1
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Hu HM, Marino G, Pérez-Mejías C, Spötl C, Yokoyama Y, Yu J, Rohling E, Kano A, Ludwig P, Pinto JG, Michel V, Valensi P, Zhang X, Jiang X, Mii HS, Chien WY, Tsai HC, Sung WH, Hsu CH, Starnini E, Zunino M, Shen CC. Sustained North Atlantic warming drove anomalously intense MIS 11c interglacial. Nat Commun 2024; 15:5933. [PMID: 39009621 PMCID: PMC11251152 DOI: 10.1038/s41467-024-50207-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Accepted: 07/01/2024] [Indexed: 07/17/2024] Open
Abstract
The Marine Isotope Stage (MIS) 11c interglacial and its preceding glacial termination represent an enigmatically intense climate response to relatively weak insolation forcing. So far, a lack of radiometric age control has confounded a detailed assessment of the insolation-climate relationship during this period. Here, we present 230Th-dated speleothem proxy data from northern Italy and compare them with palaeoclimate records from the North Atlantic region. We find that interglacial conditions started in subtropical to middle latitudes at 423.1 ± 1.3 thousand years (kyr) before present, during a first weak insolation maximum, whereas northern high latitudes remained glaciated (sea level ~ 40 m below present). Some 14.5 ± 2.8 kyr after this early subtropical onset, peak interglacial conditions were reached globally, with sea level 6-13 m above present, despite weak insolation forcing. We attribute this remarkably intense climate response to an exceptionally long (~15 kyr) episode of intense poleward heat flux transport prior to the MIS 11c optimum.
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Affiliation(s)
- Hsun-Ming Hu
- High-Precision Mass Spectrometry and Environment Change Laboratory (HISPEC), Department of Geosciences, National Taiwan University, Taipei, 10617, ROC, Taiwan.
- Radiogenic Isotope Facility, School of Earth and Environmental Sciences, The University of Queensland, Brisbane, QLD 4072, Australia.
- Research Center for Future Earth, National Taiwan University, Taipei, 10617, ROC, Taiwan.
| | - Gianluca Marino
- Centro de Investigación Mariña, GEOMA, Palaeoclimatology Lab, Universidade de Vigo, Vigo, 3610, Spain.
| | - Carlos Pérez-Mejías
- Institute of Global Environmental Change, Xi'an Jiaotong University, 710049, Xi'an, China
| | - Christoph Spötl
- Institute of Geology, University of Innsbruck, Innrain 52, 6020, Innsbruck, Austria
| | - Yusuke Yokoyama
- Atmosphere and Ocean Research Institute, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba, 277-8564, Japan
- Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Jimin Yu
- Laoshan Laboratory, Qingdao, 266237, China
- Research School of Earth Sciences, The Australian National University, Canberra, ACT 2601, Australia
| | - Eelco Rohling
- Department of Earth Sciences, Utrecht University, 3584, CB, Utrecht, Netherlands
- Ocean and Earth Science, University of Southampton, National Oceanography Centre, Southampton, SO14 3ZH, UK
| | - Akihiro Kano
- Atmosphere and Ocean Research Institute, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba, 277-8564, Japan
| | - Patrick Ludwig
- Institute of Meteorology and Climate Research Troposphere Research (IMKTRO), Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
| | - Joaquim G Pinto
- Institute of Meteorology and Climate Research Troposphere Research (IMKTRO), Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
| | - Véronique Michel
- Université Côte d'Azur, CNRS, CEPAM, 06300, Nice, France
- Université Côte d'Azur, CNRS, OCA, IRD, Géoazur, 06560, Valbonne, France
| | - Patricia Valensi
- UMR7194 HNHP (MNHN-CNRS-UPVD), Institut de Paléontologie Humaine, 75013, Paris, France
| | - Xin Zhang
- Key Laboratory of Humid Subtropical Eco-Geographical Processes, Ministry of Education, College of Geography Science, Fujian Normal University, Fuzhou, 350007, China
| | - Xiuyang Jiang
- Key Laboratory of Humid Subtropical Eco-Geographical Processes, Ministry of Education, College of Geography Science, Fujian Normal University, Fuzhou, 350007, China
| | - Horng-Sheng Mii
- Department of Earth Sciences, National Taiwan Normal University, Taipei, 11677, ROC, Taiwan
| | - Wei-Yi Chien
- High-Precision Mass Spectrometry and Environment Change Laboratory (HISPEC), Department of Geosciences, National Taiwan University, Taipei, 10617, ROC, Taiwan
| | - Hsien-Chen Tsai
- High-Precision Mass Spectrometry and Environment Change Laboratory (HISPEC), Department of Geosciences, National Taiwan University, Taipei, 10617, ROC, Taiwan
| | - Wen-Hui Sung
- High-Precision Mass Spectrometry and Environment Change Laboratory (HISPEC), Department of Geosciences, National Taiwan University, Taipei, 10617, ROC, Taiwan
| | - Chia-Hao Hsu
- High-Precision Mass Spectrometry and Environment Change Laboratory (HISPEC), Department of Geosciences, National Taiwan University, Taipei, 10617, ROC, Taiwan
| | - Elisabetta Starnini
- Department of Civilizations and Forms of Knowledge, University of Pisa, Via dei Mille 19, 56126, Pisa, Italy
| | - Marta Zunino
- Toirano Cave, Piazzale D. Maineri 1, 17055, Toirano (SV), Italy
| | - Chuan-Chou Shen
- High-Precision Mass Spectrometry and Environment Change Laboratory (HISPEC), Department of Geosciences, National Taiwan University, Taipei, 10617, ROC, Taiwan.
- Research Center for Future Earth, National Taiwan University, Taipei, 10617, ROC, Taiwan.
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2
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Christ AJ, Rittenour TM, Bierman PR, Keisling BA, Knutz PC, Thomsen TB, Keulen N, Fosdick JC, Hemming SR, Tison JL, Blard PH, Steffensen JP, Caffee MW, Corbett LB, Dahl-Jensen D, Dethier DP, Hidy AJ, Perdrial N, Peteet DM, Steig EJ, Thomas EK. Deglaciation of northwestern Greenland during Marine Isotope Stage 11. Science 2023; 381:330-335. [PMID: 37471537 DOI: 10.1126/science.ade4248] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Accepted: 06/21/2023] [Indexed: 07/22/2023]
Abstract
Past interglacial climates with smaller ice sheets offer analogs for ice sheet response to future warming and contributions to sea level rise; however, well-dated geologic records from formerly ice-free areas are rare. Here we report that subglacial sediment from the Camp Century ice core preserves direct evidence that northwestern Greenland was ice free during the Marine Isotope Stage (MIS) 11 interglacial. Luminescence dating shows that sediment just beneath the ice sheet was deposited by flowing water in an ice-free environment 416 ± 38 thousand years ago. Provenance analyses and cosmogenic nuclide data and calculations suggest the sediment was reworked from local materials and exposed at the surface <16 thousand years before deposition. Ice sheet modeling indicates that ice-free conditions at Camp Century require at least 1.4 meters of sea level equivalent contribution from the Greenland Ice Sheet.
