1
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Moretti S, Auderset A, Deutsch C, Schmitz R, Gerber L, Thomas E, Luciani V, Petrizzo MR, Schiebel R, Tripati A, Sexton P, Norris R, D'Onofrio R, Zachos J, Sigman DM, Haug GH, Martínez-García A. Oxygen rise in the tropical upper ocean during the Paleocene-Eocene Thermal Maximum. Science 2024; 383:727-731. [PMID: 38359106 DOI: 10.1126/science.adh4893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2023] [Accepted: 01/14/2024] [Indexed: 02/17/2024]
Abstract
The global ocean's oxygen inventory is declining in response to global warming, but the future of the low-oxygen tropics is uncertain. We report new evidence for tropical oxygenation during the Paleocene-Eocene Thermal Maximum (PETM), a warming event that serves as a geologic analog to anthropogenic warming. Foraminifera-bound nitrogen isotopes indicate that the tropical North Pacific oxygen-deficient zone contracted during the PETM. A concomitant increase in foraminifera size implies that oxygen availability rose in the shallow subsurface throughout the tropical North Pacific. These changes are consistent with ocean model simulations of warming, in which a decline in biological productivity allows tropical subsurface oxygen to rise even as global ocean oxygen declines. The tropical oxygen increase may have helped avoid a mass extinction during the PETM.
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Affiliation(s)
- Simone Moretti
- Climate Geochemistry Department, Max Planck Institute for Chemistry, Mainz, Germany
- Istituto di Scienze Polari, Consiglio Nazionale delle Ricerche, Bologna, Italy
| | - Alexandra Auderset
- Climate Geochemistry Department, Max Planck Institute for Chemistry, Mainz, Germany
- School of Ocean and Earth Science, University of Southampton, Southampton, UK
| | - Curtis Deutsch
- Department of Geosciences, Princeton University, Princeton, NJ, USA
| | - Ronja Schmitz
- Climate Geochemistry Department, Max Planck Institute for Chemistry, Mainz, Germany
| | - Lukas Gerber
- Climate Geochemistry Department, Max Planck Institute for Chemistry, Mainz, Germany
| | - Ellen Thomas
- Department of Earth and Planetary Sciences, Yale University, New Haven, CT, USA
- Department of Earth and Environmental Sciences, Wesleyan University, Middletown, CT, USA
| | - Valeria Luciani
- Dipartimento di Fisica e Scienze della Terra, Università di Ferrara, Ferrara, Italy
| | - Maria Rose Petrizzo
- Dipartimento di Scienze della Terra "Ardito Desio," Università Degli Studi di Milano, Milan, Italy
| | - Ralf Schiebel
- Climate Geochemistry Department, Max Planck Institute for Chemistry, Mainz, Germany
| | - Aradhna Tripati
- Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, Los Angeles, CA, USA
- Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, Los Angeles, CA, USA
- Department of Institute of the Environment and Sustainability, University of California, Los Angeles, Los Angeles, CA, USA
| | - Philip Sexton
- School of Environment, Earth and Ecosystem Sciences, The Open University, Milton Keynes, UK
| | - Richard Norris
- Scripps Institute of Oceanography, University of California, San Diego, La Jolla, CA, USA
| | - Roberta D'Onofrio
- Dipartimento di Fisica e Scienze della Terra, Università di Ferrara, Ferrara, Italy
- Present address: CNR, Marine Science Institute (ISMAR), Arsenale Castello 2737/f, 30122 Venezia, Italy
| | - James Zachos
- Department of Earth and Planetary Sciences, University of California, Santa Cruz, Santa Cruz, CA, USA
| | - Daniel M Sigman
- Department of Geosciences, Princeton University, Princeton, NJ, USA
| | - Gerald H Haug
- Climate Geochemistry Department, Max Planck Institute for Chemistry, Mainz, Germany
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2
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Levy EJ, Vonhof HB, Bar-Matthews M, Martínez-García A, Ayalon A, Matthews A, Silverman V, Raveh-Rubin S, Zilberman T, Yasur G, Schmitt M, Haug GH. Weakened AMOC related to cooling and atmospheric circulation shifts in the last interglacial Eastern Mediterranean. Nat Commun 2023; 14:5180. [PMID: 37620353 PMCID: PMC10449873 DOI: 10.1038/s41467-023-40880-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Accepted: 08/14/2023] [Indexed: 08/26/2023] Open
Abstract
There is limited understanding of temperature and atmospheric circulation changes that accompany an Atlantic Meridional Overturning Circulation (AMOC) slowdown beyond the North Atlantic realm. A Peqi'in Cave (Israel) speleothem dated to the last interglacial period (LIG), 129-116 thousand years ago (ka), together with a large modern rainfall monitoring dataset, serve as the base for investigating past AMOC slowdown effects on the Eastern Mediterranean. Here, we reconstruct LIG temperatures and rainfall source using organic proxies (TEX86) and fluid inclusion water d-excess. The TEX86 data show a stepwise cooling from 19.8 ± 0.2° (ca. 128-126 ka) to 16.5 ± 0.6 °C (ca. 124-123 ka), while d-excess values decrease abruptly (ca. 126 ka). The d-excess shift suggests that rainfall was derived from more zonal Mediterranean air flow during the weakened AMOC interval. Decreasing rainfall d-excess trends over the last 25 years raise the question whether similar atmospheric circulation changes are also occurring today.
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Affiliation(s)
- Elan J Levy
- Department of Climate Geochemistry, Max-Planck Institute for Chemistry, Mainz, Germany.
- The Geological Survey of Israel, Jerusalem, Israel.
| | - Hubert B Vonhof
- Department of Climate Geochemistry, Max-Planck Institute for Chemistry, Mainz, Germany
| | | | | | - Avner Ayalon
- The Geological Survey of Israel, Jerusalem, Israel
| | - Alan Matthews
- The Fredy & Nadine Herrmann Institute of Earth Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Vered Silverman
- Department of Earth and Planetary Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Shira Raveh-Rubin
- Department of Earth and Planetary Sciences, Weizmann Institute of Science, Rehovot, Israel
| | | | - Gal Yasur
- The Geological Survey of Israel, Jerusalem, Israel
| | - Mareike Schmitt
- Department of Climate Geochemistry, Max-Planck Institute for Chemistry, Mainz, Germany
| | - Gerald H Haug
- Department of Climate Geochemistry, Max-Planck Institute for Chemistry, Mainz, Germany
- Department of Earth Sciences, ETH Zurich, Zürich, Switzerland
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3
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Baxter AJ, Verschuren D, Peterse F, Miralles DG, Martin-Jones CM, Maitituerdi A, Van der Meeren T, Van Daele M, Lane CS, Haug GH, Olago DO, Sinninghe Damsté JS. Reversed Holocene temperature-moisture relationship in the Horn of Africa. Nature 2023; 620:336-343. [PMID: 37558848 PMCID: PMC10412447 DOI: 10.1038/s41586-023-06272-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2022] [Accepted: 05/25/2023] [Indexed: 08/11/2023]
Abstract
Anthropogenic climate change is predicted to severely impact the global hydrological cycle1, particularly in tropical regions where agriculture-based economies depend on monsoon rainfall2. In the Horn of Africa, more frequent drought conditions in recent decades3,4 contrast with climate models projecting precipitation to increase with rising temperature5. Here we use organic geochemical climate-proxy data from the sediment record of Lake Chala (Kenya and Tanzania) to probe the stability of the link between hydroclimate and temperature over approximately the past 75,000 years, hence encompassing a sufficiently wide range of temperatures to test the 'dry gets drier, wet gets wetter' paradigm6 of anthropogenic climate change in the time domain. We show that the positive relationship between effective moisture and temperature in easternmost Africa during the cooler last glacial period shifted to negative around the onset of the Holocene 11,700 years ago, when the atmospheric carbon dioxide concentration exceeded 250 parts per million and mean annual temperature approached modern-day values. Thus, at that time, the budget between monsoonal precipitation and continental evaporation7 crossed a tipping point such that the positive influence of temperature on evaporation became greater than its positive influence on precipitation. Our results imply that under continued anthropogenic warming, the Horn of Africa will probably experience further drying, and they highlight the need for improved simulation of both dynamic and thermodynamic processes in the tropical hydrological cycle.
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Affiliation(s)
- A J Baxter
- Department of Earth Sciences, Faculty of Geosciences, Utrecht University, Utrecht, The Netherlands.
| | - D Verschuren
- Department of Biology, Limnology Unit, Ghent University, Gent, Belgium
| | - F Peterse
- Department of Earth Sciences, Faculty of Geosciences, Utrecht University, Utrecht, The Netherlands
| | - D G Miralles
- Department of Environment, Hydro-Climate Extremes Lab (H-CEL), Ghent University, Gent, Belgium
| | | | - A Maitituerdi
- Dr. Moses Strauss Department of Marine Geosciences, Leon H. Charney School of Marine Sciences, University of Haifa, Mount Carmel, Israel
| | - T Van der Meeren
- Department of Biology, Limnology Unit, Ghent University, Gent, Belgium
| | - M Van Daele
- Renard Centre of Marine Geology, Department of Geology, Ghent University, Gent, Belgium
| | - C S Lane
- Department of Geography, University of Cambridge, Cambridge, UK
| | - G H Haug
- Department of Climate Geochemistry, Max Planck Institute for Chemistry, Mainz, Germany
| | - D O Olago
- Institute for Climate Change and Adaptation, Department of Earth and Climate Science, University of Nairobi, Nairobi, Kenya
| | - J S Sinninghe Damsté
- Department of Earth Sciences, Faculty of Geosciences, Utrecht University, Utrecht, The Netherlands
- Department of Marine Microbiology and Biogeochemistry, NIOZ Royal Netherlands Institute for Sea Research, Den Burg, The Netherlands
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4
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Wörmer L, Wendt J, Boehman B, Haug GH, Hinrichs KU. Deglacial increase of seasonal temperature variability in the tropical ocean. Nature 2022; 612:88-91. [DOI: 10.1038/s41586-022-05350-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Accepted: 08/17/2022] [Indexed: 12/02/2022]
Abstract
AbstractThe relatively stable Holocene climate was preceded by a pronounced event of abrupt warming in the Northern Hemisphere, the termination of the Younger Dryas (YD) cold period1,2. Although this transition has been intensively studied, its imprint on low-latitude ocean temperature is still controversial and its effects on sub-annual to decadal climate variability remain poorly understood1,3,4. Sea surface temperature (SST) variability at these timescales in the tropical Atlantic is expected to intensify under current and future global warming and has considerable consequences for environmental conditions in Africa and South America, and for tropical Pacific climate5–8. Here we present a 100-µm-resolution record obtained by mass spectrometry imaging (MSI) of long-chain alkenones in sediments from the Cariaco Basin9–11 and find that annually averaged SST remained stable during the transition into the Holocene. However, seasonality increased more than twofold and approached modern values of 1.6 °C, probably driven by the position and/or annual range of the Intertropical Convergence Zone (ITCZ). We further observe that interannual variability intensified during the early Holocene. Our results demonstrate that sub-decadal-scale SST variability in the tropical Atlantic is sensitive to abrupt changes in climate background, such as those witnessed during the most recent glacial to interglacial transition.
