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  • 1
    Publication Date: 2001-04-17
    Description: Spectral analyses of an uninterrupted 5.5-million-year (My)-long chronology of late Oligocene-early Miocene climate and ocean carbon chemistry from two deep-sea cores recovered in the western equatorial Atlantic reveal variance concentrated at all Milankovitch frequencies. Exceptional spectral power in climate is recorded at the 406-thousand-year (ky) period eccentricity band over a 3.4-million-year period [20 to 23.4 My ago (Ma)] as well as in the 125- and 95-ky bands over a 1.3-million-year period (21.7 to 23.0 Ma) of suspected low greenhouse gas levels. Moreover, a major transient glaciation at the epoch boundary ( approximately 23 Ma), Mi-1, corresponds with a rare orbital congruence involving obliquity and eccentricity. The anomaly, which consists of low-amplitude variance in obliquity (a node) and a minimum in eccentricity, results in an extended period ( approximately 200 ky) of low seasonality orbits favorable to ice-sheet expansion on Antarctica.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Zachos, J C -- Shackleton, N J -- Revenaugh, J S -- Palike, H -- Flower, B P -- New York, N.Y. -- Science. 2001 Apr 13;292(5515):274-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Earth Sciences Department, Center for Dynamics and Evolution of the Land-Sea Interface, University of California, Santa Cruz, CA 95064, USA. jzachos@es.ucsc.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11303100" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Antarctic Regions ; Atlantic Ocean ; Atmosphere ; Carbon Dioxide ; Carbon Isotopes/*analysis ; *Climate ; Eukaryota ; Geologic Sediments ; Ice ; Oxygen Isotopes/*analysis ; Plankton ; Spectrum Analysis ; Time
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 2
    Publication Date: 2008-10-04
    Description: The long-standing view of Earth's Cenozoic glacial history calls for the first continental-scale glaciation of Antarctica in the earliest Oligocene epoch ( approximately 33.6 million years ago), followed by the onset of northern-hemispheric glacial cycles in the late Pliocene epoch, about 31 million years later. The pivotal early Oligocene event is characterized by a rapid shift of 1.5 parts per thousand in deep-sea benthic oxygen-isotope values (Oi-1) within a few hundred thousand years, reflecting a combination of terrestrial ice growth and deep-sea cooling. The apparent absence of contemporaneous cooling in deep-sea Mg/Ca records, however, has been argued to reflect the growth of more ice than can be accommodated on Antarctica; this, combined with new evidence of continental cooling and ice-rafted debris in the Northern Hemisphere during this period, raises the possibility that Oi-1 represents a precursory bipolar glaciation. Here we test this hypothesis using an isotope-capable global climate/ice-sheet model that accommodates both the long-term decline of Cenozoic atmospheric CO(2) levels and the effects of orbital forcing. We show that the CO(2) threshold below which glaciation occurs in the Northern Hemisphere ( approximately 280 p.p.m.v.) is much lower than that for Antarctica ( approximately 750 p.p.m.v.). Therefore, the growth of ice sheets in the Northern Hemisphere immediately following Antarctic glaciation would have required rapid CO(2) drawdown within the Oi-1 timeframe, to levels lower than those estimated by geochemical proxies and carbon-cycle models. Instead of bipolar glaciation, we find that Oi-1 is best explained by Antarctic glaciation alone, combined with deep-sea cooling of up to 4 degrees C and Antarctic ice that is less isotopically depleted (-30 to -35 per thousand) than previously suggested. Proxy CO(2) estimates remain above our model's northern-hemispheric glaciation threshold of approximately 280 p.p.m.v. until approximately 25 Myr ago, but have been near or below that level ever since. This implies that episodic northern-hemispheric ice sheets have been possible some 20 million years earlier than currently assumed (although still much later than Oi-1) and could explain some of the variability in Miocene sea-level records.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Deconto, Robert M -- Pollard, David -- Wilson, Paul A -- Palike, Heiko -- Lear, Caroline H -- Pagani, Mark -- England -- Nature. 2008 Oct 2;455(7213):652-6. doi: 10.1038/nature07337.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Geosciences, University of Massachusetts, Amherst, Massachusetts 01003, USA. deconto@geo.umass.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18833277" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Antarctic Regions ; Atmosphere/*chemistry ; Calcium ; Carbon Dioxide/*analysis ; *Cold Climate ; Greenhouse Effect ; History, 21st Century ; History, Ancient ; *Ice Cover ; Magnesium ; Oxygen Isotopes ; Seasons
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 3
    Publication Date: 2006-12-23