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Affiliation(s)
- Andrew J Christ
- Rubenstein School of the Environment and Natural Resources, University of Vermont, Burlington, VT 05405, USA
- Gund Institute for Environment, University of Vermont, Burlington, VT 05405, USA
| | - Tammy M Rittenour
- Department of Geosciences, Utah State University, Logan, UT 84322, USA
| | - Paul R Bierman
- Rubenstein School of the Environment and Natural Resources, University of Vermont, Burlington, VT 05405, USA
- Gund Institute for Environment, University of Vermont, Burlington, VT 05405, USA
| | - Benjamin A Keisling
- University of Texas Institute for Geophysics, Jackson School of Geosciences, University of Texas at Austin, Austin, TX 78754, USA
| | - Paul C Knutz
- Geological Survey of Denmark and Greenland, 1350 Copenhagen, Denmark
| | - Tonny B Thomsen
- Geological Survey of Denmark and Greenland, 1350 Copenhagen, Denmark
| | - Nynke Keulen
- Geological Survey of Denmark and Greenland, 1350 Copenhagen, Denmark
| | - Julie C Fosdick
- Department of Earth Sciences, University of Connecticut, Storrs, CT 06269, USA
| | - Sidney R Hemming
- Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964, USA
| | - Jean-Louis Tison
- Laboratoire de Glaciologie, DGES-IGEOS, Université Libre de Bruxelles, 1050 Brussels, Belgium
| | - Pierre-Henri Blard
- Laboratoire de Glaciologie, DGES-IGEOS, Université Libre de Bruxelles, 1050 Brussels, Belgium
- Centre de Recherches Pétrographiques et Géochimiques, CNRS, Université de Lorraine, 54500 Nancy, France
| | - Jørgen P Steffensen
- Centre for Ice and Climate, PICE, Niels Bohr Institute, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Marc W Caffee
- Department of Physics and Astronomy, Purdue University, West Lafayette, IN 47907, USA
- Department of Earth, Atmospheric, and Planetary Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Lee B Corbett
- Gund Institute for Environment, University of Vermont, Burlington, VT 05405, USA
| | - Dorthe Dahl-Jensen
- Centre for Ice and Climate, PICE, Niels Bohr Institute, University of Copenhagen, 2200 Copenhagen, Denmark
- Centre for Earth Observation Science, University of Manitoba, Winnipeg, MB R3T 2N2, Canada
| | - David P Dethier
- Department of Geosciences, Williams College, Williamstown, MA 01267, USA
| | - Alan J Hidy
- Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
| | - Nicolas Perdrial
- Rubenstein School of the Environment and Natural Resources, University of Vermont, Burlington, VT 05405, USA
- Department of Geography and Geosciences, University of Vermont, Burlington, VT 05405, USA
| | - Dorothy M Peteet
- Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964, USA
- NASA Goddard Institute for Space Studies, New York, NY 10025, USA
| | - Eric J Steig
- Department of Earth and Space Sciences, University of Washington, Seattle, WA 98195, USA
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3
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Moncel MH, García-Medrano P, Despriée J, Arnaud J, Voinchet P, Bahain JJ. Tracking behavioral persistence and innovations during the Middle Pleistocene in Western Europe. Shift in occupations between 700 and 450 ka at la Noira site (Centre, France). J Hum Evol 2021; 156:103009. [PMID: 34049270 DOI: 10.1016/j.jhevol.2021.103009] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 03/30/2021] [Accepted: 04/06/2021] [Indexed: 11/19/2022]
Abstract
Some areas in Western Europe indicate hiatuses in human occupations, which cannot be systematically attributed to taphonomic factors and poor site preservation. The site of la Noira in the center of France records two occupation phases with a significant time gap. The older one is dated to around 700 ka (stratum a) with an Acheulean assemblage, among the earliest in Western Europe, and the upper phase of the sequence (stratum c) is dated to ca. 450 ka. Humans left the area at around 670 ka, at the beginning of the marine isotope stage (MIS) 16 glacial stage, when cold conditions became too severe. No sites between 650 and 450 ka have yet been discovered in the center region despite systematic surveys over the past three decades. The archaeological evidence indicates that populations returned to the area, at the end of MIS 12 or the beginning of the long interglacial MIS 11. Here, we use technological behaviors common to the two levels of la Noira-strata a and c to evaluate their differences. Compared to other key European sequences, this site can be used to address the evolution of the behavioral strategies in Europe between MIS 17 and 11. We formulate two hypotheses concerning the human settlement of this area: (1) local behavioral evolution over time of populations occasionally occupying the region when the climate was favorable or (2) dispersal and arrival of new populations from other areas. The results focus on (1) changes in land-use patterns with the extension of the territory used by hominins in the upper level, (2) the introduction of new core technologies, including some evidence of early Levallois debitage, and (3) more intensive shaping of bifaces and bifacial tools. Results attest that the la Noira archaeological assemblages record similar regional behavioral evolution as observed at a larger scale in Europe.
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Affiliation(s)
- Marie-Hélène Moncel
- UMR 7194 HNHP, MNHN-CNRS-UPVD, Département Homme et Environnement, Muséum National D'Histoire Naturelle, IPH 1 Rue René Panhard, 75013, Paris, France.
| | - Paula García-Medrano
- UMR 7194 HNHP, MNHN-CNRS-UPVD, Département Homme et Environnement, Muséum National D'Histoire Naturelle, IPH 1 Rue René Panhard, 75013, Paris, France; Dept. Britain, Europe and Prehistory, British Museum, Frank House, 56 Orsman Road, N1 5QJ, London, UK; Institut Català de Paleoecologia Humana I Evolució Social (IPHES-CERCA), Zona Educacional 4, Campus Sescelades URV (Edifici W3), 43007 Tarragona, Spain; Universitat Rovira I Virgili, Departament D'Història I Història de L'Art, Avinguda de Catalunya 35, 43002 Tarragona, Spain
| | - Jackie Despriée
- UMR 7194 HNHP, MNHN-CNRS-UPVD, Département Homme et Environnement, Muséum National D'Histoire Naturelle, IPH 1 Rue René Panhard, 75013, Paris, France
| | - Julie Arnaud
- UMR 7194 HNHP, MNHN-CNRS-UPVD, Département Homme et Environnement, Muséum National D'Histoire Naturelle, IPH 1 Rue René Panhard, 75013, Paris, France; Dipartimento di Studi Umanistici, Università Degli Studi di Ferrara, 44121 Ferrara, Italy
| | - Pierre Voinchet
- UMR 7194 HNHP, MNHN-CNRS-UPVD, Département Homme et Environnement, Muséum National D'Histoire Naturelle, IPH 1 Rue René Panhard, 75013, Paris, France
| | - Jean-Jacques Bahain
- UMR 7194 HNHP, MNHN-CNRS-UPVD, Département Homme et Environnement, Muséum National D'Histoire Naturelle, IPH 1 Rue René Panhard, 75013, Paris, France
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4
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Droxler AW, Jorry SJ. The Origin of Modern Atolls: Challenging Darwin's Deeply Ingrained Theory. ANNUAL REVIEW OF MARINE SCIENCE 2021; 13:537-573. [PMID: 32976731 DOI: 10.1146/annurev-marine-122414-034137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
In 1842, Darwin identified three types of reefs: fringing reefs, which are directly attached to volcanic islands; barrier reefs, which are separated from volcanic islands by lagoons; and ring reefs, which enclose only a lagoon and are defined as atolls. Moreover, he linked these reef types through an evolutionary model in which an atoll is the logical end point of a subsiding volcanic edifice, as he was unaware of Quaternary glaciations. As an alternative, starting in the 1930s, several authors proposed the antecedent karst model; in this model, atolls formed as a direct interaction between subsidence and karst dissolution that occurred preferentially in the bank interiors rather than on their margins through exposure during glacial lowstands of sea level. Atolls then developed during deglacial reflooding of the glacial karstic morphologies by preferential stacked coral-reef growth along their margins. Here, a comprehensive new model is proposed, based on the antecedent karst model and well-established sea-level fluctuations during the last 5 million years, by demonstrating that most modern atolls from the Maldives Archipelago and from the tropical Pacific and southwest Indian Oceans are rooted on top of late Pliocene flat-topped banks. The volcanic basement, therefore, has had no influence on the late Quaternary development of these flat-topped banks into modern atolls. During the multiple glacial sea-level lowstands that intensified throughout the Quaternary, the tops of these banks were karstified; then, during each of the five mid-to-late Brunhes deglaciations, coral reoccupied their raised margins and grew vertically, keeping up with sea-level rise and creating the modern atolls.
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Affiliation(s)
- André W Droxler
- Department of Earth, Environmental, and Planetary Sciences, Rice University, Houston, Texas 77005, USA;
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5
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A new sea-level record for the Neogene/Quaternary boundary reveals transition to a more stable East Antarctic Ice Sheet. Proc Natl Acad Sci U S A 2020; 117:30980-30987. [PMID: 33229561 DOI: 10.1073/pnas.2004209117] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Sea-level rise resulting from the instability of polar continental ice sheets represents a major socioeconomic hazard arising from anthropogenic warming, but the response of the largest component of Earth's cryosphere, the East Antarctic Ice Sheet (EAIS), to global warming is poorly understood. Here we present a detailed record of North Atlantic deep-ocean temperature, global sea-level, and ice-volume change for ∼2.75 to 2.4 Ma ago, when atmospheric partial pressure of carbon dioxide (pCO2) ranged from present-day (>400 parts per million volume, ppmv) to preindustrial (<280 ppmv) values. Our data reveal clear glacial-interglacial cycles in global ice volume and sea level largely driven by the growth and decay of ice sheets in the Northern Hemisphere. Yet, sea-level values during Marine Isotope Stage (MIS) 101 (∼2.55 Ma) also signal substantial melting of the EAIS, and peak sea levels during MIS G7 (∼2.75 Ma) and, perhaps, MIS G1 (∼2.63 Ma) are also suggestive of EAIS instability. During the succeeding glacial-interglacial cycles (MIS 100 to 95), sea levels were distinctly lower than before, strongly suggesting a link between greater stability of the EAIS and increased land-ice volumes in the Northern Hemisphere. We propose that lower sea levels driven by ice-sheet growth in the Northern Hemisphere decreased EAIS susceptibility to ocean melting. Our findings have implications for future EAIS vulnerability to a rapidly warming world.
