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Bard E, Miramont C, Capano M, Guibal F, Marschal C, Rostek F, Tuna T, Fagault Y, Heaton TJ. A radiocarbon spike at 14 300 cal yr BP in subfossil trees provides the impulse response function of the global carbon cycle during the Late Glacial. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2023; 381:20220206. [PMID: 37807686 PMCID: PMC10586540 DOI: 10.1098/rsta.2022.0206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Accepted: 03/06/2023] [Indexed: 10/10/2023]
Abstract
We present new 14C results measured on subfossil Scots Pines recovered in the eroded banks of the Drouzet watercourse in the Southern French Alps. About 400 new 14C ages have been analysed on 15 trees sampled at annual resolution. The resulting Δ14C record exhibits an abrupt spike occurring in a single year at 14 300-14 299 cal yr BP and a century-long event between 14 and 13.9 cal kyr BP. In order to identify the causes of these events, we compare the Drouzet Δ14C record with simulations of Δ14C based on the 10Be record in Greenland ice used as an input of a carbon cycle model. The correspondence with 10Be anomalies allows us to propose the 14.3 cal kyr BP event as a solar energetic particle event. By contrast, the 14 cal kyr BP event lasted about a century and is most probably a common Maunder-type solar minimum linked to the modulation of galactic cosmic particles by the heliomagnetic field. We also discuss and speculate about the synchroneity and the possible causes of the 14 cal kyr BP event with the brief cold phase called Older Dryas, which separates the Bølling and Allerød millennium-long warm phases of the Late Glacial period. This article is part of the Theo Murphy meeting issue 'Radiocarbon in the Anthropocene'.
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Affiliation(s)
- Edouard Bard
- CEREGE, Aix-Marseille University, CNRS, IRD, INRAE, Collège de France, Technopôle de l'Arbois, BP 80, 13545 Aix-en-Provence, France
| | - Cécile Miramont
- IMBE, Aix-Marseille University, CNRS, IRD, Avignon University, Technopôle de l'Arbois, 13545 Aix-en-Provence, France
| | - Manuela Capano
- CEREGE, Aix-Marseille University, CNRS, IRD, INRAE, Collège de France, Technopôle de l'Arbois, BP 80, 13545 Aix-en-Provence, France
| | - Frédéric Guibal
- IMBE, Aix-Marseille University, CNRS, IRD, Avignon University, Technopôle de l'Arbois, 13545 Aix-en-Provence, France
| | - Christian Marschal
- IMBE, Aix-Marseille University, CNRS, IRD, Avignon University, Technopôle de l'Arbois, 13545 Aix-en-Provence, France
| | - Frauke Rostek
- CEREGE, Aix-Marseille University, CNRS, IRD, INRAE, Collège de France, Technopôle de l'Arbois, BP 80, 13545 Aix-en-Provence, France
| | - Thibaut Tuna
- CEREGE, Aix-Marseille University, CNRS, IRD, INRAE, Collège de France, Technopôle de l'Arbois, BP 80, 13545 Aix-en-Provence, France
| | - Yoann Fagault
- CEREGE, Aix-Marseille University, CNRS, IRD, INRAE, Collège de France, Technopôle de l'Arbois, BP 80, 13545 Aix-en-Provence, France
| | - Timothy J. Heaton
- Department of Statistics, School of Mathematics, University of Leeds, Leeds LS2 9JT, UK
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2
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Eglinton TI, Graven HD, Raymond PA, Trumbore SE, Aluwihare L, Bard E, Basu S, Friedlingstein P, Hammer S, Lester J, Sanderman J, Schuur EAG, Sierra CA, Synal HA, Turnbull JC, Wacker L. Making the case for an International Decade of Radiocarbon. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2023; 381:20230081. [PMID: 37807687 PMCID: PMC10642805 DOI: 10.1098/rsta.2023.0081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Accepted: 08/08/2023] [Indexed: 10/10/2023]
Abstract
Radiocarbon (14C) is a critical tool for understanding the global carbon cycle. During the Anthropocene, two new processes influenced 14C in atmospheric, land and ocean carbon reservoirs. First, 14C-free carbon derived from fossil fuel burning has diluted 14C, at rates that have accelerated with time. Second, 'bomb' 14C produced by atmospheric nuclear weapon tests in the mid-twentieth century provided a global isotope tracer that is used to constrain rates of air-sea gas exchange, carbon turnover, large-scale atmospheric and ocean transport, and other key C cycle processes. As we write, the 14C/12C ratio of atmospheric CO2 is dropping below pre-industrial levels, and the rate of decline in the future will depend on global fossil fuel use and net exchange of bomb 14C between the atmosphere, ocean and land. This milestone coincides with a rapid increase in 14C measurement capacity worldwide. Leveraging future 14C measurements to understand processes and test models requires coordinated international effort-a 'decade of radiocarbon' with multiple goals: (i) filling observational gaps using archives, (ii) building and sustaining observation networks to increase measurement density across carbon reservoirs, (iii) developing databases, synthesis and modelling tools and (iv) establishing metrics for identifying and verifying changes in carbon sources and sinks. This article is part of the Theo Murphy meeting issue 'Radiocarbon in the Anthropocene'.
