Articles | Volume 12, issue 7
https://doi.org/10.5194/gmd-12-3149-2019
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/gmd-12-3149-2019
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Model experiment description paper
| 
25 Jul 2019
Model experiment description paper |
| 25 Jul 2019
| 25 Jul 2019
The DeepMIP contribution to PMIP4: methodologies for selection, compilation and analysis of latest Paleocene and early Eocene climate proxy data, incorporating version 0.1 of the DeepMIP database
Christopher J. Hollis
CORRESPONDING AUTHOR
GNS Science, Lower Hutt, New Zealand
Tom Dunkley Jones
School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham, UK
Eleni Anagnostou
Ocean and Earth Science, National Oceanography Centre Southampton, University of Southampton, Southampton, UK
GEOMAR Helmholtz Centre for Ocean Research, Kiel, Kiel, Germany
Peter K. Bijl
Department of Earth Sciences, Faculty of Geosciences, Utrecht University, Utrecht, the Netherlands
Marlow Julius Cramwinckel
Department of Earth Sciences, Faculty of Geosciences, Utrecht University, Utrecht, the Netherlands
Ying Cui
Department of Earth and Environmental Studies, Montclair State University, Montclair, New Jersey, USA
Gerald R. Dickens
Department of Earth, Environmental and Planetary Sciences, Rice University, Houston, Texas, USA
Kirsty M. Edgar
School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham, UK
Yvette Eley
School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham, UK
David Evans
Institute of Geosciences, Goethe University Frankfurt, Frankfurt am Main, Frankfurt, Germany
Gavin L. Foster
Ocean and Earth Science, National Oceanography Centre Southampton, University of Southampton, Southampton, UK
Joost Frieling
Department of Earth Sciences, Faculty of Geosciences, Utrecht University, Utrecht, the Netherlands
Gordon N. Inglis
School of Chemistry & School of Earth Sciences, University of Bristol, Bristol, UK
Elizabeth M. Kennedy
GNS Science, Lower Hutt, New Zealand
Reinhard Kozdon
Lamont–Doherty Earth Observatory of Columbia University, Pallisades, New York, USA
Vittoria Lauretano
School of Chemistry & School of Earth Sciences, University of Bristol, Bristol, UK
Caroline H. Lear
School of Earth and Ocean Sciences, Cardiff University, Cardiff, UK
Kate Littler
Camborne School of Mines & Environment and Sustainability Institute, University of Exeter, Exeter, UK
Lucas Lourens
Department of Earth Sciences, Faculty of Geosciences, Utrecht University, Utrecht, the Netherlands
A. Nele Meckler
Bjerknes Centre for Climate Research and Department of Earth Science, University of Bergen, Bergen, Norway
B. David A. Naafs
School of Chemistry & School of Earth Sciences, University of Bristol, Bristol, UK
Heiko Pälike
MARUM – Center for Marine and Environmental Sciences, University of Bremen, Bremen, Germany
Richard D. Pancost
School of Chemistry & School of Earth Sciences, University of Bristol, Bristol, UK
Paul N. Pearson
School of Earth and Ocean Sciences, Cardiff University, Cardiff, UK
Ursula Röhl
MARUM – Center for Marine and Environmental Sciences, University of Bremen, Bremen, Germany
Dana L. Royer
Department of Earth & Environmental Sciences, Wesleyan University, Middletown, Connecticut, USA
Ulrich Salzmann
Department of Geography, Northumbria University, Newcastle, UK
Brian A. Schubert
School of Geosciences, University of Louisiana at Lafayette, Louisiana, Lafayette, USA
Hannu Seebeck
GNS Science, Lower Hutt, New Zealand
Appy Sluijs
Department of Earth Sciences, Faculty of Geosciences, Utrecht University, Utrecht, the Netherlands
Robert P. Speijer
Department of Earth and Environmental Sciences, KU Leuven, Leuven, Belgium
Peter Stassen
Department of Earth and Environmental Sciences, KU Leuven, Leuven, Belgium
Jessica Tierney
Department of Geosciences, University of Arizona, Tucson, Arizona, USA
Aradhna Tripati
Department of Earth and Planetary Sciences, Institute of the Environment and Sustainability, Department of Atmospheric and Oceanic Sciences, Center for Diverse Leadership in Science, University of California, Los Angeles, California, USA
Bridget Wade
Department of Earth Sciences, University College London, London, UK
Thomas Westerhold
MARUM – Center for Marine and Environmental Sciences, University of Bremen, Bremen, Germany
Caitlyn Witkowski
Department of Marine Microbiology and Biogeochemistry (MMB), NIOZ Royal Netherlands Institute for Sea Research and Utrecht University, Den Burg, the Netherlands
James C. Zachos
Earth and Planetary Sciences Department, University of California, Santa Cruz, California, USA
Yi Ge Zhang
Department of Oceanography, Texas A&M University, College Station, Texas, USA
Matthew Huber
Department of Earth, Atmospheric, and Planetary Sciences, Purdue University, West Lafayette, Indiana, USA
Daniel J. Lunt
School of Geographical Sciences, University of Bristol, Bristol, UK
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Revised manuscript accepted for CP
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Peter K. Bijl
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Johan Vellekoop, Daan Vanhove, Inge Jelu, Philippe Claeys, Linda C. Ivany, Niels J. de Winter, Robert P. Speijer, and Etienne Steurbaut
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Alice R. Paine, Isabel M. Fendley, Joost Frieling, Tamsin A. Mather, Jack H. Lacey, Bernd Wagner, Stuart A. Robinson, David M. Pyle, Alexander Francke, Theodore R. Them II, and Konstantinos Panagiotopoulos
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Nico Wunderling, Anna S. von der Heydt, Yevgeny Aksenov, Stephen Barker, Robbin Bastiaansen, Victor Brovkin, Maura Brunetti, Victor Couplet, Thomas Kleinen, Caroline H. Lear, Johannes Lohmann, Rosa Maria Roman-Cuesta, Sacha Sinet, Didier Swingedouw, Ricarda Winkelmann, Pallavi Anand, Jonathan Barichivich, Sebastian Bathiany, Mara Baudena, John T. Bruun, Cristiano M. Chiessi, Helen K. Coxall, David Docquier, Jonathan F. Donges, Swinda K. J. Falkena, Ann Kristin Klose, David Obura, Juan Rocha, Stefanie Rynders, Norman Julius Steinert, and Matteo Willeit
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Michiel Baatsen, Peter Bijl, Anna von der Heydt, Appy Sluijs, and Henk Dijkstra
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Heather M. Stoll, Leopoldo D. Pena, Ivan Hernandez-Almeida, José Guitián, Thomas Tanner, and Heiko Pälike
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Madeleine L. Vickers, Morgan T. Jones, Jack Longman, David Evans, Clemens V. Ullmann, Ella Wulfsberg Stokke, Martin Vickers, Joost Frieling, Dustin T. Harper, Vincent J. Clementi, and IODP Expedition 396 Scientists
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Clim. Past, 19, 2569–2580, https://doi.org/10.5194/cp-19-2569-2023, https://doi.org/10.5194/cp-19-2569-2023, 2023
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Oceanic Anoxic Event 2 (OAE 2), about 93.5 million years ago, is characterized by widespread deoxygenated ocean and massive burial of organic-rich sediments. Our results show that the marine deoxygenation at the equatorial Atlantic that predates the OAE 2 interval was driven by global warming and associated with the nutrient status of the site, with factors like temperature-modulated upwelling and hydrology-induced weathering contributing to enhanced nutrient delivery over various timescales.
Peter K. Bijl and Henk Brinkhuis
J. Micropalaeontol., 42, 309–314, https://doi.org/10.5194/jm-42-309-2023, https://doi.org/10.5194/jm-42-309-2023, 2023
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We developed an online, open-access database for taxonomic descriptions, stratigraphic information and images of organic-walled dinoflagellate cyst species. With this new resource for applied and academic research, teaching and training, we open up organic-walled dinoflagellate cysts for the academic era of open science. We expect that palsys.org represents a starting point to improve taxonomic concepts, and we invite the community to contribute.
Elwyn de la Vega, Thomas B. Chalk, Mathis P. Hain, Megan R. Wilding, Daniel Casey, Robin Gledhill, Chongguang Luo, Paul A. Wilson, and Gavin L. Foster
Clim. Past, 19, 2493–2510, https://doi.org/10.5194/cp-19-2493-2023, https://doi.org/10.5194/cp-19-2493-2023, 2023
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We evaluate how faithfully the boron isotope composition of foraminifera records atmospheric CO2 by comparing it to the high-fidelity CO2 record from the Antarctic ice cores. We evaluate potential factors and find that partial dissolution of foraminifera shells, assumptions of seawater chemistry, and the biology of foraminifera all have a negligible effect on reconstructed CO2. This gives confidence in the use of boron isotopes beyond the interval when ice core CO2 is available.
Joost Frieling, Linda van Roij, Iris Kleij, Gert-Jan Reichart, and Appy Sluijs
Biogeosciences, 20, 4651–4668, https://doi.org/10.5194/bg-20-4651-2023, https://doi.org/10.5194/bg-20-4651-2023, 2023
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We present a first species-specific evaluation of marine core-top dinoflagellate cyst carbon isotope fractionation (εp) to assess natural pCO2 dependency on εp and explore its geological deep-time paleo-pCO2 proxy potential. We find that εp differs between genera and species and that in Operculodinium centrocarpum, εp is controlled by pCO2 and nutrients. Our results highlight the added value of δ13C analyses of individual micrometer-scale sedimentary organic carbon particles.
Paul N. Pearson, Jeremy Young, David J. King, and Bridget S. Wade
J. Micropalaeontol., 42, 211–255, https://doi.org/10.5194/jm-42-211-2023, https://doi.org/10.5194/jm-42-211-2023, 2023
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Planktonic foraminifera are marine plankton that have a long and continuous fossil record. They are used for correlating and dating ocean sediments and studying evolution and past climates. This paper presents new information about Pulleniatina, one of the most widespread and abundant groups, from an important site in the Pacific Ocean. It also brings together a very large amount of information on the fossil record from other sites globally.
Anna Hauge Braaten, Kim A. Jakob, Sze Ling Ho, Oliver Friedrich, Eirik Vinje Galaasen, Stijn De Schepper, Paul A. Wilson, and Anna Nele Meckler
Clim. Past, 19, 2109–2125, https://doi.org/10.5194/cp-19-2109-2023, https://doi.org/10.5194/cp-19-2109-2023, 2023
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In the context of understanding current global warming, the middle Pliocene (3.3–3.0 million years ago) is an important interval in Earth's history because atmospheric carbon dioxide concentrations were similar to levels today. We have reconstructed deep-sea temperatures at two different locations for this period, and find that a very different mode of ocean circulation or mixing existed, with important implications for how heat was transported in the deep ocean.
Xin Ren, Daniel J. Lunt, Erica Hendy, Anna von der Heydt, Ayako Abe-Ouchi, Bette Otto-Bliesner, Charles J. R. Williams, Christian Stepanek, Chuncheng Guo, Deepak Chandan, Gerrit Lohmann, Julia C. Tindall, Linda E. Sohl, Mark A. Chandler, Masa Kageyama, Michiel L. J. Baatsen, Ning Tan, Qiong Zhang, Ran Feng, Stephen Hunter, Wing-Le Chan, W. Richard Peltier, Xiangyu Li, Youichi Kamae, Zhongshi Zhang, and Alan M. Haywood
Clim. Past, 19, 2053–2077, https://doi.org/10.5194/cp-19-2053-2023, https://doi.org/10.5194/cp-19-2053-2023, 2023
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We investigate the Maritime Continent climate in the mid-Piacenzian warm period and find it is warmer and wetter and the sea surface salinity is lower compared with preindustrial period. Besides, the fresh and warm water transfer through the Maritime Continent was stronger. In order to avoid undue influence from closely related models in the multimodel results, we introduce a new metric, the multi-cluster mean, which could reveal spatial signals that are not captured by the multimodel mean.
