1
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Fillion EN, Harrison T. Hominin turnover at Laetoli is associated with vegetation change: Multiproxy evidence from the large herbivore community. J Hum Evol 2024; 191:103546. [PMID: 38795630 DOI: 10.1016/j.jhevol.2024.103546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 04/25/2024] [Accepted: 04/26/2024] [Indexed: 05/28/2024]
Abstract
Vegetation change in eastern Africa during the Pliocene would have had an important impact on hominin adaptation and ecology, and it may have been a key driver of hominin macroevolution, including the extinction of Australopithecus and the emergence of Paranthropus and Homo. The Pliocene paleoanthropological site of Laetoli in Tanzania provides an opportunity to investigate the relationship between vegetation change and hominin turnover because it encompasses the time period when grass cover was spreading across eastern Africa and because hominin species turnover occurred locally at Laetoli, with Paranthropus aethiopicus in the Upper Ndolanya Beds (UNB) replacing Australopithecus afarensis in the Upper Laetolil Beds (ULB). However, it remains unresolved how the vegetation of the UNB and the ULB differed from each other. To examine differences between the two stratigraphic units, multiple proxies-hypsodonty, mesowear, and stable carbon isotopes of tooth enamel (δ13Cenamel)-are used to infer the diets of large herbivores and compare the dietary guild structure of the large herbivore communities. All three proxies indicate an increase in the abrasiveness and C4-content in the diets of the large herbivores in the UNB relative to those in the ULB. After inferring the diets of species based on all three proxies, the large herbivore community of the UNB had a greater proportion of grazers and a smaller proportion of mixed feeders than in the ULB but maintained a similar proportion of browsers and frugivores. The ULB community has few modern-day analogs, whereas the UNB community is most closely analogous to those in modern African grasslands. Thus, hominin turnover at Laetoli is associated with an increase in grass cover within a woodland-grassland mosaic and is part of a broader transformation of the herbivore community structure.
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Affiliation(s)
- Elizabeth N Fillion
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT, 06520, USA.
| | - Terry Harrison
- Center for the Study of Human Origins, Department of Anthropology, New York University, 25 Waverly Pl., New York, NY, 10003, USA; New York Consortium in Evolutionary Primatology, New York, NY, 10024, USA
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2
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Bridges JD, Tarduno JA, Cottrell RD, Herbert TD. Rapid strengthening of westerlies accompanied intensification of Northern Hemisphere glaciation. Nat Commun 2023; 14:3905. [PMID: 37400450 DOI: 10.1038/s41467-023-39557-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Accepted: 06/19/2023] [Indexed: 07/05/2023] Open
Abstract
The trigger, pace, and nature of the intensification of Northern Hemisphere Glaciation (iNHG) are uncertain, but can be probed by study of ODP Site 1208 North Pacific marine sediments. Herein, we present magnetic proxy data that indicate a 4-fold increase of dust between ~ 2.73 and ~ 2.72 Ma, with subsequent increases at the start of glacials thereafter, indicating a strengthening of the mid-latitude westerlies. Moreover, a permanent shift in dust composition after 2.72 Ma is observed, consistent with drier conditions in the source region and/or the incorporation of material which could not have been transported via the weaker Pliocene winds. The sudden increase in our dust proxy data, a coeval rapid rise in dust recorded by proxy dust data in the North Atlantic (Site U1313), and the Site 1208 shift in dust composition, suggest that the iNHG represents a permanent crossing of a climate threshold toward global cooling and ice sheet growth, ultimately driven by lower atmospheric CO2.
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Affiliation(s)
- Joshua D Bridges
- Department of Earth and Environmental Sciences, University of Rochester, Rochester, NY, 14627, USA.
| | - John A Tarduno
- Department of Earth and Environmental Sciences, University of Rochester, Rochester, NY, 14627, USA.
- Department of Physics and Astronomy, University of Rochester, Rochester, NY, 14627, USA.
- Laboratory of Laser Energetics, University of Rochester, Rochester, NY, 14623, USA.
| | - Rory D Cottrell
- Department of Earth and Environmental Sciences, University of Rochester, Rochester, NY, 14627, USA
| | - Timothy D Herbert
- Department of Earth, Environmental and Planetary Sciences, Brown University, Providence, RI, 02912, USA
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3
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Willeit M, Ganopolski A, Calov R, Brovkin V. Mid-Pleistocene transition in glacial cycles explained by declining CO 2 and regolith removal. SCIENCE ADVANCES 2019; 5:eaav7337. [PMID: 30949580 PMCID: PMC6447376 DOI: 10.1126/sciadv.aav7337] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Accepted: 02/08/2019] [Indexed: 05/03/2023]
Abstract
Variations in Earth's orbit pace the glacial-interglacial cycles of the Quaternary, but the mechanisms that transform regional and seasonal variations in solar insolation into glacial-interglacial cycles are still elusive. Here, we present transient simulations of coevolution of climate, ice sheets, and carbon cycle over the past 3 million years. We show that a gradual lowering of atmospheric CO2 and regolith removal are essential to reproduce the evolution of climate variability over the Quaternary. The long-term CO2 decrease leads to the initiation of Northern Hemisphere glaciation and an increase in the amplitude of glacial-interglacial variations, while the combined effect of CO2 decline and regolith removal controls the timing of the transition from a 41,000- to 100,000-year world. Our results suggest that the current CO2 concentration is unprecedented over the past 3 million years and that global temperature never exceeded the preindustrial value by more than 2°C during the Quaternary.
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Affiliation(s)
- M. Willeit
- Potsdam Institute for Climate Impact Research, Potsdam, Germany
- Corresponding author.
| | - A. Ganopolski
- Potsdam Institute for Climate Impact Research, Potsdam, Germany
| | - R. Calov
- Potsdam Institute for Climate Impact Research, Potsdam, Germany
| | - V. Brovkin
- Max Planck Institute for Meteorology, Hamburg, Germany
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4
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Clotten C, Stein R, Fahl K, Schreck M, Risebrobakken B, De Schepper S. On the causes of Arctic sea ice in the warm Early Pliocene. Sci Rep 2019; 9:989. [PMID: 30700730 PMCID: PMC6353896 DOI: 10.1038/s41598-018-37047-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Accepted: 11/30/2018] [Indexed: 11/09/2022] Open
Abstract
Scattered and indirect evidence suggests that sea ice occurred as far south as the Iceland Sea during the Early Pliocene, when the global climate was warmer than present. However, conclusive evidence as well as potential mechanisms governing sea ice occurrence outside the Arctic Ocean during a time with elevated greenhouse gas concentrations are still elusive. Here we present a suite of organic biomarkers and palynological records from the Iceland Sea and Yermak Plateau. We show that sea ice appeared as early as ~4.5 Ma in the Iceland Sea. The sea ice either occurred seasonally or was transported southward with the East Greenland Current. The Yermak Plateau mostly remained free of sea ice and was influenced dominantly by Atlantic water. From ~4.0 Ma, occurrence of extended sea ice conditions at both the Yermak Plateau and Iceland Sea document a substantial expansion of sea ice in the Arctic. The expansion occurred contemporaneous with increased northward heat and moisture transport in the North Atlantic region, which likely led to a fresher Arctic Ocean that favors sea ice formation. This extensive sea ice cover along the pathway of the East Greenland Current gradually isolated Greenland from warmer Atlantic water in the Late Pliocene, providing a positive feedback for ice sheet expansion in Greenland.