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Affiliation(s)
| | | | | | - Susan E. Trumbore
- Department of Biogeochemical Processes, Max Planck Institute for Biogeochemistry, Jena, Germany
| | - Lihini Aluwihare
- Geosciences Research Division, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA, USA
| | - Edouard Bard
- CEREGE, Aix-Marseille University, CNRS, IRD, INRAE, Collège de France, Aix-en-Provence, France
| | - Sourish Basu
- Global Modeling and Assimilation Office, NASA Goddard Space Flight Center, Greenbelt, MD, USA
- Earth System Science Interdisciplinary Center, University of Maryland, College Park, MD, USA
| | - Pierre Friedlingstein
- College of Engineering, Mathematics, and Physical Sciences, University of Exeter, Exeter, UK
| | - Samuel Hammer
- Institut für Umweltphysik, Heidelberg University, Heidelberg, Germany
| | - Joanna Lester
- Department of Physics, Imperial College London, London, UK
| | | | - Edward A. G. Schuur
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, USA
| | - Carlos A. Sierra
- Department of Biogeochemical Processes, Max Planck Institute for Biogeochemistry, Jena, Germany
| | | | - Jocelyn C. Turnbull
- Rafter Radiocarbon Laboratory, GNS Science, Lower Hutt, New Zealand
- CIRES, University of Colorado at Boulder, Boulder, CO, USA
| | - Lukas Wacker
- Department of Physics, ETH Zurich, Zurich, Switzerland
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3
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Wu J, Mollenhauer G, Stein R, Köhler P, Hefter J, Fahl K, Grotheer H, Wei B, Nam SI. Deglacial release of petrogenic and permafrost carbon from the Canadian Arctic impacting the carbon cycle. Nat Commun 2022; 13:7172. [PMID: 36418299 PMCID: PMC9684420 DOI: 10.1038/s41467-022-34725-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2021] [Accepted: 11/04/2022] [Indexed: 11/24/2022] Open
Abstract
The changes in atmospheric pCO2 provide evidence for the release of large amounts of ancient carbon during the last deglaciation. However, the sources and mechanisms that contributed to this process remain unresolved. Here, we present evidence for substantial ancient terrestrial carbon remobilization in the Canadian Arctic following the Laurentide Ice Sheet retreat. Glacial-retreat-induced physical erosion of bedrock has mobilized petrogenic carbon, as revealed by sedimentary records of radiocarbon dates and thermal maturity of organic carbon from the Canadian Beaufort Sea. Additionally, coastal erosion during the meltwater pulses 1a and 1b has remobilized pre-aged carbon from permafrost. Assuming extensive petrogenic organic carbon oxidation during the glacial retreat, a model-based assessment suggests that the combined processes have contributed 12 ppm to the deglacial CO2 rise. Our findings suggest potentially positive climate feedback of ice-sheet retreat by accelerating terrestrial organic carbon remobilization and subsequent oxidation during the glacial-interglacial transition.
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Affiliation(s)
- Junjie Wu
- grid.10894.340000 0001 1033 7684Alfred-Wegener-Institut Helmholtz-Zentrum für Polar-und Meeresforschung (AWI), Bremerhaven, 27568 Germany ,grid.10548.380000 0004 1936 9377Present Address: Department of Environmental Science, Stockholm University, Stockholm, 11418 Sweden
| | - Gesine Mollenhauer
- grid.10894.340000 0001 1033 7684Alfred-Wegener-Institut Helmholtz-Zentrum für Polar-und Meeresforschung (AWI), Bremerhaven, 27568 Germany ,grid.7704.40000 0001 2297 4381MARUM–Center for Marine Environmental Sciences and Faculty of Geosciences, University of Bremen, Bremen, 28359 Germany
| | - Ruediger Stein
- grid.10894.340000 0001 1033 7684Alfred-Wegener-Institut Helmholtz-Zentrum für Polar-und Meeresforschung (AWI), Bremerhaven, 27568 Germany ,grid.7704.40000 0001 2297 4381MARUM–Center for Marine Environmental Sciences and Faculty of Geosciences, University of Bremen, Bremen, 28359 Germany ,grid.4422.00000 0001 2152 3263Frontiers Science Center for Deep Ocean Multispheres and Earth System, and Key Laboratory of Marine Chemistry Theory and Technology, Ocean University of China, Qingdao, 266100 China
| | - Peter Köhler
- grid.10894.340000 0001 1033 7684Alfred-Wegener-Institut Helmholtz-Zentrum für Polar-und Meeresforschung (AWI), Bremerhaven, 27568 Germany
| | - Jens Hefter
- grid.10894.340000 0001 1033 7684Alfred-Wegener-Institut Helmholtz-Zentrum für Polar-und Meeresforschung (AWI), Bremerhaven, 27568 Germany
| | - Kirsten Fahl
- grid.10894.340000 0001 1033 7684Alfred-Wegener-Institut Helmholtz-Zentrum für Polar-und Meeresforschung (AWI), Bremerhaven, 27568 Germany
| | - Hendrik Grotheer
- grid.10894.340000 0001 1033 7684Alfred-Wegener-Institut Helmholtz-Zentrum für Polar-und Meeresforschung (AWI), Bremerhaven, 27568 Germany
| | - Bingbing Wei
- grid.24516.340000000123704535State Key Laboratory of Marine Geology, Tongji University, Shanghai, 200092 China
| | - Seung-Il Nam
- grid.410913.e0000 0004 0400 5538Korea Polar Research Institute, Incheon, 21990 Republic of Korea
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4
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Ronge TA, Frische M, Fietzke J, Stephens AL, Bostock H, Tiedemann R. Southern Ocean contribution to both steps in deglacial atmospheric CO 2 rise. Sci Rep 2021; 11:22117. [PMID: 34764385 PMCID: PMC8585946 DOI: 10.1038/s41598-021-01657-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Accepted: 10/29/2021] [Indexed: 12/01/2022] Open
Abstract
The transfer of vast amounts of carbon from a deep oceanic reservoir to the atmosphere is considered to be a dominant driver of the deglacial rise in atmospheric CO2. Paleoceanographic reconstructions reveal evidence for the existence of CO2-rich waters in the mid to deep Southern Ocean. These water masses ventilate to the atmosphere south of the Polar Front, releasing CO2 prior to the formation and subduction of intermediate-waters. Changes in the amount of CO2 in the sea water directly affect the oceanic carbon chemistry system. Here we present B/Ca ratios, a proxy for delta carbonate ion concentrations Δ[CO32-], and stable isotopes (δ13C) from benthic foraminifera from a sediment core bathed in Antarctic Intermediate Water (AAIW), offshore New Zealand in the Southwest Pacific. We find two transient intervals of rising [CO32-] and δ13C that that are consistent with the release of CO2 via the Southern Ocean. These intervals coincide with the two pulses in rising atmospheric CO2 at ~ 17.5-14.3 ka and 12.9-11.1 ka. Our results lend support for the release of sequestered CO2 from the deep ocean to surface and atmospheric reservoirs during the last deglaciation, although further work is required to pin down the detailed carbon transfer pathways.
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Affiliation(s)
- Thomas A. Ronge
- grid.10894.340000 0001 1033 7684Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung, Am Alten Hafen 26, 27568 Bremerhaven, Germany
| | - Matthias Frische
- grid.15649.3f0000 0000 9056 9663GEOMAR Helmholtz-Zentrum für Ozeanforschung, Kiel, Germany
| | - Jan Fietzke
- grid.15649.3f0000 0000 9056 9663GEOMAR Helmholtz-Zentrum für Ozeanforschung, Kiel, Germany
| | | | - Helen Bostock
- grid.1003.20000 0000 9320 7537The University of Queensland, Brisbane, Australia
| | - Ralf Tiedemann
- grid.10894.340000 0001 1033 7684Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung, Am Alten Hafen 26, 27568 Bremerhaven, Germany
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5
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Heaton TJ, Bard E, Bronk Ramsey C, Butzin M, Köhler P, Muscheler R, Reimer PJ, Wacker L. Radiocarbon: A key tracer for studying Earth's dynamo, climate system, carbon cycle, and Sun. Science 2021; 374:eabd7096. [PMID: 34735228 DOI: 10.1126/science.abd7096] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
[Figure: see text].