Stephen P. Hesselbo, Aisha Al-Suwaidi, Sarah J. Baker, Giorgia Ballabio, Claire M. Belcher, Andrew Bond, Ian Boomer, Remco Bos, Christian J. Bjerrum, Kara Bogus, Richard Boyle, James V. Browning, Alan R. Butcher, Daniel J. Condon, Philip Copestake, Stuart Daines, Christopher Dalby, Magret Damaschke, Susana E. Damborenea, Jean-Francois Deconinck, Alexander J. Dickson, Isabel M. Fendley, Calum P. Fox, Angela Fraguas, Joost Frieling, Thomas A. Gibson, Tianchen He, Kat Hickey, Linda A. Hinnov, Teuntje P. Hollaar, Chunju Huang, Alexander J. L. Hudson, Hugh C. Jenkyns, Erdem Idiz, Mengjie Jiang, Wout Krijgsman, Christoph Korte, Melanie J. Leng, Timothy M. Lenton, Katharina Leu, Crispin T. S. Little, Conall MacNiocaill, Miguel O. Manceñido, Tamsin A. Mather, Emanuela Mattioli, Kenneth G. Miller, Robert J. Newton, Kevin N. Page, József Pálfy, Gregory Pieńkowski, Richard J. Porter, Simon W. Poulton, Alberto C. Riccardi, James B. Riding, Ailsa Roper, Micha Ruhl, Ricardo L. Silva, Marisa S. Storm, Guillaume Suan, Dominika Szűcs, Nicolas Thibault, Alfred Uchman, James N. Stanley, Clemens V. Ullmann, Bas van de Schootbrugge, Madeleine L. Vickers, Sonja Wadas, Jessica H. Whiteside, Paul B. Wignall, Thomas Wonik, Weimu Xu, Christian Zeeden, and Ke Zhao
Sci. Dril., 32, 1–25, https://doi.org/10.5194/sd-32-1-2023, https://doi.org/10.5194/sd-32-1-2023, 2023
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We present initial results from a 650 m long core of Late Triasssic to Early Jurassic (190–202 Myr) sedimentary strata from the Cheshire Basin, UK, which is shown to be an exceptional record of Earth evolution for the time of break-up of the supercontinent Pangaea. Further work will determine periodic changes in depositional environments caused by solar system dynamics and used to reconstruct orbital history.
Frida S. Hoem, Adrián López-Quirós, Suzanna van de Lagemaat, Johan Etourneau, Marie-Alexandrine Sicre, Carlota Escutia, Henk Brinkhuis, Francien Peterse, Francesca Sangiorgi, and Peter K. Bijl
Clim. Past, 19, 1931–1949, https://doi.org/10.5194/cp-19-1931-2023, https://doi.org/10.5194/cp-19-1931-2023, 2023
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We present two new sea surface temperature (SST) records in comparison with available SST records to reconstruct South Atlantic paleoceanographic evolution. Our results show a low SST gradient in the Eocene–early Oligocene due to the persistent gyral circulation. A higher SST gradient in the Middle–Late Miocene infers a stronger circumpolar current. The southern South Atlantic was the coldest region in the Southern Ocean and likely the main deep-water formation location in the Middle Miocene.
Jenny Maccali, Anna Nele Meckler, Stein-Erik Lauritzen, Torill Brekken, Helen Aase Rokkan, Alvaro Fernandez, Yves Krüger, Jane Adigun, Stéphane Affolter, and Markus Leuenberger
Clim. Past, 19, 1847–1862, https://doi.org/10.5194/cp-19-1847-2023, https://doi.org/10.5194/cp-19-1847-2023, 2023
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The southern coast of South Africa hosts some key archeological sites for the study of early human evolution. Here we present a short but high-resolution record of past changes in the hydroclimate and temperature on the southern coast of South Africa based on the study of a speleothem collected from Bloukrantz Cave. Overall, the paleoclimate indicators suggest stable temperature from 48.3 to 45.2 ka, whereas precipitation was variable, with marked short drier episodes.
William Rush, Jean Self-Trail, Yang Zhang, Appy Sluijs, Henk Brinkhuis, James Zachos, James G. Ogg, and Marci Robinson
Clim. Past, 19, 1677–1698, https://doi.org/10.5194/cp-19-1677-2023, https://doi.org/10.5194/cp-19-1677-2023, 2023
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The Eocene contains several brief warming periods referred to as hyperthermals. Studying these events and how they varied between locations can help provide insight into our future warmer world. This study provides a characterization of two of these events in the mid-Atlantic region of the USA. The records of climate that we measured demonstrate significant changes during this time period, but the type and timing of these changes highlight the complexity of climatic changes.
Morgan T. Jones, Ella W. Stokke, Alan D. Rooney, Joost Frieling, Philip A. E. Pogge von Strandmann, David J. Wilson, Henrik H. Svensen, Sverre Planke, Thierry Adatte, Nicolas Thibault, Madeleine L. Vickers, Tamsin A. Mather, Christian Tegner, Valentin Zuchuat, and Bo P. Schultz
Clim. Past, 19, 1623–1652, https://doi.org/10.5194/cp-19-1623-2023, https://doi.org/10.5194/cp-19-1623-2023, 2023
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There are periods in Earth’s history when huge volumes of magma are erupted at the Earth’s surface. The gases released from volcanic eruptions and from sediments heated by the magma are believed to have caused severe climate changes in the geological past. We use a variety of volcanic and climatic tracers to assess how the North Atlantic Igneous Province (56–54 Ma) affected the oceans and atmosphere during a period of extreme global warming.
Marcin Latas, Paul N. Pearson, Christopher R. Poole, Alessio Fabbrini, and Bridget S. Wade
J. Micropalaeontol., 42, 57–81, https://doi.org/10.5194/jm-42-57-2023, https://doi.org/10.5194/jm-42-57-2023, 2023
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Planktonic foraminifera are microscopic single-celled organisms populating world oceans. They have one of the most complete fossil records; thanks to their great abundance, they are widely used to study past marine environments. We analysed and measured series of foraminifera shells from Indo-Pacific sites, which led to the description of a new species of fossil planktonic foraminifera. Part of its population exhibits pink pigmentation, which is only the third such case among known species.
Peter K. Bijl
Earth Syst. Sci. Data Discuss., https://doi.org/10.5194/essd-2023-169, https://doi.org/10.5194/essd-2023-169, 2023
Publication in ESSD not foreseen
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This new version release of DINOSTRAT, version 2.0, aligns stratigraphic ranges of dinoflagellate cysts, a microfossil group, to the Geologic Time Scale. In this release we present the evolution of dinocyst subfamilies from the mid-Triassic to the modern.
Lena Mareike Thöle, Peter Dirk Nooteboom, Suning Hou, Rujian Wang, Senyan Nie, Elisabeth Michel, Isabel Sauermilch, Fabienne Marret, Francesca Sangiorgi, and Peter Kristian Bijl
J. Micropalaeontol., 42, 35–56, https://doi.org/10.5194/jm-42-35-2023, https://doi.org/10.5194/jm-42-35-2023, 2023
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Dinoflagellate cysts can be used to infer past oceanographic conditions in the Southern Ocean. This requires knowledge of their present-day ecologic affinities. We add 66 Antarctic-proximal surface sediment samples to the Southern Ocean data and derive oceanographic conditions at those stations. Dinoflagellate cysts are clearly biogeographically separated along latitudinal gradients of temperature, sea ice, nutrients, and salinity, which allows us to reconstruct these parameters for the past.
Bjørg Risebrobakken, Mari F. Jensen, Helene R. Langehaug, Tor Eldevik, Anne Britt Sandø, Camille Li, Andreas Born, Erin Louise McClymont, Ulrich Salzmann, and Stijn De Schepper
Clim. Past, 19, 1101–1123, https://doi.org/10.5194/cp-19-1101-2023, https://doi.org/10.5194/cp-19-1101-2023, 2023
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In the observational period, spatially coherent sea surface temperatures characterize the northern North Atlantic at multidecadal timescales. We show that spatially non-coherent temperature patterns are seen both in further projections and a past warm climate period with a CO2 level comparable to the future low-emission scenario. Buoyancy forcing is shown to be important for northern North Atlantic temperature patterns.
Suning Hou, Foteini Lamprou, Frida S. Hoem, Mohammad Rizky Nanda Hadju, Francesca Sangiorgi, Francien Peterse, and Peter K. Bijl
Clim. Past, 19, 787–802, https://doi.org/10.5194/cp-19-787-2023, https://doi.org/10.5194/cp-19-787-2023, 2023
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Neogene climate cooling is thought to be accompanied by increased Equator-to-pole temperature gradients, but mid-latitudes are poorly represented. We use biomarkers to reconstruct a 23 Myr continuous sea surface temperature record of the mid-latitude Southern Ocean. We note a profound mid-latitude cooling which narrowed the latitudinal temperature gradient with the northward expansion of subpolar conditions. We surmise that this reflects the strengthening of the ACC and the expansion of sea ice.
Caitlyn R. Witkowski, Vittoria Lauretano, Alex Farnsworth, Shufeng Li, Shi-Hu Li, Jan Peter Mayser, B. David A. Naafs, Robert A. Spicer, Tao Su, He Tang, Zhe-Kun Zhou, Paul J. Valdes, and Richard D. Pancost
EGUsphere, https://doi.org/10.5194/egusphere-2023-373, https://doi.org/10.5194/egusphere-2023-373, 2023
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Untangling the complex tectonic evolution in the Tibetan region can help us understand its impacts on climate, the Asian monsoon system, and the development of major biodiversity hotspots. We show that this “missing link” site between high elevation Tibet and low elevation coastal China had a dynamic environment but no temperature change, meaning its been at its current-day elevation for the past 34 million years.
David A. Hodell, Simon J. Crowhurst, Lucas Lourens, Vasiliki Margari, John Nicolson, James E. Rolfe, Luke C. Skinner, Nicola C. Thomas, Polychronis C. Tzedakis, Maryline J. Mleneck-Vautravers, and Eric W. Wolff
Clim. Past, 19, 607–636, https://doi.org/10.5194/cp-19-607-2023, https://doi.org/10.5194/cp-19-607-2023, 2023
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We produced a 1.5-million-year-long history of climate change at International Ocean Discovery Program Site U1385 of the Iberian margin, a well-known location for rapidly accumulating sediments on the seafloor. Our record demonstrates that longer-term orbital changes in Earth's climate were persistently overprinted by abrupt millennial-to-centennial climate variability. The occurrence of abrupt climate change is modulated by the slower variations in Earth's orbit and climate background state.
Yord W. Yedema, Francesca Sangiorgi, Appy Sluijs, Jaap S. Sinninghe Damsté, and Francien Peterse
Biogeosciences, 20, 663–686, https://doi.org/10.5194/bg-20-663-2023, https://doi.org/10.5194/bg-20-663-2023, 2023
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Terrestrial organic matter (TerrOM) is transported to the ocean by rivers, where its burial can potentially form a long-term carbon sink. This burial is dependent on the type and characteristics of the TerrOM. We used bulk sediment properties, biomarkers, and palynology to identify the dispersal patterns of plant-derived, soil–microbial, and marine OM in the northern Gulf of Mexico and show that plant-derived OM is transported further into the coastal zone than soil and marine-produced TerrOM.
Pauline Cornuault, Thomas Westerhold, Heiko Pälike, Torsten Bickert, Karl-Heinz Baumann, and Michal Kucera
Biogeosciences, 20, 597–618, https://doi.org/10.5194/bg-20-597-2023, https://doi.org/10.5194/bg-20-597-2023, 2023
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We generated high-resolution records of carbonate accumulation rate from the Miocene to the Quaternary in the tropical Atlantic Ocean to characterize the variability in pelagic carbonate production during warm climates. It follows orbital cycles, responding to local changes in tropical conditions, as well as to long-term shifts in climate and ocean chemistry. These changes were sufficiently large to play a role in the carbon cycle and global climate evolution.
Julia E. Weiffenbach, Michiel L. J. Baatsen, Henk A. Dijkstra, Anna S. von der Heydt, Ayako Abe-Ouchi, Esther C. Brady, Wing-Le Chan, Deepak Chandan, Mark A. Chandler, Camille Contoux, Ran Feng, Chuncheng Guo, Zixuan Han, Alan M. Haywood, Qiang Li, Xiangyu Li, Gerrit Lohmann, Daniel J. Lunt, Kerim H. Nisancioglu, Bette L. Otto-Bliesner, W. Richard Peltier, Gilles Ramstein, Linda E. Sohl, Christian Stepanek, Ning Tan, Julia C. Tindall, Charles J. R. Williams, Qiong Zhang, and Zhongshi Zhang
Clim. Past, 19, 61–85, https://doi.org/10.5194/cp-19-61-2023, https://doi.org/10.5194/cp-19-61-2023, 2023
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We study the behavior of the Atlantic Meridional Overturning Circulation (AMOC) in the mid-Pliocene. The mid-Pliocene was about 3 million years ago and had a similar CO2 concentration to today. We show that the stronger AMOC during this period relates to changes in geography and that this has a significant influence on ocean temperatures and heat transported northwards by the Atlantic Ocean. Understanding the behavior of the mid-Pliocene AMOC can help us to learn more about our future climate.