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Affiliation(s)
- Caroline Clotten
- Uni Research Climate, Bjerknes Centre for Climate Research, Jahnebakken 5, 5007, Bergen, Norway.
| | - Ruediger Stein
- Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Am Alten Hafen 26, 27568, Bremerhaven, Germany.,MARUM and Faculty of Geosciences, University of Bremen, PO Box 330440, 28334, Bremen, Germany
| | - Kirsten Fahl
- Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Am Alten Hafen 26, 27568, Bremerhaven, Germany
| | - Michael Schreck
- Department of Geosciences, UiT The Arctic University of Norway in Tromsø, P.O. Box 6050, Langnes, 9037, Tromsø, Norway
| | - Bjørg Risebrobakken
- NORCE Norwegian Research Centre, Bjerknes Centre for Climate Research, Bergen, Norway
| | - Stijn De Schepper
- NORCE Norwegian Research Centre, Bjerknes Centre for Climate Research, Bergen, Norway
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5
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Tan N, Ladant JB, Ramstein G, Dumas C, Bachem P, Jansen E. Dynamic Greenland ice sheet driven by pCO 2 variations across the Pliocene Pleistocene transition. Nat Commun 2018; 9:4755. [PMID: 30420596 PMCID: PMC6232173 DOI: 10.1038/s41467-018-07206-w] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Accepted: 10/10/2018] [Indexed: 11/18/2022] Open
Abstract
It is generally considered that the perennial glaciation of Greenland lasting several orbital cycles began around 2.7 Ma along with the intensification of Northern Hemisphere glaciation (NHG). Both data and model studies have demonstrated that a decline in atmospheric pCO2 was instrumental in establishing a perennial Greenland ice sheet (GrIS), yet models have generally used simplistic pCO2 constraints rather than data-inferred pCO2 evolution. Here, using a method designed for the long-term coupling of climate and cryosphere models and pCO2 scenarios from different studies, we highlight the pivotal role of pCO2 on the GrIS expansion across the Plio-Pleistocene Transition (PPT, 3.0–2.5 Ma), in particular in the range between 280 and 320 ppm. Good qualitative agreement is obtained between various IRD reconstructions and some of the possible evolutions of the GrIS simulated by our model. Our results underline the dynamism of the GrIS waxing and waning under pCO2 levels similar to or lower than today, which supports recent evidence of a dynamic GrIS during the Plio-Pleistocene. Previous work has argued for a CO2 control on the development of the Plio-Pleistocene Transition (PPT, 3.0–2.5 Ma) Greenland Ice Sheet (GrIS). Here based on transient ice sheet experiments, the authors demonstrate the pivotal role of modern-like CO2 on the onset and dynamism of the PPT GrIS.
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Affiliation(s)
- Ning Tan
- Laboratoire des Sciences du Climat et de l'Environnement, LSCE/IPSL, CEA-CNRS-UVSQ, Université Paris-Saclay, 91191, Gif-sur-Yvette, France. .,Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, 100029, Beijing, China.
| | - Jean-Baptiste Ladant
- Laboratoire des Sciences du Climat et de l'Environnement, LSCE/IPSL, CEA-CNRS-UVSQ, Université Paris-Saclay, 91191, Gif-sur-Yvette, France.,Département de Géosciences, École Normale Supérieure, Paris, 75005, France.,LMD/IPSL, CNRS/ENS/UPMC, Ecole Polytechnique, Paris, 75005, France
| | - Gilles Ramstein
- Laboratoire des Sciences du Climat et de l'Environnement, LSCE/IPSL, CEA-CNRS-UVSQ, Université Paris-Saclay, 91191, Gif-sur-Yvette, France
| | - Christophe Dumas
- Laboratoire des Sciences du Climat et de l'Environnement, LSCE/IPSL, CEA-CNRS-UVSQ, Université Paris-Saclay, 91191, Gif-sur-Yvette, France
| | - Paul Bachem
- Uni Research Climate, Bjerknes Centre for Climate Research, Jahnebakken 5, 5007, Bergen, Norway
| | - Eystein Jansen
- Dep. of Earth Science, University of Bergen, Bjerknes Center for Climate Research, Jahnebakken 5, 5007, Bergen, Norway
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6
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Dyez KA, Hönisch B, Schmidt GA. Early Pleistocene obliquity-scale pCO 2 variability at ~1.5 million years ago. PALEOCEANOGRAPHY AND PALEOCLIMATOLOGY 2018; 33:1270-1291. [PMID: 32715282 PMCID: PMC7380090 DOI: 10.1029/2018pa003349] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Accepted: 10/31/2018] [Indexed: 05/12/2023]
Abstract
In the early Pleistocene, global temperature cycles predominantly varied with ~41-kyr (obliquity-scale) periodicity. Atmospheric greenhouse gas concentrations likely played a role in these climate cycles; marine sediments provide an indirect geochemical means to estimate early Pleistocene CO2. Here we present a boron isotope-based record of continuous high-resolution surface ocean pH and inferred atmospheric CO2 changes. Our results show that, within a window of time in the early Pleistocene (1.38-1.54 Ma), pCO2 varied with obliquity, confirming that, analogous to late Pleistocene conditions, the carbon cycle and climate covaried at ~1.5 Ma. Pairing the reconstructed early Pleistocene pCO2 amplitude (92 ±13 μatm) with a comparably smaller global surface temperature glacial/interglacial amplitude (3.0 ±0.5 K), yields a surface temperature change to CO2 radiative forcing ratio of S [CO2]~0.75 (± 0.5) °C/Wm-2, as compared to the late Pleistocene S [CO2] value of ~1.75 (± 0.6) °C/Wm-2. This direct comparison of pCO2 and temperature implicitly incorporates the large ice sheet forcing as an internal feedback and is not directly applicable to future warming. We evaluate this result with a simple climate model, and show that the presumably thinner, though extensive, northern hemisphere ice sheets would increase surface temperature sensitivity to radiative forcing. Thus, the mechanism to dampen actual temperature variability in the early Pleistocene more likely lies with Southern Ocean circulation dynamics or antiphase hemispheric forcing. We also compile this new carbon dioxide record with published Plio-Pleistocene δ11B records using consistent boundary conditions and explore potential reasons for the discrepancy between Pliocene pCO2 based on different planktic foraminifera.
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Affiliation(s)
- Kelsey A. Dyez
- Lamont-Doherty Earth Observatory, Columbia University, New York, NY, USA
- Now at Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, MI, USA
| | - Bärbel Hönisch
- Lamont-Doherty Earth Observatory, Columbia University, New York, NY, USA
- Department of Earth and Environmental Sciences, Columbia University, New York, NY, USA
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7
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Abstract
Earth’s modern climate is defined by the presence of ice at both poles, but that ice is now disappearing. Therefore understanding the origin and causes of polar ice stability is more critical than ever. Here we provide novel geochemical data that constrain past dynamics of glacial ice on Greenland and Arctic sea ice. Based on accurate source determinations of individual ice-rafted Fe-oxide grains, we find evidence for episodic glaciation of distinct source regions on Greenland as far-ranging as ~68°N and ~80°N synchronous with ice-rafting from circum-Arctic sources, beginning in the middle Eocene. Glacial intervals broadly coincide with reduced CO2, with a potential threshold for glacial ice stability near ~500 p.p.m.v. The middle Eocene represents the Cenozoic onset of a dynamic cryosphere, with ice in both hemispheres during transient glacials and substantial regional climate heterogeneity. A more stable cryosphere developed at the Eocene-Oligocene transition, and is now threatened by anthropogenic emissions. With rapidly disappearing ice, understanding the past behavior of the cryosphere is critical. Here, the authors indicate the initiation and disappearance of glaciation on Greenland and Arctic sea ice coincided in the past, synchronous with Antarctic ice and global ice volume, and a CO2 threshold of ~500 p.p.m.v.
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8
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Smith YM, Hill DJ, Dolan AM, Haywood AM, Dowsett HJ, Risebrobakken B. Icebergs in the Nordic Seas Throughout the Late Pliocene. PALEOCEANOGRAPHY AND PALEOCLIMATOLOGY 2018; 33:318-335. [PMID: 31058258 PMCID: PMC6485528 DOI: 10.1002/2017pa003240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Revised: 02/19/2018] [Accepted: 02/21/2018] [Indexed: 06/09/2023]
Abstract
The Arctic cryosphere is changing and making a significant contribution to sea level rise. The Late Pliocene had similar CO2 levels to the present and a warming comparable to model predictions for the end of this century. However, the state of the Arctic cryosphere during the Pliocene remains poorly constrained. For the first time we combine outputs from a climate model with a thermodynamic iceberg model to simulate likely source regions for ice-rafted debris (IRD) found in the Nordic Seas from Marine Isotope Stage M2 to the mid-Piacenzian Warm Period and what this implies about the nature of the Arctic cryosphere at this time. We compare the fraction of melt given by the model scenarios with IRD data from four Ocean Drilling Program sites in the Nordic Seas. Sites 911A, 909C, and 907A show a persistent occurrence of IRD that model results suggest is consistent with permanent ice on Svalbard. Our results indicate that icebergs sourced from the east coast of Greenland do not reach the Nordic Seas sites during the warm Late Pliocene but instead travel south into the North Atlantic. In conclusion, we suggest a continuous occurrence of marine-terminating glaciers on Svalbard and on East Greenland (due to the elevation of the East Greenland Mountains during the Late Pliocene). The study has highlighted the usefulness of coupled climate model-iceberg trajectory modeling for understanding ice sheet behavior when proximal geological records for Pliocene ice presence or absence are absent or are inconclusive.