    Description: A 13-million-year continuous record of Oligocene climate from the equatorial Pacific reveals a pronounced "heartbeat" in the global carbon cycle and periodicity of glaciations. This heartbeat consists of 405,000-, 127,000-, and 96,000-year eccentricity cycles and 1.2-million-year obliquity cycles in periodically recurring glacial and carbon cycle events. That climate system response to intricate orbital variations suggests a fundamental interaction of the carbon cycle, solar forcing, and glacial events. Box modeling shows that the interaction of the carbon cycle and solar forcing modulates deep ocean acidity as well as the production and burial of global biomass. The pronounced 405,000-year eccentricity cycle is amplified by the long residence time of carbon in the oceans.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Palike, Heiko -- Norris, Richard D -- Herrle, Jens O -- Wilson, Paul A -- Coxall, Helen K -- Lear, Caroline H -- Shackleton, Nicholas J -- Tripati, Aradhna K -- Wade, Bridget S -- New York, N.Y. -- Science. 2006 Dec 22;314(5807):1894-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉National Oceanography Centre, Southampton, School of Ocean and Earth Science, European Way, Southampton SO14 3ZH, UK. H.Palike@soton.ac.uk〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17185595" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Biomass ; Calcium Carbonate/analysis ; *Carbon ; Carbon Isotopes/analysis ; *Climate ; Geologic Sediments/chemistry ; *Ice Cover ; Oxygen Isotopes/analysis ; Pacific Ocean ; Plankton ; Sunlight ; Time
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 4
    Publication Date: 2011-03-18
    Description: 'Hyperthermals' are intervals of rapid, pronounced global warming known from six episodes within the Palaeocene and Eocene epochs ( approximately 65-34 million years (Myr) ago). The most extreme hyperthermal was the approximately 170 thousand year (kyr) interval of 5-7 degrees C global warming during the Palaeocene-Eocene Thermal Maximum (PETM, 56 Myr ago). The PETM is widely attributed to massive release of greenhouse gases from buried sedimentary carbon reservoirs, and other, comparatively modest, hyperthermals have also been linked to the release of sedimentary carbon. Here we show, using new 2.4-Myr-long Eocene deep ocean records, that the comparatively modest hyperthermals are much more numerous than previously documented, paced by the eccentricity of Earth's orbit and have shorter durations ( approximately 40 kyr) and more rapid recovery phases than the PETM. These findings point to the operation of fundamentally different forcing and feedback mechanisms than for the PETM, involving redistribution of carbon among Earth's readily exchangeable surface reservoirs rather than carbon exhumation from, and subsequent burial back into, the sedimentary reservoir. Specifically, we interpret our records to indicate repeated, large-scale releases of dissolved organic carbon (at least 1,600 gigatonnes) from the ocean by ventilation (strengthened oxidation) of the ocean interior. The rapid recovery of the carbon cycle following each Eocene hyperthermal strongly suggests that carbon was re-sequestered by the ocean, rather than the much slower process of silicate rock weathering proposed for the PETM. Our findings suggest that these pronounced climate warming events were driven not by repeated releases of carbon from buried sedimentary sources, but, rather, by patterns of surficial carbon redistribution familiar from younger intervals of Earth history.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Sexton, Philip F -- Norris, Richard D -- Wilson, Paul A -- Palike, Heiko -- Westerhold, Thomas -- Rohl, Ursula -- Bolton, Clara T -- Gibbs, Samantha -- England -- Nature. 2011 Mar 17;471(7338):349-52. doi: 10.1038/nature09826.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California 92093, USA. P.F.Sexton@open.ac.uk〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/21412336" target="_blank"〉PubMed〈/a〉
    Keywords: Atlantic Ocean ; Atmosphere/*chemistry ; *Carbon Cycle ; Foraminifera/metabolism ; Geologic Sediments/chemistry ; Global Warming/*history ; History, Ancient ; Oceans and Seas ; Seawater/*chemistry ; Temperature
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 5
    Publication Date: 2012-08-31
    Description: Atmospheric carbon dioxide concentrations and climate are regulated on geological timescales by the balance between carbon input from volcanic and metamorphic outgassing and its removal by weathering feedbacks; these feedbacks involve the erosion of silicate rocks and organic-carbon-bearing rocks. The integrated effect of these processes is reflected in the calcium carbonate compensation depth, which is the oceanic depth at which calcium carbonate is dissolved. Here we present a carbonate accumulation record that covers the past 53 million years from a depth transect in the equatorial Pacific Ocean. The carbonate compensation depth tracks long-term ocean cooling, deepening from 3.0-3.5 kilometres during the early Cenozoic (approximately 55 million years ago) to 4.6 kilometres at present, consistent with an overall Cenozoic increase in weathering. We find large superimposed fluctuations in carbonate compensation depth during the middle and late Eocene. Using Earth system models, we identify changes in weathering and the mode of organic-carbon delivery as two key processes to explain these large-scale Eocene fluctuations of the carbonate compensation depth.