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Affiliation(s)
- T J Heaton
- School of Mathematics and Statistics, University of Sheffield, Sheffield S3 7RH, UK
| | - E Bard
- CEREGE, Aix-Marseille University, CNRS, IRD, INRAE, Collège de France, Technopole de l'Arbois BP 80, 13545 Aix-en-Provence Cedex 4, France
| | - C Bronk Ramsey
- Research Laboratory for Archaeology and the History of Art, University of Oxford, Oxford OX1 3TG, UK
| | - M Butzin
- Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung (AWI), D-27515 Bremerhaven, Germany
| | - P Köhler
- Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung (AWI), D-27515 Bremerhaven, Germany
| | - R Muscheler
- Quaternary Sciences, Department of Geology, Lund University, 223 62 Lund, Sweden
| | - P J Reimer
- 14CHRONO Centre for Climate, the Environment and Chronology, School of Natural and Built Environment, Queen's University, Belfast BT7 1NN, UK
| | - L Wacker
- Laboratory of Ion Beam Physics, ETH Zürich, CH-8093 Zürich, Switzerland
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6
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Yokohata T, Saito K, Ito A, Ohno H, Tanaka K, Hajima T, Iwahana G. Future projection of greenhouse gas emissions due to permafrost degradation using a simple numerical scheme with a global land surface model. PROGRESS IN EARTH AND PLANETARY SCIENCE 2020; 7:56. [PMID: 33088673 PMCID: PMC7532133 DOI: 10.1186/s40645-020-00366-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Accepted: 08/20/2020] [Indexed: 06/11/2023]
Abstract
The Yedoma layer, a permafrost layer containing a massive amount of underground ice in the Arctic regions, is reported to be rapidly thawing. In this study, we develop the Permafrost Degradation and Greenhouse gasses Emission Model (PDGEM), which describes the thawing of the Arctic permafrost including the Yedoma layer due to climate change and the greenhouse gas (GHG) emissions. The PDGEM includes the processes by which high-concentration GHGs (CO2 and CH4) contained in the pores of the Yedoma layer are released directly by dynamic degradation, as well as the processes by which GHGs are released by the decomposition of organic matter in the Yedoma layer and other permafrost. Our model simulations show that the total GHG emissions from permafrost degradation in the RCP8.5 scenario was estimated to be 31-63 PgC for CO2 and 1261-2821 TgCH4 for CH4 (68th percentile of the perturbed model simulations, corresponding to a global average surface air temperature change of 0.05-0.11 °C), and 14-28 PgC for CO2 and 618-1341 TgCH4 for CH4 (0.03-0.07 °C) in the RCP2.6 scenario. GHG emissions resulting from the dynamic degradation of the Yedoma layer were estimated to be less than 1% of the total emissions from the permafrost in both scenarios, possibly because of the small area ratio of the Yedoma layer. An advantage of PDGEM is that geographical distributions of GHG emissions can be estimated by combining a state-of-the-art land surface model featuring detailed physical processes with a GHG release model using a simple scheme, enabling us to consider a broad range of uncertainty regarding model parameters. In regions with large GHG emissions due to permafrost thawing, it may be possible to help reduce GHG emissions by taking measures such as restraining land development.
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Affiliation(s)
- Tokuta Yokohata
- Center for Global Environmental Research, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, 305-8506 Japan
| | - Kazuyuki Saito
- Research Center for Environmental Modeling and Application, Japan Agency for Marine-Earth Science and Technology, 3173-25 Showamachi, Kanazawaku, Yokohama, 236-0001 Japan
| | - Akihiko Ito
- Center for Global Environmental Research, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, 305-8506 Japan
| | - Hiroshi Ohno
- School of Earth, Energy and Environmental Engineering, Kitami Institute of Technology, 165 Koen-cho, Kitami, 090-8507 Japan
| | - Katsumasa Tanaka
- Center for Global Environmental Research, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, 305-8506 Japan
- Laboratoire des Sciences du Climat et de l’Environnement (LSCE), Commissariat à l’énergie atomique et aux énergies alternatives (CEA), Gif-sur-Yvette, France
| | - Tomohiro Hajima
- Research Center for Environmental Modeling and Application, Japan Agency for Marine-Earth Science and Technology, 3173-25 Showamachi, Kanazawaku, Yokohama, 236-0001 Japan
| | - Go Iwahana
- International Arctic Research Center, 739, The University of Alaska Fairbanks, 2160 Koyukuk Dr, Fairbanks, AK 740 99775-7340 USA
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7
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Martens J, Wild B, Muschitiello F, O'Regan M, Jakobsson M, Semiletov I, Dudarev OV, Gustafsson Ö. Remobilization of dormant carbon from Siberian-Arctic permafrost during three past warming events. SCIENCE ADVANCES 2020; 6:6/42/eabb6546. [PMID: 33067229 PMCID: PMC7567595 DOI: 10.1126/sciadv.abb6546] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Accepted: 09/04/2020] [Indexed: 05/13/2023]
Abstract
Carbon cycle models suggest that past warming events in the Arctic may have caused large-scale permafrost thaw and carbon remobilization, thus affecting atmospheric CO2 levels. However, observational records are sparse, preventing spatially extensive and time-continuous reconstructions of permafrost carbon release during the late Pleistocene and early Holocene. Using carbon isotopes and biomarkers, we demonstrate that the three most recent warming events recorded in Greenland ice cores-(i) Dansgaard-Oeschger event 3 (~28 ka B.P.), (ii) Bølling-Allerød (14.7 to 12.9 ka B.P.), and (iii) early Holocene (~11.7 ka B.P.)-caused massive remobilization and carbon degradation from permafrost across northeast Siberia. This amplified permafrost carbon release by one order of magnitude, particularly during the last deglaciation when global sea-level rise caused rapid flooding of the land area thereafter constituting the vast East Siberian Arctic Shelf. Demonstration of past warming-induced release of permafrost carbon provides a benchmark for the sensitivity of these large carbon pools to changing climate.
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Affiliation(s)
- Jannik Martens
- Department of Environmental Science, Stockholm University, 11418 Stockholm, Sweden.