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5
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Lüdecke T, Leichliter JN, Aldeias V, Bamford MK, Biro D, Braun DR, Capelli C, Cybulski JD, Duprey NN, Ferreira da Silva MJ, Foreman AD, Habermann JM, Haug GH, Martínez FI, Mathe J, Mulch A, Sigman DM, Vonhof H, Bobe R, Carvalho S, Martínez-García A. Carbon, nitrogen, and oxygen stable isotopes in modern tooth enamel: A case study from Gorongosa National Park, central Mozambique. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.958032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
The analyses of the stable isotope ratios of carbon (δ13C), nitrogen (δ15N), and oxygen (δ18O) in animal tissues are powerful tools for reconstructing the feeding behavior of individual animals and characterizing trophic interactions in food webs. Of these biomaterials, tooth enamel is the hardest, most mineralized vertebrate tissue and therefore least likely to be affected by chemical alteration (i.e., its isotopic composition can be preserved over millions of years), making it an important and widely available archive for biologists and paleontologists. Here, we present the first combined measurements of δ13C, δ15N, and δ18O in enamel from the teeth of modern fauna (herbivores, carnivores, and omnivores) from the well-studied ecosystem of Gorongosa National Park (GNP) in central Mozambique. We use two novel methods to produce high-precision stable isotope enamel data: (i) the “oxidation-denitrification method,” which permits the measurement of mineral-bound organic nitrogen in tooth enamel (δ15Nenamel), which until now, has not been possible due to enamel’s low organic content, and (ii) the “cold trap method,” which greatly reduces the sample size required for traditional measurements of inorganic δ13Cenamel and δ18Oenamel (from ≥0.5 to ≤0.1 mg), permitting analysis of small or valuable teeth and high-resolution serial sampling of enamel. The stable isotope results for GNP fauna reveal important ecological information about the trophic level, dietary niche, and resource consumption. δ15Nenamel values clearly differentiate trophic level (i.e., carnivore δ15Nenamel values are 4.0‰ higher, on average, than herbivores), δ13Cenamel values distinguish C3 and/or C4 biomass consumption, and δ18Oenamel values reflect local meteoric water (δ18Owater) in the park. Analysis of combined carbon, nitrogen, and oxygen stable isotope data permits geochemical separation of grazers, browsers, omnivores, and carnivores according to their isotopic niche, while mixed-feeding herbivores cannot be clearly distinguished from other dietary groups. These results confirm that combined C, N, and O isotope analyses of a single aliquot of tooth enamel can be used to reconstruct diet and trophic niches. Given its resistance to chemical alteration, the analysis of these three isotopes in tooth enamel has a high potential to open new avenues of research in (paleo)ecology and paleontology.
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6
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Auderset A, Moretti S, Taphorn B, Ebner PR, Kast E, Wang XT, Schiebel R, Sigman DM, Haug GH, Martínez-García A. Enhanced ocean oxygenation during Cenozoic warm periods. Nature 2022; 609:77-82. [PMID: 36045236 PMCID: PMC9433325 DOI: 10.1038/s41586-022-05017-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Accepted: 06/09/2022] [Indexed: 11/09/2022]
Abstract
Dissolved oxygen (O2) is essential for most ocean ecosystems, fuelling organisms’ respiration and facilitating the cycling of carbon and nutrients. Oxygen measurements have been interpreted to indicate that the ocean’s oxygen-deficient zones (ODZs) are expanding under global warming1,2. However, models provide an unclear picture of future ODZ change in both the near term and the long term3–6. The paleoclimate record can help explore the possible range of ODZ changes in warmer-than-modern periods. Here we use foraminifera-bound nitrogen (N) isotopes to show that water-column denitrification in the eastern tropical North Pacific was greatly reduced during the Middle Miocene Climatic Optimum (MMCO) and the Early Eocene Climatic Optimum (EECO). Because denitrification is restricted to oxygen-poor waters, our results indicate that, in these two Cenozoic periods of sustained warmth, ODZs were contracted, not expanded. ODZ contraction may have arisen from a decrease in upwelling-fuelled biological productivity in the tropical Pacific, which would have reduced oxygen demand in the subsurface. Alternatively, invigoration of deep-water ventilation by the Southern Ocean may have weakened the ocean’s ‘biological carbon pump’, which would have increased deep-ocean oxygen. The mechanism at play would have determined whether the ODZ contractions occurred in step with the warming or took centuries or millennia to develop. Thus, although our results from the Cenozoic do not necessarily apply to the near-term future, they might imply that global warming may eventually cause ODZ contraction. By using foraminifera-bound nitrogen isotopes, it is shown that, during two warm periods of the Cenozoic, oxygen-deficient zones contracted rather than expanded, suggesting that global warming may not necessarily lead to increased oceanic anoxia.
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Affiliation(s)
- Alexandra Auderset
- Climate Geochemistry Department, Max Planck Institute for Chemistry, Mainz, Germany. .,Department of Earth Sciences, ETH Zurich, Zurich, Switzerland.
| | - Simone Moretti
- Climate Geochemistry Department, Max Planck Institute for Chemistry, Mainz, Germany.,Department of Earth Sciences, ETH Zurich, Zurich, Switzerland
| | - Björn Taphorn
- Climate Geochemistry Department, Max Planck Institute for Chemistry, Mainz, Germany
| | - Pia-Rebecca Ebner
- Climate Geochemistry Department, Max Planck Institute for Chemistry, Mainz, Germany
| | - Emma Kast
- Department of Geosciences, Princeton University, Princeton, NJ, USA.,Department of Earth Sciences, University of Cambridge, Cambridge, UK
| | - Xingchen T Wang
- Department of Earth and Environmental Sciences, Boston College, Chestnut Hill, MA, USA
| | - Ralf Schiebel
- Climate Geochemistry Department, Max Planck Institute for Chemistry, Mainz, Germany
| | - Daniel M Sigman
- Department of Geosciences, Princeton University, Princeton, NJ, USA
| | - Gerald H Haug
- Climate Geochemistry Department, Max Planck Institute for Chemistry, Mainz, Germany.,Department of Earth Sciences, ETH Zurich, Zurich, Switzerland
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7
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Kast ER, Griffiths ML, Kim SL, Rao ZC, Shimada K, Becker MA, Maisch HM, Eagle RA, Clarke CA, Neumann AN, Karnes ME, Lüdecke T, Leichliter JN, Martínez-García A, Akhtar AA, Wang XT, Haug GH, Sigman DM. Cenozoic megatooth sharks occupied extremely high trophic positions. Sci Adv 2022; 8:eabl6529. [PMID: 35731884 PMCID: PMC9217088 DOI: 10.1126/sciadv.abl6529] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Accepted: 05/05/2022] [Indexed: 06/15/2023]
Abstract
Trophic position is a fundamental characteristic of animals, yet it is unknown in many extinct species. In this study, we ground-truth the 15N/14N ratio of enameloid-bound organic matter (δ15NEB) as a trophic level proxy by comparison to dentin collagen δ15N and apply this method to the fossil record to reconstruct the trophic level of the megatooth sharks (genus Otodus). These sharks evolved in the Cenozoic, culminating in Otodus megalodon, a shark with a maximum body size of more than 15 m, which went extinct 3.5 million years ago. Very high δ15NEB values (22.9 ± 4.4‰) of O. megalodon from the Miocene and Pliocene show that it occupied a higher trophic level than is known for any marine species, extinct or extant. δ15NEB also indicates a dietary shift in sharks of the megatooth lineage as they evolved toward the gigantic O. megalodon, with the highest trophic level apparently reached earlier than peak size.