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Palike, Heiko -- Lyle, Mitchell W -- Nishi, Hiroshi -- Raffi, Isabella -- Ridgwell, Andy -- Gamage, Kusali -- Klaus, Adam -- Acton, Gary -- Anderson, Louise -- Backman, Jan -- Baldauf, Jack -- Beltran, Catherine -- Bohaty, Steven M -- Bown, Paul -- Busch, William -- Channell, Jim E T -- Chun, Cecily O J -- Delaney, Margaret -- Dewangan, Pawan -- Dunkley Jones, Tom -- Edgar, Kirsty M -- Evans, Helen -- Fitch, Peter -- Foster, Gavin L -- Gussone, Nikolaus -- Hasegawa, Hitoshi -- Hathorne, Ed C -- Hayashi, Hiroki -- Herrle, Jens O -- Holbourn, Ann -- Hovan, Steve -- Hyeong, Kiseong -- Iijima, Koichi -- Ito, Takashi -- Kamikuri, Shin-ichi -- Kimoto, Katsunori -- Kuroda, Junichiro -- Leon-Rodriguez, Lizette -- Malinverno, Alberto -- Moore, Ted C Jr -- Murphy, Brandon H -- Murphy, Daniel P -- Nakamura, Hideto -- Ogane, Kaoru -- Ohneiser, Christian -- Richter, Carl -- Robinson, Rebecca -- Rohling, Eelco J -- Romero, Oscar -- Sawada, Ken -- Scher, Howie -- Schneider, Leah -- Sluijs, Appy -- Takata, Hiroyuki -- Tian, Jun -- Tsujimoto, Akira -- Wade, Bridget S -- Westerhold, Thomas -- Wilkens, Roy -- Williams, Trevor -- Wilson, Paul A -- Yamamoto, Yuhji -- Yamamoto, Shinya -- Yamazaki, Toshitsugu -- Zeebe, Richard E -- England -- Nature. 2012 Aug 30;488(7413):609-14. doi: 10.1038/nature11360.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Ocean and Earth Science, National Oceanography Centre Southampton, University of Southampton, Waterfront Campus, European Way, Southampton SO14 3ZH, UK. hpaelike@marum.de〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22932385" target="_blank"〉PubMed〈/a〉
    Keywords: *Altitude ; Atmosphere/chemistry ; Calcium Carbonate/*analysis ; *Carbon Cycle ; Carbon Dioxide/analysis ; Diatoms/metabolism ; Foraminifera/metabolism ; Geologic Sediments/chemistry ; Global Warming/history/statistics & numerical data ; History, 21st Century ; History, Ancient ; Marine Biology ; Oxygen/metabolism ; Pacific Ocean ; Seawater/*chemistry ; Temperature
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 6
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2013-02-09
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Palike, Heiko -- New York, N.Y. -- Science. 2013 Feb 8;339(6120):655-6. doi: 10.1126/science.1233948.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉MARUM-Center for Marine Environmental Sciences, University of Bremen, Leobener Strasse, 28359 Bremen, Germany. hpaelike@marum.de〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23393253" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Ecosystem ; *Extinction, Biological ; *Minor Planets
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 7
    Publication Date: 2006-08-01
    Print ISSN: 0016-7037
    Electronic ISSN: 1872-9533
    Topics: Chemistry and Pharmacology , Geosciences
    Published by Elsevier
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  • 8
  • 9
    Publication Date: 2019-07-13
    Description: Many palaeoclimate studies have quantified pre-anthropogenic climate change to calculate climate sensitivity (equilibrium temperature change in response to radiative forcing change), but a lack of consistent methodologies produces a wide range of estimates and hinders comparability of results. Here we present a stricter approach, to improve intercomparison of palaeoclimate sensitivity estimates in a manner compatible with equilibrium projections for future climate change. Over the past 65 million years, this reveals a climate sensitivity (in K W1 m2) of 0.3-1.9 or 0.6-1.3 at 95% or 68% probability, respectively. The latter implies a warming of 2.2-4.8 K per doubling of atmospheric CO2, which agrees with IPCC estimates.
    Keywords: Meteorology and Climatology
    Type: GSFC-E-DAA-TN8833 , Nature; 491; 683-691
    Format: application/pdf
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  • 10
    Publication Date: 2021-01-25
    Description: We present an astronomically tuned polarity timescale for the late Eocene/early Oligocene based on a cyclic limestone/marls sedimentary succession exposed at Massignano, Italy (GSSP for the Eocene- Oligocene boundary). Here we applied spectral analysis techniques to the high-resolution magnetic susceptibility record. The results provide clear evidence of a regular and cyclic signal that allows us to discard a stochastic mechanism as controlling these fluctuations. Conversely, these outcomes reveal the presence of stable and notable periodicities that are in tune with those associated with orbital forcing. Through a cyclostratigraphic analysis of the rhythmic sedimentary alternations and combination with the results of time series analysis of the proxy record, we refine the late Eocene portion of the GPTS. Through astronomical tuning of the rhythmic sedimentary alternations to recent astronomically calculated variations of Earth’s orbit we recalibrated the polarity boundaries ages and the main stratigraphic events recognized throughout the sedimentary record. Among these, an age of 33.714 Ma is proposed for the E/O boundary.
    Description: Published
    Description: Q07012
    Description: reserved
    Keywords: environmental magnetism; ; Eocene/Oligocene ; 04. Solid Earth::04.05. Geomagnetism::04.05.07. Rock magnetism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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