- Bolin Centre for Climate Research, Stockholm University, 10691 Stockholm, Sweden
| | - Birgit Wild
- Department of Environmental Science, Stockholm University, 11418 Stockholm, Sweden
- Bolin Centre for Climate Research, Stockholm University, 10691 Stockholm, Sweden
| | - Francesco Muschitiello
- Department of Geography, University of Cambridge, CB2 3EN Cambridge, UK
- NORCE Norwegian Research Centre, 5007 Bergen, Norway
| | - Matt O'Regan
- Bolin Centre for Climate Research, Stockholm University, 10691 Stockholm, Sweden
- Department of Geological Sciences, Stockholm University, 10691 Stockholm, Sweden
| | - Martin Jakobsson
- Bolin Centre for Climate Research, Stockholm University, 10691 Stockholm, Sweden
- Department of Geological Sciences, Stockholm University, 10691 Stockholm, Sweden
| | - Igor Semiletov
- Pacific Oceanological Institute FEB RAS Vladivostok, 690041 Vladivostok, Russia
- Institute of Natural Resources, Tomsk Polytechnic University, 634050 Tomsk, Russia
- International Arctic Research Center, University of Alaska Fairbanks, Fairbanks, 99775 AK, USA
| | - Oleg V Dudarev
- Pacific Oceanological Institute FEB RAS Vladivostok, 690041 Vladivostok, Russia
| | - Örjan Gustafsson
- Department of Environmental Science, Stockholm University, 11418 Stockholm, Sweden.
- Bolin Centre for Climate Research, Stockholm University, 10691 Stockholm, Sweden
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8
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Nehrbass-Ahles C, Shin J, Schmitt J, Bereiter B, Joos F, Schilt A, Schmidely L, Silva L, Teste G, Grilli R, Chappellaz J, Hodell D, Fischer H, Stocker TF. Abrupt CO 2 release to the atmosphere under glacial and early interglacial climate conditions. Science 2020; 369:1000-1005. [PMID: 32820127 DOI: 10.1126/science.aay8178] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Accepted: 07/09/2020] [Indexed: 11/02/2022]
Abstract
Pulse-like carbon dioxide release to the atmosphere on centennial time scales has only been identified for the most recent glacial and deglacial periods and is thought to be absent during warmer climate conditions. Here, we present a high-resolution carbon dioxide record from 330,000 to 450,000 years before present, revealing pronounced carbon dioxide jumps (CDJ) under cold and warm climate conditions. CDJ come in two varieties that we attribute to invigoration or weakening of the Atlantic meridional overturning circulation (AMOC) and associated northward and southward shifts of the intertropical convergence zone, respectively. We find that CDJ are pervasive features of the carbon cycle that can occur during interglacial climate conditions if land ice masses are sufficiently extended to be able to disturb the AMOC by freshwater input.
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Affiliation(s)
- C Nehrbass-Ahles
- Climate and Environmental Physics, Physics Institute, University of Bern, Bern, Switzerland. .,Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland.,Godwin Laboratory for Palaeoclimate Research, Department of Earth Sciences, University of Cambridge, Cambridge, UK
| | - J Shin
- Institute of Environmental Geosciences (IGE), Grenoble INP, IRD, CNRS, Université Grenoble Alpes, Grenoble, France
| | - J Schmitt
- Climate and Environmental Physics, Physics Institute, University of Bern, Bern, Switzerland.,Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland
| | - B Bereiter
- Climate and Environmental Physics, Physics Institute, University of Bern, Bern, Switzerland.,Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland.,Laboratory for Air Pollution/Environmental Technology, Empa-Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland
| | - F Joos
- Climate and Environmental Physics, Physics Institute, University of Bern, Bern, Switzerland.,Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland
| | - A Schilt
- Climate and Environmental Physics, Physics Institute, University of Bern, Bern, Switzerland.,Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland
| | - L Schmidely
- Climate and Environmental Physics, Physics Institute, University of Bern, Bern, Switzerland.,Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland
| | - L Silva
- Climate and Environmental Physics, Physics Institute, University of Bern, Bern, Switzerland.,Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland
| | - G Teste
- Institute of Environmental Geosciences (IGE), Grenoble INP, IRD, CNRS, Université Grenoble Alpes, Grenoble, France
| | - R Grilli
- Institute of Environmental Geosciences (IGE), Grenoble INP, IRD, CNRS, Université Grenoble Alpes, Grenoble, France
| | - J Chappellaz
- Institute of Environmental Geosciences (IGE), Grenoble INP, IRD, CNRS, Université Grenoble Alpes, Grenoble, France
| | - D Hodell
- Godwin Laboratory for Palaeoclimate Research, Department of Earth Sciences, University of Cambridge, Cambridge, UK
| | - H Fischer
- Climate and Environmental Physics, Physics Institute, University of Bern, Bern, Switzerland.,Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland
| | - T F Stocker
- Climate and Environmental Physics, Physics Institute, University of Bern, Bern, Switzerland.,Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland
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9
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Wang Q, Lv W, Li B, Zhou Y, Jiang L, Piao S, Wang Y, Zhang L, Meng F, Liu P, Hong H, Li Y, Dorji T, Luo C, Zhang Z, Ciais P, Peñuelas J, Kardol P, Zhou H, Wang S. Annual ecosystem respiration is resistant to changes in freeze-thaw periods in semi-arid permafrost. GLOBAL CHANGE BIOLOGY 2020; 26:2630-2641. [PMID: 31883193 DOI: 10.1111/gcb.14979] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Accepted: 12/02/2019] [Indexed: 06/10/2023]
Abstract
Warming in cold regions alters freezing and thawing (F-T) of soil in winter, exposing soil organic carbon to decomposition. Carbon-rich permafrost is expected to release more CO2 to the atmosphere through ecosystem respiration (Re) under future climate scenarios. However, the mechanisms of the responses of freeze-thaw periods to climate change and their coupling with Re in situ are poorly understood. Here, using 2 years of continuous data, we test how changes in F-T events relate to annual Re under four warming levels and precipitation addition in a semi-arid grassland with discontinuous alpine permafrost. Warming shortened the entire F-T period because the frozen period shortened more than the extended freezing period. It decreased total Re during the F-T period mainly due to decrease in mean Re rate. However, warming did not alter annual Re because of reduced soil water content and the small contribution of total Re during the F-T period to annual Re. Although there were no effects of precipitation addition alone or interactions with warming on F-T events, precipitation addition increased total Re during the F-T period and the whole year. This decoupling between changes in soil freeze-thaw events and annual Re could result from their different driving factors. Our results suggest that annual Re could be mainly determined by soil water content rather than by change in freeze-thaw periods induced by warming in semi-arid alpine permafrost.