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6
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Ice retreat in Wilkes Basin of East Antarctica during a warm interglacial. Nature 2020; 583:554-559. [PMID: 32699394 DOI: 10.1038/s41586-020-2484-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Accepted: 05/21/2020] [Indexed: 11/08/2022]
Abstract
Efforts to improve sea level forecasting on a warming planet have focused on determining the temperature, sea level and extent of polar ice sheets during Earth's past interglacial warm periods1-3. About 400,000 years ago, during the interglacial period known as Marine Isotopic Stage 11 (MIS11), the global temperature was 1 to 2 degrees Celsius greater2 and sea level was 6 to 13 metres higher1,3. Sea level estimates in excess of about 10 metres, however, have been discounted because these require a contribution from the East Antarctic Ice Sheet3, which has been argued to have remained stable for millions of years before and includes MIS114,5. Here we show how the evolution of 234U enrichment within the subglacial waters of East Antarctica recorded the ice sheet's response to MIS11 warming. Within the Wilkes Basin, subglacial chemical precipitates of opal and calcite record accumulation of 234U (the product of rock-water contact within an isolated subglacial reservoir) up to 20 times higher than that found in marine waters. The timescales of 234U enrichment place the inception of this reservoir at MIS11. Informed by the 234U cycling observed in the Laurentide Ice Sheet, where 234U accumulated during periods of ice stability6 and was flushed to global oceans in response to deglaciation7, we interpret our East Antarctic dataset to represent ice loss within the Wilkes Basin at MIS11. The 234U accumulation within the Wilkes Basin is also observed in the McMurdo Dry Valleys brines8-10, indicating11 that the brine originated beneath the adjacent East Antarctic Ice Sheet. The marine origin of brine salts10 and bacteria12 implies that MIS11 ice loss was coupled with marine flooding. Collectively, these data indicate that during one of the warmest Pleistocene interglacials, the ice sheet margin at the Wilkes Basin retreated to near the precipitate location, about 700 kilometres inland from the current position of the ice margin, which-assuming current ice volumes-would have contributed about 3 to 4 metres13 to global sea levels.
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Ávila SP, Melo C, Berning B, Sá N, Quartau R, Rijsdijk KF, Ramalho RS, Cordeiro R, De Sá NC, Pimentel A, Baptista L, Medeiros A, Gil A, Johnson ME. Towards a 'Sea-Level Sensitive' dynamic model: impact of island ontogeny and glacio-eustasy on global patterns of marine island biogeography. Biol Rev Camb Philos Soc 2019; 94:1116-1142. [PMID: 30609249 DOI: 10.1111/brv.12492] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Revised: 11/29/2018] [Accepted: 12/03/2018] [Indexed: 01/04/2023]
Abstract
A synthetic model is presented to enlarge the evolutionary framework of the General Dynamic Model (GDM) and the Glacial Sensitive Model (GSM) of oceanic island biogeography from the terrestrial to the marine realm. The proposed 'Sea-Level Sensitive' dynamic model (SLS) of marine island biogeography integrates historical and ecological biogeography with patterns of glacio-eustasy, merging concepts from areas as diverse as taxonomy, biogeography, marine biology, volcanology, sedimentology, stratigraphy, palaeontology, geochronology and geomorphology. Fundamental to the SLS model is the dynamic variation of the littoral area of volcanic oceanic islands (defined as the area between the intertidal and the 50-m isobath) in response to sea-level oscillations driven by glacial-interglacial cycles. The following questions are considered by means of this revision: (i) what was the impact of (global) glacio-eustatic sea-level oscillations, particularly those of the Pleistocene glacial-interglacial episodes, on the littoral marine fauna and flora of volcanic oceanic islands? (ii) What are the main factors that explain the present littoral marine biodiversity on volcanic oceanic islands? (iii) How can differences in historical and ecological biogeography be reconciled, from a marine point of view? These questions are addressed by compiling the bathymetry of 11 Atlantic archipelagos/islands to obtain quantitative data regarding changes in the littoral area based on Pleistocene sea-level oscillations, from 150 thousand years ago (ka) to the present. Within the framework of a model sensitive to changing sea levels, we discuss the principal factors affecting the geographical range of marine species; the relationships between modes of larval development, dispersal strategies and geographical range; the relationships between times of speciation, modes of larval development, ecological zonation and geographical range; the influence of sea-surface temperatures and latitude on littoral marine species diversity; the effect of eustatic sea-level changes and their impact on the littoral marine biota; island marine species-area relationships; and finally, the physical effects of island ontogeny and its associated submarine topography and marine substrate on littoral biota. Based on the SLS dynamic model, we offer a number of predictions for tropical, subtropical and temperate volcanic oceanic islands on how rates of immigration, colonization, in-situ speciation, local disappearance, and extinction interact and affect the marine biodiversity around islands during glacials and interglacials, thus allowing future testing of the theory.
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Affiliation(s)
- Sérgio P Ávila
- CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO Laboratório Associado, Pólo dos Açores, Ponta Delgada 9501-801, Portugal.,Departamento de Biologia, Faculdade de Ciências e Tecnologia da Universidade dos Açores, Ponta Delgada 9501-801, Portugal.,MPB-Marine PalaeoBiogeography Working Group of the University of the Azores, Rua da Mãe de Deus, Ponta Delgada 9501-801, Portugal
| | - Carlos Melo
- CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO Laboratório Associado, Pólo dos Açores, Ponta Delgada 9501-801, Portugal.,MPB-Marine PalaeoBiogeography Working Group of the University of the Azores, Rua da Mãe de Deus, Ponta Delgada 9501-801, Portugal.,Departamento de Geologia, Faculdade de Ciências, Universidade de Lisboa, Lisbon 1749-016, Portugal
| | - Björn Berning
- CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO Laboratório Associado, Pólo dos Açores, Ponta Delgada 9501-801, Portugal.,Oberösterreichisches Landesmuseum, Geowissenschaftliche Sammlungen, Leonding 4060, Austria
| | - Nuno Sá
- Departamento de Ciências Tecnológicas e do Desenvolvimento, Faculdade de Ciências da Universidade dos Açores, Ponta Delgada 9501-801, Portugal
| | - Rui Quartau
- Instituto Dom Luiz, Faculdade de Ciências da Universidade de Lisboa, Lisboa, Portugal.,Divisão de Geologia Marinha, Instituto Hidrográfico, Lisboa, Portugal
| | - Kenneth F Rijsdijk
- Theoretical and Computational Ecology, Institute for Biodiversity and Ecosystem, University of Amsterdam, Amsterdam 1098, The Netherlands
| | - Ricardo S Ramalho
- Departamento de Geologia, Faculdade de Ciências, Universidade de Lisboa, Lisbon 1749-016, Portugal.,Instituto Dom Luiz, Faculdade de Ciências da Universidade de Lisboa, Lisboa, Portugal.,School of Earth Sciences, University of Bristol, Bristol, BS8 1RJ, U.K
| | - Ricardo Cordeiro
- CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO Laboratório Associado, Pólo dos Açores, Ponta Delgada 9501-801, Portugal.,Departamento de Biologia, Faculdade de Ciências e Tecnologia da Universidade dos Açores, Ponta Delgada 9501-801, Portugal.,MPB-Marine PalaeoBiogeography Working Group of the University of the Azores, Rua da Mãe de Deus, Ponta Delgada 9501-801, Portugal
| | - Nuno C De Sá
- Institute of Environmental Sciences, Leiden University, Leiden, 2300, The Netherlands
| | - Adriano Pimentel
- Centro de Informação e Vigilância Sismovulcânica dos Açores, Rua Mãe de Deus, Ponta Delgada, 9501-801, Portugal.,Instituto de Investigação em Vulcanologia e Avaliação de Riscos, University of the Azores, Ponta Delgada, 9501-801, Portugal
| | - Lara Baptista
- CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO Laboratório Associado, Pólo dos Açores, Ponta Delgada 9501-801, Portugal.,MPB-Marine PalaeoBiogeography Working Group of the University of the Azores, Rua da Mãe de Deus, Ponta Delgada 9501-801, Portugal
| | - António Medeiros
- Departamento de Biologia, Faculdade de Ciências e Tecnologia da Universidade dos Açores, Ponta Delgada 9501-801, Portugal
| | - Artur Gil
- Departamento de Biologia, Faculdade de Ciências e Tecnologia da Universidade dos Açores, Ponta Delgada 9501-801, Portugal.,Ce3C - Centre for Ecology, Evolution and Environmental Changes, Azorean Biodiversity Group, University of the Azores, Ponta Delgada, 9501-801, Portugal