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Affiliation(s)
- Y. M. Smith
- School of Earth and EnvironmentUniversity of LeedsLeedsUK
| | - D. J. Hill
- School of Earth and EnvironmentUniversity of LeedsLeedsUK
| | - A. M. Dolan
- School of Earth and EnvironmentUniversity of LeedsLeedsUK
| | - A. M. Haywood
- School of Earth and EnvironmentUniversity of LeedsLeedsUK
| | | | - B. Risebrobakken
- Uni Research ClimateBjerknes Centre for Climate ResearchBergenNorway
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9
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A persistent and dynamic East Greenland Ice Sheet over the past 7.5 million years. Nature 2017; 540:256-260. [PMID: 27929005 DOI: 10.1038/nature20147] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Accepted: 10/06/2016] [Indexed: 11/08/2022]
Abstract
Climate models show that ice-sheet melt will dominate sea-level rise over the coming centuries, but our understanding of ice-sheet variations before the last interglacial 125,000 years ago remains fragmentary. This is because terrestrial deposits of ancient glacial and interglacial periods are overrun and eroded by more recent glacial advances, and are therefore usually rare, isolated and poorly dated. In contrast, material shed almost continuously from continents is preserved as marine sediment that can be analysed to infer the time-varying state of major ice sheets. Here we show that the East Greenland Ice Sheet existed over the past 7.5 million years, as indicated by beryllium and aluminium isotopes (10Be and 26Al) in quartz sand removed by deep, ongoing glacial erosion on land and deposited offshore in the marine sedimentary record. During the early Pleistocene epoch, ice cover in East Greenland was dynamic; in contrast, East Greenland was mostly ice-covered during the mid-to-late Pleistocene. The isotope record we present is consistent with distinct signatures of changes in ice sheet behaviour coincident with major climate transitions. Although our data are continuous, they are from low-deposition-rate sites and sourced only from East Greenland. Consequently, the signal of extensive deglaciation during short, intense interglacials could be missed or blurred, and we cannot distinguish between a remnant ice sheet in the East Greenland highlands and a diminished continent-wide ice sheet. A clearer constraint on the behaviour of the ice sheet during past and, ultimately, future interglacial warmth could be produced by 10Be and 26Al records from a coring site with a higher deposition rate. Nonetheless, our analysis challenges the possibility of complete and extended deglaciation over the past several million years.
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10
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Modelled ocean changes at the Plio-Pleistocene transition driven by Antarctic ice advance. Nat Commun 2017; 8:14376. [PMID: 28252023 PMCID: PMC5337981 DOI: 10.1038/ncomms14376] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Accepted: 12/21/2016] [Indexed: 11/15/2022] Open
Abstract
The Earth underwent a major transition from the warm climates of the Pliocene to the Pleistocene ice ages between 3.2 and 2.6 million years ago. The intensification of Northern Hemisphere Glaciation is the most obvious result of the Plio-Pleistocene transition. However, recent data show that the ocean also underwent a significant change, with the convergence of deep water mass properties in the North Pacific and North Atlantic Ocean. Here we show that the lack of coastal ice in the Pacific sector of Antarctica leads to major reductions in Pacific Ocean overturning and the loss of the modern North Pacific Deep Water (NPDW) mass in climate models of the warmest periods of the Pliocene. These results potentially explain the convergence of global deep water mass properties at the Plio-Pleistocene transition, as Circumpolar Deep Water (CDW) became the common source. Global deep water mass properties converged in the North Pacific and Atlantic oceans during the Pliocene-Pleistocene. Here, using a coupled ocean-atmosphere climate model, the authors show that a reduction in coastal ice in the Pacific sector of Antarctica was likely responsible for this change.
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11
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Ujiié Y, Ishitani Y. Evolution of a Planktonic Foraminifer during Environmental Changes in the Tropical Oceans. PLoS One 2016; 11:e0148847. [PMID: 26886349 PMCID: PMC4757448 DOI: 10.1371/journal.pone.0148847] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Accepted: 01/25/2016] [Indexed: 11/18/2022] Open
Abstract
Ecological adaptation to environmental changes is a strong driver of evolution, enabling speciation of pelagic plankton in the open ocean without the presence of effective physical barriers to gene flow. The tropical ocean environment, which plays an important role in shaping marine biodiversity, has drastically and frequently changed since the Pliocene. Nevertheless, the evolutionary history of tropical pelagic plankton has been poorly understood, as phylogeographic investigations are still in the developing state and paleontological approaches are insufficient to obtain a sequential record from the deep-sea sediments. The planktonic foraminifer Pulleniatina obliquiloculata is widely distributed in the tropical area throughout the world’s oceans, and its phylogeography is well established. It is thus one of the best candidates to examine how past environmental changes may have shifted the spatial distribution and affected the diversification of tropical pelagic plankton. Such an examination requires the divergence history of the planktonic foraminifers, yet the gene marker (partial small subunit (SSU) rDNA) previously used for phylogeographic studies was not powerful enough to achieve a high accuracy in estimating the divergence times. The present study focuses on improving the precision of divergence time estimates for the splits between sibling species (genetic types) of planktonic foraminifers by increasing the number of genes as well as the number of nucleotide bases used for molecular clock estimates. We have amplified the entire coding regions of two ribosomal RNA genes (SSU rDNA and large subunit (LSU) rDNA) of three genetic types of P. obliquiloculata and two closely related species for the first time and applied them to the Bayesian relaxed clock method. The comparison of the credible intervals of the four datasets consisting either of sequences of the partial SSU rDNA, the complete SSU rDNA, LSU rDNA, or a combination of both genes (SSU+LSU) clearly demonstrated that the two-gene dataset improved the accuracy of divergence time estimates. The P. obliquiloculata lineage diverged twice, first at the end of the Pliocene (3.1 Ma) and again in the middle Pleistocene (1.4 Ma). Both timings coincided with the environmental changes, which indirectly involved geographic separation of populations. The habitat of P. obliquiloculata was expanded toward the higher latitudinal zones during the stable warm periods and subsequently placed on the steep environmental gradients following the global cooling. Different environmental conditions in the stable warm tropics and unstable higher latitudes may have triggered ecological divergence among the populations, leading to adaptive differentiation and eventually speciation. A comprehensive analysis of divergence time estimates combined with phylogeography enabled us to reveal the evolutionary history of the pelagic plankton and to find the potential paleoenvironmental events, which could have changed their biogeography and ecology.
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Affiliation(s)
- Yurika Ujiié
- Department of Biology, Shinshu University, Matsumoto, Nagano, Japan
- * E-mail:
| | - Yoshiyuki Ishitani
- Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Chiba, Japan
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12
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Yuan ML, Zhang QL, Wang ZF, Guo ZL, Bao GS. Molecular Phylogeny of Grassland Caterpillars (Lepidoptera: Lymantriinae: Gynaephora) Endemic to the Qinghai-Tibetan Plateau. PLoS One 2015; 10:e0127257. [PMID: 26053874 PMCID: PMC4459697 DOI: 10.1371/journal.pone.0127257] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2014] [Accepted: 04/14/2015] [Indexed: 11/19/2022] Open
Abstract
Gynaephora (Lepidoptera Erebidae: Lymantriinae) is a small genus, consisting of 15 nominated species, of which eight species are endemic to the Qinghai-Tibetan Plateau (QTP). In this study, we employed both mitochondrial and nuclear loci to infer a molecular phylogeny for the eight QTP Gynaephora spp. We used the phylogeny to estimate divergence dates in a molecular dating analysis and to delimit species. This information allowed us to investigate associations between the diversification history of the eight QTP species and geological and climatic events. Phylogenetic analyses indicated that the eight QTP species formed a monophyletic group with strong supports in both Bayesian and maximum likelihood analyses. The low K2P genetic distances between the eight QTP species suggested that diversification occurred relatively quickly and recently. Out of the eight species, five species were highly supported as monophyletic, which were also recovered by species delimitation analyses. Samples of the remaining three species (G. aureata, G. rouergensis, and G. minora) mixed together, suggesting that further studies using extensive population sampling and comprehensive morphological approaches are necessary to clarify their species status. Divergence time estimation results demonstrated that the diversification and speciation of Gynaephora on the QTP began during the late Miocene/early Pliocene and was potentially affected by the QTP uplift and associated climate changes during this time.