Ji-Eun Kim, Thomas Westerhold, Laia Alegret, Anna Joy Drury, Ursula Röhl, and Elizabeth M. Griffith
Clim. Past, 18, 2631–2641, https://doi.org/10.5194/cp-18-2631-2022, https://doi.org/10.5194/cp-18-2631-2022, 2022
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This study attempts to gain a better understanding of the marine biological carbon pump and ecosystem functioning under warmer-than-today conditions. Our records from marine sediments show the Pacific tropical marine biological carbon pump was driven by variations in seasonal insolation in the tropics during the Late Cretaceous and may play a key role in modulating climate and the carbon cycle globally in the future.
Rick Hennekam, Katharine M. Grant, Eelco J. Rohling, Rik Tjallingii, David Heslop, Andrew P. Roberts, Lucas J. Lourens, and Gert-Jan Reichart
Clim. Past, 18, 2509–2521, https://doi.org/10.5194/cp-18-2509-2022, https://doi.org/10.5194/cp-18-2509-2022, 2022
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The ratio of titanium to aluminum (Ti/Al) is an established way to reconstruct North African climate in eastern Mediterranean Sea sediments. We demonstrate here how to obtain reliable Ti/Al data using an efficient scanning method that allows rapid acquisition of long climate records at low expense. Using this method, we reconstruct a 3-million-year North African climate record. African environmental variability was paced predominantly by low-latitude insolation from 3–1.2 million years ago.
Carolien M. H. van der Weijst, Koen J. van der Laan, Francien Peterse, Gert-Jan Reichart, Francesca Sangiorgi, Stefan Schouten, Tjerk J. T. Veenstra, and Appy Sluijs
Clim. Past, 18, 1947–1962, https://doi.org/10.5194/cp-18-1947-2022, https://doi.org/10.5194/cp-18-1947-2022, 2022
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The TEX86 proxy is often used by paleoceanographers to reconstruct past sea-surface temperatures. However, the origin of the TEX86 signal in marine sediments has been debated since the proxy was first proposed. In our paper, we show that TEX86 carries a mixed sea-surface and subsurface temperature signal and should be calibrated accordingly. Using our 15-million-year record, we subsequently show how a TEX86 subsurface temperature record can be used to inform us on past sea-surface temperatures.
Paul N. Pearson, Eleanor John, Bridget S. Wade, Simon D'haenens, and Caroline H. Lear
J. Micropalaeontol., 41, 107–127, https://doi.org/10.5194/jm-41-107-2022, https://doi.org/10.5194/jm-41-107-2022, 2022
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The microscopic shells of planktonic foraminifera accumulate on the sea floor over millions of years, providing a rich archive for understanding the history of the oceans. We examined an extinct group that flourished between about 63 and 32 million years ago using scanning electron microscopy and show that they were covered with needle-like spines in life. This has implications for analytical methods that we use to determine past seawater temperature and acidity.
Karen M. Brandenburg, Björn Rost, Dedmer B. Van de Waal, Mirja Hoins, and Appy Sluijs
Biogeosciences, 19, 3305–3315, https://doi.org/10.5194/bg-19-3305-2022, https://doi.org/10.5194/bg-19-3305-2022, 2022
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Reconstructions of past CO2 concentrations rely on proxy estimates, with one line of proxies relying on the CO2-dependence of stable carbon isotope fractionation in marine phytoplankton. Culturing experiments provide insights into which processes may impact this. We found, however, that the methods with which these culturing experiments are performed also influence 13C fractionation. Caution should therefore be taken when extrapolating results from these experiments to proxy applications.
Julia C. Tindall, Alan M. Haywood, Ulrich Salzmann, Aisling M. Dolan, and Tamara Fletcher
Clim. Past, 18, 1385–1405, https://doi.org/10.5194/cp-18-1385-2022, https://doi.org/10.5194/cp-18-1385-2022, 2022
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The mid-Pliocene (MP; ∼3.0 Ma) had CO2 levels similar to today and average temperatures ∼3°C warmer. At terrestrial high latitudes, MP temperatures from climate models are much lower than those reconstructed from data. This mismatch occurs in the winter but not the summer. The winter model–data mismatch likely has multiple causes. One novel cause is that the MP climate may be outside the modern sample, and errors could occur when using information from the modern era to reconstruct climate.
Christopher J. Hollis, Sebastian Naeher, Christopher D. Clowes, B. David A. Naafs, Richard D. Pancost, Kyle W. R. Taylor, Jenny Dahl, Xun Li, G. Todd Ventura, and Richard Sykes
Clim. Past, 18, 1295–1320, https://doi.org/10.5194/cp-18-1295-2022, https://doi.org/10.5194/cp-18-1295-2022, 2022
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Previous studies of Paleogene greenhouse climates identified short-lived global warming events, termed hyperthermals, that provide insights into global warming scenarios. Within the same time period, we have identified a short-lived cooling event in the late Paleocene, which we term a hypothermal, that has potential to provide novel insights into the feedback mechanisms at work in a greenhouse climate.
David De Vleeschouwer, Marion Peral, Marta Marchegiano, Angelina Füllberg, Niklas Meinicke, Heiko Pälike, Gerald Auer, Benjamin Petrick, Christophe Snoeck, Steven Goderis, and Philippe Claeys
Clim. Past, 18, 1231–1253, https://doi.org/10.5194/cp-18-1231-2022, https://doi.org/10.5194/cp-18-1231-2022, 2022
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The Leeuwin Current transports warm water along the western coast of Australia: from the tropics to the Southern Hemisphere midlatitudes. Therewith, the current influences climate in two ways: first, as a moisture source for precipitation in southwestern Australia; second, as a vehicle for Equator-to-pole heat transport. In this study, we study sediment cores along the Leeuwin Current pathway to understand its ocean–climate interactions between 4 and 2 Ma.
Carolien M. H. van der Weijst, Josse Winkelhorst, Wesley de Nooijer, Anna von der Heydt, Gert-Jan Reichart, Francesca Sangiorgi, and Appy Sluijs
Clim. Past, 18, 961–973, https://doi.org/10.5194/cp-18-961-2022, https://doi.org/10.5194/cp-18-961-2022, 2022
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A hypothesized link between Pliocene (5.3–2.5 million years ago) global climate and tropical thermocline depth is currently only backed up by data from the Pacific Ocean. In our paper, we present temperature, salinity, and thermocline records from the tropical Atlantic Ocean. Surprisingly, the Pliocene thermocline evolution was remarkably different in the Atlantic and Pacific. We need to reevaluate the mechanisms that drive thermocline depth, and how these are tied to global climate change.
Michael Amoo, Ulrich Salzmann, Matthew J. Pound, Nick Thompson, and Peter K. Bijl
Clim. Past, 18, 525–546, https://doi.org/10.5194/cp-18-525-2022, https://doi.org/10.5194/cp-18-525-2022, 2022
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Late Eocene to earliest Oligocene (37.97–33.06 Ma) climate and vegetation dynamics around the Tasmanian Gateway region reveal that changes in ocean circulation due to accelerated deepening of the Tasmanian Gateway may not have been solely responsible for the changes in terrestrial climate and vegetation; a series of regional and global events, including a change in stratification of water masses and changes in pCO2, may have played significant roles.
Stephen C. Phillips and Kate Littler
Sci. Dril., 30, 59–74, https://doi.org/10.5194/sd-30-59-2022, https://doi.org/10.5194/sd-30-59-2022, 2022
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Smear slides are a method of estimating sediment composition that is widely used as part of scientific drilling expeditions. These estimates are frequently used to classify sediments but are often not used in further analysis. We show that smear slide estimates, even if not highly accurate, track well with downcore physical property and elemental analyses. This work gives confidence in smear slide estimates in characterizing trends and cycles in sediment composition.
Henry Hooghiemstra, Gustavo Sarmiento Pérez, Vladimir Torres Torres, Juan-Carlos Berrío, Lucas Lourens, and Suzette G. A. Flantua
Sci. Dril., 30, 1–15, https://doi.org/10.5194/sd-30-1-2022, https://doi.org/10.5194/sd-30-1-2022, 2022
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This is a brief overview of long continental fossil pollen records globally in relationship with marine records. Specifically, the Northern Andes is a key area in developing and testing hypotheses in the fields of ecology, paleobiogeography, and climate change in tropical regions. We review 60 years of deep drilling experience in this region that have led to landmark records. We also highlight the early development of long continental pollen records from unique, deep, sediment-filled basins.
Peter D. Nooteboom, Peter K. Bijl, Christian Kehl, Erik van Sebille, Martin Ziegler, Anna S. von der Heydt, and Henk A. Dijkstra
Earth Syst. Dynam., 13, 357–371, https://doi.org/10.5194/esd-13-357-2022, https://doi.org/10.5194/esd-13-357-2022, 2022
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Having descended through the water column, microplankton in ocean sediments represents the ocean surface environment and is used as an archive of past and present surface oceanographic conditions. However, this microplankton is advected by turbulent ocean currents during its sinking journey. We use simulations of sinking particles to define ocean bottom provinces and detect these provinces in datasets of sedimentary microplankton, which has implications for palaeoclimate reconstructions.
Peter K. Bijl
Earth Syst. Sci. Data, 14, 579–617, https://doi.org/10.5194/essd-14-579-2022, https://doi.org/10.5194/essd-14-579-2022, 2022
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Using microfossils to gauge the age of rocks and sediments requires an accurate age of their first (origination) and last (extinction) appearances. But how do you know such ages can then be applied worldwide? And what causes regional differences? This paper investigates the regional consistency of ranges of species of a specific microfossil group, organic-walled dinoflagellate cysts. This overview helps in identifying regional differences in the stratigraphic ranges of species and their causes.
Flavia Boscolo-Galazzo, Amy Jones, Tom Dunkley Jones, Katherine A. Crichton, Bridget S. Wade, and Paul N. Pearson
Biogeosciences, 19, 743–762, https://doi.org/10.5194/bg-19-743-2022, https://doi.org/10.5194/bg-19-743-2022, 2022
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Deep-living organisms are a major yet poorly known component of ocean biomass. Here we reconstruct the evolution of deep-living zooplankton and phytoplankton. Deep-dwelling zooplankton and phytoplankton did not occur 15 Myr ago, when the ocean was several degrees warmer than today. Deep-dwelling species first evolve around 7.5 Myr ago, following global climate cooling. Their evolution was driven by colder ocean temperatures allowing more food, oxygen, and light at depth.
Nick Thompson, Ulrich Salzmann, Adrián López-Quirós, Peter K. Bijl, Frida S. Hoem, Johan Etourneau, Marie-Alexandrine Sicre, Sabine Roignant, Emma Hocking, Michael Amoo, and Carlota Escutia
Clim. Past, 18, 209–232, https://doi.org/10.5194/cp-18-209-2022, https://doi.org/10.5194/cp-18-209-2022, 2022
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New pollen and spore data from the Antarctic Peninsula region reveal temperate rainforests that changed and adapted in response to Eocene climatic cooling, roughly 35.5 Myr ago, and glacially related disturbance in the early Oligocene, approximately 33.5 Myr ago. The timing of these events indicates that the opening of ocean gateways alone did not trigger Antarctic glaciation, although ocean gateways may have played a role in climate cooling.
Maxence Guillermic, Sambuddha Misra, Robert Eagle, and Aradhna Tripati
Clim. Past, 18, 183–207, https://doi.org/10.5194/cp-18-183-2022, https://doi.org/10.5194/cp-18-183-2022, 2022
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Here we reconstruct atmospheric CO2 values across major climate transitions over the past 16 million years (Myr) from two sites in the West Pacific Warm Pool using a pH proxy on surface-dwelling foraminifera. We are able to reproduce pCO2 data from ice cores; therefore we apply the same framework to older samples to create a long-term pH and pCO2 reconstruction. We give quantitative constraints on pH and pCO2 changes over the main climate transitions of the last 16 Myr.