| | - Markes E Johnson
- Department of Geosciences, Williams College, Williamstown, MA 01267, U.S.A
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Zanolli C, Martinón-Torres M, Bernardini F, Boschian G, Coppa A, Dreossi D, Mancini L, Martínez de Pinillos M, Martín-Francés L, Bermúdez de Castro JM, Tozzi C, Tuniz C, Macchiarelli R. The Middle Pleistocene (MIS 12) human dental remains from Fontana Ranuccio (Latium) and Visogliano (Friuli-Venezia Giulia), Italy. A comparative high resolution endostructural assessment. PLoS One 2018; 13:e0189773. [PMID: 30281595 PMCID: PMC6169847 DOI: 10.1371/journal.pone.0189773] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Accepted: 07/16/2018] [Indexed: 12/17/2022] Open
Abstract
The penecontemporaneous Middle Pleistocene sites of Fontana Ranuccio (Latium) and Visogliano (Friuli-Venezia Giulia), set c. 450 km apart in central and northeastern Italy, respectively, have yielded some among the oldest human fossil remains testifying to a peopling phase of the Italian Peninsula broadly during the glacial MIS 12, a stage associated with one among the harshest climatic conditions in the Northern hemisphere during the entire Quaternary period. Together with the large samples from Atapuerca Sima de los Huesos, Spain, and Caune de l’Arago at Tautavel, France, the remains from Fontana Ranuccio and Visogliano are among the few mid-Middle Pleistocene dental assemblages from Western Europe available for investigating the presence of an early Neanderthal signature in their inner structure. We applied two- three-dimensional techniques of virtual imaging and geometric morphometrics to the high-resolution X-ray microtomography record of the dental remains from these two Italian sites and compared the results to the evidence from a selected number of Pleistocene and extant human specimens/samples from Europe and North Africa. Depending on their preservation quality and on the degree of occlusal wear, we comparatively assessed: (i) the crown enamel and radicular dentine thickness topographic variation of a uniquely represented lower incisor; (ii) the lateral crown tissue proportions of premolars and molars; (iii) the enamel-dentine junction, and (iv) the pulp cavity morphology of all available specimens. Our analyses reveal in both samples a Neanderthal-like inner structural signal, for some aspects also resembling the condition shown by the contemporary assemblage from Atapuerca SH, and clearly distinct from the recent human figures. This study provides additional evidence indicating that an overall Neanderthal morphological dental template was preconfigured in Western Europe at least 430 to 450 ka ago.
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Affiliation(s)
- Clément Zanolli
- Laboratoire AMIS, UMR 5288 CNRS, Université Toulouse III Paul Sabatier, Toulouse, France
- * E-mail:
| | - María Martinón-Torres
- Centro Nacional de Investigación sobre la Evolución Humana (CENIEH), Burgos, Spain
- Department of Anthropology, University College London (UCL), London, United Kingdom
| | - Federico Bernardini
- Centro Fermi, Museo Storico della Fisica e Centro di Studi e Ricerche "Enrico Fermi", Rome, Italy
- Multidisciplinary Laboratory, The "Abdus Salam" International Centre for Theoretical Physics, Trieste, Italy
| | - Giovanni Boschian
- Dipartimento di Civiltà e Forme del Sapere, Università di Pisa, Pisa, Italy
| | - Alfredo Coppa
- Dipartimento di Biologia Ambientale, Università di Roma "La Sapienza", Rome, Italy
| | - Diego Dreossi
- SYRMEP Group, Elettra-Sincrotrone Trieste S.C.p.A., Basovizza (Trieste), Italy
| | - Lucia Mancini
- SYRMEP Group, Elettra-Sincrotrone Trieste S.C.p.A., Basovizza (Trieste), Italy
| | - Marina Martínez de Pinillos
- Centro Nacional de Investigación sobre la Evolución Humana (CENIEH), Burgos, Spain
- Department of Anthropology, University College London (UCL), London, United Kingdom
| | - Laura Martín-Francés
- Centro Nacional de Investigación sobre la Evolución Humana (CENIEH), Burgos, Spain
- Laboratoire PACEA, UMR 5199, Université de Bordeaux, Bordeaux, France
| | - José María Bermúdez de Castro
- Centro Nacional de Investigación sobre la Evolución Humana (CENIEH), Burgos, Spain
- Department of Anthropology, University College London (UCL), London, United Kingdom
| | - Carlo Tozzi
- Dipartimento di Civiltà e Forme del Sapere, Università di Pisa, Pisa, Italy
| | - Claudio Tuniz
- Centro Fermi, Museo Storico della Fisica e Centro di Studi e Ricerche "Enrico Fermi", Rome, Italy
- Multidisciplinary Laboratory, The "Abdus Salam" International Centre for Theoretical Physics, Trieste, Italy
- Centre for Archaeological Science, University of Wollongong, Wollongong, Australia
| | - Roberto Macchiarelli
- Laboratoire HNHP, UMR 7194 CNRS, Muséum national d'Histoire naturelle (MNHN), Paris, France
- Unité de Formation Géosciences, Université de Poitiers, Poitiers, France
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9
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Anderson JG, Clapp CE. Coupling free radical catalysis, climate change, and human health. Phys Chem Chem Phys 2018; 20:10569-10587. [PMID: 29638230 DOI: 10.1039/c7cp08331a] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We present the chain of mechanisms linking free radical catalytic loss of stratospheric ozone, specifically over the central United States in summer, to increased climate forcing by CO2 and CH4 from fossil fuel use. This case directly engages detailed knowledge, emerging from in situ aircraft observations over the polar regions in winter, defining the temperature and water vapor dependence of the kinetics of heterogeneous catalytic conversion of inorganic chlorine (HCl and ClONO2) to free radical form (ClO). Analysis is placed in the context of irreversible changes to specific subsystems of the climate, most notably coupled feedbacks that link rapid changes in the Arctic with the discovery that convective storms over the central US in summer both suppress temperatures and inject water vapor deep into the stratosphere. This places the lower stratosphere over the US in summer within the same photochemical catalytic domain as the lower stratosphere of the Arctic in winter engaging the risk of amplifying the rate limiting step in the ClO dimer catalytic mechanism by some six orders of magnitude. This transitions the catalytic loss rate of ozone in lower stratosphere over the United States in summer from HOx radical control to ClOx radical control, increasing the overall ozone loss rate by some two orders of magnitude over that of the unperturbed state. Thus we address, through a combination of observations and modeling, the mechanistic foundation defining why stratospheric ozone, vulnerable to increased climate forcing, is one of the most delicate aspects of habitability on the planet.
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Affiliation(s)
- J G Anderson
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA.
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10
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Larour E, Ivins ER, Adhikari S. Should coastal planners have concern over where land ice is melting? SCIENCE ADVANCES 2017; 3:e1700537. [PMID: 29152565 PMCID: PMC5687855 DOI: 10.1126/sciadv.1700537] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Accepted: 10/26/2017] [Indexed: 05/11/2023]
Abstract
There is a general consensus among Earth scientists that melting of land ice greatly contributes to sea-level rise (SLR) and that future warming will exacerbate the risks posed to human civilization. As land ice is lost to the oceans, both the Earth's gravitational and rotational potentials are perturbed, resulting in strong spatial patterns in SLR, termed sea-level fingerprints. We lack robust forecasting models for future ice changes, which diminishes our ability to use these fingerprints to accurately predict local sea-level (LSL) changes. We exploit an advanced mathematical property of adjoint systems and determine the exact gradient of sea-level fingerprints with respect to local variations in the ice thickness of all of the world's ice drainage systems. By exhaustively mapping these fingerprint gradients, we form a new diagnosis tool, henceforth referred to as gradient fingerprint mapping (GFM), that readily allows for improved assessments of future coastal inundation or emergence. We demonstrate that for Antarctica and Greenland, changes in the predictions of inundation at major port cities depend on the location of the drainage system. For example, in London, GFM shows LSL that is significantly affected by changes on the western part of the Greenland Ice Sheet (GrIS), whereas in New York, LSL change predictions are greatly sensitive to changes in the northeastern portions of the GrIS. We apply GFM to 293 major port cities to allow coastal planners to readily calculate LSL change as more reliable predictions of cryospheric mass changes become available.