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Affiliation(s)
- Emma R. Kast
- Department of Geosciences, Princeton University, Princeton, NJ 08544, USA
- Department of Earth Sciences, University of Cambridge, Cambridge, CB23EQ, UK
| | - Michael L. Griffiths
- Department of Environmental Science, William Paterson University of New Jersey, Wayne, NJ 07470, USA
| | - Sora L. Kim
- Department of Life and Environmental Sciences, University of California Merced, Merced, CA 95343, USA
| | - Zixuan C. Rao
- Department of Geosciences, Princeton University, Princeton, NJ 08544, USA
| | - Kenshu Shimada
- Department of Environmental Science and Studies, DePaul University, Chicago, IL 60614, USA
- Department of Biological Sciences, DePaul University, Chicago, IL 60614, USA
- Sternberg Museum of Natural History, Fort Hays State University, Hays, KS 67601, USA
| | - Martin A. Becker
- Department of Environmental Science, William Paterson University of New Jersey, Wayne, NJ 07470, USA
| | - Harry M. Maisch
- Department of Marine and Earth Sciences, Florida Gulf Coast University, Fort Myers, FL 33965, USA
| | - Robert A. Eagle
- Department of Atmospheric and Oceanic Sciences. Institute of the Environment and Sustainability, University of California, Los Angeles, CA 90095, USA
| | - Chelesia A. Clarke
- Department of Environmental Science, William Paterson University of New Jersey, Wayne, NJ 07470, USA
| | - Allison N. Neumann
- Department of Environmental Science, William Paterson University of New Jersey, Wayne, NJ 07470, USA
| | - Molly E. Karnes
- Department of Life and Environmental Sciences, University of California Merced, Merced, CA 95343, USA
| | - Tina Lüdecke
- Emmy Noether Group for Hominin Meat Consumption, Max Planck Institute for Chemistry, 55128 Mainz, Germany
- Senckenberg Biodiversity and Climate Research Centre, 60325 Frankfurt, Germany
| | - Jennifer N. Leichliter
- Emmy Noether Group for Hominin Meat Consumption, Max Planck Institute for Chemistry, 55128 Mainz, Germany
- Johannes Gutenberg University, Institute of Geosciences, 55128 Mainz, Germany
| | - Alfredo Martínez-García
- Department of Climate Geochemistry, Max Planck Institute for Chemistry, 55128 Mainz, Germany
| | - Alliya A. Akhtar
- Department of Geosciences, Princeton University, Princeton, NJ 08544, USA
| | - Xingchen T. Wang
- Department of Earth and Environmental Sciences, Boston College, Chestnut Hill, MA 02467, USA
| | - Gerald H. Haug
- Department of Climate Geochemistry, Max Planck Institute for Chemistry, 55128 Mainz, Germany
- Department of Earth Sciences, ETH Zürich, CH-8092 Zürich, Switzerland
| | - Daniel M. Sigman
- Department of Geosciences, Princeton University, Princeton, NJ 08544, USA
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8
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Arns AI, Schiebel R, Evans D, Fink L, Alig E, Schmidt MU, Jantschke A, Linckens J, Haug GH. Rietveld and pair distribution function analysis of nanogranular mesocrystalline shells of hyaline foraminifers. Acta Crystallogr A Found Adv 2021. [DOI: 10.1107/s0108767321086335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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9
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de Graaf S, Vonhof HB, Levy EJ, Markowska M, Haug GH. Isotope ratio infrared spectroscopy analysis of water samples without memory effects. Rapid Commun Mass Spectrom 2021; 35:e9055. [PMID: 33521977 DOI: 10.1002/rcm.9055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2020] [Revised: 01/21/2021] [Accepted: 01/22/2021] [Indexed: 06/12/2023]
Abstract
RATIONALE Since their introduction more than a decade ago, isotope ratio infrared spectroscopy (IRIS) systems have rapidly become the standard for oxygen (δ18 O) and hydrogen (δ2 H) isotope analysis of water samples. An important disadvantage of IRIS systems is the well-documented sample-to-sample memory effect, which requires each sample to be analyzed multiple times before the desired accuracy is reached, lengthening analysis times and driving up the costs of analyses. METHODS We present an adapted set-up and calculation protocol for fully automated analysis of water samples using a Picarro L2140-i cavity ring-down spectroscopy instrument. The adaptation removes memory effects by use of a continuously moisturized nitrogen carrier gas. Water samples of 0.5 μL are measured on top of the water vapor background, after which isotope ratios are calculated by subtraction of the background from the sample peaks. RESULTS With this new technique, single injections of water samples have internal precisions (1σ) below 0.05‰ for δ18 O values and 0.1‰ for δ2 H values, regardless of the isotope ratio of the previous sample. Precision is worse, however, when the isotope difference between the sample and background water is too large (i.e., exceeding approximately 9‰ for δ18 O values and 70‰ for δ2 H values). Isotope ratios show negligible drift across the four weeks within which the experiments were performed. The single-injection 1σ precision for 17 O excess (Δ'17 O) determined with this method is 60 per meg. CONCLUSIONS Our experiments demonstrate that by removing sample-to-sample memory effects with a moisturized carrier gas, the time for measurement of δ18 O and δ2 H values using an IRIS system can be reduced markedly without compromising the analytical precision and accuracy. Thorough replication is needed to achieve sufficiently low uncertainties for Δ'17 O.
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Affiliation(s)
- Stefan de Graaf
- Climate Geochemistry Department, Max Planck Institute for Chemistry, Mainz, Germany
| | - Hubert B Vonhof
- Climate Geochemistry Department, Max Planck Institute for Chemistry, Mainz, Germany
| | - Elan J Levy
- Climate Geochemistry Department, Max Planck Institute for Chemistry, Mainz, Germany
| | - Monika Markowska
- Climate Geochemistry Department, Max Planck Institute for Chemistry, Mainz, Germany
| | - Gerald H Haug
- Climate Geochemistry Department, Max Planck Institute for Chemistry, Mainz, Germany
- Department of Earth Sciences, ETH Zürich, Sonneggstrasse 5, Zürich, 8092, Switzerland
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10
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Ai XE, Studer AS, Sigman DM, Martínez-García A, Fripiat F, Thöle LM, Michel E, Gottschalk J, Arnold L, Moretti S, Schmitt M, Oleynik S, Jaccard SL, Haug GH. Southern Ocean upwelling, Earth's obliquity, and glacial-interglacial atmospheric CO 2 change. Science 2020; 370:1348-1352. [PMID: 33303618 DOI: 10.1126/science.abd2115] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Accepted: 10/30/2020] [Indexed: 11/02/2022]
Abstract
Previous studies have suggested that during the late Pleistocene ice ages, surface-deep exchange was somehow weakened in the Southern Ocean's Antarctic Zone, which reduced the leakage of deeply sequestered carbon dioxide and thus contributed to the lower atmospheric carbon dioxide levels of the ice ages. Here, high-resolution diatom-bound nitrogen isotope measurements from the Indian sector of the Antarctic Zone reveal three modes of change in Southern Westerly Wind-driven upwelling, each affecting atmospheric carbon dioxide. Two modes, related to global climate and the bipolar seesaw, have been proposed previously. The third mode-which arises from the meridional temperature gradient as affected by Earth's obliquity (axial tilt)-can explain the lag of atmospheric carbon dioxide behind climate during glacial inception and deglaciation. This obliquity-induced lag, in turn, makes carbon dioxide a delayed climate amplifier in the late Pleistocene glacial cycles.
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Affiliation(s)
- Xuyuan E Ai
- Department of Geosciences, Princeton University, Princeton, NJ 08544, USA. .,Climate Geochemistry Department, Max Planck Institute for Chemistry, Mainz 55128, Germany
| | - Anja S Studer
- Department of Environmental Sciences, University of Basel, Basel, Switzerland
| | - Daniel M Sigman
- Department of Geosciences, Princeton University, Princeton, NJ 08544, USA
| | | | - François Fripiat
- Department of Geosciences, Environment and Society, Université Libre de Bruxelles, Brussels, Belgium
| | - Lena M Thöle
- Institute of Geological Sciences and Oeschger Center for Climate Change Research, University of Bern, Bern, Switzerland.,Department of Earth Sciences, Utrecht University, Utrecht, Netherlands
| | - Elisabeth Michel
- Laboratoire des Sciences du Climat et de l'Environnement (LSCE), Laboratoire CNRS-CEA-UVSQ, Gif-sur-Yvette, France
| | | | - Laura Arnold
- Department of Earth Sciences, ETH Zürich, Zürich, Switzerland
| | - Simone Moretti
- Climate Geochemistry Department, Max Planck Institute for Chemistry, Mainz 55128, Germany.,Department of Earth Sciences, ETH Zürich, Zürich, Switzerland
| | - Mareike Schmitt
- Climate Geochemistry Department, Max Planck Institute for Chemistry, Mainz 55128, Germany
| | - Sergey Oleynik
- Department of Geosciences, Princeton University, Princeton, NJ 08544, USA
| | - Samuel L Jaccard
- Institute of Geological Sciences and Oeschger Center for Climate Change Research, University of Bern, Bern, Switzerland
| | - Gerald H Haug
- Climate Geochemistry Department, Max Planck Institute for Chemistry, Mainz 55128, Germany.,Department of Earth Sciences, ETH Zürich, Zürich, Switzerland
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11
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Vonhof HB, de Graaf S, Spero HJ, Schiebel R, Verdegaal SJA, Metcalfe B, Haug GH. High-precision stable isotope analysis of <5 μg CaCO 3 samples by continuous-flow mass spectrometry. Rapid Commun Mass Spectrom 2020; 34:e8878. [PMID: 32632996 DOI: 10.1002/rcm.8878] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 07/01/2020] [Accepted: 07/04/2020] [Indexed: 06/11/2023]
Abstract
RATIONALE Oxygen (δ18 O) and carbon (δ13 C) isotope analysis of foraminifera and other CaCO3 samples has been a key technique for paleoceanographical and paleoclimatological research for more than 60 years. There is ongoing demand for the analysis of ever smaller CaCO3 samples, driven, for example, by the desire to analyse single specimen planktic foraminifera, or small samples of tooth enamel. METHODS We present a continuous-flow mass spectrometric technique that uses cryo-focusing of sample CO2 to analyse CaCO3 samples in a weight range between 10 and 3 μg. These are considerably lower sample weights than achievable on most currently available standard instrumentation. The technique is automated, so that sample throughput lies at >60 samples per day. The method involves an on-line vial-flushing routine designed to remove machine drift due to blank CO2 build-up in the sample vials. RESULTS In a series of experiments the effect of blank CO2 build-up is quantified, and outgassing from the chlorobutyl septa identified as the source. An improved flushing routine together with the use of a cryo-focusing step in the analysis is demonstrated to provide the analytical stability and sensitivity to analyse CaCO3 samples in a weight range between 10 and 3 μg at ≤0.1‰ precision (1σ) for both δ18 O and δ13 C values. The technique yields similarly precise results for the analysis of the structural carbonate fraction of small tooth enamel samples. CONCLUSIONS This study demonstrates that high-precision oxygen and carbon isotope analysis is possible on CaCO3 samples smaller than 5 μg by use of a continuous-flow isotope technique. Of key importance are (1) the application of a cold trap that drastically reduces sample gas loss, and (2) a modified flushing regime that eliminates increasing background CO2 build-up in sample vials during longer automated sample runs.