Zixuan Han, Qiong Zhang, Qiang Li, Ran Feng, Alan M. Haywood, Julia C. Tindall, Stephen J. Hunter, Bette L. Otto-Bliesner, Esther C. Brady, Nan Rosenbloom, Zhongshi Zhang, Xiangyu Li, Chuncheng Guo, Kerim H. Nisancioglu, Christian Stepanek, Gerrit Lohmann, Linda E. Sohl, Mark A. Chandler, Ning Tan, Gilles Ramstein, Michiel L. J. Baatsen, Anna S. von der Heydt, Deepak Chandan, W. Richard Peltier, Charles J. R. Williams, Daniel J. Lunt, Jianbo Cheng, Qin Wen, and Natalie J. Burls
Clim. Past, 17, 2537–2558, https://doi.org/10.5194/cp-17-2537-2021, https://doi.org/10.5194/cp-17-2537-2021, 2021
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Understanding the potential processes responsible for large-scale hydrological cycle changes in a warmer climate is of great importance. Our study implies that an imbalance in interhemispheric atmospheric energy during the mid-Pliocene could have led to changes in the dynamic effect, offsetting the thermodynamic effect and, hence, altering mid-Pliocene hydroclimate cycling. Moreover, a robust westward shift in the Pacific Walker circulation can moisten the northern Indian Ocean.
Arthur M. Oldeman, Michiel L. J. Baatsen, Anna S. von der Heydt, Henk A. Dijkstra, Julia C. Tindall, Ayako Abe-Ouchi, Alice R. Booth, Esther C. Brady, Wing-Le Chan, Deepak Chandan, Mark A. Chandler, Camille Contoux, Ran Feng, Chuncheng Guo, Alan M. Haywood, Stephen J. Hunter, Youichi Kamae, Qiang Li, Xiangyu Li, Gerrit Lohmann, Daniel J. Lunt, Kerim H. Nisancioglu, Bette L. Otto-Bliesner, W. Richard Peltier, Gabriel M. Pontes, Gilles Ramstein, Linda E. Sohl, Christian Stepanek, Ning Tan, Qiong Zhang, Zhongshi Zhang, Ilana Wainer, and Charles J. R. Williams
Clim. Past, 17, 2427–2450, https://doi.org/10.5194/cp-17-2427-2021, https://doi.org/10.5194/cp-17-2427-2021, 2021
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In this work, we have studied the behaviour of El Niño events in the mid-Pliocene, a period of around 3 million years ago, using a collection of 17 climate models. It is an interesting period to study, as it saw similar atmospheric carbon dioxide levels to the present day. We find that the El Niño events were less strong in the mid-Pliocene simulations, when compared to pre-industrial climate. Our results could help to interpret El Niño behaviour in future climate projections.
Peter K. Bijl, Joost Frieling, Marlow Julius Cramwinckel, Christine Boschman, Appy Sluijs, and Francien Peterse
Clim. Past, 17, 2393–2425, https://doi.org/10.5194/cp-17-2393-2021, https://doi.org/10.5194/cp-17-2393-2021, 2021
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Here, we use the latest insights for GDGT and dinocyst-based paleotemperature and paleoenvironmental reconstructions in late Cretaceous–early Oligocene sediments from ODP Site 1172 (East Tasman Plateau, Australia). We reconstruct strong river runoff during the Paleocene–early Eocene, a progressive decline thereafter with increased wet/dry seasonality in the northward-drifting hinterland. Our critical review leaves the anomalous warmth of the Eocene SW Pacific Ocean unexplained.
Frida S. Hoem, Isabel Sauermilch, Suning Hou, Henk Brinkhuis, Francesca Sangiorgi, and Peter K. Bijl
J. Micropalaeontol., 40, 175–193, https://doi.org/10.5194/jm-40-175-2021, https://doi.org/10.5194/jm-40-175-2021, 2021
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We use marine microfossil (dinocyst) assemblage data as well as seismic and tectonic investigations to reconstruct the oceanographic history south of Australia 37–20 Ma as the Tasmanian Gateway widens and deepens. Our results show stable conditions with typically warmer dinocysts south of Australia, which contrasts with the colder dinocysts closer to Antarctica, indicating the establishment of modern oceanographic conditions with a strong Southern Ocean temperature gradient and frontal systems.
Thomas J. Leutert, Sevasti Modestou, Stefano M. Bernasconi, and A. Nele Meckler
Clim. Past, 17, 2255–2271, https://doi.org/10.5194/cp-17-2255-2021, https://doi.org/10.5194/cp-17-2255-2021, 2021
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The Miocene climatic optimum associated with high atmospheric CO2 levels (~17–14 Ma) was followed by a period of dramatic climate change. We present a clumped isotope-based bottom-water temperature record from the Southern Ocean covering this key climate transition. Our record reveals warm conditions and a substantial cooling preceding the main ice volume increase, possibly caused by thresholds involved in ice growth and/or regional effects at our study site.
Katherine A. Crichton, Andy Ridgwell, Daniel J. Lunt, Alex Farnsworth, and Paul N. Pearson
Clim. Past, 17, 2223–2254, https://doi.org/10.5194/cp-17-2223-2021, https://doi.org/10.5194/cp-17-2223-2021, 2021
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The middle Miocene (15 Ma) was a period of global warmth up to 8 °C warmer than present. We investigate changes in ocean circulation and heat distribution since the middle Miocene and the cooling to the present using the cGENIE Earth system model. We create seven time slices at ~2.5 Myr intervals, constrained with paleo-proxy data, showing a progressive reduction in atmospheric CO2 and a strengthening of the Atlantic Meridional Overturning Circulation.
Charles J. R. Williams, Alistair A. Sellar, Xin Ren, Alan M. Haywood, Peter Hopcroft, Stephen J. Hunter, William H. G. Roberts, Robin S. Smith, Emma J. Stone, Julia C. Tindall, and Daniel J. Lunt
Clim. Past, 17, 2139–2163, https://doi.org/10.5194/cp-17-2139-2021, https://doi.org/10.5194/cp-17-2139-2021, 2021
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Computer simulations of the geological past are an important tool to improve our understanding of climate change. We present results from a simulation of the mid-Pliocene (approximately 3 million years ago) using the latest version of the UK’s climate model. The simulation reproduces temperatures as expected and shows some improvement relative to previous versions of the same model. The simulation is, however, arguably too warm when compared to other models and available observations.
Anna Joy Drury, Diederik Liebrand, Thomas Westerhold, Helen M. Beddow, David A. Hodell, Nina Rohlfs, Roy H. Wilkens, Mitchell Lyle, David B. Bell, Dick Kroon, Heiko Pälike, and Lucas J. Lourens
Clim. Past, 17, 2091–2117, https://doi.org/10.5194/cp-17-2091-2021, https://doi.org/10.5194/cp-17-2091-2021, 2021
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We use the first high-resolution southeast Atlantic carbonate record to see how climate dynamics evolved since 30 million years ago (Ma). During ~ 30–13 Ma, eccentricity (orbital circularity) paced carbonate deposition. After the mid-Miocene Climate Transition (~ 14 Ma), precession (Earth's tilt direction) increasingly drove carbonate variability. In the latest Miocene (~ 8 Ma), obliquity (Earth's tilt) pacing appeared, signalling increasing high-latitude influence.
Kate E. Ashley, Xavier Crosta, Johan Etourneau, Philippine Campagne, Harry Gilchrist, Uthmaan Ibraheem, Sarah E. Greene, Sabine Schmidt, Yvette Eley, Guillaume Massé, and James Bendle
Biogeosciences, 18, 5555–5571, https://doi.org/10.5194/bg-18-5555-2021, https://doi.org/10.5194/bg-18-5555-2021, 2021
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We explore the potential for the use of carbon isotopes of algal fatty acid as a new proxy for past primary productivity in Antarctic coastal zones. Coastal polynyas are hotspots of primary productivity and are known to draw down CO2 from the atmosphere. Reconstructions of past productivity changes could provide a baseline for the role of these areas as sinks for atmospheric CO2.
Jakub Witkowski, Karolina Bryłka, Steven M. Bohaty, Elżbieta Mydłowska, Donald E. Penman, and Bridget S. Wade
Clim. Past, 17, 1937–1954, https://doi.org/10.5194/cp-17-1937-2021, https://doi.org/10.5194/cp-17-1937-2021, 2021
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We reconstruct the history of biogenic opal accumulation through the early to middle Paleogene in the western North Atlantic. Biogenic opal accumulation was controlled by deepwater temperatures, atmospheric greenhouse gas levels, and continental weathering intensity. Overturning circulation in the Atlantic was established at the end of the extreme early Eocene greenhouse warmth period. We also show that the strength of the link between climate and continental weathering varies through time.
Bridget S. Wade, Mohammed H. Aljahdali, Yahya A. Mufrreh, Abdullah M. Memesh, Salih A. AlSoubhi, and Iyad S. Zalmout
J. Micropalaeontol., 40, 145–161, https://doi.org/10.5194/jm-40-145-2021, https://doi.org/10.5194/jm-40-145-2021, 2021
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We examined the planktonic foraminifera (calcareous zooplankton) from a section in northern Saudi Arabia. We found the assemblages to be diverse, well-preserved and of late Eocene age. Our study provides new insights into the stratigraphic ranges of many species and indicates that the late Eocene had a higher tropical/subtropical diversity of planktonic foraminifera than previously reported.
Ellen Berntell, Qiong Zhang, Qiang Li, Alan M. Haywood, Julia C. Tindall, Stephen J. Hunter, Zhongshi Zhang, Xiangyu Li, Chuncheng Guo, Kerim H. Nisancioglu, Christian Stepanek, Gerrit Lohmann, Linda E. Sohl, Mark A. Chandler, Ning Tan, Camille Contoux, Gilles Ramstein, Michiel L. J. Baatsen, Anna S. von der Heydt, Deepak Chandan, William Richard Peltier, Ayako Abe-Ouchi, Wing-Le Chan, Youichi Kamae, Charles J. R. Williams, Daniel J. Lunt, Ran Feng, Bette L. Otto-Bliesner, and Esther C. Brady
Clim. Past, 17, 1777–1794, https://doi.org/10.5194/cp-17-1777-2021, https://doi.org/10.5194/cp-17-1777-2021, 2021
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The mid-Pliocene Warm Period (~ 3.2 Ma) is often considered an analogue for near-future climate projections, and model results from the PlioMIP2 ensemble show an increase of rainfall over West Africa and the Sahara region compared to pre-industrial conditions. Though previous studies of future projections show a west–east drying–wetting contrast over the Sahel, these results indicate a uniform rainfall increase over the Sahel in warm climates characterized by increased greenhouse gas forcing.
Nicolai Schleinkofer, David Evans, Max Wisshak, Janina Vanessa Büscher, Jens Fiebig, André Freiwald, Sven Härter, Horst R. Marschall, Silke Voigt, and Jacek Raddatz
Biogeosciences, 18, 4733–4753, https://doi.org/10.5194/bg-18-4733-2021, https://doi.org/10.5194/bg-18-4733-2021, 2021
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We have measured the chemical composition of the carbonate shells of the parasitic foraminifera Hyrrokkin sarcophaga in order to test if it is influenced by the host organism (bivalve or coral). We find that both the chemical and isotopic composition is influenced by the host organism. For example strontium is enriched in foraminifera that grew on corals, whose skeleton is built from aragonite, which is naturally enriched in strontium compared to the bivalves' calcite shell.
Felipe S. Freitas, Philip A. Pika, Sabine Kasten, Bo B. Jørgensen, Jens Rassmann, Christophe Rabouille, Shaun Thomas, Henrik Sass, Richard D. Pancost, and Sandra Arndt
Biogeosciences, 18, 4651–4679, https://doi.org/10.5194/bg-18-4651-2021, https://doi.org/10.5194/bg-18-4651-2021, 2021
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It remains challenging to fully understand what controls carbon burial in marine sediments globally. Thus, we use a model–data approach to identify patterns of organic matter reactivity at the seafloor across distinct environmental conditions. Our findings support the notion that organic matter reactivity is a dynamic ecosystem property and strongly influences biogeochemical cycling and exchange. Our results are essential to improve predictions of future changes in carbon cycling and climate.
Gerrit Müller, Jack J. Middelburg, and Appy Sluijs
Earth Syst. Sci. Data, 13, 3565–3575, https://doi.org/10.5194/essd-13-3565-2021, https://doi.org/10.5194/essd-13-3565-2021, 2021
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Rivers are major freshwater resources, connectors and transporters on Earth. As the composition of river waters and particles results from processes in their catchment, such as erosion, weathering, environmental pollution, nutrient and carbon cycling, Earth-spanning databases of river composition are needed for studies of these processes on a global scale. While extensive resources on water and nutrient composition exist, we provide a database of river particle composition.