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Affiliation(s)
- Eric Larour
- Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, USA
- Corresponding author.
| | - Erik R. Ivins
- Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, USA
| | - Surendra Adhikari
- Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, USA
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11
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Origin, paleoecology, and extirpation of bluebirds and crossbills in the Bahamas across the last glacial-interglacial transition. Proc Natl Acad Sci U S A 2017; 114:9924-9929. [PMID: 28847933 DOI: 10.1073/pnas.1707660114] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
On low islands or island groups such as the Bahamas, surrounded by shallow oceans, Quaternary glacial-interglacial changes in climate and sea level had major effects on terrestrial plant and animal communities. We examine the paleoecology of two species of songbirds (Passeriformes) recorded as Late Pleistocene fossils on the Bahamian island of Abaco-the Eastern bluebird (Sialia sialis) and Hispaniolan crossbill (Loxia megaplaga). Each species lives today only outside of the Bahamian Archipelago, with S. sialis occurring in North and Central America and L. megaplaga endemic to Hispaniola. Unrecorded in the Holocene fossil record of Abaco, both of these species probably colonized Abaco during the last glacial interval but were eliminated when the island became much smaller, warmer, wetter, and more isolated during the last glacial-interglacial transition from ∼15 to 9 ka. Today's warming temperatures and rising sea levels, although not as great in magnitude as those that took place from ∼15 to 9 ka, are occurring rapidly and may contribute to considerable biotic change on islands by acting in synergy with direct human impacts.
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12
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MIS-11 duration key to disappearance of the Greenland ice sheet. Nat Commun 2017; 8:16008. [PMID: 28681860 PMCID: PMC5504289 DOI: 10.1038/ncomms16008] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Accepted: 05/18/2017] [Indexed: 11/08/2022] Open
Abstract
Palaeo data suggest that Greenland must have been largely ice free during Marine Isotope Stage 11 (MIS-11). However, regional summer insolation anomalies were modest during this time compared to MIS-5e, when the Greenland ice sheet likely lost less volume. Thus it remains unclear how such conditions led to an almost complete disappearance of the ice sheet. Here we use transient climate-ice sheet simulations to simultaneously constrain estimates of regional temperature anomalies and Greenland's contribution to the MIS-11 sea-level highstand. We find that Greenland contributed 6.1 m (3.9-7.0 m, 95% credible interval) to sea level, ∼7 kyr after the peak in regional summer temperature anomalies of 2.8 °C (2.1-3.4 °C). The moderate warming produced a mean rate of mass loss in sea-level equivalent of only around 0.4 m per kyr, which means the long duration of MIS-11 interglacial conditions around Greenland was a necessary condition for the ice sheet to disappear almost completely.
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13
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Salas-Leiva DE, Meerow AW, Calonje M, Francisco-Ortega J, Griffith MP, Nakamura K, Sánchez V, Knowles L, Knowles D. Shifting Quaternary migration patterns in the Bahamian archipelago: Evidence from the Zamia pumila complex at the northern limits of the Caribbean island biodiversity hotspot. AMERICAN JOURNAL OF BOTANY 2017; 104:757-771. [PMID: 28515078 DOI: 10.3732/ajb.1700054] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Accepted: 04/10/2017] [Indexed: 06/07/2023]
Abstract
PREMISE OF THE STUDY The Bahamas archipelago is formed by young, tectonically stable carbonate banks that harbor direct geological evidence of global ice-volume changes. We sought to detect signatures of major changes on gene flow patterns and reconstruct the phylogeographic history of the monophyletic Zamia pumila complex across the Bahamas. METHODS Nuclear molecular markers with both high and low mutation rates were used to capture two different time scale signatures and test several gene flow and demographic hypotheses. KEY RESULTS Single-copy nuclear genes unveiled apparent ancestral admixture on Andros, suggesting a significant role of this island as main hub of diversity of the archipelago. We detected demographic and spatial expansion of the Zamia pumila complex on both paleo-provinces around the Piacenzian (Pliocene)/Gelasian (Pleistocene). Populations evidenced signatures of different migration models that have occurred at two different times. Populations on Long Island (Z. lucayana) may either represent a secondary colonization of the Bahamas by Zamia or a rapid and early-divergence event of at least one population on the Bahamas. CONCLUSIONS Despite changes in migration patterns with global climate, expected heterozygosity with both marker systems remains within the range reported for cycads, but with significant levels of increased inbreeding detected by the microsatellites. This finding is likely associated with reduced gene flow between and within paleo-provinces, accompanied by genetic drift, as rising seas enforced isolation. Our study highlights the importance of the maintenance of the predominant direction of genetic exchange and the role of overseas dispersion among the islands during climate oscillations.
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Affiliation(s)
- Dayana E Salas-Leiva
- International Center for Tropical Botany, Department of Biological Sciences, 11200 S.W. 8th Street, Florida International University, Miami, Florida 33199 USA
- USDA-ARS-SHRS, 13601 Old Cutler Road, Miami, Florida 33158 USA
- Montgomery Botanical Center, 11901 Old Cutler Road, Coral Gables, Florida 33156 USA
| | - Alan W Meerow
- USDA-ARS-SHRS, 13601 Old Cutler Road, Miami, Florida 33158 USA
| | - Michael Calonje
- Montgomery Botanical Center, 11901 Old Cutler Road, Coral Gables, Florida 33156 USA
| | - Javier Francisco-Ortega
- International Center for Tropical Botany, Department of Biological Sciences, 11200 S.W. 8th Street, Florida International University, Miami, Florida 33199 USA
- Kushlan Tropical Science Institute, 11935 Old Cutler Road, Fairchild Tropical Botanic Garden, Coral Gables, Florida 33156 USA
| | - M Patrick Griffith
- Montgomery Botanical Center, 11901 Old Cutler Road, Coral Gables, Florida 33156 USA
| | - Kyoko Nakamura
- USDA-ARS-SHRS, 13601 Old Cutler Road, Miami, Florida 33158 USA
| | - Vanessa Sánchez
- USDA-ARS-SHRS, 13601 Old Cutler Road, Miami, Florida 33158 USA
| | - Lindy Knowles
- Bahamas National Trust, P. O. Box N-4105, Bay Street Business Centre, Bay Street, Nassau
| | - David Knowles
- The Bahamas, Bahamas National Trust, Abaco National Park, P.O. Box AB-20953, Marsh Harbour, Abaco, The Bahamas
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14
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Response of the North Atlantic surface and intermediate ocean structure to climate warming of MIS 11. Sci Rep 2017; 7:46192. [PMID: 28393849 PMCID: PMC5385537 DOI: 10.1038/srep46192] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Accepted: 03/10/2017] [Indexed: 11/30/2022] Open
Abstract
Investigating past interglacial climates not only help to understand how the climate system operates in general, it also forms a vital basis for climate predictions. We reconstructed vertical stratification changes in temperature and salinity in the North Atlantic for a period some 400 ka ago (MIS11), an interglacial time analogue of a future climate. As inferred from a unique set of biogeochemical, geochemical, and faunal data, the internal upper ocean stratification across MIS 11 shows distinct depth-dependent dynamical changes related to vertical as well as lateral shifts in the upper Atlantic meridional circulation system. Importantly, transient cold events are recognized near the end of the long phase of postglacial warming at surface, subsurface, mid, and deeper water layers. These data demonstrate that MIS 11 coolings over the North Atlantic were initially triggered by freshwater input at the surface and expansion of cold polar waters into the Subpolar Gyre. The cooling signal was then transmitted downwards into mid-water depths. Since the cold events occurred after the main deglacial phase we suggest that their cause might be related to continuous melting of the Greenland ice sheet, a mechanism that might also be relevant for the present and upcoming climate.
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15
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DeConto RM, Pollard D. Contribution of Antarctica to past and future sea-level rise. Nature 2016; 531:591-7. [PMID: 27029274 DOI: 10.1038/nature17145] [Citation(s) in RCA: 276] [Impact Index Per Article: 34.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Accepted: 01/12/2016] [Indexed: 11/09/2022]
Abstract
Polar temperatures over the last several million years have, at times, been slightly warmer than today, yet global mean sea level has been 6-9 metres higher as recently as the Last Interglacial (130,000 to 115,000 years ago) and possibly higher during the Pliocene epoch (about three million years ago). In both cases the Antarctic ice sheet has been implicated as the primary contributor, hinting at its future vulnerability. Here we use a model coupling ice sheet and climate dynamics-including previously underappreciated processes linking atmospheric warming with hydrofracturing of buttressing ice shelves and structural collapse of marine-terminating ice cliffs-that is calibrated against Pliocene and Last Interglacial sea-level estimates and applied to future greenhouse gas emission scenarios. Antarctica has the potential to contribute more than a metre of sea-level rise by 2100 and more than 15 metres by 2500, if emissions continue unabated. In this case atmospheric warming will soon become the dominant driver of ice loss, but prolonged ocean warming will delay its recovery for thousands of years.