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Affiliation(s)
- Qi Wang
- Key Laboratory of Alpine Ecology, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, China
- University of the Chinese Academy of Sciences, Beijing, China
| | - Wangwang Lv
- Key Laboratory of Alpine Ecology, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, China
- University of the Chinese Academy of Sciences, Beijing, China
| | - Bowen Li
- Key Laboratory of Alpine Ecology, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, China
- University of the Chinese Academy of Sciences, Beijing, China
| | - Yang Zhou
- Key Laboratory of Alpine Ecology, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, China
- University of the Chinese Academy of Sciences, Beijing, China
| | - Lili Jiang
- Key Laboratory of Alpine Ecology, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, China
| | - Shilong Piao
- Key Laboratory of Alpine Ecology, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, China
- CAS Center for Excellence in Tibetan Plateau Earth Science of the Chinese Academy of Sciences, Beijing, China
| | - Yanfen Wang
- University of the Chinese Academy of Sciences, Beijing, China
- CAS Center for Excellence in Tibetan Plateau Earth Science of the Chinese Academy of Sciences, Beijing, China
| | - Lirong Zhang
- Key Laboratory of Alpine Ecology, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, China
| | - Fandong Meng
- Key Laboratory of Alpine Ecology, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, China
| | - Peipei Liu
- Key Laboratory of Alpine Ecology, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, China
- University of the Chinese Academy of Sciences, Beijing, China
| | - Huan Hong
- Key Laboratory of Alpine Ecology, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, China
- University of the Chinese Academy of Sciences, Beijing, China
| | - Yaoming Li
- College of Grassland, Beijing Forestry University, Beijing, China
| | - Tsechoe Dorji
- Key Laboratory of Alpine Ecology, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, China
- Northwestern Institute of Plateau Biology, Qinghai Provincial Key Laboratory of Restoration Ecology of Cold Area, Chinese Academy of Sciences, Xining, China
| | - Caiyun Luo
- Northwestern Institute of Plateau Biology, Qinghai Provincial Key Laboratory of Restoration Ecology of Cold Area, Chinese Academy of Sciences, Xining, China
| | - Zhenhua Zhang
- Northwestern Institute of Plateau Biology, Qinghai Provincial Key Laboratory of Restoration Ecology of Cold Area, Chinese Academy of Sciences, Xining, China
| | - Philippe Ciais
- Laboratoire des Sciences du Climat et de l'Environment, CEA CNRS UVSQ, Gif sur Yvette, France
| | - Josep Peñuelas
- CREAF, Barcelona, Spain
- Global Ecology Unit CREAF-CEAB-CSIC-UAB, CSIC, Barcelona, Spain
| | - Paul Kardol
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Umeå, Sweden
| | - Huakun Zhou
- Northwestern Institute of Plateau Biology, Qinghai Provincial Key Laboratory of Restoration Ecology of Cold Area, Chinese Academy of Sciences, Xining, China
| | - Shiping Wang
- Key Laboratory of Alpine Ecology, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, China
- CAS Center for Excellence in Tibetan Plateau Earth Science of the Chinese Academy of Sciences, Beijing, China
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10
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Martens J, Wild B, Pearce C, Tesi T, Andersson A, Bröder L, O'Regan M, Jakobsson M, Sköld M, Gemery L, Cronin TM, Semiletov I, Dudarev OV, Gustafsson Ö. Remobilization of Old Permafrost Carbon to Chukchi Sea Sediments During the End of the Last Deglaciation. GLOBAL BIOGEOCHEMICAL CYCLES 2019; 33:2-14. [PMID: 31007381 PMCID: PMC6472570 DOI: 10.1029/2018gb005969] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Revised: 11/27/2018] [Accepted: 12/11/2018] [Indexed: 05/26/2023]
Abstract
Climate warming is expected to destabilize permafrost carbon (PF-C) by thaw-erosion and deepening of the seasonally thawed active layer and thereby promote PF-C mineralization to CO2 and CH4. A similar PF-C remobilization might have contributed to the increase in atmospheric CO2 during deglacial warming after the last glacial maximum. Using carbon isotopes and terrestrial biomarkers (Δ14C, δ13C, and lignin phenols), this study quantifies deposition of terrestrial carbon originating from permafrost in sediments from the Chukchi Sea (core SWERUS-L2-4-PC1). The sediment core reconstructs remobilization of permafrost carbon during the late Allerød warm period starting at 13,000 cal years before present (BP), the Younger Dryas, and the early Holocene warming until 11,000 cal years BP and compares this period with the late Holocene, from 3,650 years BP until present. Dual-carbon-isotope-based source apportionment demonstrates that Ice Complex Deposit-ice- and carbon-rich permafrost from the late Pleistocene (also referred to as Yedoma)-was the dominant source of organic carbon (66 ± 8%; mean ± standard deviation) to sediments during the end of the deglaciation, with fluxes more than twice as high (8.0 ± 4.6 g·m-2·year-1) as in the late Holocene (3.1 ± 1.0 g·m-2·year-1). These results are consistent with late deglacial PF-C remobilization observed in a Laptev Sea record, yet in contrast with PF-C sources, which at that location were dominated by active layer material from the Lena River watershed. Release of dormant PF-C from erosion of coastal permafrost during the end of the last deglaciation indicates vulnerability of Ice Complex Deposit in response to future warming and sea level changes.