Paul J. Valdes, Christopher R. Scotese, and Daniel J. Lunt
Clim. Past, 17, 1483–1506, https://doi.org/10.5194/cp-17-1483-2021, https://doi.org/10.5194/cp-17-1483-2021, 2021
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Deep ocean temperatures are widely used as a proxy for global mean surface temperature in the past, but the underlying assumptions have not been tested. We use two unique sets of 109 climate model simulations for the last 545 million years to show that the relationship is valid for approximately the last 100 million years but breaks down for older time periods when the continents (and hence ocean circulation) are in very different positions.
Daniel J. Lunt, Deepak Chandan, Alan M. Haywood, George M. Lunt, Jonathan C. Rougier, Ulrich Salzmann, Gavin A. Schmidt, and Paul J. Valdes
Geosci. Model Dev., 14, 4307–4317, https://doi.org/10.5194/gmd-14-4307-2021, https://doi.org/10.5194/gmd-14-4307-2021, 2021
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Often in science we carry out experiments with computers in which several factors are explored, for example, in the field of climate science, how the factors of greenhouse gases, ice, and vegetation affect temperature. We can explore the relative importance of these factors by
swapping in and outdifferent values of these factors, and can also carry out experiments with many different combinations of these factors. This paper discusses how best to analyse the results from such experiments.
Frida S. Hoem, Luis Valero, Dimitris Evangelinos, Carlota Escutia, Bella Duncan, Robert M. McKay, Henk Brinkhuis, Francesca Sangiorgi, and Peter K. Bijl
Clim. Past, 17, 1423–1442, https://doi.org/10.5194/cp-17-1423-2021, https://doi.org/10.5194/cp-17-1423-2021, 2021
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We present new offshore palaeoceanographic reconstructions for the Oligocene (33.7–24.4 Ma) in the Ross Sea, Antarctica. Our study of dinoflagellate cysts and lipid biomarkers indicates warm-temperate sea surface conditions. We posit that warm surface-ocean conditions near the continental shelf during the Oligocene promoted increased precipitation and heat delivery towards Antarctica that led to dynamic terrestrial ice sheet volumes in the warmer climate state of the Oligocene.
Masa Kageyama, Sandy P. Harrison, Marie-L. Kapsch, Marcus Lofverstrom, Juan M. Lora, Uwe Mikolajewicz, Sam Sherriff-Tadano, Tristan Vadsaria, Ayako Abe-Ouchi, Nathaelle Bouttes, Deepak Chandan, Lauren J. Gregoire, Ruza F. Ivanovic, Kenji Izumi, Allegra N. LeGrande, Fanny Lhardy, Gerrit Lohmann, Polina A. Morozova, Rumi Ohgaito, André Paul, W. Richard Peltier, Christopher J. Poulsen, Aurélien Quiquet, Didier M. Roche, Xiaoxu Shi, Jessica E. Tierney, Paul J. Valdes, Evgeny Volodin, and Jiang Zhu
Clim. Past, 17, 1065–1089, https://doi.org/10.5194/cp-17-1065-2021, https://doi.org/10.5194/cp-17-1065-2021, 2021
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The Last Glacial Maximum (LGM; ~21 000 years ago) is a major focus for evaluating how well climate models simulate climate changes as large as those expected in the future. Here, we compare the latest climate model (CMIP6-PMIP4) to the previous one (CMIP5-PMIP3) and to reconstructions. Large-scale climate features (e.g. land–sea contrast, polar amplification) are well captured by all models, while regional changes (e.g. winter extratropical cooling, precipitations) are still poorly represented.
Zhongshi Zhang, Xiangyu Li, Chuncheng Guo, Odd Helge Otterå, Kerim H. Nisancioglu, Ning Tan, Camille Contoux, Gilles Ramstein, Ran Feng, Bette L. Otto-Bliesner, Esther Brady, Deepak Chandan, W. Richard Peltier, Michiel L. J. Baatsen, Anna S. von der Heydt, Julia E. Weiffenbach, Christian Stepanek, Gerrit Lohmann, Qiong Zhang, Qiang Li, Mark A. Chandler, Linda E. Sohl, Alan M. Haywood, Stephen J. Hunter, Julia C. Tindall, Charles Williams, Daniel J. Lunt, Wing-Le Chan, and Ayako Abe-Ouchi
Clim. Past, 17, 529–543, https://doi.org/10.5194/cp-17-529-2021, https://doi.org/10.5194/cp-17-529-2021, 2021
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The Atlantic Meridional Overturning Circulation (AMOC) is an important topic in the Pliocene Model Intercomparison Project. Previous studies have suggested a much stronger AMOC during the Pliocene than today. However, our current multi-model intercomparison shows large model spreads and model–data discrepancies, which can not support the previous hypothesis. Our study shows good consistency with future projections of the AMOC.
Bas de Boer, Marit Peters, and Lucas J. Lourens
Clim. Past, 17, 331–344, https://doi.org/10.5194/cp-17-331-2021, https://doi.org/10.5194/cp-17-331-2021, 2021
David K. Hutchinson, Helen K. Coxall, Daniel J. Lunt, Margret Steinthorsdottir, Agatha M. de Boer, Michiel Baatsen, Anna von der Heydt, Matthew Huber, Alan T. Kennedy-Asser, Lutz Kunzmann, Jean-Baptiste Ladant, Caroline H. Lear, Karolin Moraweck, Paul N. Pearson, Emanuela Piga, Matthew J. Pound, Ulrich Salzmann, Howie D. Scher, Willem P. Sijp, Kasia K. Śliwińska, Paul A. Wilson, and Zhongshi Zhang
Clim. Past, 17, 269–315, https://doi.org/10.5194/cp-17-269-2021, https://doi.org/10.5194/cp-17-269-2021, 2021
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The Eocene–Oligocene transition was a major climate cooling event from a largely ice-free world to the first major glaciation of Antarctica, approximately 34 million years ago. This paper reviews observed changes in temperature, CO2 and ice sheets from marine and land-based records at this time. We present a new model–data comparison of this transition and find that CO2-forced cooling provides the best explanation of the observed global temperature changes.
Annique van der Boon, Klaudia F. Kuiper, Robin van der Ploeg, Marlow Julius Cramwinckel, Maryam Honarmand, Appy Sluijs, and Wout Krijgsman
Clim. Past, 17, 229–239, https://doi.org/10.5194/cp-17-229-2021, https://doi.org/10.5194/cp-17-229-2021, 2021
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40.5 million years ago, Earth's climate warmed, but it is unknown why. Enhanced volcanism has been suggested, but this has not yet been tied to a specific region. We explore an increase in volcanism in Iran. We dated igneous rocks and compiled ages from the literature. We estimated the volume of igneous rocks in Iran in order to calculate the amount of CO2 that could have been released due to enhanced volcanism. We conclude that an increase in volcanism in Iran is a plausible cause of warming.
Daniel J. Lunt, Fran Bragg, Wing-Le Chan, David K. Hutchinson, Jean-Baptiste Ladant, Polina Morozova, Igor Niezgodzki, Sebastian Steinig, Zhongshi Zhang, Jiang Zhu, Ayako Abe-Ouchi, Eleni Anagnostou, Agatha M. de Boer, Helen K. Coxall, Yannick Donnadieu, Gavin Foster, Gordon N. Inglis, Gregor Knorr, Petra M. Langebroek, Caroline H. Lear, Gerrit Lohmann, Christopher J. Poulsen, Pierre Sepulchre, Jessica E. Tierney, Paul J. Valdes, Evgeny M. Volodin, Tom Dunkley Jones, Christopher J. Hollis, Matthew Huber, and Bette L. Otto-Bliesner
Clim. Past, 17, 203–227, https://doi.org/10.5194/cp-17-203-2021, https://doi.org/10.5194/cp-17-203-2021, 2021
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This paper presents the first modelling results from the Deep-Time Model Intercomparison Project (DeepMIP), in which we focus on the early Eocene climatic optimum (EECO, 50 million years ago). We show that, in contrast to previous work, at least three models (CESM, GFDL, and NorESM) produce climate states that are consistent with proxy indicators of global mean temperature and polar amplification, and they achieve this at a CO2 concentration that is consistent with the CO2 proxy record.
Katherine A. Crichton, Jamie D. Wilson, Andy Ridgwell, and Paul N. Pearson
Geosci. Model Dev., 14, 125–149, https://doi.org/10.5194/gmd-14-125-2021, https://doi.org/10.5194/gmd-14-125-2021, 2021
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Temperature is a controller of metabolic processes and therefore also a controller of the ocean's biological carbon pump (BCP). We calibrate a temperature-dependent version of the BCP in the cGENIE Earth system model. Since the pre-industrial period, warming has intensified near-surface nutrient recycling, supporting production and largely offsetting stratification-induced surface nutrient limitation. But at the same time less carbon that sinks out of the surface then reaches the deep ocean.
Tom Dunkley Jones, Yvette L. Eley, William Thomson, Sarah E. Greene, Ilya Mandel, Kirsty Edgar, and James A. Bendle
Clim. Past, 16, 2599–2617, https://doi.org/10.5194/cp-16-2599-2020, https://doi.org/10.5194/cp-16-2599-2020, 2020
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We explore the utiliity of the composition of fossil lipid biomarkers, which are commonly preserved in ancient marine sediments, in providing estimates of past ocean temperatures. The group of lipids concerned show compositional changes across the modern oceans that are correlated, to some extent, with local surface ocean temperatures. Here we present new machine learning approaches to improve our understanding of this temperature sensitivity and its application to reconstructing past climates.
Michiel Baatsen, Anna S. von der Heydt, Matthew Huber, Michael A. Kliphuis, Peter K. Bijl, Appy Sluijs, and Henk A. Dijkstra
Clim. Past, 16, 2573–2597, https://doi.org/10.5194/cp-16-2573-2020, https://doi.org/10.5194/cp-16-2573-2020, 2020
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Warm climates of the deep past have proven to be challenging to reconstruct with the same numerical models used for future predictions. We present results of CESM simulations for the middle to late Eocene (∼ 38 Ma), in which we managed to match the available indications of temperature well. With these results we can now look into regional features and the response to external changes to ultimately better understand the climate when it is in such a warm state.
Appy Sluijs, Joost Frieling, Gordon N. Inglis, Klaas G. J. Nierop, Francien Peterse, Francesca Sangiorgi, and Stefan Schouten
Clim. Past, 16, 2381–2400, https://doi.org/10.5194/cp-16-2381-2020, https://doi.org/10.5194/cp-16-2381-2020, 2020
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We revisit 15-year-old reconstructions of sea surface temperatures in the Arctic Ocean for the late Paleocene and early Eocene epochs (∼ 57–53 million years ago) based on the distribution of fossil membrane lipids of archaea preserved in Arctic Ocean sediments. We find that improvements in the methods over the past 15 years do not lead to different results. However, data quality is now higher and potential biases better characterized. Results confirm remarkable Arctic warmth during this time.
Eric Salomon, Atle Rotevatn, Thomas Berg Kristensen, Sten-Andreas Grundvåg, Gijs Allard Henstra, Anna Nele Meckler, Richard Albert, and Axel Gerdes
Solid Earth, 11, 1987–2013, https://doi.org/10.5194/se-11-1987-2020, https://doi.org/10.5194/se-11-1987-2020, 2020
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This study focuses on the impact of major rift border faults on fluid circulation and hanging wall sediment diagenesis by investigating a well-exposed example in NE Greenland using field observations, U–Pb calcite dating, clumped isotope, and minor element analyses. We show that fault-proximal sediments became calcite cemented quickly after deposition to form a near-impermeable barrier along the fault, which has important implications for border fault zone evolution and reservoir assessments.