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Affiliation(s)
- Hubert B Vonhof
- Department of Climate Geochemistry, Max Planck Institute for Chemistry, Hahn-Meitner-Weg 1, Mainz, 55128, Germany
| | - Stefan de Graaf
- Department of Climate Geochemistry, Max Planck Institute for Chemistry, Hahn-Meitner-Weg 1, Mainz, 55128, Germany
| | - Howard J Spero
- Department of Earth and Planetary Sciences, University California Davis, Davis, CA, 95616, USA
| | - Ralf Schiebel
- Department of Climate Geochemistry, Max Planck Institute for Chemistry, Hahn-Meitner-Weg 1, Mainz, 55128, Germany
| | - Suzan J A Verdegaal
- Department of Earth Sciences, Faculty of Science, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Brett Metcalfe
- Department of Earth Sciences, Faculty of Science, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Gerald H Haug
- Department of Climate Geochemistry, Max Planck Institute for Chemistry, Hahn-Meitner-Weg 1, Mainz, 55128, Germany
- Department of Earth Sciences, ETH Zürich, Sonneggstrasse 5, Zürich, 8092, Switzerland
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12
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de Graaf S, Vonhof HB, Weissbach T, Wassenburg JA, Levy EJ, Kluge T, Haug GH. A comparison of isotope ratio mass spectrometry and cavity ring-down spectroscopy techniques for isotope analysis of fluid inclusion water. Rapid Commun Mass Spectrom 2020; 34:e8837. [PMID: 32424983 DOI: 10.1002/rcm.8837] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2020] [Revised: 05/12/2020] [Accepted: 05/14/2020] [Indexed: 06/11/2023]
Abstract
RATIONALE Online oxygen (δ18 O) and hydrogen (δ2 H) isotope analysis of fluid inclusion water entrapped in minerals is widely applied in paleo-fluid studies. In the state of the art of fluid inclusion isotope research, however, there is a scarcity of reported inter-technique comparisons to account for possible analytical offsets. Along with improving analytical precisions and sample size limitations, interlaboratory comparisons can lead to a more robust application of fluid inclusion isotope records. METHODS Mineral samples-including speleothem, travertine, and vein material-were analyzed on two newly setup systems for fluid inclusion isotope analysis to provide an inter-platform comparison. One setup uses a crusher unit connected online to a continuous-flow pyrolysis furnace and an isotope ratio mass spectrometry (IRMS) instrument. In the other setup, a crusher unit is lined up with a cavity ring-down spectroscopy (CRDS) system, and water samples are analyzed on a continuous standard water background to achieve precisions on water injections better than 0.1‰ for δ18 O values and 0.4‰ for δ2 H values for amounts down to 0.2 μL. RESULTS Fluid inclusion isotope analyses on the IRMS setup have an average 1σ reproducibility of 0.4‰ and 2.0‰ for δ18 O and δ2 H values, respectively. The CRDS setup has a better 1σ reproducibility (0.3‰ for δ18 O values and 1.1‰ for δ2 H values) and also a more rapid sample throughput (<30 min per sample). Fluid inclusion isotope analyses are reproducible at these uncertainties for water amounts down to 0.1 μL on both setups. Fluid inclusion isotope data show no systematic offsets between the setups. CONCLUSIONS The close match in fluid inclusion isotope results between the two setups demonstrates the high accuracy of the presented continuous-flow techniques for fluid inclusion isotope analysis. Ideally, experiments such as the one presented in this study will lead to further interlaboratory comparison efforts and the selection of suitable reference materials for fluid inclusion isotopes studies.
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Affiliation(s)
- Stefan de Graaf
- Climate Geochemistry Department, Max Planck Institute for Chemistry, Mainz, Germany
| | - Hubert B Vonhof
- Climate Geochemistry Department, Max Planck Institute for Chemistry, Mainz, Germany
| | - Therese Weissbach
- Ruprecht-Karls University Heidelberg, Institute of Environmental Physics, Heidelberg, Germany
| | - Jasper A Wassenburg
- Climate Geochemistry Department, Max Planck Institute for Chemistry, Mainz, Germany
| | - Elan J Levy
- Climate Geochemistry Department, Max Planck Institute for Chemistry, Mainz, Germany
| | - Tobias Kluge
- Ruprecht-Karls University Heidelberg, Institute of Environmental Physics, Heidelberg, Germany
| | - Gerald H Haug
- Climate Geochemistry Department, Max Planck Institute for Chemistry, Mainz, Germany
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13
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Duprey NN, Wang TX, Kim T, Cybulski JD, Vonhof HB, Crutzen PJ, Haug GH, Sigman DM, Martínez-García A, Baker DM. Megacity development and the demise of coastal coral communities: Evidence from coral skeleton δ 15 N records in the Pearl River estuary. Glob Chang Biol 2020; 26:1338-1353. [PMID: 31732999 DOI: 10.1111/gcb.14923] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2019] [Revised: 10/24/2019] [Accepted: 10/24/2019] [Indexed: 06/10/2023]
Abstract
Historical coral skeleton (CS) δ18 O and δ15 N records were produced from samples recovered from sedimentary deposits, held in natural history museum collections, and cored into modern coral heads. These records were used to assess the influence of global warming and regional eutrophication, respectively, on the decline of coastal coral communities following the development of the Pearl River Delta (PRD) megacity, China. We find that, until 2007, ocean warming was not a major threat to coral communities in the Pearl River estuary; instead, nitrogen (N) inputs dominated impacts. The high but stable CS-δ15 N values (9‰-12‰ vs. air) observed from the mid-Holocene until 1980 indicate that soil and stream denitrification reduced and modulated the hydrologic inputs of N, blunting the rise in coastal N sources during the early phase of the Pearl River estuary urbanization. However, an unprecedented CS-δ15 N peak was observed from 1987 to 1993 (>13‰ vs. air), concomitant to an increase of NH4+ concentration, consistent with the rapid Pearl River estuary urbanization as the main cause for this eutrophication event. We suggest that widespread discharge of domestic sewage entered directly into the estuary, preventing removal by natural denitrification hotspots. We argue that this event caused the dramatic decline of the Pearl River estuary coral communities reported from 1980 to 2000. Subsequently, the coral record shows that the implementation of improved wastewater management policies succeeded in bringing down both CS-δ15 N and NH4+ concentrations in the early 2000s. This study points to the potential importance of eutrophication over ocean warming in coral decline along urbanized coastlines and in particular in the vicinity of megacities.
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Affiliation(s)
- Nicolas N Duprey
- Max Planck Institute for Chemistry, Otto Hahn Institute, Mainz, Germany
- The Swire Institute of Marine Science, The University of Hong Kong, Shek O, HKSAR
- School of Biological Sciences, The University of Hong Kong, Pok Fu Lam, HKSAR
| | - Tony X Wang
- Department of Geosciences, Princeton University, Princeton, NJ, USA
- Department of Earth and Environmental Sciences, Boston College, Chestnut Hill, MA, USA
| | - Taihun Kim
- The Swire Institute of Marine Science, The University of Hong Kong, Shek O, HKSAR
- School of Biological Sciences, The University of Hong Kong, Pok Fu Lam, HKSAR
| | - Jonathan D Cybulski
- The Swire Institute of Marine Science, The University of Hong Kong, Shek O, HKSAR
- School of Biological Sciences, The University of Hong Kong, Pok Fu Lam, HKSAR
| | - Hubert B Vonhof
- Max Planck Institute for Chemistry, Otto Hahn Institute, Mainz, Germany
| | - Paul J Crutzen
- Max Planck Institute for Chemistry, Otto Hahn Institute, Mainz, Germany
| | - Gerald H Haug
- Max Planck Institute for Chemistry, Otto Hahn Institute, Mainz, Germany
| | - Daniel M Sigman
- Department of Geosciences, Princeton University, Princeton, NJ, USA
| | | | - David M Baker
- The Swire Institute of Marine Science, The University of Hong Kong, Shek O, HKSAR
- School of Biological Sciences, The University of Hong Kong, Pok Fu Lam, HKSAR
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14
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Petrick B, Martínez-García A, Auer G, Reuning L, Auderset A, Deik H, Takayanagi H, De Vleeschouwer D, Iryu Y, Haug GH. Glacial Indonesian Throughflow weakening across the Mid-Pleistocene Climatic Transition. Sci Rep 2019; 9:16995. [PMID: 31740711 PMCID: PMC6861309 DOI: 10.1038/s41598-019-53382-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 10/29/2019] [Indexed: 11/30/2022] Open
Abstract
The Indonesian Throughflow (ITF) controls the oceanic flux of heat and salt between the Pacific and Indian Oceans and therewith plays an important role in modulating the meridional overturning circulation and low latitude hydrological cycle. Here, we report new sea surface temperature and aridity records from the west coast of Australia (IODP Site U1460), which allow us to assess the sensitivity of the eastern Indian Ocean to the major reorganization of Earth’s climate that occurred during the Mid-Pleistocene Transition. Our records indicate glacial coolings at 1.55 and 0.65 million years ago that are best explained by a weakening of the ITF as a consequence of global sea level and tectonic changes. These coincide with the development of pronounced gradients in the carbon isotope composition of the different ocean basins and with substantial changes in regional aridity, suggesting that the restrictions of the ITF influenced both the evolution of global ocean circulation and the development of the modern hydrological cycle in Western Australia.
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Affiliation(s)
- Benjamin Petrick
- Max Planck Institute for Chemistry, Climate Geochemistry Department, Hahn-Meitner-Weg 1, 55128, Mainz, Germany.
| | - Alfredo Martínez-García
- Max Planck Institute for Chemistry, Climate Geochemistry Department, Hahn-Meitner-Weg 1, 55128, Mainz, Germany
| | - Gerald Auer
- Department of Biogeochemistry Frontier Bldg, 4F, Japan Agency for Marine-Earth Science and Technology (JAMSTEC) 2-15 Natsushima-cho, Yokosuka, Kanagawa, 237-0061, Japan
| | - Lars Reuning
- Kiel University, Institute for Geosciences, Ludewig-Meyn-Str. 10, 24118, Kiel, Germany.,RWTH Aachen University, Geological Institute, Wüllnerstrasse 2, 52062, Aachen, Germany
| | - Alexandra Auderset
- Max Planck Institute for Chemistry, Climate Geochemistry Department, Hahn-Meitner-Weg 1, 55128, Mainz, Germany
| | - Hanaa Deik
- RWTH Aachen University, Geological Institute, Wüllnerstrasse 2, 52062, Aachen, Germany
| | - Hideko Takayanagi
- Institute of Geology and Paleontology, Tohoku University, Aobayama, Sendai, 980-8578, Japan
| | - David De Vleeschouwer
- MARUM-Center for Marine and Environmental Sciences, Klagenfurterstraße 2-4, Bremen, 28359, Germany
| | - Yasufumi Iryu
- RWTH Aachen University, Geological Institute, Wüllnerstrasse 2, 52062, Aachen, Germany
| | - Gerald H Haug
- Max Planck Institute for Chemistry, Climate Geochemistry Department, Hahn-Meitner-Weg 1, 55128, Mainz, Germany.,Geologisches Institut, Eidgenössische Technische Hochschule Zürich, 8092, Zürich, Switzerland
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15
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Kast ER, Stolper DA, Auderset A, Higgins JA, Ren H, Wang XT, Martínez-García A, Haug GH, Sigman DM. Nitrogen isotope evidence for expanded ocean suboxia in the early Cenozoic. Science 2019; 364:386-389. [PMID: 31023923 DOI: 10.1126/science.aau5784] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Accepted: 03/26/2019] [Indexed: 11/03/2022]
Abstract
The million-year variability of the marine nitrogen cycle is poorly understood. Before 57 million years (Ma) ago, the 15N/14N ratio (δ15N) of foraminifera shell-bound organic matter from three sediment cores was high, indicating expanded water column suboxia and denitrification. Between 57 and 50 Ma ago, δ15N declined by 13 to 16 per mil in the North Pacific and by 3 to 8 per mil in the Atlantic. The decline preceded global cooling and appears to have coincided with the early stages of the Asia-India collision. Warm, salty intermediate-depth water forming along the Tethys Sea margins may have caused the expanded suboxia, ending with the collision. From 50 to 35 Ma ago, δ15N was lower than modern values, suggesting widespread sedimentary denitrification on broad continental shelves. δ15N rose at 35 Ma ago, as ice sheets grew, sea level fell, and continental shelves narrowed.