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Affiliation(s)
- Jannik Martens
- Department of Environmental Science and Analytical Chemistry (ACES)Stockholm UniversityStockholmSweden
- Bolin Centre for Climate ResearchStockholm UniversityStockholmSweden
| | - Birgit Wild
- Department of Environmental Science and Analytical Chemistry (ACES)Stockholm UniversityStockholmSweden
- Bolin Centre for Climate ResearchStockholm UniversityStockholmSweden
| | - Christof Pearce
- Bolin Centre for Climate ResearchStockholm UniversityStockholmSweden
- Department of Geological Sciences (IGV)Stockholm UniversityStockholmSweden
- Department of Geoscience, Arctic Research Centre and ClimateAarhus UniversityAarhusDenmark
| | - Tommaso Tesi
- Department of Environmental Science and Analytical Chemistry (ACES)Stockholm UniversityStockholmSweden
- Bolin Centre for Climate ResearchStockholm UniversityStockholmSweden
- Institute of Marine SciencesNational Research CouncilBolognaItaly
| | - August Andersson
- Department of Environmental Science and Analytical Chemistry (ACES)Stockholm UniversityStockholmSweden
- Bolin Centre for Climate ResearchStockholm UniversityStockholmSweden
| | - Lisa Bröder
- Department of Environmental Science and Analytical Chemistry (ACES)Stockholm UniversityStockholmSweden
- Bolin Centre for Climate ResearchStockholm UniversityStockholmSweden
- Department of Earth SciencesVrije Universiteit AmsterdamAmsterdamNetherlands
| | - Matt O'Regan
- Bolin Centre for Climate ResearchStockholm UniversityStockholmSweden
- Department of Geological Sciences (IGV)Stockholm UniversityStockholmSweden
| | - Martin Jakobsson
- Bolin Centre for Climate ResearchStockholm UniversityStockholmSweden
- Department of Geological Sciences (IGV)Stockholm UniversityStockholmSweden
| | - Martin Sköld
- Department of MathematicsStockholm UniversityStockholmSweden
| | | | | | - Igor Semiletov
- Pacific Oceanological Institute FEB RASVladivostokRussia
- Institute of Natural ResourcesTomsk Polytechnic UniversityTomskRussia
- International Arctic Research CenterUniversity of Alaska FairbanksFairbanksAKUSA
| | - Oleg V. Dudarev
- Pacific Oceanological Institute FEB RASVladivostokRussia
- Institute of Natural ResourcesTomsk Polytechnic UniversityTomskRussia
| | - Örjan Gustafsson
- Department of Environmental Science and Analytical Chemistry (ACES)Stockholm UniversityStockholmSweden
- Bolin Centre for Climate ResearchStockholm UniversityStockholmSweden
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11
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Rae JWB, Burke A, Robinson LF, Adkins JF, Chen T, Cole C, Greenop R, Li T, Littley EFM, Nita DC, Stewart JA, Taylor BJ. CO 2 storage and release in the deep Southern Ocean on millennial to centennial timescales. Nature 2018; 562:569-573. [PMID: 30356182 DOI: 10.1038/s41586-018-0614-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Accepted: 08/29/2018] [Indexed: 11/09/2022]
Abstract
The cause of changes in atmospheric carbon dioxide (CO2) during the recent ice ages is yet to be fully explained. Most mechanisms for glacial-interglacial CO2 change have centred on carbon exchange with the deep ocean, owing to its large size and relatively rapid exchange with the atmosphere1. The Southern Ocean is thought to have a key role in this exchange, as much of the deep ocean is ventilated to the atmosphere in this region2. However, it is difficult to reconstruct changes in deep Southern Ocean carbon storage, so few direct tests of this hypothesis have been carried out. Here we present deep-sea coral boron isotope data that track the pH-and thus the CO2 chemistry-of the deep Southern Ocean over the past forty thousand years. At sites closest to the Antarctic continental margin, and most influenced by the deep southern waters that form the ocean's lower overturning cell, we find a close relationship between ocean pH and atmospheric CO2: during intervals of low CO2, ocean pH is low, reflecting enhanced ocean carbon storage; and during intervals of rising CO2, ocean pH rises, reflecting loss of carbon from the ocean to the atmosphere. Correspondingly, at shallower sites we find rapid (millennial- to centennial-scale) decreases in pH during abrupt increases in CO2, reflecting the rapid transfer of carbon from the deep ocean to the upper ocean and atmosphere. Our findings confirm the importance of the deep Southern Ocean in ice-age CO2 change, and show that deep-ocean CO2 release can occur as a dynamic feedback to rapid climate change on centennial timescales.
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Affiliation(s)
- J W B Rae
- School of Earth and Environmental Sciences, University of St Andrews, St Andrews, UK.
| | - A Burke
- School of Earth and Environmental Sciences, University of St Andrews, St Andrews, UK
| | - L F Robinson
- School of Earth Sciences, University of Bristol, Bristol, UK
| | - J F Adkins
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, USA
| | - T Chen
- School of Earth Sciences, University of Bristol, Bristol, UK.,School of Earth Sciences and Engineering, Nanjing University, Nanjing, China
| | - C Cole
- School of Earth and Environmental Sciences, University of St Andrews, St Andrews, UK
| | - R Greenop
- School of Earth and Environmental Sciences, University of St Andrews, St Andrews, UK
| | - T Li
- School of Earth Sciences, University of Bristol, Bristol, UK.,School of Earth Sciences and Engineering, Nanjing University, Nanjing, China
| | - E F M Littley
- School of Earth and Environmental Sciences, University of St Andrews, St Andrews, UK
| | - D C Nita
- School of Earth and Environmental Sciences, University of St Andrews, St Andrews, UK.,Faculty of Environmental Science and Engineering, Babes-Bolyai University, Cluj-Napoca, Romania
| | - J A Stewart
- School of Earth and Environmental Sciences, University of St Andrews, St Andrews, UK.,School of Earth Sciences, University of Bristol, Bristol, UK
| | - B J Taylor
- School of Earth and Environmental Sciences, University of St Andrews, St Andrews, UK
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12
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Deglacial mobilization of pre-aged terrestrial carbon from degrading permafrost. Nat Commun 2018; 9:3666. [PMID: 30201999 PMCID: PMC6131488 DOI: 10.1038/s41467-018-06080-w] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Accepted: 08/13/2018] [Indexed: 11/16/2022] Open
Abstract
The mobilization of glacial permafrost carbon during the last glacial–interglacial transition has been suggested by indirect evidence to be an additional and significant source of greenhouse gases to the atmosphere, especially at times of rapid sea-level rise. Here we present the first direct evidence for the release of ancient carbon from degrading permafrost in East Asia during the last 17 kyrs, using biomarkers and radiocarbon dating of terrigenous material found in two sediment cores from the Okhotsk Sea. Upscaling our results to the whole Arctic shelf area, we show by carbon cycle simulations that deglacial permafrost-carbon release through sea-level rise likely contributed significantly to the changes in atmospheric CO2 around 14.6 and 11.5 kyrs BP. Permafrost-derived carbon (C) may have been an additional source of greenhouse gases during the last glacial-interglacial transition. Here the authors show that ancient C from degrading permafrost was mobilised during phases of rapid sea-level rise, partially explaining changes in atmospheric CO2 and ∆14C.