Alan M. Haywood, Julia C. Tindall, Harry J. Dowsett, Aisling M. Dolan, Kevin M. Foley, Stephen J. Hunter, Daniel J. Hill, Wing-Le Chan, Ayako Abe-Ouchi, Christian Stepanek, Gerrit Lohmann, Deepak Chandan, W. Richard Peltier, Ning Tan, Camille Contoux, Gilles Ramstein, Xiangyu Li, Zhongshi Zhang, Chuncheng Guo, Kerim H. Nisancioglu, Qiong Zhang, Qiang Li, Youichi Kamae, Mark A. Chandler, Linda E. Sohl, Bette L. Otto-Bliesner, Ran Feng, Esther C. Brady, Anna S. von der Heydt, Michiel L. J. Baatsen, and Daniel J. Lunt
Clim. Past, 16, 2095–2123, https://doi.org/10.5194/cp-16-2095-2020, https://doi.org/10.5194/cp-16-2095-2020, 2020
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The large-scale features of middle Pliocene climate from the 16 models of PlioMIP Phase 2 are presented. The PlioMIP2 ensemble average was ~ 3.2 °C warmer and experienced ~ 7 % more precipitation than the pre-industrial era, although there are large regional variations. PlioMIP2 broadly agrees with a new proxy dataset of Pliocene sea surface temperatures. Combining PlioMIP2 and proxy data suggests that a doubling of atmospheric CO2 would increase globally averaged temperature by 2.6–4.8 °C.
Gordon N. Inglis, Fran Bragg, Natalie J. Burls, Marlow Julius Cramwinckel, David Evans, Gavin L. Foster, Matthew Huber, Daniel J. Lunt, Nicholas Siler, Sebastian Steinig, Jessica E. Tierney, Richard Wilkinson, Eleni Anagnostou, Agatha M. de Boer, Tom Dunkley Jones, Kirsty M. Edgar, Christopher J. Hollis, David K. Hutchinson, and Richard D. Pancost
Clim. Past, 16, 1953–1968, https://doi.org/10.5194/cp-16-1953-2020, https://doi.org/10.5194/cp-16-1953-2020, 2020
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This paper presents estimates of global mean surface temperatures and climate sensitivity during the early Paleogene (∼57–48 Ma). We employ a multi-method experimental approach and show that i) global mean surface temperatures range between 27 and 32°C and that ii) estimates of
bulkequilibrium climate sensitivity (∼3 to 4.5°C) fall within the range predicted by the IPCC AR5 Report. This work improves our understanding of two key climate metrics during the early Paleogene.
Charlotte Beasley, Daniel B. Parvaz, Laura Cotton, and Kate Littler
J. Micropalaeontol., 39, 169–181, https://doi.org/10.5194/jm-39-169-2020, https://doi.org/10.5194/jm-39-169-2020, 2020
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We compared three methods of breaking apart well-cemented carbonate rocks in order to obtain liberated fossiliferous material. The first two methods are
traditionaland the third is novel to this field. The novel technique (fragmentation using electric pulses, SELFRAG) proved to be the most efficient and effective at liberating microfossil material from surrounding rock. We suggest best practice for using this technique and further materials in which it could prove successful in future.
Marlow Julius Cramwinckel, Lineke Woelders, Emiel P. Huurdeman, Francien Peterse, Stephen J. Gallagher, Jörg Pross, Catherine E. Burgess, Gert-Jan Reichart, Appy Sluijs, and Peter K. Bijl
Clim. Past, 16, 1667–1689, https://doi.org/10.5194/cp-16-1667-2020, https://doi.org/10.5194/cp-16-1667-2020, 2020
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Phases of past transient warming can be used as a test bed to study the environmental response to climate change independent of tectonic change. Using fossil plankton and organic molecules, here we reconstruct surface ocean temperature and circulation in and around the Tasman Gateway during a warming phase 40 million years ago termed the Middle Eocene Climatic Optimum. We find that plankton assemblages track ocean circulation patterns, with superimposed variability being related to temperature.
Erin L. McClymont, Heather L. Ford, Sze Ling Ho, Julia C. Tindall, Alan M. Haywood, Montserrat Alonso-Garcia, Ian Bailey, Melissa A. Berke, Kate Littler, Molly O. Patterson, Benjamin Petrick, Francien Peterse, A. Christina Ravelo, Bjørg Risebrobakken, Stijn De Schepper, George E. A. Swann, Kaustubh Thirumalai, Jessica E. Tierney, Carolien van der Weijst, Sarah White, Ayako Abe-Ouchi, Michiel L. J. Baatsen, Esther C. Brady, Wing-Le Chan, Deepak Chandan, Ran Feng, Chuncheng Guo, Anna S. von der Heydt, Stephen Hunter, Xiangyi Li, Gerrit Lohmann, Kerim H. Nisancioglu, Bette L. Otto-Bliesner, W. Richard Peltier, Christian Stepanek, and Zhongshi Zhang
Clim. Past, 16, 1599–1615, https://doi.org/10.5194/cp-16-1599-2020, https://doi.org/10.5194/cp-16-1599-2020, 2020
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We examine the sea-surface temperature response to an interval of climate ~ 3.2 million years ago, when CO2 concentrations were similar to today and the near future. Our geological data and climate models show that global mean sea-surface temperatures were 2.3 to 3.2 ºC warmer than pre-industrial climate, that the mid-latitudes and high latitudes warmed more than the tropics, and that the warming was particularly enhanced in the North Atlantic Ocean.
Carolien Maria Hendrina van der Weijst, Josse Winkelhorst, Anna von der Heydt, Gert-Jan Reichart, Francesca Sangiorgi, and Appy Sluijs
Clim. Past Discuss., https://doi.org/10.5194/cp-2020-105, https://doi.org/10.5194/cp-2020-105, 2020
Manuscript not accepted for further review
Charles J. R. Williams, Maria-Vittoria Guarino, Emilie Capron, Irene Malmierca-Vallet, Joy S. Singarayer, Louise C. Sime, Daniel J. Lunt, and Paul J. Valdes
Clim. Past, 16, 1429–1450, https://doi.org/10.5194/cp-16-1429-2020, https://doi.org/10.5194/cp-16-1429-2020, 2020
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Computer simulations of the geological past are an important tool to improve our understanding of climate change. We present results from two simulations using the latest version of the UK's climate model, the mid-Holocene (6000 years ago) and Last Interglacial (127 000 years ago). The simulations reproduce temperatures consistent with the pattern of incoming radiation. Model–data comparisons indicate that some regions (and some seasons) produce better matches to the data than others.
Kirsty M. Edgar, Steven M. Bohaty, Helen K. Coxall, Paul R. Bown, Sietske J. Batenburg, Caroline H. Lear, and Paul N. Pearson
J. Micropalaeontol., 39, 117–138, https://doi.org/10.5194/jm-39-117-2020, https://doi.org/10.5194/jm-39-117-2020, 2020
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We identify the first continuous carbonate-bearing sediment record from the tropical ocean that spans the entirety of the global warming event, the Middle Eocene Climatic Optimum, ca. 40 Ma. We determine significant mismatches between middle Eocene calcareous microfossil datums from the tropical Pacific Ocean and established low-latitude zonation schemes. We highlight the potential of ODP Site 865 for future investigations into environmental and biotic changes throughout the early Paleogene.
Maxence Guillermic, Sambuddha Misra, Robert Eagle, Alexandra Villa, Fengming Chang, and Aradhna Tripati
Biogeosciences, 17, 3487–3510, https://doi.org/10.5194/bg-17-3487-2020, https://doi.org/10.5194/bg-17-3487-2020, 2020
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Boron isotope ratios (δ11B) of foraminifera are a promising proxy for seawater pH and can be used to constrain pCO2. In this study, we derived calibrations for new foraminiferal taxa which extend the application of the boron isotope proxy. We discuss the origin of different δ11B signatures in species and also discuss the potential of using multispecies δ11B analyses to constrain vertical pH and pCO2 gradients in ancient water columns to shed light on biogeochemical carbon cycling in the past.
Hannah K. Donald, Gavin L. Foster, Nico Fröhberg, George E. A. Swann, Alex J. Poulton, C. Mark Moore, and Matthew P. Humphreys
Biogeosciences, 17, 2825–2837, https://doi.org/10.5194/bg-17-2825-2020, https://doi.org/10.5194/bg-17-2825-2020, 2020
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The boron isotope pH proxy is increasingly being used to reconstruct ocean pH in the past. Here we detail a novel analytical methodology for measuring the boron isotopic composition (δ11B) of diatom opal and apply this to the study of the diatom Thalassiosira weissflogii grown in culture over a range of pH. To our knowledge this is the first study of its kind and provides unique insights into the way in which diatoms incorporate boron and their potential as archives of palaeoclimate records.
Alan T. Kennedy-Asser, Daniel J. Lunt, Paul J. Valdes, Jean-Baptiste Ladant, Joost Frieling, and Vittoria Lauretano
Clim. Past, 16, 555–573, https://doi.org/10.5194/cp-16-555-2020, https://doi.org/10.5194/cp-16-555-2020, 2020
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Global cooling and a major expansion of ice over Antarctica occurred ~ 34 million years ago at the Eocene–Oligocene transition (EOT). A large secondary proxy dataset for high-latitude Southern Hemisphere temperature before, after and across the EOT is compiled and compared to simulations from two coupled climate models. Although there are inconsistencies between the models and data, the comparison shows amongst other things that changes in the Drake Passage were unlikely the cause of the EOT.
Emily Dearing Crampton-Flood, Lars J. Noorbergen, Damian Smits, R. Christine Boschman, Timme H. Donders, Dirk K. Munsterman, Johan ten Veen, Francien Peterse, Lucas Lourens, and Jaap S. Sinninghe Damsté
Clim. Past, 16, 523–541, https://doi.org/10.5194/cp-16-523-2020, https://doi.org/10.5194/cp-16-523-2020, 2020
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The mid-Pliocene warm period (mPWP; 3.3–3.0 million years ago) is thought to be the last geological interval with similar atmospheric carbon dioxide concentrations as the present day. Further, the mPWP was 2–3 °C warmer than present, making it a good analogue for estimating the effects of future climate change. Here, we construct a new precise age model for the North Sea during the mPWP, and provide a detailed reconstruction of terrestrial and marine climate using a multi-proxy approach.
Gabriel J. Bowen, Brenden Fischer-Femal, Gert-Jan Reichart, Appy Sluijs, and Caroline H. Lear
Clim. Past, 16, 65–78, https://doi.org/10.5194/cp-16-65-2020, https://doi.org/10.5194/cp-16-65-2020, 2020
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Past climate conditions are reconstructed using indirect and incomplete geological, biological, and geochemical proxy data. We propose that such reconstructions are best obtained by statistical inversion of hierarchical models that represent how multi–proxy observations and calibration data are produced by variation of environmental conditions in time and/or space. These methods extract new information from traditional proxies and provide robust, comprehensive estimates of uncertainty.
Marcelo Augusto De Lira Mota, Guy Harrington, and Tom Dunkley Jones
J. Micropalaeontol., 39, 1–26, https://doi.org/10.5194/jm-39-1-2020, https://doi.org/10.5194/jm-39-1-2020, 2020
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New high-resolution microfossil record from a clay succession in the US Gulf Coastal Plain reveal more accurate age estimates for the critical Eocene–Oligocene transition (EOT), a global climate event marked by the rapid expansion of the first permanent Antarctic ice sheet 34 million years ago. These data suggest a coeval major increase in sedimentation rate. Future isotopic and palaeoecological work on this core can be more precisely integrated with other global records of the EOT.
Dana Ridha, Ian Boomer, and Kirsty M. Edgar
J. Micropalaeontol., 38, 189–229, https://doi.org/10.5194/jm-38-189-2019, https://doi.org/10.5194/jm-38-189-2019, 2019
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This paper records the spatial and temporal distribution of deep-sea benthic microfossils (Foraminifera, single-celled organisms) from the latest Oligocene to earliest Pliocene (about 28 to 4 million years ago) from Ocean Drilling Program cores in the southern Indian Ocean. Key taxa are illustrated and their stratigraphic distribution is presented as they respond to a period of marked global climatic changes, with a pronounced warm period in the mid-Miocene followed by subsequent cooling.
Christian Berndt, Sverre Planke, Damon Teagle, Ritske Huismans, Trond Torsvik, Joost Frieling, Morgan T. Jones, Dougal A. Jerram, Christian Tegner, Jan Inge Faleide, Helen Coxall, and Wei-Li Hong
Sci. Dril., 26, 69–85, https://doi.org/10.5194/sd-26-69-2019, https://doi.org/10.5194/sd-26-69-2019, 2019
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The northeast Atlantic encompasses archetypal examples of volcanic rifted margins. Twenty-five years after the last ODP leg on these volcanic margins, the reasons for excess melting are still disputed with at least three competing hypotheses being discussed. We are proposing a new drilling campaign that will constrain the timing, rates of volcanism, and vertical movements of rifted margins.
