. Palaeogeogr. Palaeoclimatol. Palaeoecol. 426, 139â158 (2015).
Rea, D. K. The paleoclimatic record provided by eolian deposition in the deep sea: the geologic history of wind. Rev. Geophys. 32, 159â195 (1994).
Wu, F. et al. PlioâQuaternary stepwise drying of Asia: evidence from a 3-Ma pollen record from the Chinese Loess Plateau. Earth Planet. Sci. Lett. 257, 160â169 (2007).
Acknowledgements
We thank F. Pavia, J. Middleton, M. Ting, M. Raymo, J. Schaefer, S. Rahimi, T. Weiss and J. Bridges for discussions that greatly improved the research and manuscript. Support at the Lamont-Doherty Earth Observatory laboratories was provided by R. Schwartz, M. Fleisher, L. Bolge, L. Baker, J. Hansen and C. Chang. ODP 1208 and ODP 885/886 core samples were provided by the Integrated Ocean Drilling Program (IODP). IODP is sponsored by the US National Science Foundation (NSF) and participating countries under the management of Joint Oceanographic Institutions, Inc. We acknowledge the NSF-PIRE project (PIRE: DUST) that supported the work through funding to G.W., R.F.A. and T.D.H., and a Climate Center Grant from Lamont-Doherty Earth Observatory.
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J.T.A. and G.W. designed the project and developed the conceptual framework. J.T.A. collected all isotope, major and trace element, and opal data; T.D.H. collected alkenone data. J.T.A. and G.W. analysed data. J.T.A. and G.W. wrote the manuscript, and all authors provided comments and revisions.
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Extended data figures and tables
Extended Data Fig. 1 Modelled dust flux ratios show little zonal dust variability between the LGM and today.
Contours represent the ratio of annual average LGM and modern dust deposition rates to the North Pacific. The model output is from the C4fn and C4fn-lgm simulations of ref. 34.
Extended Data Fig. 2 SST, dust and export productivity records from ODP 1208 for the period ~2.5â4.5Â Ma.
a, Benthic oxygen isotope stack from ref. 21 and ODP 1208 from ref. 50. b, Alkenone-derived SSTs. The record is a combination of data produced in this study and those from ref. 45. c, Dust fluxes determined from Th concentrations and 3HeET -derived sediment fluxes. Blue filled circles indicate samples with measured 3HeET. d, C37total fluxes. The record is a combination of data produced in this study and those from ref. 46. e, Baxs fluxes. Purple filled circles indicate samples with measured 3HeET. f, Opal fluxes. Light blue filled circles indicate samples with measured 3HeET. All error bars or âcloudsâ for dust and export production proxies represent propagated analytical errors on concentrations, as well as analytical and statistical uncertainties for the 3HeET -derived MARs (1Ï).
Extended Data Fig. 3 Fractional differences for helium isotope replicates.
a, Frequency of ODP 1208 fractional differences between replicate samples for 3HeET (blue, top) and 4Heterr (red, bottom). b, Same as a, except for ODP 885/886. c, Combined data for both cores. Fractional differences are calculated by dividing the absolute value of the maximum difference between replicates samples (if more than one replicate is run) by the average.
Extended Data Fig. 4 Comparison of 3HeET sediment fluxes and age-model-derived MARs/LSRs.
a, ODP 1208. b, ODP 885/886. Both CFP records use the Quaternary constant flux of 3HeET (0.8 pcc cm-2 kyr-1). Error bars represent propagated uncertainties on analytical and statistical uncertainties for the 3HeET-derived MARs (1Ï). The LSRs/MARs for ODP 1208 are based on the age models of refs. 50,53 and dry bulk densities. The higher-resolution MARs between astronomically tuned reversal tie-points for the period of ~3.7â4.5 Ma at site 1208 are calculated using samples for which densities are provided from shipboard measurements. In the later portion of the ODP 1208 record, for which oxygen isotope stratigraphy is available (~2.5â3.7 Ma), densities are interpolated to samples with oxygen isotope data for determination of MARs. LSRs/MARs for ODP 885/886 are based on the age model of ref. 31 and dry bulk densities. The higher-resolution MARs between magnetic reversal stratigraphy tie-points at site 885/886 are calculated using the provided shipboard measurements of density interpolated to sample depths used in this study, which have higher resolution.
Extended Data Fig. 5 Comparison of dust proxy concentrations for ODP 1208 and 885/886.
aâd, 4Heterr (a), Al (b), Fe (c) and Ti (d) are plotted against Th for ODP 1208. eâh, Same as aâd, but for ODP 885/886. Black lines denote the UCC relationships of the elements59,75 (see Methods). All error bars denote analytical uncertainties on measured concentrations (1Ï), except for 4Heterr, where the error bars incorporate the additional statistical uncertainty associated with replicates (1Ï) (see Methods).
Extended Data Fig. 6 ODP 1208 and 885/886 dust fluxes derived from all five dust proxies used in this study.
a, 4Heterr-derived dust fluxes for ODP 1208. b, Th-derived dust fluxes for ODP 1208. c, Al-derived dust fluxes for ODP 1208. d, Fe-derived dust fluxes for ODP 1208. e, Ti-derived dust fluxes for ODP 1208. fâj, Same as aâe, but for ODP 885/886. Error bars include propagated analytical uncertainties on concentrations as well as analytical and statistical uncertainties for the 3HeET-derived MARs (1Ï). The much lower 4Heterr-derived dust fluxes are probably a result of the large uncertainty in the terrestrial endmember59.
Extended Data Fig. 7 Compilation of dust flux reconstructions from the open-ocean Pliocene North Pacific.
a, LR04 benthic oxygen isotope stack21. b, Th- and 3HeET-derived dust fluxes from ODP 1208. c, Siliciclastic (>2 μm) fluxes from ODP 88278. d, Th- and 3HeET-derived dust flux data from ODP 885/886. e, Aeolian flux from ODP 885/88628. f, Flux of relative Hm+Gt from ODP 885/88679. Error bars for records in this study represent propagated analytical uncertainties on concentrations, as well as analytical and statistical uncertainties for the 3HeET-derived MARs (1Ï).
Extended Data Fig. 8 ODP 885/886 dust concentrations and fluxes derived from various methods.
a, Aeolian percentages (grey curve) from ref. 28 are determined using a sequential leaching procedure to removed opal and Fe-Mn (oxy)hydroxides. Dust concentrations from this study are calculated using Th concentrations. Error bars represent analytical uncertainties on element concentration measurements (1Ï). b, Aeolian fluxes (black curve) from ref. 28 are based on aeolian percentages and age-model-derived MARs. Dust fluxes from this study are calculated using Th concentrations and 3HeET-derived MARs. Error bars represent propagated analytical uncertainties on concentrations, as well as analytical and statistical uncertainties for the 3HeET-derived MARs (1Ï).
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Abell, J.T., Winckler, G., Anderson, R.F. et al. Poleward and weakened westerlies during Pliocene warmth. Nature 589, 70â75 (2021). https://doi.org/10.1038/s41586-020-03062-1
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DOI: https://doi.org/10.1038/s41586-020-03062-1