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13
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Bock M, Schmitt J, Beck J, Seth B, Chappellaz J, Fischer H. Glacial/interglacial wetland, biomass burning, and geologic methane emissions constrained by dual stable isotopic CH 4 ice core records. Proc Natl Acad Sci U S A 2017; 114:E5778-E5786. [PMID: 28673973 PMCID: PMC5530640 DOI: 10.1073/pnas.1613883114] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Atmospheric methane (CH4) records reconstructed from polar ice cores represent an integrated view on processes predominantly taking place in the terrestrial biogeosphere. Here, we present dual stable isotopic methane records [δ13CH4 and δD(CH4)] from four Antarctic ice cores, which provide improved constraints on past changes in natural methane sources. Our isotope data show that tropical wetlands and seasonally inundated floodplains are most likely the controlling sources of atmospheric methane variations for the current and two older interglacials and their preceding glacial maxima. The changes in these sources are steered by variations in temperature, precipitation, and the water table as modulated by insolation, (local) sea level, and monsoon intensity. Based on our δD(CH4) constraint, it seems that geologic emissions of methane may play a steady but only minor role in atmospheric CH4 changes and that the glacial budget is not dominated by these sources. Superimposed on the glacial/interglacial variations is a marked difference in both isotope records, with systematically higher values during the last 25,000 y compared with older time periods. This shift cannot be explained by climatic changes. Rather, our isotopic methane budget points to a marked increase in fire activity, possibly caused by biome changes and accumulation of fuel related to the late Pleistocene megafauna extinction, which took place in the course of the last glacial.
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Affiliation(s)
- Michael Bock
- Climate and Environmental Physics, Physics Institute, University of Bern, 3012 Bern, Switzerland;
- Oeschger Centre for Climate Change Research, University of Bern, 3012 Bern, Switzerland
| | - Jochen Schmitt
- Climate and Environmental Physics, Physics Institute, University of Bern, 3012 Bern, Switzerland
- Oeschger Centre for Climate Change Research, University of Bern, 3012 Bern, Switzerland
| | - Jonas Beck
- Climate and Environmental Physics, Physics Institute, University of Bern, 3012 Bern, Switzerland
- Oeschger Centre for Climate Change Research, University of Bern, 3012 Bern, Switzerland
| | - Barbara Seth
- Climate and Environmental Physics, Physics Institute, University of Bern, 3012 Bern, Switzerland
- Oeschger Centre for Climate Change Research, University of Bern, 3012 Bern, Switzerland
| | - Jérôme Chappellaz
- CNRS, IGE (Institut des Géosciences de l'Environnement), F-38000 Grenoble, France
- University of Grenoble Alpes, IGE, F-38000 Grenoble, France
- IRD (Institut de Recherche pour le Développement), IGE, F-38000 Grenoble, France
- Grenoble INP (Institut National Polytechnique), IGE, F-38000 Grenoble, France
| | - Hubertus Fischer
- Climate and Environmental Physics, Physics Institute, University of Bern, 3012 Bern, Switzerland;
- Oeschger Centre for Climate Change Research, University of Bern, 3012 Bern, Switzerland
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14
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Deaney EL, Barker S, van de Flierdt T. Timing and nature of AMOC recovery across Termination 2 and magnitude of deglacial CO 2 change. Nat Commun 2017; 8:14595. [PMID: 28239149 PMCID: PMC5333367 DOI: 10.1038/ncomms14595] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 01/17/2017] [Indexed: 11/09/2022] Open
Abstract
Large amplitude variations in atmospheric CO2 were associated with glacial terminations of the Late Pleistocene. Here we provide multiple lines of evidence suggesting that the ∼20 p.p.m.v. overshoot in CO2 at the end of Termination 2 (T2) ∼129 ka was associated with an abrupt (≤400 year) deepening of Atlantic Meridional Overturning Circulation (AMOC). In contrast to Termination 1 (T1), which was interrupted by the Bølling-Allerød (B-A), AMOC recovery did not occur until the very end of T2, and was characterized by pronounced formation of deep waters in the NW Atlantic. Considering the variable influences of ocean circulation change on atmospheric CO2, we suggest that the net change in CO2 across the last 2 terminations was approximately equal if the transient effects of deglacial oscillations in ocean circulation are taken into account. Differences in the sequence and timing of ocean circulation changes across glacial terminations could affect the magnitude of deglacial atmospheric CO2 rise. Here, the authors argue that late ocean circulation recovery during the penultimate deglaciation (T2) led to a larger rise in CO2 compared with T1.
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Affiliation(s)
- Emily L Deaney
- School of Earth and Ocean Sciences, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, UK
| | - Stephen Barker
- School of Earth and Ocean Sciences, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, UK
| | - Tina van de Flierdt
- Department of Earth Science and Engineering, South Kensington Campus, Imperial College London, London SW7 2AZ, UK
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15
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Massive remobilization of permafrost carbon during post-glacial warming. Nat Commun 2016; 7:13653. [PMID: 27897191 PMCID: PMC5141343 DOI: 10.1038/ncomms13653] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2016] [Accepted: 10/19/2016] [Indexed: 11/25/2022] Open
Abstract
Recent hypotheses, based on atmospheric records and models, suggest that permafrost carbon (PF-C) accumulated during the last glaciation may have been an important source for the atmospheric CO2 rise during post-glacial warming. However, direct physical indications for such PF-C release have so far been absent. Here we use the Laptev Sea (Arctic Ocean) as an archive to investigate PF-C destabilization during the last glacial–interglacial period. Our results show evidence for massive supply of PF-C from Siberian soils as a result of severe active layer deepening in response to the warming. Thawing of PF-C must also have brought about an enhanced organic matter respiration and, thus, these findings suggest that PF-C may indeed have been an important source of CO2 across the extensive permafrost domain. The results challenge current paradigms on the post-glacial CO2 rise and, at the same time, serve as a harbinger for possible consequences of the present-day warming of PF-C soils. Atmospheric CO2 increases during the last deglaciation have been linked to the destabilisation of permafrost carbon reservoirs. Here, using a sediment core from the Laptev Sea, Tesi et al. indicate a massive supply of permafrost carbon was released from Siberia following active layer deepening.