Johan Vellekoop, Lineke Woelders, Appy Sluijs, Kenneth G. Miller, and Robert P. Speijer
Biogeosciences, 16, 4201–4210, https://doi.org/10.5194/bg-16-4201-2019, https://doi.org/10.5194/bg-16-4201-2019, 2019
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Our micropaleontological analyses on three cores from New Jersey (USA) show that the late Maastrichtian warming event (66.4–66.1 Ma), characterized by a ~ 4.0 °C warming of sea waters on the New Jersey paleoshelf, resulted in a disruption of phytoplankton communities and a stressed benthic ecosystem. This increased ecosystem stress during the latest Maastrichtian potentially primed global ecosystems for the subsequent mass extinction following the Cretaceous–Paleogene boundary impact.
Nicolai Schleinkofer, Jacek Raddatz, André Freiwald, David Evans, Lydia Beuck, Andres Rüggeberg, and Volker Liebetrau
Biogeosciences, 16, 3565–3582, https://doi.org/10.5194/bg-16-3565-2019, https://doi.org/10.5194/bg-16-3565-2019, 2019
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In this study we tried to correlate Na / Ca ratios from cold-water corals with environmental parameters such as salinity, temperature and pH. We do not observe a correlation between Na / Ca ratios and seawater salinity, but we do observe a strong correlation with temperature. Na / Ca data from warm-water corals (Porites spp.) and bivalves (Mytilus edulis) support this correlation, indicating that similar controls on the incorporation of sodium exist in these aragonitic organisms.
Mitchell Lyle, Anna Joy Drury, Jun Tian, Roy Wilkens, and Thomas Westerhold
Clim. Past, 15, 1715–1739, https://doi.org/10.5194/cp-15-1715-2019, https://doi.org/10.5194/cp-15-1715-2019, 2019
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Ocean sediment records document changes in Earth’s carbon cycle and ocean productivity. We present 8 Myr CaCO3 and bulk sediment records from seven eastern Pacific scientific drill sites to identify intervals of excess CaCO3 dissolution (high carbon storage in the oceans) and excess burial of plankton hard parts indicating high productivity. We define the regional extent of production intervals and explore the impact of the closure of the Atlantic–Pacific Panama connection on CaCO3 burial.
Anna Mikis, Katharine R. Hendry, Jennifer Pike, Daniela N. Schmidt, Kirsty M. Edgar, Victoria Peck, Frank J. C. Peeters, Melanie J. Leng, Michael P. Meredith, Chloe L. C. Jones, Sharon Stammerjohn, and Hugh Ducklow
Biogeosciences, 16, 3267–3282, https://doi.org/10.5194/bg-16-3267-2019, https://doi.org/10.5194/bg-16-3267-2019, 2019
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Antarctic marine calcifying organisms are threatened by regional climate change and ocean acidification. Future projections of regional carbonate production are challenging due to the lack of historical data combined with complex climate variability. We present a 6-year record of flux, morphology and geochemistry of an Antarctic planktonic foraminifera, which shows that their growth is most sensitive to sea ice dynamics and is linked with the El Niño–Southern Oscillation.
Yama Dixit, Samuel Toucanne, Juan M. Lora, Christophe Fontanier, Virgil Pasquier, Lea Bonnin, Gwenael Jouet, and Aradhna Tripati
Clim. Past Discuss., https://doi.org/10.5194/cp-2019-75, https://doi.org/10.5194/cp-2019-75, 2019
Preprint withdrawn
Dana L. Royer, Kylen M. Moynihan, Melissa L. McKee, Liliana Londoño, and Peter J. Franks
Clim. Past, 15, 795–809, https://doi.org/10.5194/cp-15-795-2019, https://doi.org/10.5194/cp-15-795-2019, 2019
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Plant-based proxies for estimating atmospheric CO2 in the geologic past are becoming more popular. Here we test the reliability of a method based on leaf gas-exchange principles in a wide range of living plants. Overall, the average error rate (~28 %) is broadly similar to other paleo-CO2 proxies. Our results should increase confidence in using this recently developed method.
David J. Wilton, Marcus P. S. Badger, Euripides P. Kantzas, Richard D. Pancost, Paul J. Valdes, and David J. Beerling
Geosci. Model Dev., 12, 1351–1364, https://doi.org/10.5194/gmd-12-1351-2019, https://doi.org/10.5194/gmd-12-1351-2019, 2019
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Methane is an important greenhouse gas naturally produced in wetlands (areas of land inundated with water). Models of the Earth's past climate need estimates of the amounts of methane wetlands produce; and in order to calculate those we need to model wetlands. In this work we develop a method for modelling the fraction of an area of the Earth that is wetland, repeat this over all the Earth's land surface and apply this to a study of the Earth as it was around 50 million years ago.
Marcus P. S. Badger, Thomas B. Chalk, Gavin L. Foster, Paul R. Bown, Samantha J. Gibbs, Philip F. Sexton, Daniela N. Schmidt, Heiko Pälike, Andreas Mackensen, and Richard D. Pancost
Clim. Past, 15, 539–554, https://doi.org/10.5194/cp-15-539-2019, https://doi.org/10.5194/cp-15-539-2019, 2019
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Understanding how atmospheric CO2 has affected the climate of the past is an important way of furthering our understanding of how CO2 may affect our climate in the future. There are several ways of determining CO2 in the past; in this paper, we ground-truth one method (based on preserved organic matter from alga) against the record of CO2 preserved as bubbles in ice cores over a glacial–interglacial cycle. We find that there is a discrepancy between the two.
Zainab Al Rawahi and Tom Dunkley Jones
J. Micropalaeontol., 38, 25–54, https://doi.org/10.5194/jm-38-25-2019, https://doi.org/10.5194/jm-38-25-2019, 2019
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This research studies nannofossils (microscopic fossil remains of unicellular marine planktonic algae) recovered from the Late Cretaceous, pelagic shale Fiqa Formation of Oman. The study emphasises taxonomy and assemblage change application to understand changes in the past climate and environment during the time of deposition. This has been achieved by analysing rock samples under the microscope. The analysis of these fossils could be applied in future work for age determination.
Morgan T. Jones, Lawrence M. E. Percival, Ella W. Stokke, Joost Frieling, Tamsin A. Mather, Lars Riber, Brian A. Schubert, Bo Schultz, Christian Tegner, Sverre Planke, and Henrik H. Svensen
Clim. Past, 15, 217–236, https://doi.org/10.5194/cp-15-217-2019, https://doi.org/10.5194/cp-15-217-2019, 2019
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Mercury anomalies in sedimentary rocks are used to assess whether there were periods of elevated volcanism in the geological record. We focus on five sites that cover the Palaeocene–Eocene Thermal Maximum, an extreme global warming event that occurred 55.8 million years ago. We find that sites close to the eruptions from the North Atlantic Igneous Province display significant mercury anomalies across this time interval, suggesting that magmatism played a role in the global warming event.
Ilja J. Kocken, Marlow Julius Cramwinckel, Richard E. Zeebe, Jack J. Middelburg, and Appy Sluijs
Clim. Past, 15, 91–104, https://doi.org/10.5194/cp-15-91-2019, https://doi.org/10.5194/cp-15-91-2019, 2019
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Marine organic carbon burial could link the 405 thousand year eccentricity cycle in the long-term carbon cycle to that observed in climate records. Here, we simulate the response of the carbon cycle to astronomical forcing. We find a strong 2.4 million year cycle in the model output, which is present as an amplitude modulator of the 405 and 100 thousand year eccentricity cycles in a newly assembled composite record.
Janet E. Burke, Willem Renema, Michael J. Henehan, Leanne E. Elder, Catherine V. Davis, Amy E. Maas, Gavin L. Foster, Ralf Schiebel, and Pincelli M. Hull
Biogeosciences, 15, 6607–6619, https://doi.org/10.5194/bg-15-6607-2018, https://doi.org/10.5194/bg-15-6607-2018, 2018
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Metabolic rates are sensitive to environmental conditions and can skew geochemical measurements. However, there is no way to track these rates through time. Here we investigate the controls of test porosity in planktonic foraminifera (organisms commonly used in paleoclimate studies) as a potential proxy for metabolic rate. We found that the porosity varies with body size and temperature, two key controls on metabolic rate, and that it can respond to rapid changes in ambient temperature.
Robert McKay, Neville Exon, Dietmar Müller, Karsten Gohl, Michael Gurnis, Amelia Shevenell, Stuart Henrys, Fumio Inagaki, Dhananjai Pandey, Jessica Whiteside, Tina van de Flierdt, Tim Naish, Verena Heuer, Yuki Morono, Millard Coffin, Marguerite Godard, Laura Wallace, Shuichi Kodaira, Peter Bijl, Julien Collot, Gerald Dickens, Brandon Dugan, Ann G. Dunlea, Ron Hackney, Minoru Ikehara, Martin Jutzeler, Lisa McNeill, Sushant Naik, Taryn Noble, Bradley Opdyke, Ingo Pecher, Lowell Stott, Gabriele Uenzelmann-Neben, Yatheesh Vadakkeykath, and Ulrich G. Wortmann
Sci. Dril., 24, 61–70, https://doi.org/10.5194/sd-24-61-2018, https://doi.org/10.5194/sd-24-61-2018, 2018
Florence Sylvestre, Mathieu Schuster, Hendrik Vogel, Moussa Abdheramane, Daniel Ariztegui, Ulrich Salzmann, Antje Schwalb, Nicolas Waldmann, and the ICDP CHADRILL Consortium
Sci. Dril., 24, 71–78, https://doi.org/10.5194/sd-24-71-2018, https://doi.org/10.5194/sd-24-71-2018, 2018
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CHADRILL aims to recover a sedimentary core spanning the Miocene–Pleistocene sediment succession of Lake Chad through deep drilling. This record will provide significant insights into the modulation of orbitally forced changes in northern African hydroclimate under different climate boundary conditions and the most continuous climatic and environmental record to be compared with hominid migrations across northern Africa and the implications for understanding human evolution.
Julian D. Hartman, Peter K. Bijl, and Francesca Sangiorgi
J. Micropalaeontol., 37, 445–497, https://doi.org/10.5194/jm-37-445-2018, https://doi.org/10.5194/jm-37-445-2018, 2018
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We present an extensive overview of the organic microfossil remains found at Site U1357, Adélie Basin, East Antarctica. The organic microfossil remains are exceptionally well preserved and are derived from unicellular as well as higher organisms. We provide a morphological description, photographic images, and a discussion of the ecological preferences of the biological species from which the organic remains were derived.
Isabel S. Fenton, Ulrike Baranowski, Flavia Boscolo-Galazzo, Hannah Cheales, Lyndsey Fox, David J. King, Christina Larkin, Marcin Latas, Diederik Liebrand, C. Giles Miller, Katrina Nilsson-Kerr, Emanuela Piga, Hazel Pugh, Serginio Remmelzwaal, Zoe A. Roseby, Yvonne M. Smith, Stephen Stukins, Ben Taylor, Adam Woodhouse, Savannah Worne, Paul N. Pearson, Christopher R. Poole, Bridget S. Wade, and Andy Purvis
J. Micropalaeontol., 37, 431–443, https://doi.org/10.5194/jm-37-431-2018, https://doi.org/10.5194/jm-37-431-2018, 2018
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In this study we investigate consistency in species-level identifications and whether disagreements are predictable. Twenty-three scientists identified a set of 100 planktonic foraminifera, noting their confidence in each identification. The median accuracy of students was 57 %; 79 % for experienced researchers. Where they were confident in the identifications, the values are 75 % and 93 %, respectively. Accuracy was significantly higher if the students had been taught how to identify species.
Julian D. Hartman, Francesca Sangiorgi, Ariadna Salabarnada, Francien Peterse, Alexander J. P. Houben, Stefan Schouten, Henk Brinkhuis, Carlota Escutia, and Peter K. Bijl
Clim. Past, 14, 1275–1297, https://doi.org/10.5194/cp-14-1275-2018, https://doi.org/10.5194/cp-14-1275-2018, 2018
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We reconstructed sea surface temperatures for the Oligocene and Miocene periods (34–11 Ma) based on archaeal lipids from a site close to the Wilkes Land coast, Antarctica. Our record suggests generally warm to temperate surface waters: on average 17 °C. Based on the lithology, glacial and interglacial temperatures could be distinguished, showing an average 3 °C offset. The long-term temperature trend resembles the benthic δ18O stack, which may have implications for ice volume reconstructions.