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Affiliation(s)
- Ming-Long Yuan
- State Key Laboratory of Grassland Agro-Ecosystems, College of Pastoral Agricultural Science and Technology, Lanzhou University, Lanzhou, Gansu, People's Republic of China
| | - Qi-Lin Zhang
- State Key Laboratory of Grassland Agro-Ecosystems, College of Pastoral Agricultural Science and Technology, Lanzhou University, Lanzhou, Gansu, People's Republic of China
| | - Zhao-Feng Wang
- State Key Laboratory of Grassland Agro-Ecosystems, College of Pastoral Agricultural Science and Technology, Lanzhou University, Lanzhou, Gansu, People's Republic of China
| | - Zhong-Long Guo
- State Key Laboratory of Grassland Agro-Ecosystems, College of Pastoral Agricultural Science and Technology, Lanzhou University, Lanzhou, Gansu, People's Republic of China
| | - Gen-Sheng Bao
- State Key Laboratory of Grassland Agro-Ecosystems, College of Pastoral Agricultural Science and Technology, Lanzhou University, Lanzhou, Gansu, People's Republic of China
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13
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Yamane M, Yokoyama Y, Abe-Ouchi A, Obrochta S, Saito F, Moriwaki K, Matsuzaki H. Exposure age and ice-sheet model constraints on Pliocene East Antarctic ice sheet dynamics. Nat Commun 2015; 6:7016. [PMID: 25908601 PMCID: PMC4421805 DOI: 10.1038/ncomms8016] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2014] [Accepted: 03/24/2015] [Indexed: 11/09/2022] Open
Abstract
The Late Pliocene epoch is a potential analogue for future climate in a warming world. Here we reconstruct Plio-Pleistocene East Antarctic Ice Sheet (EAIS) variability using cosmogenic nuclide exposure ages and model simulations to better understand ice sheet behaviour under such warm conditions. New and previously published exposure ages indicate interior-thickening during the Pliocene. An ice sheet model with mid-Pliocene boundary conditions also results in interior thickening and suggests that both the Wilkes Subglacial and Aurora Basins largely melted, offsetting increased ice volume. Considering contributions from West Antarctica and Greenland, this is consistent with the most recent IPCC AR5 estimate, which indicates that the Pliocene sea level likely did not exceed +20 m on Milankovitch timescales. The inception of colder climate since ∼3 Myr has increased the sea ice cover and inhibited active moisture transport to Antarctica, resulting in reduced ice sheet thickness, at least in coastal areas.
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Affiliation(s)
- Masako Yamane
- Atmosphere and Ocean Research Institute, University of Tokyo, 5-1-5 Kashiwanoha, Chiba 277-8564, Japan
| | - Yusuke Yokoyama
- Atmosphere and Ocean Research Institute, University of Tokyo, 5-1-5 Kashiwanoha, Chiba 277-8564, Japan.,Department of Earth and Planetary Sciences, University of Tokyo, 7-3-1 Hongo, Bunkyoku, Tokyo 113-0033, Japan.,Japan Agency for Marine-Earth Science and Technology, 2-15 Natsushima-cho, Yokosuka 237-0061, Japan
| | - Ayako Abe-Ouchi
- Atmosphere and Ocean Research Institute, University of Tokyo, 5-1-5 Kashiwanoha, Chiba 277-8564, Japan.,Department of Earth and Planetary Sciences, University of Tokyo, 7-3-1 Hongo, Bunkyoku, Tokyo 113-0033, Japan.,Japan Agency for Marine-Earth Science and Technology, 3173-25, Showa-machi, Kanazawa-ku, Yokohama, Kanagawa 236-0001, Japan
| | - Stephen Obrochta
- Atmosphere and Ocean Research Institute, University of Tokyo, 5-1-5 Kashiwanoha, Chiba 277-8564, Japan.,Faculty of International Resource Science, Akita University 1-1 Tegata Gakuin-cho, Akita 010-8502, Japan
| | - Fuyuki Saito
- Japan Agency for Marine-Earth Science and Technology, 3173-25, Showa-machi, Kanazawa-ku, Yokohama, Kanagawa 236-0001, Japan
| | - Kiichi Moriwaki
- National Institute of Polar Research, 10-3, Midoricho, Tachikawa, Tokyo 190-8518, Japan
| | - Hiroyuki Matsuzaki
- The University Museum, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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14
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Hu JJ, Xing YW, Turkington R, Jacques FMB, Su T, Huang YJ, Zhou ZK. A new positive relationship between pCO2 and stomatal frequency in Quercus guyavifolia (Fagaceae): a potential proxy for palaeo-CO2 levels. ANNALS OF BOTANY 2015; 115:777-88. [PMID: 25681824 PMCID: PMC4373289 DOI: 10.1093/aob/mcv007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2014] [Revised: 12/02/2014] [Accepted: 01/05/2015] [Indexed: 05/11/2023]
Abstract
BACKGROUND AND AIMS The inverse relationship between atmospheric CO2 partial pressure (pCO2) and stomatal frequency in many species of plants has been widely used to estimate palaeoatmospheric CO2 (palaeo-CO2) levels; however, the results obtained have been quite variable. This study attempts to find a potential new proxy for palaeo-CO2 levels by analysing stomatal frequency in Quercus guyavifolia (Q. guajavifolia, Fagaceae), an extant dominant species of sclerophyllous forests in the Himalayas with abundant fossil relatives. METHODS Stomatal frequency was analysed for extant samples of Q. guyavifolia collected from17 field sites at altitudes ranging between 2493 and 4497 m. Herbarium specimens collected between 1926 and 2011 were also examined. Correlations of pCO2-stomatal frequency were determined using samples from both sources, and these were then applied to Q. preguyavaefolia fossils in order to estimate palaeo-CO2 concentrations for two late-Pliocene floras in south-western China. KEY RESULTS In contrast to the negative correlations detected for most other species that have been studied, a positive correlation between pCO2 and stomatal frequency was determined in Q. guyavifolia sampled from both extant field collections and historical herbarium specimens. Palaeo-CO2 concentrations were estimated to be approx. 180-240 ppm in the late Pliocene, which is consistent with most other previous estimates. CONCLUSIONS A new positive relationship between pCO2 and stomatal frequency in Q. guyavifolia is presented, which can be applied to the fossils closely related to this species that are widely distributed in the late-Cenozoic strata in order to estimate palaeo-CO2 concentrations. The results show that it is valid to use a positive relationship to estimate palaeo-CO2 concentrations, and the study adds to the variety of stomatal density/index relationships that available for estimating pCO2. The physiological mechanisms underlying this positive response are unclear, however, and require further research.
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Affiliation(s)
- Jin-Jin Hu
- Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China, Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla 666303, China, Institute of Systematic Botany, University of Zürich, Zürich 8008, Switzerland, Department of Botany, and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada, V6T 1Z4 and University of Chinese Academy of Sciences, Beijing 100049, China Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China, Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla 666303, China, Institute of Systematic Botany, University of Zürich, Zürich 8008, Switzerland, Department of Botany, and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada, V6T 1Z4 and University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yao-Wu Xing
- Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China, Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla 666303, China, Institute of Systematic Botany, University of Zürich, Zürich 8008, Switzerland, Department of Botany, and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada, V6T 1Z4 and University of Chinese Academy of Sciences, Beijing 100049, China
| | - Roy Turkington
- Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China, Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla 666303, China, Institute of Systematic Botany, University of Zürich, Zürich 8008, Switzerland, Department of Botany, and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada, V6T 1Z4 and University of Chinese Academy of Sciences, Beijing 100049, China
| | - Frédéric M B Jacques
- Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China, Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla 666303, China, Institute of Systematic Botany, University of Zürich, Zürich 8008, Switzerland, Department of Botany, and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada, V6T 1Z4 and University of Chinese Academy of Sciences, Beijing 100049, China
| | - Tao Su
- Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China, Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla 666303, China, Institute of Systematic Botany, University of Zürich, Zürich 8008, Switzerland, Department of Botany, and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada, V6T 1Z4 and University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yong-Jiang Huang
- Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China, Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla 666303, China, Institute of Systematic Botany, University of Zürich, Zürich 8008, Switzerland, Department of Botany, and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada, V6T 1Z4 and University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zhe-Kun Zhou
- Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China, Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla 666303, China, Institute of Systematic Botany, University of Zürich, Zürich 8008, Switzerland, Department of Botany, and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada, V6T 1Z4 and University of Chinese Academy of Sciences, Beijing 100049, China Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China, Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla 666303, China, Institute of Systematic Botany, University of Zürich, Zürich 8008, Switzerland, Department of Botany, and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada, V6T 1Z4 and University of Chinese Academy of Sciences, Beijing 100049, China
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15
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Martínez-Botí MA, Foster GL, Chalk TB, Rohling EJ, Sexton PF, Lunt DJ, Pancost RD, Badger MPS, Schmidt DN. Plio-Pleistocene climate sensitivity evaluated using high-resolution CO2 records. Nature 2015; 518:49-54. [PMID: 25652996 DOI: 10.1038/nature14145] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Accepted: 12/05/2014] [Indexed: 11/09/2022]
Abstract
Theory and climate modelling suggest that the sensitivity of Earth's climate to changes in radiative forcing could depend on the background climate. However, palaeoclimate data have thus far been insufficient to provide a conclusive test of this prediction. Here we present atmospheric carbon dioxide (CO2) reconstructions based on multi-site boron-isotope records from the late Pliocene epoch (3.3 to 2.3 million years ago). We find that Earth's climate sensitivity to CO2-based radiative forcing (Earth system sensitivity) was half as strong during the warm Pliocene as during the cold late Pleistocene epoch (0.8 to 0.01 million years ago). We attribute this difference to the radiative impacts of continental ice-volume changes (the ice-albedo feedback) during the late Pleistocene, because equilibrium climate sensitivity is identical for the two intervals when we account for such impacts using sea-level reconstructions. We conclude that, on a global scale, no unexpected climate feedbacks operated during the warm Pliocene, and that predictions of equilibrium climate sensitivity (excluding long-term ice-albedo feedbacks) for our Pliocene-like future (with CO2 levels up to maximum Pliocene levels of 450 parts per million) are well described by the currently accepted range of an increase of 1.5 K to 4.5 K per doubling of CO2.