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Affiliation(s)
- Robert M DeConto
- Department of Geosciences, University of Massachusetts, Amherst, Massachusetts 01003, USA
| | - David Pollard
- Earth and Environmental Systems Institute, Pennsylvania State University, University Park, Pennsylvania 16802, USA
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16
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Buried iceberg scours reveal reduced North Atlantic Current during the stage 12 deglacial. Nat Commun 2016; 7:10927. [PMID: 26979836 PMCID: PMC4799367 DOI: 10.1038/ncomms10927] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Accepted: 02/02/2016] [Indexed: 11/29/2022] Open
Abstract
Reconstructing past ocean-climate environments and heat transport requires proxies from which these conditions can be quantified. This is particularly important for the evaluation of numerical palaeoclimate models. Here we present new evidence for a reduced North Atlantic Current (NAC) at the termination of the third last glacial, for which palaeocurrent information was previously unavailable. This is based on an exquisitely preserved set of buried iceberg scours seen in three-dimensional seismic reflection images from the mid-Norwegian slope. The scours were formed ∼430 ka during the transition from glacial to interglacial conditions. The spiral geometry of the scours suggests that they were carved by grounded icebergs influenced by tidal and geostrophic ocean currents. Using the ratio between the estimated tidal and geostrophic current velocities and comparing them with velocities from the Last Glacial Maximum and the present, we show that the stage 12 NAC velocities may have been ∼50% slower than the present. Reconstructing past ocean conditions, particularly current velocity, is difficult due to a lack of available proxies. Here, the authors present a set of well-preserved buried iceberg scours from the mid-Norwegian slope, from which they are able to infer North Atlantic current speeds during the third-last glacial.
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17
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Hein AS, Woodward J, Marrero SM, Dunning SA, Steig EJ, Freeman SPHT, Stuart FM, Winter K, Westoby MJ, Sugden DE. Evidence for the stability of the West Antarctic Ice Sheet divide for 1.4 million years. Nat Commun 2016; 7:10325. [PMID: 26838462 PMCID: PMC4742792 DOI: 10.1038/ncomms10325] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Accepted: 12/01/2015] [Indexed: 11/09/2022] Open
Abstract
Past fluctuations of the West Antarctic Ice Sheet (WAIS) are of fundamental interest because of the possibility of WAIS collapse in the future and a consequent rise in global sea level. However, the configuration and stability of the ice sheet during past interglacial periods remains uncertain. Here we present geomorphological evidence and multiple cosmogenic nuclide data from the southern Ellsworth Mountains to suggest that the divide of the WAIS has fluctuated only modestly in location and thickness for at least the last 1.4 million years. Fluctuations during glacial-interglacial cycles appear superimposed on a long-term trajectory of ice-surface lowering relative to the mountains. This implies that as a minimum, a regional ice sheet centred on the Ellsworth-Whitmore uplands may have survived Pleistocene warm periods. If so, it constrains the WAIS contribution to global sea level rise during interglacials to about 3.3 m above present.
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Affiliation(s)
- Andrew S Hein
- School of GeoSciences, University of Edinburgh, Drummond Street, Edinburgh EH8 9XP, UK
| | - John Woodward
- Department of Geography, Northumbria University, Ellison Place, Newcastle upon Tyne NE1 8ST, UK
| | - Shasta M Marrero
- School of GeoSciences, University of Edinburgh, Drummond Street, Edinburgh EH8 9XP, UK
| | - Stuart A Dunning
- Department of Geography, Northumbria University, Ellison Place, Newcastle upon Tyne NE1 8ST, UK.,Department of Geography, School of Geography, Politics and Sociology, Newcastle University, Newcastle upon Tyne NE1 7RU, UK
| | - Eric J Steig
- School of GeoSciences, University of Edinburgh, Drummond Street, Edinburgh EH8 9XP, UK.,Quaternary Research Center and Department of Earth and Space Sciences, University of Washington, Seattle, Washington 98195, USA
| | - Stewart P H T Freeman
- Scottish Universities Environmental Research Centre, Rankine Avenue, East Kilbride G75 0QF, UK
| | - Finlay M Stuart
- Scottish Universities Environmental Research Centre, Rankine Avenue, East Kilbride G75 0QF, UK
| | - Kate Winter
- Department of Geography, Northumbria University, Ellison Place, Newcastle upon Tyne NE1 8ST, UK
| | - Matthew J Westoby
- Department of Geography, Northumbria University, Ellison Place, Newcastle upon Tyne NE1 8ST, UK
| | - David E Sugden
- School of GeoSciences, University of Edinburgh, Drummond Street, Edinburgh EH8 9XP, UK
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18
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McKay RM, Barrett PJ, Levy RS, Naish TR, Golledge NR, Pyne A. Antarctic Cenozoic climate history from sedimentary records: ANDRILL and beyond. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2016; 374:rsta.2014.0301. [PMID: 26667911 DOI: 10.1098/rsta.2014.0301] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 05/20/2015] [Indexed: 06/05/2023]
Abstract
Mounting evidence from models and geological data implies that the Antarctic Ice Sheet may behave in an unstable manner and retreat rapidly in response to a warming climate, which is a key factor motivating efforts to improve estimates of Antarctic ice volume contributions to future sea-level rise. Here, we review Antarctic cooling history since peak temperatures of the Middle Eocene Climatic Optimum (approx. 50 Ma) to provide a framework for future initiatives to recover sediment cores from subglacial lakes and sedimentary basins in Antarctica's continental interior. While the existing inventory of cores has yielded important insights into the biotic and climatic evolution of Antarctica, strata have numerous and often lengthy time breaks, providing a framework of 'snapshots' through time. Further cores, and more work on existing cores, are needed to reconcile Antarctic records with the more continuous 'far-field' records documenting the evolution of global ice volume and deep-sea temperature. To achieve this, we argue for an integrated portfolio of drilling and coring missions that encompasses existing methodologies using ship- and sea-ice-/ice-shelf-based drilling platforms as well as recently developed seafloor-based drilling and subglacial access systems. We conclude by reviewing key technological issues that will need to be overcome.
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Affiliation(s)
- R M McKay
- Antarctic Research Centre, Victoria University of Wellington, PO Box 600, Wellington 6140, New Zealand
| | - P J Barrett
- Antarctic Research Centre, Victoria University of Wellington, PO Box 600, Wellington 6140, New Zealand
| | - R S Levy
- GNS Science, PO Box 30-368, Lower Hutt 5040, New Zealand
| | - T R Naish
- Antarctic Research Centre, Victoria University of Wellington, PO Box 600, Wellington 6140, New Zealand GNS Science, PO Box 30-368, Lower Hutt 5040, New Zealand
| | - N R Golledge
- Antarctic Research Centre, Victoria University of Wellington, PO Box 600, Wellington 6140, New Zealand GNS Science, PO Box 30-368, Lower Hutt 5040, New Zealand
| | - A Pyne
- Antarctic Research Centre, Victoria University of Wellington, PO Box 600, Wellington 6140, New Zealand
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19
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Hodgson DA, Bentley MJ, Smith JA, Klepacki J, Makinson K, Smith AM, Saw K, Scherer R, Powell R, Tulaczyk S, Rose M, Pearce D, Mowlem M, Keen P, Siegert MJ. Technologies for retrieving sediment cores in Antarctic subglacial settings. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2016; 374:rsta.2015.0056. [PMID: 26667918 DOI: 10.1098/rsta.2015.0056] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 06/17/2015] [Indexed: 06/05/2023]
Abstract
Accumulations of sediment beneath the Antarctic Ice Sheet contain a range of physical and chemical proxies with the potential to document changes in ice sheet history and to identify and characterize life in subglacial settings. Retrieving subglacial sediments and sediment cores presents several unique challenges to existing technologies. This paper briefly reviews the history of sediment sampling in subglacial environments. It then outlines some of the technological challenges and constraints in developing the corers being used in sub-ice shelf settings (e.g. George VI Ice Shelf and Larsen Ice Shelf), under ice streams (e.g. Rutford Ice Stream), at or close to the grounding line (e.g. Whillans Ice Stream) and in subglacial lakes deep under the ice sheet (e.g. Lake Ellsworth). The key features of the corers designed to operate in each of these subglacial settings are described and illustrated together with comments on their deployment procedures.