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Affiliation(s)
- Emma R Kast
- Department of Geosciences, Princeton University, Princeton, NJ 08540, USA.
| | - Daniel A Stolper
- Department of Earth and Planetary Science, University of California, Berkeley, CA 94720, USA.,Earth and Environmental Sciences Area, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Alexandra Auderset
- Department of Climate Geochemistry, Max Planck Institute for Chemistry, 55128 Mainz, Germany.,Department of Earth Sciences, ETH Zürich, CH-8092 Zürich, Switzerland
| | - John A Higgins
- Department of Geosciences, Princeton University, Princeton, NJ 08540, USA
| | - Haojia Ren
- Research Center for Future Earth, National Taiwan University, Taipei 106, Taiwan
| | - Xingchen T Wang
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA
| | - Alfredo Martínez-García
- Department of Climate Geochemistry, Max Planck Institute for Chemistry, 55128 Mainz, Germany
| | - Gerald H Haug
- Department of Climate Geochemistry, Max Planck Institute for Chemistry, 55128 Mainz, Germany.,Department of Earth Sciences, ETH Zürich, CH-8092 Zürich, Switzerland
| | - Daniel M Sigman
- Department of Geosciences, Princeton University, Princeton, NJ 08540, USA
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16
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Hasenfratz AP, Jaccard SL, Martínez-García A, Sigman DM, Hodell DA, Vance D, Bernasconi SM, Kleiven HKF, Haumann FA, Haug GH. The residence time of Southern Ocean surface waters and the 100,000-year ice age cycle. Science 2019; 363:1080-1084. [PMID: 30846597 DOI: 10.1126/science.aat7067] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Accepted: 01/23/2019] [Indexed: 11/02/2022]
Abstract
From 1.25 million to 700,000 years ago, the ice age cycle deepened and lengthened from 41,000- to 100,000-year periodicity, a transition that remains unexplained. Using surface- and bottom-dwelling foraminifera from the Antarctic Zone of the Southern Ocean to reconstruct the deep-to-surface supply of water during the ice ages of the past 1.5 million years, we found that a reduction in deep water supply and a concomitant freshening of the surface ocean coincided with the emergence of the high-amplitude 100,000-year glacial cycle. We propose that this slowing of deep-to-surface circulation (i.e., a longer residence time for Antarctic surface waters) prolonged ice ages by allowing the Antarctic halocline to strengthen, which increased the resistance of the Antarctic upper water column to orbitally paced drivers of carbon dioxide release.
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Affiliation(s)
- Adam P Hasenfratz
- Geological Institute, Department of Earth Sciences, ETH Zürich, Zürich, Switzerland. .,Institute of Geological Sciences and Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland
| | - Samuel L Jaccard
- Institute of Geological Sciences and Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland.
| | | | - Daniel M Sigman
- Department of Geosciences, Guyot Hall, Princeton University, Princeton, NJ, USA
| | - David A Hodell
- Department of Earth Sciences, University of Cambridge, Cambridge, UK
| | - Derek Vance
- Institute of Geochemistry and Petrology, ETH Zürich, Zürich, Switzerland
| | - Stefano M Bernasconi
- Geological Institute, Department of Earth Sciences, ETH Zürich, Zürich, Switzerland
| | - Helga Kikki F Kleiven
- Department of Earth Science, University of Bergen and Bjerknes Centre for Climate Research, Bergen, Norway
| | - F Alexander Haumann
- British Antarctic Survey, Cambridge, UK.,Atmospheric and Oceanic Sciences, Princeton University, Princeton, NJ, USA
| | - Gerald H Haug
- Geological Institute, Department of Earth Sciences, ETH Zürich, Zürich, Switzerland.,Max Planck Institute for Chemistry, Mainz, Germany
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17
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Magill CR, Ausín B, Wenk P, McIntyre C, Skinner L, Martínez-García A, Hodell DA, Haug GH, Kenney W, Eglinton TI. Transient hydrodynamic effects influence organic carbon signatures in marine sediments. Nat Commun 2018; 9:4690. [PMID: 30410023 PMCID: PMC6224525 DOI: 10.1038/s41467-018-06973-w] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Accepted: 09/19/2018] [Indexed: 11/09/2022] Open
Abstract
Ocean dynamics served an important role during past dramatic climate changes via impacts on deep-ocean carbon storage. Such changes are recorded in sedimentary proxies of hydrographic change on continental margins, which lie at the ocean-atmosphere-earth interface. However, interpretations of these records are challenging, given complex interplays among processes delivering particulate material to and from ocean margins. Here we report radiocarbon (14C) signatures measured for organic carbon in differing grain-size sediment fractions and foraminifera in a sediment core retrieved from the southwest Iberian margin, spanning the last ~25,000 yr. Variable differences of 0-5000 yr in radiocarbon age are apparent between organic carbon in differing grain-sizes and foraminifera of the same sediment layer. The magnitude of 14C differences co-varies with key paleoceanographic indices (e.g., proximal bottom-current density gradients), which we interpret as evidence of Atlantic-Mediterranean seawater exchange influencing grain-size specific carbon accumulation and translocation. These findings underscore an important link between regional hydrodynamics and interpretations of down-core sedimentary proxies.
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Affiliation(s)
- Clayton R Magill
- Geological Institute, ETH Zürich, Zürich, 8092, Switzerland.
- Lyell Centre, Heriot-Watt University, Edinburgh, EH14 4AS, United Kingdom.
| | - Blanca Ausín
- Geological Institute, ETH Zürich, Zürich, 8092, Switzerland
| | - Pascal Wenk
- Geological Institute, ETH Zürich, Zürich, 8092, Switzerland
| | - Cameron McIntyre
- Geological Institute, ETH Zürich, Zürich, 8092, Switzerland
- Laboratory for Ion Beam Physics, ETH Zürich, Zürich, 8093, Switzerland
- Scottish Universities Environmental Research Centre (SUERC), East Kilbride, G750QF, United Kingdom
| | - Luke Skinner
- Department of Earth Sciences, University of Cambridge, Cambridge, CB2 3EQ, United Kingdom
| | - Alfredo Martínez-García
- Geological Institute, ETH Zürich, Zürich, 8092, Switzerland
- Max Planck Institute for Chemistry, D-55128, Mainz, Germany
| | - David A Hodell
- Department of Earth Sciences, University of Cambridge, Cambridge, CB2 3EQ, United Kingdom
| | - Gerald H Haug
- Geological Institute, ETH Zürich, Zürich, 8092, Switzerland
- Max Planck Institute for Chemistry, D-55128, Mainz, Germany
| | - William Kenney
- Land Use and Environmental Change Institute, University of Florida, Gainesville, FL, 32611, United States
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18
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Burls NJ, Fedorov AV, Sigman DM, Jaccard SL, Tiedemann R, Haug GH. Active Pacific meridional overturning circulation (PMOC) during the warm Pliocene. Sci Adv 2017; 3:e1700156. [PMID: 28924606 PMCID: PMC5597313 DOI: 10.1126/sciadv.1700156] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/15/2017] [Accepted: 08/14/2017] [Indexed: 06/07/2023]
Abstract
An essential element of modern ocean circulation and climate is the Atlantic meridional overturning circulation (AMOC), which includes deep-water formation in the subarctic North Atlantic. However, a comparable overturning circulation is absent in the Pacific, the world's largest ocean, where relatively fresh surface waters inhibit North Pacific deep convection. We present complementary measurement and modeling evidence that the warm, ~400-ppmv (parts per million by volume) CO2 world of the Pliocene supported subarctic North Pacific deep-water formation and a Pacific meridional overturning circulation (PMOC) cell. In Pliocene subarctic North Pacific sediments, we report orbitally paced maxima in calcium carbonate accumulation rate, with accompanying pigment and total organic carbon measurements supporting deep-ocean ventilation-driven preservation as their cause. Together with high accumulation rates of biogenic opal, these findings require vigorous bidirectional communication between surface waters and interior waters down to ~3 km in the western subarctic North Pacific, implying deep convection. Redox-sensitive trace metal data provide further evidence of higher Pliocene deep-ocean ventilation before the 2.73-Ma (million years) transition. This observational analysis is supported by climate modeling results, demonstrating that atmospheric moisture transport changes, in response to the reduced meridional sea surface temperature gradients of the Pliocene, were capable of eroding the halocline, leading to deep-water formation in the western subarctic Pacific and a strong PMOC. This second Northern Hemisphere overturning cell has important implications for heat transport, the ocean/atmosphere cycle of carbon, and potentially the equilibrium response of the Pacific to global warming.