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Affiliation(s)
- M A Martínez-Botí
- Ocean and Earth Science, University of Southampton, National Oceanography Centre Southampton, Southampton, SO14 3ZH, UK
| | - G L Foster
- Ocean and Earth Science, University of Southampton, National Oceanography Centre Southampton, Southampton, SO14 3ZH, UK
| | - T B Chalk
- Ocean and Earth Science, University of Southampton, National Oceanography Centre Southampton, Southampton, SO14 3ZH, UK
| | - E J Rohling
- 1] Ocean and Earth Science, University of Southampton, National Oceanography Centre Southampton, Southampton, SO14 3ZH, UK [2] Research School of Earth Sciences, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - P F Sexton
- Centre for Earth, Planetary, Space and Astronomical Research, The Open University, Milton Keynes, MK7 6AA, UK
| | - D J Lunt
- 1] School of Geographical Sciences, University of Bristol, University Road, Bristol, BS8 1SS, UK [2] The Cabot Institute, University of Bristol, Bristol BS8 1UJ, UK
| | - R D Pancost
- 1] The Cabot Institute, University of Bristol, Bristol BS8 1UJ, UK [2] Organic Geochemistry Unit, School of Chemistry, University of Bristol, Bristol BS8 1TS, UK
| | - M P S Badger
- 1] The Cabot Institute, University of Bristol, Bristol BS8 1UJ, UK [2] Organic Geochemistry Unit, School of Chemistry, University of Bristol, Bristol BS8 1TS, UK
| | - D N Schmidt
- 1] The Cabot Institute, University of Bristol, Bristol BS8 1UJ, UK [2] School of Earth Sciences, University of Bristol, Wills Memorial Building, Bristol, BS8 1RJ, UK
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16
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Bai YJ, Chen LQ, Ranhotra PS, Wang Q, Wang YF, Li CS. Reconstructing atmospheric CO2 during the Plio-Pleistocene transition by fossil Typha. GLOBAL CHANGE BIOLOGY 2015; 21:874-81. [PMID: 24990109 DOI: 10.1111/gcb.12670] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Accepted: 06/16/2014] [Indexed: 05/27/2023]
Abstract
The Earth has undergone a significant climate switch from greenhouse to icehouse during the Plio-Pleistocene transition (PPT) around 2.7-2.4 million years ago (Ma), marked by the intensification of the Northern Hemisphere glaciation (NHG) ~2.7 Ma. Evidence based on oceanic CO2 [(CO2)aq], supposed to be in close equilibrium with the atmospheric CO2 [(CO2)atm], suggests that the CO2 decline might drive such climate cooling. However, the rarity of direct evidence from [CO2]atm during the interval prevents determination of the atmospheric CO2 level and further assessment on the impact of its fluctuation. Here, we reconstruct the [CO2]atm level during 2.77-2.52 Ma based on a new developed proxy of stomatal index on Typha orientalis leaves from Shanxi, North China, and depict the first [CO2]atm curve over the past 5 Ma by using stomata-based [CO2]atm data. Comparisons of the terrestrial-based [CO2]atm and the existed marine-based [CO2]aq curves show a similar general trend but with different intensity of fluctuations. Our data reveal that the high peak of [CO2]atm occurred at 2.77-2.52 Ma with a lower [CO2]aq background. The subsequent sharp fall in [CO2]atm level might be responsible for the intensification of the NHG based on their general temporal synchronism. These findings shed a significant light for our understanding toward the [CO2]atm changes and its ecological impact since 5 Ma.
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Affiliation(s)
- Yun-Jun Bai
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China; University of Chinese Academy of Sciences, Beijing, 100049, China
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17
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Pacific freshening drives Pliocene cooling and Asian monsoon intensification. Sci Rep 2014; 4:5474. [PMID: 24969361 PMCID: PMC4073123 DOI: 10.1038/srep05474] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Accepted: 06/05/2014] [Indexed: 11/08/2022] Open
Abstract
The monsoon is a fundamental component of Earth's climate. The Pliocene warm period is characterized by long-term global cooling yet concurrent monsoon dynamics are poorly known. Here we present the first fully quantified and calibrated reconstructions of separate Pliocene air temperature and East Asian summer monsoon precipitation histories on the Chinese Loess Plateau through joint analysis of loess/red clay magnetic parameters with different sensitivities to air temperature and precipitation. East Asian summer monsoon precipitation shows an intensified trend, paradoxically at the same time that climate cooled. We propose a hitherto unrecognized feedback where persistently intensified East Asian summer monsoon during the late Pliocene, triggered by the gradual closure of the Panama Seaway, reinforced late Pliocene Pacific freshening, sea-ice development and ice volume increase, culminating in initiation of the extensive Northern Hemisphere glaciations of the Quaternary Ice Age. This feedback mechanism represents a fundamental reinterpretation of the origin of the Quaternary glaciations and the impact of the monsoon.
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18
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Yan Q, Zhang Z, Wang H, Zhang R. Simulation of Greenland ice sheet during the mid-Pliocene warm period. CHINESE SCIENCE BULLETIN 2013. [DOI: 10.1007/s11434-013-0001-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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19
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De Schepper S, Groeneveld J, Naafs BDA, Van Renterghem C, Hennissen J, Head MJ, Louwye S, Fabian K. Northern hemisphere glaciation during the globally warm early Late Pliocene. PLoS One 2013; 8:e81508. [PMID: 24349081 PMCID: PMC3861316 DOI: 10.1371/journal.pone.0081508] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Accepted: 10/14/2013] [Indexed: 11/19/2022] Open
Abstract
The early Late Pliocene (3.6 to ∼3.0 million years ago) is the last extended interval in Earth's history when atmospheric CO2 concentrations were comparable to today's and global climate was warmer. Yet a severe global glaciation during marine isotope stage (MIS) M2 interrupted this phase of global warmth ∼3.30 million years ago, and is seen as a premature attempt of the climate system to establish an ice-age world. Here we propose a conceptual model for the glaciation and deglaciation of MIS M2 based on geochemical and palynological records from five marine sediment cores along a Caribbean to eastern North Atlantic transect. Our records show that increased Pacific-to-Atlantic flow via the Central American Seaway weakened the North Atlantic Current and attendant northward heat transport prior to MIS M2. The consequent cooling of the northern high latitude oceans permitted expansion of the continental ice sheets during MIS M2, despite near-modern atmospheric CO2 concentrations. Sea level drop during this glaciation halted the inflow of Pacific water to the Atlantic via the Central American Seaway, allowing the build-up of a Caribbean Warm Pool. Once this warm pool was large enough, the Gulf Stream-North Atlantic Current system was reinvigorated, leading to significant northward heat transport that terminated the glaciation. Before and after MIS M2, heat transport via the North Atlantic Current was crucial in maintaining warm climates comparable to those predicted for the end of this century.