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16
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Carbon isotopes characterize rapid changes in atmospheric carbon dioxide during the last deglaciation. Proc Natl Acad Sci U S A 2016; 113:3465-70. [PMID: 26976561 DOI: 10.1073/pnas.1513868113] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
An understanding of the mechanisms that control CO2 change during glacial-interglacial cycles remains elusive. Here we help to constrain changing sources with a high-precision, high-resolution deglacial record of the stable isotopic composition of carbon in CO2(δ(13)C-CO2) in air extracted from ice samples from Taylor Glacier, Antarctica. During the initial rise in atmospheric CO2 from 17.6 to 15.5 ka, these data demarcate a decrease in δ(13)C-CO2, likely due to a weakened oceanic biological pump. From 15.5 to 11.5 ka, the continued atmospheric CO2 rise of 40 ppm is associated with small changes in δ(13)C-CO2, consistent with a nearly equal contribution from a further weakening of the biological pump and rising ocean temperature. These two trends, related to marine sources, are punctuated at 16.3 and 12.9 ka with abrupt, century-scale perturbations in δ(13)C-CO2 that suggest rapid oxidation of organic land carbon or enhanced air-sea gas exchange in the Southern Ocean. Additional century-scale increases in atmospheric CO2 coincident with increases in atmospheric CH4 and Northern Hemisphere temperature at the onset of the Bølling (14.6-14.3 ka) and Holocene (11.6-11.4 ka) intervals are associated with small changes in δ(13)C-CO2, suggesting a combination of sources that included rising surface ocean temperature.
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17
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Was millennial scale climate change during the Last Glacial triggered by explosive volcanism? Sci Rep 2015; 5:17442. [PMID: 26616338 PMCID: PMC4663491 DOI: 10.1038/srep17442] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Accepted: 10/29/2015] [Indexed: 11/24/2022] Open
Abstract
The mechanisms responsible for millennial scale climate change within glacial time
intervals are equivocal. Here we show that all eight known radiometrically-dated
Tambora-sized or larger NH eruptions over the interval 30 to 80 ka BP
are associated with abrupt Greenland cooling (>95% confidence). Additionally,
previous research reported a strong statistical correlation between the timing of
Southern Hemisphere volcanism and Dansgaard-Oeschger (DO) events (>99%
confidence), but did not identify a causative mechanism. Volcanic aerosol-induced
asymmetrical hemispheric cooling over the last few hundred years restructured
atmospheric circulation in a similar fashion as that associated with Last Glacial
millennial-scale shifts (albeit on a smaller scale). We hypothesise that following
both recent and Last Glacial NH eruptions, volcanogenic sulphate injections into the
stratosphere cooled the NH preferentially, inducing a hemispheric temperature
asymmetry that shifted atmospheric circulation cells southward. This resulted in
Greenland cooling, Antarctic warming, and a southward shifted ITCZ. However, during
the Last Glacial, the initial eruption-induced climate response was prolonged by NH
glacier and sea ice expansion, increased NH albedo, AMOC weakening, more NH cooling,
and a consequent positive feedback. Conversely, preferential SH cooling following
large SH eruptions shifted atmospheric circulation to the north, resulting in the
characteristic features of DO events.
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18
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Chen T, Robinson LF, Burke A, Southon J, Spooner P, Morris PJ, Ng HC. Synchronous centennial abrupt events in the ocean and atmosphere during the last deglaciation. Science 2015; 349:1537-41. [PMID: 26404835 DOI: 10.1126/science.aac6159] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Antarctic ice-core data reveal that the atmosphere experienced abrupt centennial increases in CO2 concentration during the last deglaciation (~18 thousand to 11 thousand years ago). Establishing the role of ocean circulation in these changes requires high-resolution, accurately dated marine records. Here, we report radiocarbon data from uranium-thorium-dated deep-sea corals in the Equatorial Atlantic and Drake Passage over the past 25,000 years. Two major deglacial radiocarbon shifts occurred in phase with centennial atmospheric CO2 rises at 14.8 thousand and 11.7 thousand years ago. We interpret these radiocarbon-enriched signals to represent two short-lived (less than 500 years) "overshoot" events, with Atlantic meridional overturning stronger than that of the modern era. These results provide compelling evidence for a close coupling of ocean circulation and centennial climate events during the last deglaciation.
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Affiliation(s)
- Tianyu Chen
- Bristol Isotope Group, School of Earth Sciences, University of Bristol, Bristol, UK.
| | - Laura F Robinson
- Bristol Isotope Group, School of Earth Sciences, University of Bristol, Bristol, UK
| | - Andrea Burke
- Department of Earth and Environmental Sciences, University of St Andrews, St. Andrews, UK
| | - John Southon
- School of Physical Sciences, University of California, Irvine, Irvine, CA, USA
| | - Peter Spooner
- Bristol Isotope Group, School of Earth Sciences, University of Bristol, Bristol, UK
| | - Paul J Morris
- Bristol Isotope Group, School of Earth Sciences, University of Bristol, Bristol, UK
| | - Hong Chin Ng
- Bristol Isotope Group, School of Earth Sciences, University of Bristol, Bristol, UK
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19
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Precise interpolar phasing of abrupt climate change during the last ice age. Nature 2015; 520:661-5. [PMID: 25925479 DOI: 10.1038/nature14401] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Accepted: 03/03/2015] [Indexed: 11/09/2022]
Abstract
The last glacial period exhibited abrupt Dansgaard-Oeschger climatic oscillations, evidence of which is preserved in a variety of Northern Hemisphere palaeoclimate archives. Ice cores show that Antarctica cooled during the warm phases of the Greenland Dansgaard-Oeschger cycle and vice versa, suggesting an interhemispheric redistribution of heat through a mechanism called the bipolar seesaw. Variations in the Atlantic meridional overturning circulation (AMOC) strength are thought to have been important, but much uncertainty remains regarding the dynamics and trigger of these abrupt events. Key information is contained in the relative phasing of hemispheric climate variations, yet the large, poorly constrained difference between gas age and ice age and the relatively low resolution of methane records from Antarctic ice cores have so far precluded methane-based synchronization at the required sub-centennial precision. Here we use a recently drilled high-accumulation Antarctic ice core to show that, on average, abrupt Greenland warming leads the corresponding Antarctic cooling onset by 218 ± 92 years (2σ) for Dansgaard-Oeschger events, including the Bølling event; Greenland cooling leads the corresponding onset of Antarctic warming by 208 ± 96 years. Our results demonstrate a north-to-south directionality of the abrupt climatic signal, which is propagated to the Southern Hemisphere high latitudes by oceanic rather than atmospheric processes. The similar interpolar phasing of warming and cooling transitions suggests that the transfer time of the climatic signal is independent of the AMOC background state. Our findings confirm a central role for ocean circulation in the bipolar seesaw and provide clear criteria for assessing hypotheses and model simulations of Dansgaard-Oeschger dynamics.
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