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Affiliation(s)
- Natalie J. Burls
- Center for Ocean-Land-Atmosphere Studies, Department of Atmospheric, Oceanic, and Earth Sciences, George Mason University, Fairfax, VA 22030, USA
- Department of Geology and Geophysics, Yale University, New Haven, CT 06511, USA
| | - Alexey V. Fedorov
- Department of Geology and Geophysics, Yale University, New Haven, CT 06511, USA
| | - Daniel M. Sigman
- Department of Geosciences, Princeton University, Princeton, NJ 08544, USA
| | - Samuel L. Jaccard
- Institute of Geological Sciences and Oeschger Center for Climate Change Research, University of Bern, Bern, Switzerland
| | | | - Gerald H. Haug
- Department of Climate Geochemistry, Max-Planck Institute for Chemistry, Mainz, Germany
- Geological Institute, Department of Earth Sciences, ETH Zürich, Switzerland
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19
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Tomonaga Y, Brennwald MS, Livingstone DM, Kwiecien O, Randlett MÈ, Stockhecke M, Unwin K, Anselmetti FS, Beer J, Haug GH, Schubert CJ, Sturm M, Kipfer R. Porewater salinity reveals past lake-level changes in Lake Van, the Earth's largest soda lake. Sci Rep 2017; 7:313. [PMID: 28331216 PMCID: PMC5428207 DOI: 10.1038/s41598-017-00371-w] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Accepted: 02/22/2017] [Indexed: 11/21/2022] Open
Abstract
In closed-basin lakes, sediment porewater salinity can potentially be used as a conservative tracer to reconstruct past fluctuations in lake level. However, until now, porewater salinity profiles did not allow quantitative estimates of past lake-level changes because, in contrast to the oceans, significant salinity changes (e.g., local concentration minima and maxima) had never been observed in lacustrine sediments. Here we show that the salinity measured in the sediment pore water of Lake Van (Turkey) allows straightforward reconstruction of two major transgressions and a major regression that occurred during the last 250 ka. We observed strong changes in the vertical salinity profiles of the pore water of the uppermost 100 m of the sediments in Lake Van. As the salinity balance of Lake Van is almost at steady-state, these salinity changes indicate major lake-level changes in the past. In line with previous studies on lake terraces and with seismic and sedimentological surveys, we identify two major transgressions of up to +105 m with respect to the current lake level at about 135 ka BP and 248 ka BP starting at the onset of the two previous interglacials (MIS5e and MIS7), and a major regression of about −200 m at about 30 ka BP during the last ice age.
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Affiliation(s)
- Yama Tomonaga
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department of Water Resources and DrinkingWater, Überlandstrasse 133, 8600, Dübendorf, Switzerland. .,Atmosphere and Ocean Research Institute, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa-shi, Chiba, 277-8564, Japan. .,Institute of Geological Sciences, University of Bern, Baltzerstrasse 1+3, 3012, Bern, Switzerland.
| | - Matthias S Brennwald
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department of Water Resources and DrinkingWater, Überlandstrasse 133, 8600, Dübendorf, Switzerland
| | - David M Livingstone
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department of Water Resources and DrinkingWater, Überlandstrasse 133, 8600, Dübendorf, Switzerland
| | - Olga Kwiecien
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department of Water Resources and DrinkingWater, Überlandstrasse 133, 8600, Dübendorf, Switzerland.,Geological Institute, Swiss Federal Institute of Technology (ETH), 8092, Zürich, Switzerland.,Ruhr-University Bochum, Universitätstrasse 150, 44801, Bochum, Germany
| | - Marie-Ève Randlett
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department Surface Water Research and Management, Seestrasse 79, 6047, Kastanienbaum, Switzerland.,Institute of Biogeochemistry and Pollutant Dynamics, Swiss Federal Institute of Technology (ETH), 8092, Zürich, Switzerland
| | - Mona Stockhecke
- Institute of Biogeochemistry and Pollutant Dynamics, Swiss Federal Institute of Technology (ETH), 8092, Zürich, Switzerland.,Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department Surface Water Research and Management, Überlandstrasse 133, 8600, Dübendorf, Switzerland
| | - Katie Unwin
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department Surface Water Research and Management, Überlandstrasse 133, 8600, Dübendorf, Switzerland
| | - Flavio S Anselmetti
- Institute of Geological Sciences, University of Bern, Baltzerstrasse 1+3, 3012, Bern, Switzerland.,Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department Surface Water Research and Management, Überlandstrasse 133, 8600, Dübendorf, Switzerland.,Oeschger Centre for Climate Change Research, University of Bern, Falkenplatz 16, 3012, Bern, Switzerland
| | - Jürg Beer
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department Surface Water Research and Management, Überlandstrasse 133, 8600, Dübendorf, Switzerland
| | - Gerald H Haug
- Geological Institute, Swiss Federal Institute of Technology (ETH), 8092, Zürich, Switzerland
| | - Carsten J Schubert
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department Surface Water Research and Management, Seestrasse 79, 6047, Kastanienbaum, Switzerland.,Institute of Biogeochemistry and Pollutant Dynamics, Swiss Federal Institute of Technology (ETH), 8092, Zürich, Switzerland
| | - Mike Sturm
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department Surface Water Research and Management, Überlandstrasse 133, 8600, Dübendorf, Switzerland
| | - Rolf Kipfer
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department of Water Resources and DrinkingWater, Überlandstrasse 133, 8600, Dübendorf, Switzerland.,Institute of Biogeochemistry and Pollutant Dynamics, Swiss Federal Institute of Technology (ETH), 8092, Zürich, Switzerland.,Institute of Geochemistry and Petrology, Swiss Federal Institute of Technology (ETH), 8092, Zurich, Switzerland
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20
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Hayes CT, Martínez-García A, Hasenfratz AP, Jaccard SL, Hodell DA, Sigman DM, Haug GH, Anderson RF. A stagnation event in the deep South Atlantic during the last interglacial period. Science 2014; 346:1514-7. [PMID: 25525246 DOI: 10.1126/science.1256620] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
During the last interglacial period, global temperatures were ~2°C warmer than at present and sea level was 6 to 8 meters higher. Southern Ocean sediments reveal a spike in authigenic uranium 127,000 years ago, within the last interglacial, reflecting decreased oxygenation of deep water by Antarctic Bottom Water (AABW). Unlike ice age reductions in AABW, the interglacial stagnation event appears decoupled from open ocean conditions and may have resulted from coastal freshening due to mass loss from the Antarctic ice sheet. AABW reduction coincided with increased North Atlantic Deep Water (NADW) formation, and the subsequent reinvigoration in AABW coincided with reduced NADW formation. Thus, alternation of deep water formation between the Antarctic and the North Atlantic, believed to characterize ice ages, apparently also occurs in warm climates.
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Affiliation(s)
- Christopher T Hayes
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology (MIT), Cambridge, MA 02142, USA. Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY 10964, USA.
| | | | | | - Samuel L Jaccard
- Institute of Geological Sciences and Oeschger Centre for Climate Change Research, University of Bern, 3012 Bern, Switzerland
| | - David A Hodell
- Department of Earth Sciences, University of Cambridge, Cambridge CB2 3EQ, UK
| | - Daniel M Sigman
- Department of Geosciences, Princeton University, Princeton, NJ 08544, USA
| | - Gerald H Haug
- Geological Institute, ETH Zürich, 8092 Zürich, Switzerland
| | - Robert F Anderson
- Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY 10964, USA
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21
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Martínez-García A, Sigman DM, Ren H, Anderson RF, Straub M, Hodell DA, Jaccard SL, Eglinton TI, Haug GH. Iron fertilization of the Subantarctic ocean during the last ice age. Science 2014; 343:1347-50. [PMID: 24653031 DOI: 10.1126/science.1246848] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
John H. Martin, who discovered widespread iron limitation of ocean productivity, proposed that dust-borne iron fertilization of Southern Ocean phytoplankton caused the ice age reduction in atmospheric carbon dioxide (CO2). In a sediment core from the Subantarctic Atlantic, we measured foraminifera-bound nitrogen isotopes to reconstruct ice age nitrate consumption, burial fluxes of iron, and proxies for productivity. Peak glacial times and millennial cold events are characterized by increases in dust flux, productivity, and the degree of nitrate consumption; this combination is uniquely consistent with Subantarctic iron fertilization. The associated strengthening of the Southern Ocean's biological pump can explain the lowering of CO2 at the transition from mid-climate states to full ice age conditions as well as the millennial-scale CO2 oscillations.
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22
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Meckler AN, Sigman DM, Gibson KA, François R, Martínez-García A, Jaccard SL, Röhl U, Peterson LC, Tiedemann R, Haug GH. Deglacial pulses of deep-ocean silicate into the subtropical North Atlantic Ocean. Nature 2013; 495:495-8. [PMID: 23538831 DOI: 10.1038/nature12006] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2012] [Accepted: 02/12/2013] [Indexed: 11/10/2022]
Abstract
Growing evidence suggests that the low atmospheric CO2 concentration of the ice ages resulted from enhanced storage of CO2 in the ocean interior, largely as a result of changes in the Southern Ocean. Early in the most recent deglaciation, a reduction in North Atlantic overturning circulation seems to have driven CO2 release from the Southern Ocean, but the mechanism connecting the North Atlantic and the Southern Ocean remains unclear. Biogenic opal export in the low-latitude ocean relies on silicate from the underlying thermocline, the concentration of which is affected by the circulation of the ocean interior. Here we report a record of biogenic opal export from a coastal upwelling system off the coast of northwest Africa that shows pronounced opal maxima during each glacial termination over the past 550,000 years. These opal peaks are consistent with a strong deglacial reduction in the formation of silicate-poor glacial North Atlantic intermediate water (GNAIW). The loss of GNAIW allowed mixing with underlying silicate-rich deep water to increase the silicate supply to the surface ocean. An increase in westerly-wind-driven upwelling in the Southern Ocean in response to the North Atlantic change has been proposed to drive the deglacial rise in atmospheric CO2 (refs 3, 4). However, such a circulation change would have accelerated the formation of Antarctic intermediate water and sub-Antarctic mode water, which today have as little silicate as North Atlantic Deep Water and would have thus maintained low silicate concentrations in the Atlantic thermocline. The deglacial opal maxima reported here suggest an alternative mechanism for the deglacial CO2 release. Just as the reduction in GNAIW led to upward silicate transport, it should also have allowed the downward mixing of warm, low-density surface water to reach into the deep ocean. The resulting decrease in the density of the deep Atlantic relative to the Southern Ocean surface promoted Antarctic overturning, which released CO2 to the atmosphere.
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Affiliation(s)
- A N Meckler
- Geological Institute, ETH Zürich, 8092 Zürich, Switzerland.