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Affiliation(s)
- Stijn De Schepper
- Department of Earth Science, University of Bergen, Bergen, Norway
- Geosciences Department, University of Bremen, Bremen, Germany
- * E-mail:
| | - Jeroen Groeneveld
- MARUM – Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany
| | - B. David A Naafs
- Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany
| | | | - Jan Hennissen
- Department of Earth Sciences, University of Toronto, Toronto, Ontario, Canada
| | - Martin J. Head
- Department of Earth Sciences, University of Toronto, Toronto, Ontario, Canada
- Department of Earth Sciences, Brock University, St. Catharines, Ontario, Canada
| | - Stephen Louwye
- Research Unit Palaeontology, Ghent University, Ghent, Belgium
| | - Karl Fabian
- Norwegian Geological Survey, Trondheim, Norway
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20
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Zhang YG, Pagani M, Liu Z, Bohaty SM, Deconto R. A 40-million-year history of atmospheric CO(2). PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2013; 371:20130096. [PMID: 24043869 DOI: 10.1098/rsta.2013.0096] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The alkenone-pCO2 methodology has been used to reconstruct the partial pressure of ancient atmospheric carbon dioxide (pCO2) for the past 45 million years of Earth's history (Middle Eocene to Pleistocene epochs). The present long-term CO2 record is a composite of data from multiple ocean localities that express a wide range of oceanographic and algal growth conditions that potentially bias CO2 results. In this study, we present a pCO2 record spanning the past 40 million years from a single marine locality, Ocean Drilling Program Site 925 located in the western equatorial Atlantic Ocean. The trends and absolute values of our new CO2 record site are broadly consistent with previously published multi-site alkenone-CO2 results. However, new pCO2 estimates for the Middle Miocene are notably higher than published records, with average pCO2 concentrations in the range of 400-500 ppm. Our results are generally consistent with recent pCO2 estimates based on boron isotope-pH data and stomatal index records, and suggest that CO2 levels were highest during a period of global warmth associated with the Middle Miocene Climatic Optimum (17-14 million years ago, Ma), followed by a decline in CO2 during the Middle Miocene Climate Transition (approx. 14 Ma). Several relationships remain contrary to expectations. For example, benthic foraminiferal δ(18)O records suggest a period of deglaciation and/or high-latitude warming during the latest Oligocene (27-23 Ma) that, based on our results, occurred concurrently with a long-term decrease in CO2 levels. Additionally, a large positive δ(18)O excursion near the Oligocene-Miocene boundary (the Mi-1 event, approx. 23 Ma), assumed to represent a period of glacial advance and retreat on Antarctica, is difficult to explain by our CO2 record alone given what is known of Antarctic ice sheet history and the strong hysteresis of the East Antarctic Ice Sheet once it has grown to continental dimensions. We also demonstrate that in the Neogene with low CO2 levels, algal carbon concentrating mechanisms and spontaneous biocarbonate-CO2 conversions are likely to play a more important role in algal carbon fixation, which provides a potential bias to the alkenone-pCO2 method.
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Affiliation(s)
- Yi Ge Zhang
- Department of Geology and Geophysics, Yale University, , New Haven, CT 06520-8109, USA
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21
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Lunt DJ, Elderfield H, Pancost R, Ridgwell A, Foster GL, Haywood A, Kiehl J, Sagoo N, Shields C, Stone EJ, Valdes P. Warm climates of the past--a lesson for the future? PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2013; 371:20130146. [PMID: 24043873 PMCID: PMC3785815 DOI: 10.1098/rsta.2013.0146] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
This Discussion Meeting Issue of the Philosophical Transactions A had its genesis in a Discussion Meeting of the Royal Society which took place on 10-11 October 2011. The Discussion Meeting, entitled 'Warm climates of the past: a lesson for the future?', brought together 16 eminent international speakers from the field of palaeoclimate, and was attended by over 280 scientists and members of the public. Many of the speakers have contributed to the papers compiled in this Discussion Meeting Issue. The papers summarize the talks at the meeting, and present further or related work. This Discussion Meeting Issue asks to what extent information gleaned from the study of past climates can aid our understanding of future climate change. Climate change is currently an issue at the forefront of environmental science, and also has important sociological and political implications. Most future predictions are carried out by complex numerical models; however, these models cannot be rigorously tested for scenarios outside of the modern, without making use of past climate data. Furthermore, past climate data can inform our understanding of how the Earth system operates, and can provide important contextual information related to environmental change. All past time periods can be useful in this context; here, we focus on past climates that were warmer than the modern climate, as these are likely to be the most similar to the future. This introductory paper is not meant as a comprehensive overview of all work in this field. Instead, it gives an introduction to the important issues therein, using the papers in this Discussion Meeting Issue, and other works from all the Discussion Meeting speakers, as exemplars of the various ways in which past climates can inform projections of future climate. Furthermore, we present new work that uses a palaeo constraint to quantitatively inform projections of future equilibrium ice sheet change.
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Affiliation(s)
- D. J. Lunt
- Cabot Institute, and School of Geographical Sciences, University of Bristol, University Road, Bristol BS8 1SS, UK
| | - H. Elderfield
- Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UK
| | - R. Pancost
- Cabot Institute, and School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK
| | - A. Ridgwell
- Cabot Institute, and School of Geographical Sciences, University of Bristol, University Road, Bristol BS8 1SS, UK
| | - G. L. Foster
- Ocean and Earth Science, University of Southampton, European Way, Southampton SO14 3ZH, UK
| | - A. Haywood
- School of Earth and Environment, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, UK
| | - J. Kiehl
- Climate and Global Dynamics, National Center for Atmospheric Research, 1850 Table Mesa Drive, Boulder, CO 80305, USA
| | - N. Sagoo
- Cabot Institute, and School of Geographical Sciences, University of Bristol, University Road, Bristol BS8 1SS, UK
| | - C. Shields
- Climate and Global Dynamics, National Center for Atmospheric Research, 1850 Table Mesa Drive, Boulder, CO 80305, USA
| | - E. J. Stone
- Cabot Institute, and School of Geographical Sciences, University of Bristol, University Road, Bristol BS8 1SS, UK
| | - P. Valdes
- Cabot Institute, and School of Geographical Sciences, University of Bristol, University Road, Bristol BS8 1SS, UK
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22
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Haywood AM, Dolan AM, Pickering SJ, Dowsett HJ, McClymont EL, Prescott CL, Salzmann U, Hill DJ, Hunter SJ, Lunt DJ, Pope JO, Valdes PJ. On the identification of a Pliocene time slice for data-model comparison. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2013; 371:20120515. [PMID: 24043865 PMCID: PMC3785814 DOI: 10.1098/rsta.2012.0515] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The characteristics of the mid-Pliocene warm period (mPWP: 3.264-3.025 Ma BP) have been examined using geological proxies and climate models. While there is agreement between models and data, details of regional climate differ. Uncertainties in prescribed forcings and in proxy data limit the utility of the interval to understand the dynamics of a warmer than present climate or evaluate models. This uncertainty comes, in part, from the reconstruction of a time slab rather than a time slice, where forcings required by climate models can be more adequately constrained. Here, we describe the rationale and approach for identifying a time slice(s) for Pliocene environmental reconstruction. A time slice centred on 3.205 Ma BP (3.204-3.207 Ma BP) has been identified as a priority for investigation. It is a warm interval characterized by a negative benthic oxygen isotope excursion (0.21-0.23‰) centred on marine isotope stage KM5c (KM5.3). It occurred during a period of orbital forcing that was very similar to present day. Climate model simulations indicate that proxy temperature estimates are unlikely to be significantly affected by orbital forcing for at least a precession cycle centred on the time slice, with the North Atlantic potentially being an important exception.