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Affiliation(s)
- Dominic A Hodgson
- British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 0ET, UK Department of Geography, Science Laboratories, Durham University, South Road, Durham DH1 3LE, UK
| | - Michael J Bentley
- Department of Geography, Science Laboratories, Durham University, South Road, Durham DH1 3LE, UK
| | - James A Smith
- British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 0ET, UK
| | - Julian Klepacki
- British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 0ET, UK
| | - Keith Makinson
- British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 0ET, UK
| | - Andrew M Smith
- British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 0ET, UK
| | - Kevin Saw
- National Oceanography Centre, European Way, Southampton SO14 3ZH, UK
| | - Reed Scherer
- Department of Geology and Environmental Geosciences, Northern Illinois University, 1425 West Lincoln Hwy, DeKalb, IL 60115-2828, USA
| | - Ross Powell
- Department of Geology and Environmental Geosciences, Northern Illinois University, 1425 West Lincoln Hwy, DeKalb, IL 60115-2828, USA
| | - Slawek Tulaczyk
- Earth and Planetary Sciences Department, University of California Santa Cruz, 1156 High Street, Santa Cruz, CA 95064, USA
| | - Mike Rose
- British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 0ET, UK
| | - David Pearce
- British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 0ET, UK Department of Applied Sciences, Northumbria University, Ellison Place 2, Newcastle-upon-Tyne NE1 8ST, UK
| | - Matt Mowlem
- National Oceanography Centre, European Way, Southampton SO14 3ZH, UK
| | - Peter Keen
- Keen Marine Limited, 15 Minerva Road, East Cowes, Isle of Wight PO32 6HD, UK
| | - Martin J Siegert
- The Grantham Institute and Department of Earth Science and Engineering, Imperial College London, South Kensington, London SW7 2AZ, UK
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Dutton A, Carlson AE, Long AJ, Milne GA, Clark PU, DeConto R, Horton BP, Rahmstorf S, Raymo ME. SEA-LEVEL RISE. Sea-level rise due to polar ice-sheet mass loss during past warm periods. Science 2015; 349:aaa4019. [PMID: 26160951 DOI: 10.1126/science.aaa4019] [Citation(s) in RCA: 86] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Interdisciplinary studies of geologic archives have ushered in a new era of deciphering magnitudes, rates, and sources of sea-level rise from polar ice-sheet loss during past warm periods. Accounting for glacial isostatic processes helps to reconcile spatial variability in peak sea level during marine isotope stages 5e and 11, when the global mean reached 6 to 9 meters and 6 to 13 meters higher than present, respectively. Dynamic topography introduces large uncertainties on longer time scales, precluding robust sea-level estimates for intervals such as the Pliocene. Present climate is warming to a level associated with significant polar ice-sheet loss in the past. Here, we outline advances and challenges involved in constraining ice-sheet sensitivity to climate change with use of paleo-sea level records.
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Affiliation(s)
- A Dutton
- Department of Geological Sciences, University of Florida,Gainesville, FL 32611, USA.
| | - A E Carlson
- College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR 97331, USA
| | - A J Long
- Department of Geography, Durham University, Durham, UK
| | - G A Milne
- Department of Earth Sciences, University of Ottawa, Ottawa, Canada
| | - P U Clark
- College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR 97331, USA
| | - R DeConto
- Department of Geosciences, University of Massachusetts, Amherst, MA 01003, USA
| | - B P Horton
- Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ 08901, USA. Earth Observatory of Singapore, Nanyang Technological University, Singapore, 639798
| | - S Rahmstorf
- Potsdam Institute for Climate Impact Research, Potsdam, Germany
| | - M E Raymo
- Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964, USA
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Sithaldeen R, Ackermann RR, Bishop JM. Pleistocene aridification cycles shaped the contemporary genetic architecture of Southern African baboons. PLoS One 2015; 10:e0123207. [PMID: 25970269 PMCID: PMC4430493 DOI: 10.1371/journal.pone.0123207] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Accepted: 03/01/2015] [Indexed: 02/05/2023] Open
Abstract
Plio-Pleistocene environmental change influenced the evolutionary history of many animal lineages in Africa, highlighting key roles for both climate and tectonics in the evolution of Africa’s faunal diversity. Here, we explore diversification in the southern African chacma baboon Papio ursinus sensu lato and reveal a dominant role for increasingly arid landscapes during past glacial cycles in shaping contemporary genetic structure. Recent work on baboons (Papio spp.) supports complex lineage structuring with a dominant pulse of diversification occurring 1-2Ma, and yet the link to palaeoenvironmental change remains largely untested. Phylogeographic reconstruction based on mitochondrial DNA sequence data supports a scenario where chacma baboon populations were likely restricted to refugia during periods of regional cooling and drying through the Late Pleistocene. The two lineages of chacma baboon, ursinus and griseipes, are strongly geographically structured, and demographic reconstruction together with spatial analysis of genetic variation point to possible climate-driven isolating events where baboons may have retreated to more optimum conditions during cooler, drier periods. Our analysis highlights a period of continuous population growth beginning in the Middle to Late Pleistocene in both the ursinus and the PG2 griseipes lineages. All three clades identified in the study then enter a state of declining population size (Nef) through to the Holocene; this is particularly marked in the last 20,000 years, most likely coincident with the Last Glacial Maximum. The pattern recovered here conforms to expectations based on the dynamic regional climate trends in southern Africa through the Pleistocene and provides further support for complex patterns of diversification in the region’s biodiversity.
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Affiliation(s)
- Riashna Sithaldeen
- Department of Archaeology, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa
| | - Rebecca Rogers Ackermann
- Department of Archaeology, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa
| | - Jacqueline M. Bishop
- Department of Biological Sciences, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa
- * E-mail:
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Noss RF, Platt WJ, Sorrie BA, Weakley AS, Means DB, Costanza J, Peet RK. How global biodiversity hotspots may go unrecognized: lessons from the North American Coastal Plain. DIVERS DISTRIB 2014. [DOI: 10.1111/ddi.12278] [Citation(s) in RCA: 273] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Affiliation(s)
- Reed F. Noss
- Department of Biology; University of Central Florida; Orlando FL 32816-2368 USA
| | - William J. Platt
- Department of Biological Sciences; Louisiana State University; Baton Rouge LA 70803 USA
| | - Bruce A. Sorrie
- North Carolina Botanical Garden; UNC Herbarium; University of North Carolina; Chapel Hill NC 27599 USA
| | - Alan S. Weakley
- North Carolina Botanical Garden; UNC Herbarium; University of North Carolina; Chapel Hill NC 27599 USA
| | - D. Bruce Means
- Coastal Plains Institute and Land Conservancy; Tallahassee FL 32303 USA
| | - Jennifer Costanza
- Department of Forestry and Environmental Resources; NC State University; Raleigh NC 27695 USA
| | - Robert K. Peet
- Biology Department; University of North Carolina; Chapel Hill NC 27599 USA
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South Greenland ice-sheet collapse during Marine Isotope Stage 11. Nature 2014; 510:525-8. [DOI: 10.1038/nature13456] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2013] [Accepted: 05/02/2014] [Indexed: 11/08/2022]
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A geological perspective on potential future sea-level rise. Sci Rep 2013; 3:3461. [PMID: 24336564 PMCID: PMC3860070 DOI: 10.1038/srep03461] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Accepted: 11/21/2013] [Indexed: 11/09/2022] Open
Abstract
During ice-age cycles, continental ice volume kept pace with slow, multi-millennial scale, changes in climate forcing. Today, rapid greenhouse gas (GHG) increases have outpaced ice-volume responses, likely committing us to > 9 m of long-term sea-level rise (SLR). We portray a context of naturally precedented SLR from geological evidence, for comparison with historical observations and future projections. This context supports SLR of up to 0.9 (1.8) m by 2100 and 2.7 (5.0) m by 2200, relative to 2000, at 68% (95%) probability. Historical SLR observations and glaciological assessments track the upper 68% limit. Hence, modern change is rapid by past interglacial standards but within the range of 'normal' processes. The upper 95% limit offers a useful low probability/high risk value. Exceedance would require conditions without natural interglacial precedents, such as catastrophic ice-sheet collapse, or activation of major East Antarctic mass loss at sustained CO2 levels above 1000 ppmv.