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23
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Kennett DJ, Hajdas I, Culleton BJ, Belmecheri S, Martin S, Neff H, Awe J, Graham HV, Freeman KH, Newsom L, Lentz DL, Anselmetti FS, Robinson M, Marwan N, Southon J, Hodell DA, Haug GH. Correlating the ancient Maya and modern European calendars with high-precision AMS 14C dating. Sci Rep 2013; 3:1597. [PMID: 23579869 PMCID: PMC3623374 DOI: 10.1038/srep01597] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2012] [Accepted: 03/14/2013] [Indexed: 11/09/2022] Open
Abstract
The reasons for the development and collapse of Maya civilization remain controversial and historical events carved on stone monuments throughout this region provide a remarkable source of data about the rise and fall of these complex polities. Use of these records depends on correlating the Maya and European calendars so that they can be compared with climate and environmental datasets. Correlation constants can vary up to 1000 years and remain controversial. We report a series of high-resolution AMS (14)C dates on a wooden lintel collected from the Classic Period city of Tikal bearing Maya calendar dates. The radiocarbon dates were calibrated using a Bayesian statistical model and indicate that the dates were carved on the lintel between AD 658-696. This strongly supports the Goodman-Martínez-Thompson (GMT) correlation and the hypothesis that climate change played an important role in the development and demise of this complex civilization.
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Affiliation(s)
- Douglas J Kennett
- Department of Anthropology, The Pennsylvania State University, University Park, PA 16802, USA.
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24
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Jaccard SL, Hayes CT, Martínez-García A, Hodell DA, Anderson RF, Sigman DM, Haug GH. Two modes of change in Southern Ocean productivity over the past million years. Science 2013; 339:1419-23. [PMID: 23520109 DOI: 10.1126/science.1227545] [Citation(s) in RCA: 169] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Export of organic carbon from surface waters of the Antarctic Zone of the Southern Ocean decreased during the last ice age, coinciding with declining atmospheric carbon dioxide (CO(2)) concentrations, signaling reduced exchange of CO(2) between the ocean interior and the atmosphere. In contrast, in the Subantarctic Zone, export production increased into ice ages coinciding with rising dust fluxes, thus suggesting iron fertilization of subantarctic phytoplankton. Here, a new high-resolution productivity record from the Antarctic Zone is compiled with parallel subantarctic data over the past million years. Together, they fit the view that the combination of these two modes of Southern Ocean change determines the temporal structure of the glacial-interglacial atmospheric CO(2) record, including during the interval of "lukewarm" interglacials between 450 and 800 thousand years ago.
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Affiliation(s)
- S L Jaccard
- Geological Institute, Department of Earth Sciences, ETH Zurich, Zurich, Switzerland.
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25
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Kennett DJ, Breitenbach SFM, Aquino VV, Asmerom Y, Awe J, Baldini JUL, Bartlein P, Culleton BJ, Ebert C, Jazwa C, Macri MJ, Marwan N, Polyak V, Prufer KM, Ridley HE, Sodemann H, Winterhalder B, Haug GH. Development and disintegration of Maya political systems in response to climate change. Science 2012; 338:788-91. [PMID: 23139330 DOI: 10.1126/science.1226299] [Citation(s) in RCA: 357] [Impact Index Per Article: 29.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The role of climate change in the development and demise of Classic Maya civilization (300 to 1000 C.E.) remains controversial because of the absence of well-dated climate and archaeological sequences. We present a precisely dated subannual climate record for the past 2000 years from Yok Balum Cave, Belize. From comparison of this record with historical events compiled from well-dated stone monuments, we propose that anomalously high rainfall favored unprecedented population expansion and the proliferation of political centers between 440 and 660 C.E. This was followed by a drying trend between 660 and 1000 C.E. that triggered the balkanization of polities, increased warfare, and the asynchronous disintegration of polities, followed by population collapse in the context of an extended drought between 1020 and 1100 C.E.
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Affiliation(s)
- Douglas J Kennett
- Department of Anthropology, Pennsylvania State University, University Park, PA 16802, USA.
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26
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Wolff C, Haug GH, Timmermann A, Sinninghe Damsté JS, Brauer A, Sigman DM, Cane MA, Verschuren D. Reduced interannual rainfall variability in East Africa during the last ice age. Science 2011; 333:743-7. [PMID: 21817050 DOI: 10.1126/science.1203724] [Citation(s) in RCA: 124] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Interannual rainfall variations in equatorial East Africa are tightly linked to the El Niño Southern Oscillation (ENSO), with more rain and flooding during El Niño and droughts in La Niña years, both having severe impacts on human habitation and food security. Here we report evidence from an annually laminated lake sediment record from southeastern Kenya for interannual to centennial-scale changes in ENSO-related rainfall variability during the last three millennia and for reductions in both the mean rate and the variability of rainfall in East Africa during the Last Glacial period. Climate model simulations support forward extrapolation from these lake sediment data that future warming will intensify the interannual variability of East Africa's rainfall.
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Affiliation(s)
- Christian Wolff
- Helmholtz Centre Potsdam GeoForschungsZentrum (GFZ-German Research Centre for Geosciences), Section 5.2-Climate Dynamics and Landscape Evolution, Telegrafenberg, D-14473 Potsdam, Germany
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27
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Cheng H, Edwards RL, Haug GH. Comment on “On linking climate to Chinese dynastic change: Spatial and temporal variations of monsoonal rain”. ACTA ACUST UNITED AC 2010. [DOI: 10.1007/s11434-010-4122-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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28
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Martínez-Garcia A, Rosell-Melé A, McClymont EL, Gersonde R, Haug GH. Subpolar link to the emergence of the modern equatorial Pacific cold tongue. Science 2010; 328:1550-3. [PMID: 20558716 DOI: 10.1126/science.1184480] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The cold upwelling "tongue" of the eastern equatorial Pacific is a central energetic feature of the ocean, dominating both the mean state and temporal variability of climate in the tropics and beyond. Recent evidence for the development of the modern cold tongue during the Pliocene-Pleistocene transition has been explained as the result of extratropical cooling that drove a shoaling of the thermocline. We have found that the sub-Antarctic and sub-Arctic regions underwent substantial cooling nearly synchronous to the cold tongue development, thereby providing support for this hypothesis. In addition, we show that sub-Antarctic climate changed in its response to Earth's orbital variations, from a subtropical to a subpolar pattern, as expected if cooling shrank the warm-water sphere of the ocean and thus contracted the subtropical gyres.
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29
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Verschuren D, Sinninghe Damsté JS, Moernaut J, Kristen I, Blaauw M, Fagot M, Haug GH. Half-precessional dynamics of monsoon rainfall near the East African Equator. Nature 2009; 462:637-41. [PMID: 19956257 DOI: 10.1038/nature08520] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2009] [Accepted: 09/15/2009] [Indexed: 11/10/2022]
Abstract
External climate forcings-such as long-term changes in solar insolation-generate different climate responses in tropical and high latitude regions. Documenting the spatial and temporal variability of past climates is therefore critical for understanding how such forcings are translated into regional climate variability. In contrast to the data-rich middle and high latitudes, high-quality climate-proxy records from equatorial regions are relatively few, especially from regions experiencing the bimodal seasonal rainfall distribution associated with twice-annual passage of the Intertropical Convergence Zone. Here we present a continuous and well-resolved climate-proxy record of hydrological variability during the past 25,000 years from equatorial East Africa. Our results, based on complementary evidence from seismic-reflection stratigraphy and organic biomarker molecules in the sediment record of Lake Challa near Mount Kilimanjaro, reveal that monsoon rainfall in this region varied at half-precessional ( approximately 11,500-year) intervals in phase with orbitally controlled insolation forcing. The southeasterly and northeasterly monsoons that advect moisture from the western Indian Ocean were strengthened in alternation when the inter-hemispheric insolation gradient was at a maximum; dry conditions prevailed when neither monsoon was intensified and modest local March or September insolation weakened the rain season that followed. On sub-millennial timescales, the temporal pattern of hydrological change on the East African Equator bears clear high-northern-latitude signatures, but on the orbital timescale it mainly responded to low-latitude insolation forcing. Predominance of low-latitude climate processes in this monsoon region can be attributed to the low-latitude position of its continental regions of surface air flow convergence, and its relative isolation from the Atlantic Ocean, where prominent meridional overturning circulation more tightly couples low-latitude climate regimes to high-latitude boundary conditions.
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Affiliation(s)
- Dirk Verschuren
- Limnology Unit, Department of Biology, Ghent University, Ledeganckstraat 35, 9000 Gent, Belgium.
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30
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Yancheva G, Nowaczyk NR, Mingram J, Dulski P, Schettler G, Negendank JFW, Liu J, Sigman DM, Peterson LC, Haug GH. Yancheva et al. reply. Nature 2007. [DOI: 10.1038/nature06339] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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31
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Yancheva G, Nowaczyk NR, Mingram J, Dulski P, Schettler G, Negendank JFW, Liu J, Sigman DM, Peterson LC, Haug GH. Yancheva et al. reply. Nature 2007. [DOI: 10.1038/nature06409] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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32
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Yancheva G, Nowaczyk NR, Mingram J, Dulski P, Schettler G, Negendank JFW, Liu J, Sigman DM, Peterson LC, Haug GH. Influence of the intertropical convergence zone on the East Asian monsoon. Nature 2007; 445:74-7. [PMID: 17203059 DOI: 10.1038/nature05431] [Citation(s) in RCA: 657] [Impact Index Per Article: 38.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2006] [Accepted: 11/06/2006] [Indexed: 11/09/2022]
Abstract
The Asian-Australian monsoon is an important component of the Earth's climate system that influences the societal and economic activity of roughly half the world's population. The past strength of the rain-bearing East Asian summer monsoon can be reconstructed with archives such as cave deposits, but the winter monsoon has no such signature in the hydrological cycle and has thus proved difficult to reconstruct. Here we present high-resolution records of the magnetic properties and the titanium content of the sediments of Lake Huguang Maar in coastal southeast China over the past 16,000 years, which we use as proxies for the strength of the winter monsoon winds. We find evidence for stronger winter monsoon winds before the Bølling-Allerød warming, during the Younger Dryas episode and during the middle and late Holocene, when cave stalagmites suggest weaker summer monsoons. We conclude that this anticorrelation is best explained by migrations in the intertropical convergence zone. Similar migrations of the intertropical convergence zone have been observed in Central America for the period ad 700 to 900 (refs 4-6), suggesting global climatic changes at that time. From the coincidence in timing, we suggest that these migrations in the tropical rain belt could have contributed to the declines of both the Tang dynasty in China and the Classic Maya in Central America.