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Affiliation(s)
- Alan M. Haywood
- School of Earth and Environment, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, UK
| | - Aisling M. Dolan
- School of Earth and Environment, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, UK
| | - Steven J. Pickering
- School of Earth and Environment, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, UK
| | - Harry J. Dowsett
- Eastern Geology and Paleoclimate Science Center, USGS, 926A National Center, Reston, VA 20192, USA
| | - Erin L. McClymont
- Department of Geography, Durham University, South Road, Durham DH1 3LE, UK
| | - Caroline L. Prescott
- School of Earth and Environment, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, UK
| | - Ulrich Salzmann
- School of Built and Natural Environment, Northumbria University, Ellison Building, Newcastle upon Tyne NE1 8ST, UK
| | - Daniel J. Hill
- School of Earth and Environment, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, UK
- British Geological Survey, Environmental Science Centre, Keyworth, Nottingham NG12 5GG, UK
| | - Stephen J. Hunter
- School of Earth and Environment, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, UK
| | - Daniel J. Lunt
- School of Geographical Sciences, University of Bristol, University Road, Bristol BS8 1SS, UK
| | - James O. Pope
- School of Earth and Environment, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, UK
| | - Paul J. Valdes
- School of Geographical Sciences, University of Bristol, University Road, Bristol BS8 1SS, UK
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23
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Li S, He K, Yu FH, Yang QS. Molecular phylogeny and biogeography of Petaurista inferred from the cytochrome b gene, with implications for the taxonomic status of P. caniceps, P. marica and P. sybilla. PLoS One 2013; 8:e70461. [PMID: 23922995 PMCID: PMC3724786 DOI: 10.1371/journal.pone.0070461] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2012] [Accepted: 06/24/2013] [Indexed: 11/19/2022] Open
Abstract
The polymorphic genus Petaurista includes a group of diverse species and subspecies that are adapted for gliding and arboreal life. This morphological diversity has resulted in taxonomic discrepancies, and molecular phylogenetic studies have been limited by taxon sampling. To clarify this controversial taxonomy, we used the cytochrome b gene to reconstruct the phylogeny to obtain a more accurate picture of the evolutionary relationships, species differentiation and divergence pattern of Petaurista. The results revealed a significant inconsistency between taxonomic designations, phylogeny and genetic distances. When 6 recognized species were included, species delimitation revealed 15 putative species, a finding that warrants a comprehensive morphological diagnosis and a re-assessment of the species status. The validity of P. caniceps and P. marica was discussed. An estimation of the molecular divergence time demonstrated that the diversification and speciation of Petaurista began during the later Miocene and may have been affected by the uplifting of the Qinghai-Tibet plateau and subsequent climate change.
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Affiliation(s)
- Song Li
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, China.
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Fedorov AV, Brierley CM, Lawrence KT, Liu Z, Dekens PS, Ravelo AC. Patterns and mechanisms of early Pliocene warmth. Nature 2013; 496:43-9. [PMID: 23552943 DOI: 10.1038/nature12003] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Accepted: 02/11/2013] [Indexed: 11/09/2022]
Abstract
About five to four million years ago, in the early Pliocene epoch, Earth had a warm, temperate climate. The gradual cooling that followed led to the establishment of modern temperature patterns, possibly in response to a decrease in atmospheric CO2 concentration, of the order of 100 parts per million, towards preindustrial values. Here we synthesize the available geochemical proxy records of sea surface temperature and show that, compared with that of today, the early Pliocene climate had substantially lower meridional and zonal temperature gradients but similar maximum ocean temperatures. Using an Earth system model, we show that none of the mechanisms currently proposed to explain Pliocene warmth can simultaneously reproduce all three crucial features. We suggest that a combination of several dynamical feedbacks underestimated in the models at present, such as those related to ocean mixing and cloud albedo, may have been responsible for these climate conditions.
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Affiliation(s)
- A V Fedorov
- Department of Geology and Geophysics, Yale University, New Haven, Connecticut 06511, USA.
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Nielsen T, Kuijpers A. Only 5 southern Greenland shelf edge glaciations since the early Pliocene. Sci Rep 2013; 3:1875. [PMID: 23698710 PMCID: PMC3662008 DOI: 10.1038/srep01875] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2013] [Accepted: 04/25/2013] [Indexed: 11/17/2022] Open
Abstract
Much uncertainty exists about the history of the Greenland Ice Sheet (GIS), particularly as to the frequency of extreme shelf edge glaciations. Because the last glaciation removed most of the record of earlier GIS extent on land and shelf exploration of the older GIS glacial record requires the use of deeper marine archives. Here we present seismic evidence for the frequency of extreme shelf edge glaciations offshore southwest Greenland. Our findings reveal that since the GIS formation only 5 glaciations were characterized by an ice sheet covering the entire shelf of southern Greenland. We estimate an age of around 4.5 million years (my) for the oldest episode and found that such extreme GIS expansions may have occur here only 3 times within the past c. 1.5 my. We thus conclude that the first large shelf edge glaciation of southern Greenland did occur prior to the Pliocene warmth epoch.
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Affiliation(s)
- Tove Nielsen
- Geological Survey of Denmark and Greenland, Øster Voldgade 10, 1350 Copenhagen K, Denmark
| | - Antoon Kuijpers
- Geological Survey of Denmark and Greenland, Øster Voldgade 10, 1350 Copenhagen K, Denmark
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26
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Late Miocene decoupling of oceanic warmth and atmospheric carbon dioxide forcing. Nature 2012; 486:97-100. [PMID: 22678287 DOI: 10.1038/nature11200] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2011] [Accepted: 05/02/2012] [Indexed: 11/08/2022]
Abstract
Deep-time palaeoclimate studies are vitally important for developing a complete understanding of climate responses to changes in the atmospheric carbon dioxide concentration (that is, the atmospheric partial pressure of CO(2), p(co(2))). Although past studies have explored these responses during portions of the Cenozoic era (the most recent 65.5 million years (Myr) of Earth history), comparatively little is known about the climate of the late Miocene (∼12-5 Myr ago), an interval with p(co(2)) values of only 200-350 parts per million by volume but nearly ice-free conditions in the Northern Hemisphere and warmer-than-modern temperatures on the continents. Here we present quantitative geochemical sea surface temperature estimates from the Miocene mid-latitude North Pacific Ocean, and show that oceanic warmth persisted throughout the interval of low p(co(2)) ∼12-5 Myr ago. We also present new stable isotope measurements from the western equatorial Pacific that, in conjunction with previously published data, reveal a long-term trend of thermocline shoaling in the equatorial Pacific since ∼13 Myr ago. We propose that a relatively deep global thermocline, reductions in low-latitude gradients in sea surface temperature, and cloud and water vapour feedbacks may help to explain the warmth of the late Miocene. Additional shoaling of the thermocline after 5 Myr ago probably explains the stronger coupling between p(co(2)), sea surface temperatures and climate that is characteristic of the more recent Pliocene and Pleistocene epochs.
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Antarctic and Southern Ocean influences on Late Pliocene global cooling. Proc Natl Acad Sci U S A 2012; 109:6423-8. [PMID: 22496594 DOI: 10.1073/pnas.1112248109] [Citation(s) in RCA: 132] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The influence of Antarctica and the Southern Ocean on Late Pliocene global climate reconstructions has remained ambiguous due to a lack of well-dated Antarctic-proximal, paleoenvironmental records. Here we present ice sheet, sea-surface temperature, and sea ice reconstructions from the ANDRILL AND-1B sediment core recovered from beneath the Ross Ice Shelf. We provide evidence for a major expansion of an ice sheet in the Ross Sea that began at ∼3.3 Ma, followed by a coastal sea surface temperature cooling of ∼2.5 °C, a stepwise expansion of sea ice, and polynya-style deep mixing in the Ross Sea between 3.3 and 2.5 Ma. The intensification of Antarctic cooling resulted in strengthened westerly winds and invigorated ocean circulation. The associated northward migration of Southern Ocean fronts has been linked with reduced Atlantic Meridional Overturning Circulation by restricting surface water connectivity between the ocean basins, with implications for heat transport to the high latitudes of the North Atlantic. While our results do not exclude low-latitude mechanisms as drivers for Pliocene cooling, they indicate an additional role played by southern high-latitude cooling during development of the bipolar world.
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Xavier R, Santos AM, Harris DJ, Sezgin M, Machado M, Branco M. Phylogenetic analysis of the north-east Atlantic and Mediterranean species of the genus Stenosoma (Isopoda, Valvifera, Idoteidae). ZOOL SCR 2012. [DOI: 10.1111/j.1463-6409.2012.00537.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Southern Ocean dust-climate coupling over the past four million years. Nature 2011; 476:312-5. [PMID: 21814203 DOI: 10.1038/nature10310] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2011] [Accepted: 06/16/2011] [Indexed: 11/08/2022]
Abstract
Dust has the potential to modify global climate by influencing the radiative balance of the atmosphere and by supplying iron and other essential limiting micronutrients to the ocean. Indeed, dust supply to the Southern Ocean increases during ice ages, and 'iron fertilization' of the subantarctic zone may have contributed up to 40 parts per million by volume (p.p.m.v.) of the decrease (80-100 p.p.m.v.) in atmospheric carbon dioxide observed during late Pleistocene glacial cycles. So far, however, the magnitude of Southern Ocean dust deposition in earlier times and its role in the development and evolution of Pleistocene glacial cycles have remained unclear. Here we report a high-resolution record of dust and iron supply to the Southern Ocean over the past four million years, derived from the analysis of marine sediments from ODP Site 1090, located in the Atlantic sector of the subantarctic zone. The close correspondence of our dust and iron deposition records with Antarctic ice core reconstructions of dust flux covering the past 800,000 years (refs 8, 9) indicates that both of these archives record large-scale deposition changes that should apply to most of the Southern Ocean, validating previous interpretations of the ice core data. The extension of the record beyond the interval covered by the Antarctic ice cores reveals that, in contrast to the relatively gradual intensification of glacial cycles over the past three million years, Southern Ocean dust and iron flux rose sharply at the Mid-Pleistocene climatic transition around 1.25 million years ago. This finding complements previous observations over late Pleistocene glacial cycles, providing new evidence of a tight connection between high dust input to the Southern Ocean and the emergence of the deep glaciations that characterize the past one million years of Earth history.