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Abstract
AbstractIce could play a role in identifying and defining the Anthropocene. The recurrence of northern hemisphere glaciation and the stability of the Greenland Ice Sheet are both potentially vulnerable to human impact on the environment. However, only a very long hiatus in either would be unusual in the context of the Quaternary Period, requiring the definition of a geological boundary. Human influence can clearly be discerned in several ice-core measurements. These include a sharp boundary in radioactivity due to atmospheric nuclear testing; increases, unprecedented at least in the Holocene, in Greenland concentrations of sulphate, nitrate and metals such as lead; the appearance in ice-core air bubbles of previously undetectable compounds such as SF6; and the rise, unprecedented in the last 800 ka, in concentrations of carbon dioxide and methane. Some combination of these changes could be used by future generations to clearly identify the onset of a new epoch defined at a particular calendar date. However, it is not yet clear what the character of the fully developed Anthropocene will be, and it might be wise to let future generations decide, with hindsight, when the Anthropocene started, acknowledging only that we are in the transition towards it.
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Affiliation(s)
- Eric W. Wolff
- British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 0ET, UK
- Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UK (e-mail: )
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Hansen J, Sato M, Russell G, Kharecha P. Climate sensitivity, sea level and atmospheric carbon dioxide. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2013; 371:20120294. [PMID: 24043864 PMCID: PMC3785813 DOI: 10.1098/rsta.2012.0294] [Citation(s) in RCA: 146] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Cenozoic temperature, sea level and CO2 covariations provide insights into climate sensitivity to external forcings and sea-level sensitivity to climate change. Climate sensitivity depends on the initial climate state, but potentially can be accurately inferred from precise palaeoclimate data. Pleistocene climate oscillations yield a fast-feedback climate sensitivity of 3±1(°)C for a 4 W m(-2) CO2 forcing if Holocene warming relative to the Last Glacial Maximum (LGM) is used as calibration, but the error (uncertainty) is substantial and partly subjective because of poorly defined LGM global temperature and possible human influences in the Holocene. Glacial-to-interglacial climate change leading to the prior (Eemian) interglacial is less ambiguous and implies a sensitivity in the upper part of the above range, i.e. 3-4(°)C for a 4 W m(-2) CO2 forcing. Slow feedbacks, especially change of ice sheet size and atmospheric CO2, amplify the total Earth system sensitivity by an amount that depends on the time scale considered. Ice sheet response time is poorly defined, but we show that the slow response and hysteresis in prevailing ice sheet models are exaggerated. We use a global model, simplified to essential processes, to investigate state dependence of climate sensitivity, finding an increased sensitivity towards warmer climates, as low cloud cover is diminished and increased water vapour elevates the tropopause. Burning all fossil fuels, we conclude, would make most of the planet uninhabitable by humans, thus calling into question strategies that emphasize adaptation to climate change.
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Affiliation(s)
- James Hansen
- The Earth Institute, Columbia University, New York, NY 10027, USA
- e-mail:
| | - Makiko Sato
- The Earth Institute, Columbia University, New York, NY 10027, USA
| | - Gary Russell
- NASA Goddard Institute for Space Studies, New York, NY 10027, USA
| | - Pushker Kharecha
- The Earth Institute, Columbia University, New York, NY 10027, USA
- NASA Goddard Institute for Space Studies, New York, NY 10027, USA
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Abstract
Global mean sea level has been steadily rising over the last century, is projected to increase by the end of this century, and will continue to rise beyond the year 2100 unless the current global mean temperature trend is reversed. Inertia in the climate and global carbon system, however, causes the global mean temperature to decline slowly even after greenhouse gas emissions have ceased, raising the question of how much sea-level commitment is expected for different levels of global mean temperature increase above preindustrial levels. Although sea-level rise over the last century has been dominated by ocean warming and loss of glaciers, the sensitivity suggested from records of past sea levels indicates important contributions should also be expected from the Greenland and Antarctic Ice Sheets. Uncertainties in the paleo-reconstructions, however, necessitate additional strategies to better constrain the sea-level commitment. Here we combine paleo-evidence with simulations from physical models to estimate the future sea-level commitment on a multimillennial time scale and compute associated regional sea-level patterns. Oceanic thermal expansion and the Antarctic Ice Sheet contribute quasi-linearly, with 0.4 m °C(-1) and 1.2 m °C(-1) of warming, respectively. The saturation of the contribution from glaciers is overcompensated by the nonlinear response of the Greenland Ice Sheet. As a consequence we are committed to a sea-level rise of approximately 2.3 m °C(-1) within the next 2,000 y. Considering the lifetime of anthropogenic greenhouse gases, this imposes the need for fundamental adaptation strategies on multicentennial time scales.
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Vaks A, Gutareva OS, Breitenbach SFM, Avirmed E, Mason AJ, Thomas AL, Osinzev AV, Kononov AM, Henderson GM. Speleothems reveal 500,000-year history of Siberian permafrost. Science 2013; 340:183-6. [PMID: 23429705 DOI: 10.1126/science.1228729] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Soils in permafrost regions contain twice as much carbon as the atmosphere, and permafrost has an important influence on the natural and built environment at high northern latitudes. The response of permafrost to warming climate is uncertain and occurs on time scales longer than those assessed by direct observation. We dated periods of speleothem growth in a north-south transect of caves in Siberia to reconstruct the history of permafrost in past climate states. Speleothem growth is restricted to full interglacial conditions in all studied caves. In the northernmost cave (at 60°N), no growth has occurred since Marine Isotopic Stage (MIS) 11. Growth at that time indicates that global climates only slightly warmer than today are sufficient to thaw extensive regions of permafrost.
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Affiliation(s)
- A Vaks
- Department of Earth Sciences, University of Oxford, Oxford, UK.
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Dynamics of the last glacial maximum Antarctic ice-sheet and its response to ocean forcing. Proc Natl Acad Sci U S A 2012; 109:16052-6. [PMID: 22988078 DOI: 10.1073/pnas.1205385109] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Retreat of the Last Glacial Maximum (LGM) Antarctic ice sheet is thought to have been initiated by changes in ocean heat and eustatic sea level propagated from the Northern Hemisphere (NH) as northern ice sheets melted under rising atmospheric temperatures. The extent to which spatial variability in ice dynamics may have modulated the resultant pattern and timing of decay of the Antarctic ice sheet has so far received little attention, however, despite the growing recognition that dynamic effects account for a sizeable proportion of mass-balance changes observed in modern ice sheets. Here we use a 5-km resolution whole-continent numerical ice-sheet model to assess whether differences in the mechanisms governing ice sheet flow could account for discrepancies between geochronological studies in different parts of the continent. We first simulate the geometry and flow characteristics of an equilibrium LGM ice sheet, using pan-Antarctic terrestrial and marine geological data for constraint, then perturb the system with sea level and ocean heat flux increases to investigate ice-sheet vulnerability. Our results identify that fast-flowing glaciers in the eastern Weddell Sea, the Amundsen Sea, central Ross Sea, and in the Amery Trough respond most rapidly to ocean forcings, in agreement with empirical data. Most significantly, we find that although ocean warming and sea-level rise bring about mainly localized glacier acceleration, concomitant drawdown of ice from neighboring areas leads to widespread thinning of entire glacier catchments-a discovery that has important ramifications for the dynamic changes presently being observed in modern ice sheets.
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Abstract
During the last interglacial period, ~125,000 years ago, sea level was at least several meters higher than at present, with substantial variability observed for peak sea level at geographically diverse sites. Speculation that the West Antarctic ice sheet collapsed during the last interglacial period has drawn particular interest to understanding climate and ice-sheet dynamics during this time interval. We provide an internally consistent database of coral U-Th ages to assess last interglacial sea-level observations in the context of isostatic modeling and stratigraphic evidence. These data indicate that global (eustatic) sea level peaked 5.5 to 9 meters above present sea level, requiring smaller ice sheets in both Greenland and Antarctica relative to today and indicating strong sea-level sensitivity to small changes in radiative forcing.
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Affiliation(s)
- A Dutton
- Research School of Earth Sciences, The Australian National University, 1 Mills Road, Canberra, ACT 0200, Australia.
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Melles M, Brigham-Grette J, Minyuk PS, Nowaczyk NR, Wennrich V, DeConto RM, Anderson PM, Andreev AA, Coletti A, Cook TL, Haltia-Hovi E, Kukkonen M, Lozhkin AV, Rosen P, Tarasov P, Vogel H, Wagner B. 2.8 Million Years of Arctic Climate Change from Lake El'gygytgyn, NE Russia. Science 2012; 337:315-20. [DOI: 10.1126/science.1222135] [Citation(s) in RCA: 342] [Impact Index Per Article: 28.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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