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Affiliation(s)
- Gergana Yancheva
- GeoForschungsZentrum (GFZ), Section 3.3, Telegrafenberg, Potsdam D-14473, Germany
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33
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Treydte KS, Schleser GH, Helle G, Frank DC, Winiger M, Haug GH, Esper J. The twentieth century was the wettest period in northern Pakistan over the past millennium. Nature 2006; 440:1179-82. [PMID: 16641993 DOI: 10.1038/nature04743] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2005] [Accepted: 03/23/2006] [Indexed: 11/09/2022]
Abstract
Twentieth-century warming could lead to increases in the moisture-holding capacity of the atmosphere, altering the hydrological cycle and the characteristics of precipitation. Such changes in the global rate and distribution of precipitation may have a greater direct effect on human well-being and ecosystem dynamics than changes in temperature itself. Despite the co-variability of both of these climate variables, attention in long-term climate reconstruction has mainly concentrated on temperature changes. Here we present an annually resolved oxygen isotope record from tree-rings, providing a millennial-scale reconstruction of precipitation variability in the high mountains of northern Pakistan. The climatic signal originates mainly from winter precipitation, and is robust over ecologically different sites. Centennial-scale variations reveal dry conditions at the beginning of the past millennium and through the eighteenth and early nineteenth centuries, with precipitation increasing during the late nineteenth and the twentieth centuries to yield the wettest conditions of the past 1,000 years. Comparison with other long-term precipitation reconstructions indicates a large-scale intensification of the hydrological cycle coincident with the onset of industrialization and global warming, and the unprecedented amplitude argues for a human role.
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Affiliation(s)
- Kerstin S Treydte
- Swiss Federal Research Institute WSL, Zürcherstrasse 111, CH- 8903 Birmensdorf, Switzerland.
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34
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Haug GH, Peterson LC. Nicholas Shackleton (1937–2006). Nature 2006; 439:928. [PMID: 16495987 DOI: 10.1038/439928a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Gerald H Haug
- Gerald H. Haug is at the Geoforschungszentrum Potsdam, 14473 Potsdam,
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35
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Abstract
Since the first evidence of low algal productivity during ice ages in the Antarctic Zone of the Southern Ocean was discovered, there has been debate as to whether it was associated with increased polar ocean stratification or with sea-ice cover, shortening the productive season. The sediment concentration of biogenic barium at Ocean Drilling Program site 882 indicates low algal productivity during ice ages in the Subarctic North Pacific as well. Site 882 is located southeast of the summer sea-ice extent even during glacial maxima, ruling out sea-ice-driven light limitation and supporting stratification as the explanation, with implications for the glacial cycles of atmospheric carbon dioxide concentration.
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Affiliation(s)
- S L Jaccard
- Department of Earth Sciences, Sonneggstrasse 5, ETHZ, 8092 Zurich, Switzerland.
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36
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Haug GH, Ganopolski A, Sigman DM, Rosell-Mele A, Swann GEA, Tiedemann R, Jaccard SL, Bollmann J, Maslin MA, Leng MJ, Eglinton G. North Pacific seasonality and the glaciation of North America 2.7 million years ago. Nature 2005; 433:821-5. [PMID: 15729332 DOI: 10.1038/nature03332] [Citation(s) in RCA: 291] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2004] [Accepted: 12/30/2004] [Indexed: 11/09/2022]
Abstract
In the context of gradual Cenozoic cooling, the timing of the onset of significant Northern Hemisphere glaciation 2.7 million years ago is consistent with Milankovitch's orbital theory, which posited that ice sheets grow when polar summertime insolation and temperature are low. However, the role of moisture supply in the initiation of large Northern Hemisphere ice sheets has remained unclear. The subarctic Pacific Ocean represents a significant source of water vapour to boreal North America, but it has been largely overlooked in efforts to explain Northern Hemisphere glaciation. Here we present alkenone unsaturation ratios and diatom oxygen isotope ratios from a sediment core in the western subarctic Pacific Ocean, indicating that 2.7 million years ago late-summer sea surface temperatures in this ocean region rose in response to an increase in stratification. At the same time, winter sea surface temperatures cooled, winter floating ice became more abundant and global climate descended into glacial conditions. We suggest that the observed summer warming extended into the autumn, providing water vapour to northern North America, where it precipitated and accumulated as snow, and thus allowed the initiation of Northern Hemisphere glaciation.
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Affiliation(s)
- Gerald H Haug
- Geoforschungszentrum Potsdam (GFZ), 14473 Potsdam, Germany.
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37
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Stott L, Cannariato K, Thunell R, Haug GH, Koutavas A, Lund S. Decline of surface temperature and salinity in the western tropical Pacific Ocean in the Holocene epoch. Nature 2004; 431:56-9. [PMID: 15343330 DOI: 10.1038/nature02903] [Citation(s) in RCA: 363] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2004] [Accepted: 07/26/2004] [Indexed: 11/09/2022]
Abstract
In the present-day climate, surface water salinities are low in the western tropical Pacific Ocean and increase towards the eastern part of the basin. The salinity of surface waters in the tropical Pacific Ocean is thought to be controlled by a combination of atmospheric convection, precipitation, evaporation and ocean dynamics, and on interannual timescales significant variability is associated with the El Niño/Southern Oscillation cycles. However, little is known about the variability of the coupled ocean-atmosphere system on timescales of centuries to millennia. Here we combine oxygen isotope and Mg/Ca data from foraminifers retrieved from three sediment cores in the western tropical Pacific Ocean to reconstruct Holocene sea surface temperatures and salinities in the region. We find a decrease in sea surface temperatures of approximately 0.5 degrees C over the past 10,000 yr, whereas sea surface salinities decreased by approximately 1.5 practical salinity units. Our data imply either that the Pacific basin as a whole has become progressively less salty or that the present salinity gradient along the Equator has developed relatively recently.
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Affiliation(s)
- Lowell Stott
- Department of Earth Sciences, University of Southern California, Los Angeles, California 90089, USA.
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38
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Abstract
The low-latitude ocean is strongly stratified by the warmth of its surface water. As a result, the great volume of the deep ocean has easiest access to the atmosphere through the polar surface ocean. In the modern polar ocean during the winter, the vertical distribution of temperature promotes overturning, with colder water over warmer, while the salinity distribution typically promotes stratification, with fresher water over saltier. However, the sensitivity of seawater density to temperature is reduced as temperature approaches the freezing point, with potential consequences for global ocean circulation under cold climates. Here we present deep-sea records of biogenic opal accumulation and sedimentary nitrogen isotopic composition from the Subarctic North Pacific Ocean and the Southern Ocean. These records indicate that vertical stratification increased in both northern and southern high latitudes 2.7 million years ago, when Northern Hemisphere glaciation intensified in association with global cooling during the late Pliocene epoch. We propose that the cooling caused this increased stratification by weakening the role of temperature in polar ocean density structure so as to reduce its opposition to the stratifying effect of the vertical salinity distribution. The shift towards stratification in the polar ocean 2.7 million years ago may have increased the quantity of carbon dioxide trapped in the abyss, amplifying the global cooling.
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Affiliation(s)
- Daniel M Sigman
- Department of Geosciences, Princeton University, Princeton, New Jersey 08544, USA.
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39
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Abstract
In the anoxic Cariaco Basin of the southern Caribbean, the bulk titanium content of undisturbed sediment reflects variations in riverine input and the hydrological cycle over northern tropical South America. A seasonally resolved record of titanium shows that the collapse of Maya civilization in the Terminal Classic Period occurred during an extended regional dry period, punctuated by more intense multiyear droughts centered at approximately 810, 860, and 910 A.D. These new data suggest that a century-scale decline in rainfall put a general strain on resources in the region, which was then exacerbated by abrupt drought events, contributing to the social stresses that led to the Maya demise.
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Affiliation(s)
- Gerald H Haug
- Department of Earth Sciences, ETH, CH-8092 Zürich, Switzerland.
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40
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Abstract
Titanium and iron concentration data from the anoxic Cariaco Basin, off the Venezuelan coast, can be used to infer variations in the hydrological cycle over northern South America during the past 14,000 years with subdecadal resolution. Following a dry Younger Dryas, a period of increased precipitation and riverine discharge occurred during the Holocene "thermal maximum." Since approximately 5400 years ago, a trend toward drier conditions is evident from the data, with high-amplitude fluctuations and precipitation minima during the time interval 3800 to 2800 years ago and during the "Little Ice Age." These regional changes in precipitation are best explained by shifts in the mean latitude of the Atlantic Intertropical Convergence Zone (ITCZ), potentially driven by Pacific-based climate variability. The Cariaco Basin record exhibits strong correlations with climate records from distant regions, including the high-latitude Northern Hemisphere, providing evidence for global teleconnections among regional climates.
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Affiliation(s)
- G H Haug
- Department of Earth Sciences, Eidgenössische Technische Hochschule-Zentrum, CH-8092 Zürich, Switzerland
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41
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Abstract
Sedimentary time series of color reflectance and major element chemistry from the anoxic Cariaco Basin off the coast of northern Venezuela record large and abrupt shifts in the hydrologic cycle of the tropical Atlantic during the past 90,000 years. Marine productivity maxima and increased precipitation and riverine discharge from northern South America are closely linked to interstadial (warm) climate events of marine isotope stage 3, as recorded in Greenland ice cores. Increased precipitation at this latitude during interstadials suggests the potential for greater moisture export from the Atlantic to Pacific, which could have affected the salinity balance of the Atlantic and increased thermohaline heat transport to high northern latitudes. This supports the notion that tropical feedbacks played an important role in modulating global climate during the last glacial period.
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Affiliation(s)
- L C Peterson
- Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, FL 33149, USA.
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42
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43
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Abstract
The cause of Northern Hemisphere glaciation about 3 million years ago remains uncertain. Closing the Panamanian Isthmus increased thermohaline circulation and enhanced moisture supply to high latitudes, but the accompanying heat would have inhibited ice growth. One possible solution is that enhanced moisture transported to Eurasia also enhanced freshwater delivery to the Arctic via Siberian rivers. Freshwater input to the Arctic would facilitate sea ice formation, increase the albedo, and isolate the high heat capacity of the ocean from the atmosphere. It would also act as a negative feedback on the efficiency of the "conveyor belt" heat pump.
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Affiliation(s)
- NW Driscoll
- N. W. Driscoll, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA. G. H. Haug, GEOMAR, Forschungszentrum fur Marine Geowissenschaften, Universitat Kiel, Wischhofstrasse 1-3, D-24148 Kiel, Germany
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