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Wolff EW. Greenhouse gases in the Earth system: a palaeoclimate perspective. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2011; 369:2133-2147. [PMID: 21502180 DOI: 10.1098/rsta.2010.0225] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
While the trends in greenhouse gas concentrations in recent decades are clear, their significance is only revealed when viewed in the context of a longer time period. Fortunately, the air bubbles in polar ice cores provide an unusually direct method of determining the concentrations of stable gases over a period of (so far) 800,000 years. Measurements on different cores with varying characteristics, as well as an overlap of ice-core and atmospheric measurements covering the same time period, show that the ice-core record provides a faithful record of changing atmospheric composition. The mixing ratio of CO(2) is now 30 per cent higher than any value observed in the ice-core record, while methane is more than double any observed value; the rate of change also appears extraordinary compared with natural changes. Before the period when anthropogenic changes have dominated, there are very interesting natural changes in concentration, particularly across glacial/interglacial cycles, and these can be used to understand feedbacks in the Earth system. The phasing of changes in temperature and CO(2) across glacial/interglacial transitions is consistent with the idea that CO(2) acts as an important amplifier of climate changes in the natural system. Even larger changes are inferred to have occurred in periods earlier than the ice cores cover, and these events might be used to constrain assessments of the way the Earth could respond to higher than present concentrations of CO(2), and to a large release of carbon: however, more certainty about CO(2) concentrations beyond the time period covered by ice cores is needed before such constraints can be fully realized.
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Affiliation(s)
- Eric W Wolff
- British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 0ET, UK.
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Haywood AM, Ridgwell A, Lunt DJ, Hill DJ, Pound MJ, Dowsett HJ, Dolan AM, Francis JE, Williams M. Are there pre-Quaternary geological analogues for a future greenhouse warming? PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2011; 369:933-956. [PMID: 21282155 DOI: 10.1098/rsta.2010.0317] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Given the inherent uncertainties in predicting how climate and environments will respond to anthropogenic emissions of greenhouse gases, it would be beneficial to society if science could identify geological analogues to the human race's current grand climate experiment. This has been a focus of the geological and palaeoclimate communities over the last 30 years, with many scientific papers claiming that intervals in Earth history can be used as an analogue for future climate change. Using a coupled ocean-atmosphere modelling approach, we test this assertion for the most probable pre-Quaternary candidates of the last 100 million years: the Mid- and Late Cretaceous, the Palaeocene-Eocene Thermal Maximum (PETM), the Early Eocene, as well as warm intervals within the Miocene and Pliocene epochs. These intervals fail as true direct analogues since they either represent equilibrium climate states to a long-term CO(2) forcing--whereas anthropogenic emissions of greenhouse gases provide a progressive (transient) forcing on climate--or the sensitivity of the climate system itself to CO(2) was different. While no close geological analogue exists, past warm intervals in Earth history provide a unique opportunity to investigate processes that operated during warm (high CO(2)) climate states. Palaeoclimate and environmental reconstruction/modelling are facilitating the assessment and calculation of the response of global temperatures to increasing CO(2) concentrations in the longer term (multiple centuries); this is now referred to as the Earth System Sensitivity, which is critical in identifying CO(2) thresholds in the atmosphere that must not be crossed to avoid dangerous levels of climate change in the long term. Palaeoclimatology also provides a unique and independent way to evaluate the qualities of climate and Earth system models used to predict future climate.
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Affiliation(s)
- Alan M Haywood
- School of Earth and Environment, Earth and Environment Building, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, UK.
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He K, Li YJ, Brandley MC, Lin LK, Wang YX, Zhang YP, Jiang XL. A multi-locus phylogeny of Nectogalini shrews and influences of the paleoclimate on speciation and evolution. Mol Phylogenet Evol 2010; 56:734-46. [PMID: 20363345 DOI: 10.1016/j.ympev.2010.03.039] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2009] [Revised: 03/24/2010] [Accepted: 03/30/2010] [Indexed: 11/16/2022]
Abstract
Nectogaline shrews are a major component of the small mammalian fauna of Europe and Asia, and are notable for their diverse ecology, including utilization of aquatic habitats. So far, molecular phylogenetic analyses including nectogaline species have been unable to infer a well-resolved, well-supported phylogeny, thus limiting the power of comparative evolutionary and ecological analyses of the group. Here, we employ Bayesian phylogenetic analyses of eight mitochondrial and three nuclear genes to infer the phylogenetic relationships of nectogaline shrews. We subsequently use this phylogeny to assess the genetic diversity within the genus Episoriculus, and determine whether adaptation to aquatic habitats evolved independently multiple times. Moreover, we both analyze the fossil record and employ Bayesian relaxed clock divergence dating analyses of DNA to assess the impact of historical global climate change on the biogeography of Nectogalini. We infer strong support for the polyphyly of the genus Episoriculus. We also find strong evidence that the ability to heavily utilize aquatic habitats evolved independently in both Neomys and Chimarrogale+Nectogale lineages. Our Bayesian molecular divergence analysis suggests that the early history of Nectogalini is characterized by a rapid radiation at the Miocene/Pliocene boundary, thus potentially explaining the lack of resolution at the base of the tree. Finally, we find evidence that nectogalines once inhabited northern latitudes, but the global cooling and desiccating events at the Miocene/Pliocene and Pliocene/Pleistocene boundaries and Pleistocene glaciation resulted in the migration of most Nectogalini lineages to their present day southern distribution.
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Affiliation(s)
- Kai He
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, China
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Tripati AK, Roberts CD, Eagle RA. Coupling of CO2 and Ice Sheet Stability Over Major Climate Transitions of the Last 20 Million Years. Science 2009; 326:1394-7. [DOI: 10.1126/science.1178296] [Citation(s) in RCA: 286] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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35
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Astronomically modulated late Pliocene equatorial Pacific climate transition and Northern Hemisphere ice sheet expansion. CHINESE SCIENCE BULLETIN-CHINESE 2009. [DOI: 10.1007/s11434-009-0310-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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36
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Sosdian S, Rosenthal Y. Deep-Sea Temperature and Ice Volume Changes Across the Pliocene-Pleistocene Climate Transitions. Science 2009; 325:306-10. [DOI: 10.1126/science.1169938] [Citation(s) in RCA: 212] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- Sindia Sosdian
- Institute of Marine and Coastal Science and Department of Earth and Planetary Sciences, Rutgers University, New Brunswick, NJ 08901, USA
| | - Yair Rosenthal
- Institute of Marine and Coastal Science and Department of Earth and Planetary Sciences, Rutgers University, New Brunswick, NJ 08901, USA
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37
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Haywood AM, Dowsett HJ, Valdes PJ, Lunt DJ, Francis JE, Sellwood BW. Introduction. Pliocene climate, processes and problems. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2009; 367:3-17. [PMID: 18852089 DOI: 10.1098/rsta.2008.0205] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Climate predictions produced by numerical climate models, often referred to as general circulation models (GCMs), suggest that by the end of the twenty-first century global mean annual surface air temperatures will increase by 1.1-6.4 degrees C. Trace gas records from ice cores indicate that atmospheric concentrations of CO2 are already higher than at any time during the last 650000 years. In the next 50 years, atmospheric CO2 concentrations are expected to reach a level not encountered since an epoch of time known as the Pliocene. Uniformitarianism is a key principle of geological science, but can the past also be a guide to the future? To what extent does an examination of the Pliocene geological record enable us to successfully understand and interpret this guide? How reliable are the 'retrodictions' of Pliocene climates produced by GCMs and what does this tell us about the accuracy of model predictions for the future? These questions provide the scientific rationale for this Theme Issue.
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Affiliation(s)
- Alan M Haywood
- School of Earth and Environment, University of Leeds, Leeds LS2 9JT, UK.
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