Tom Dunkley Jones, Hayley R. Manners, Murray Hoggett, Sandra Kirtland Turner, Thomas Westerhold, Melanie J. Leng, Richard D. Pancost, Andy Ridgwell, Laia Alegret, Rob Duller, and Stephen T. Grimes
Clim. Past, 14, 1035–1049, https://doi.org/10.5194/cp-14-1035-2018, https://doi.org/10.5194/cp-14-1035-2018, 2018
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The Paleocene–Eocene Thermal Maximum (PETM) is a transient global warming event associated with a doubling of atmospheric carbon dioxide concentrations. Here we document a major increase in sediment accumulation rates on a subtropical continental margin during the PETM, likely due to marked changes in hydro-climates and sediment transport. These high sedimentation rates persist through the event and may play a key role in the removal of carbon from the atmosphere by the burial of organic carbon.
Peter K. Bijl, Alexander J. P. Houben, Julian D. Hartman, Jörg Pross, Ariadna Salabarnada, Carlota Escutia, and Francesca Sangiorgi
Clim. Past, 14, 1015–1033, https://doi.org/10.5194/cp-14-1015-2018, https://doi.org/10.5194/cp-14-1015-2018, 2018
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We document Southern Ocean surface ocean conditions and changes therein during the Oligocene and Miocene (34–10 Myr ago). We infer profound long-term and short-term changes in ice-proximal oceanographic conditions: sea surface temperature, nutrient conditions and sea ice. Our results point to warm-temperate, oligotrophic, ice-proximal oceanographic conditions. These distinct oceanographic conditions may explain the high amplitude in inferred Oligocene–Miocene Antarctic ice volume changes.
Ariadna Salabarnada, Carlota Escutia, Ursula Röhl, C. Hans Nelson, Robert McKay, Francisco J. Jiménez-Espejo, Peter K. Bijl, Julian D. Hartman, Stephanie L. Strother, Ulrich Salzmann, Dimitris Evangelinos, Adrián López-Quirós, José Abel Flores, Francesca Sangiorgi, Minoru Ikehara, and Henk Brinkhuis
Clim. Past, 14, 991–1014, https://doi.org/10.5194/cp-14-991-2018, https://doi.org/10.5194/cp-14-991-2018, 2018
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Here we reconstruct ice sheet and paleoceanographic configurations in the East Antarctic Wilkes Land margin based on a multi-proxy study conducted in late Oligocene (26–25 Ma) sediments from IODP Site U1356. The new obliquity-forced glacial–interglacial sedimentary model shows that, under the high CO2 values of the late Oligocene, ice sheets had mostly retreated to their terrestrial margins and the ocean was very dynamic with shifting positions of the polar fronts and associated water masses.
Niels J. de Winter, Johan Vellekoop, Robin Vorsselmans, Asefeh Golreihan, Jeroen Soete, Sierra V. Petersen, Kyle W. Meyer, Silvio Casadio, Robert P. Speijer, and Philippe Claeys
Clim. Past, 14, 725–749, https://doi.org/10.5194/cp-14-725-2018, https://doi.org/10.5194/cp-14-725-2018, 2018
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In this work, we apply a range of methods to measure the geochemical composition of the calcite from fossil shells of Pycnodonte vesicularis (so-called honeycomb oysters). The goal is to investigate how the composition of these shells reflect the environment in which the animals grew. Ultimately, we propose a methodology to check whether the shells of pycnodonte oysters are well-preserved and to reconstruct meaningful information about the seasonal changes in the past climate and environment.
Michiel Baatsen, Anna S. von der Heydt, Matthew Huber, Michael A. Kliphuis, Peter K. Bijl, Appy Sluijs, and Henk A. Dijkstra
Clim. Past Discuss., https://doi.org/10.5194/cp-2018-43, https://doi.org/10.5194/cp-2018-43, 2018
Revised manuscript not accepted
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The Eocene marks a period where the climate was in a hothouse state, without any continental-scale ice sheets. Such climates have proven difficult to reproduce in models, especially their low temperature difference between equator and poles. Here, we present high resolution CESM simulations using a new geographic reconstruction of the middle-to-late Eocene. The results provide new insights into a period for which knowledge is limited, leading up to a transition into the present icehouse state.
Timme H. Donders, Niels A. G. M. van Helmond, Roel Verreussel, Dirk Munsterman, Johan ten Veen, Robert P. Speijer, Johan W. H. Weijers, Francesca Sangiorgi, Francien Peterse, Gert-Jan Reichart, Jaap S. Sinninghe Damsté, Lucas Lourens, Gesa Kuhlmann, and Henk Brinkhuis
Clim. Past, 14, 397–411, https://doi.org/10.5194/cp-14-397-2018, https://doi.org/10.5194/cp-14-397-2018, 2018
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The buildup and melting of ice during the early glaciations in the Northern Hemisphere, around 2.5 million years ago, were far shorter in duration than during the last million years. Based on molecular compounds and microfossils from sediments dating back to the early glaciations we show that the temperature on land and in the sea changed simultaneously and was a major factor in the ice buildup in the Northern Hemisphere. These data provide key insights into the dynamics of early glaciations.
Masa Kageyama, Pascale Braconnot, Sandy P. Harrison, Alan M. Haywood, Johann H. Jungclaus, Bette L. Otto-Bliesner, Jean-Yves Peterschmitt, Ayako Abe-Ouchi, Samuel Albani, Patrick J. Bartlein, Chris Brierley, Michel Crucifix, Aisling Dolan, Laura Fernandez-Donado, Hubertus Fischer, Peter O. Hopcroft, Ruza F. Ivanovic, Fabrice Lambert, Daniel J. Lunt, Natalie M. Mahowald, W. Richard Peltier, Steven J. Phipps, Didier M. Roche, Gavin A. Schmidt, Lev Tarasov, Paul J. Valdes, Qiong Zhang, and Tianjun Zhou
Geosci. Model Dev., 11, 1033–1057, https://doi.org/10.5194/gmd-11-1033-2018, https://doi.org/10.5194/gmd-11-1033-2018, 2018
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The Paleoclimate Modelling Intercomparison Project (PMIP) takes advantage of the existence of past climate states radically different from the recent past to test climate models used for climate projections and to better understand these climates. This paper describes the PMIP contribution to CMIP6 (Coupled Model Intercomparison Project, 6th phase) and possible analyses based on PMIP results, as well as on other CMIP6 projects.
Thomas Westerhold, Ursula Röhl, Roy H. Wilkens, Philip D. Gingerich, William C. Clyde, Scott L. Wing, Gabriel J. Bowen, and Mary J. Kraus
Clim. Past, 14, 303–319, https://doi.org/10.5194/cp-14-303-2018, https://doi.org/10.5194/cp-14-303-2018, 2018
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Here we present a high-resolution timescale synchronization of continental and marine deposits for one of the most pronounced global warming events, the Paleocene–Eocene Thermal Maximum, which occurred 56 million years ago. New high-resolution age models for the Bighorn Basin Coring Project (BBCP) drill cores help to improve age models for climate records from deep-sea drill cores and for the first time point to a concurrent major change in marine and terrestrial biota 54.25 million years ago.
Anna Joy Drury, Thomas Westerhold, David Hodell, and Ursula Röhl
Clim. Past, 14, 321–338, https://doi.org/10.5194/cp-14-321-2018, https://doi.org/10.5194/cp-14-321-2018, 2018
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North Atlantic Site 982 is key to our understanding of climate evolution over the past 12 million years. However, the stratigraphy and age model are unverified. We verify the composite splice using XRF core scanning data and establish a revised benthic foraminiferal stable isotope astrochronology from 8.0–4.5 million years ago. Our new stratigraphy accurately correlates the Atlantic and the Mediterranean and suggests a connection between late Miocene cooling and dynamic ice sheet expansion.
Helen M. Beddow, Diederik Liebrand, Douglas S. Wilson, Frits J. Hilgen, Appy Sluijs, Bridget S. Wade, and Lucas J. Lourens
Clim. Past, 14, 255–270, https://doi.org/10.5194/cp-14-255-2018, https://doi.org/10.5194/cp-14-255-2018, 2018
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We present two astronomy-based timescales for climate records from the Pacific Ocean. These records range from 24 to 22 million years ago, a time period when Earth was warmer than today and the only land ice was located on Antarctica. We use tectonic plate-pair spreading rates to test the two timescales, which shows that the carbonate record yields the best timescale. In turn, this implies that Earth’s climate system and carbon cycle responded slowly to changes in incoming solar radiation.
Joost Frieling, Emiel P. Huurdeman, Charlotte C. M. Rem, Timme H. Donders, Jörg Pross, Steven M. Bohaty, Guy R. Holdgate, Stephen J. Gallagher, Brian McGowran, and Peter K. Bijl
J. Micropalaeontol., 37, 317–339, https://doi.org/10.5194/jm-37-317-2018, https://doi.org/10.5194/jm-37-317-2018, 2018
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The hothouse climate of the early Paleogene and the associated violent carbon cycle perturbations are of particular interest to understanding current and future global climate change. Using dinoflagellate cysts and stable carbon isotope analyses, we identify several significant events, e.g., the Paleocene–Eocene Thermal Maximum in sedimentary deposits from the Otway Basin, SE Australia. We anticipate that this study will facilitate detailed climate reconstructions west of the Tasmanian Gateway.
Joost Frieling, Gert-Jan Reichart, Jack J. Middelburg, Ursula Röhl, Thomas Westerhold, Steven M. Bohaty, and Appy Sluijs
Clim. Past, 14, 39–55, https://doi.org/10.5194/cp-14-39-2018, https://doi.org/10.5194/cp-14-39-2018, 2018
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Past periods of rapid global warming such as the Paleocene–Eocene Thermal Maximum are used to study biotic response to climate change. We show that very high peak PETM temperatures in the tropical Atlantic (~ 37 ºC) caused heat stress in several marine plankton groups. However, only slightly cooler temperatures afterwards allowed highly diverse plankton communities to bloom. This shows that tropical plankton communities may be susceptible to extreme warming, but may also recover rapidly.
Peter K. Bijl, Alexander J. P. Houben, Anja Bruls, Jörg Pross, and Francesca Sangiorgi
J. Micropalaeontol., 37, 105–138, https://doi.org/10.5194/jm-37-105-2018, https://doi.org/10.5194/jm-37-105-2018, 2018
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In order to use ocean sediments as a recorder of past oceanographic changes, a critical first step is to stratigraphically date the sediments. The absence of microfossils with known stratigraphic ranges has always hindered dating of Southern Ocean sediments. Here we tie dinocyst ranges to the international timescale in a well-dated sediment core from offshore Antarctica. With this, we can now use dinocysts as a biostratigraphic tool in otherwise stratigraphically poorly dated sediments.
Paul N. Pearson and IODP Expedition 363 Shipboard Scientific
Party
J. Micropalaeontol., 37, 97–104, https://doi.org/10.5194/jm-37-97-2018, https://doi.org/10.5194/jm-37-97-2018, 2018
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We describe an unusual millimetre-long tube that was discovered in sediment from the deep sea floor. The tube was made by a single-celled organism by cementing together sedimentary grains from its environment. The specimen is unusual because it implies that the organism used a very high degree of discrimination in selecting its grains, as they are all of one type and most are oriented the same way. It raises intriguing questions of how the organism accomplished this activity.
PAGES Hydro2k Consortium
Clim. Past, 13, 1851–1900, https://doi.org/10.5194/cp-13-1851-2017, https://doi.org/10.5194/cp-13-1851-2017, 2017
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Water availability is fundamental to societies and ecosystems, but our understanding of variations in hydroclimate (including extreme events, flooding, and decadal periods of drought) is limited due to a paucity of modern instrumental observations. We review how proxy records of past climate and climate model simulations can be used in tandem to understand hydroclimate variability over the last 2000 years and how these tools can also inform risk assessments of future hydroclimatic extremes.
Natalie S. Lord, Michel Crucifix, Dan J. Lunt, Mike C. Thorne, Nabila Bounceur, Harry Dowsett, Charlotte L. O'Brien, and Andy Ridgwell
Clim. Past, 13, 1539–1571, https://doi.org/10.5194/cp-13-1539-2017, https://doi.org/10.5194/cp-13-1539-2017, 2017
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We present projections of long-term changes in climate, produced using a statistical emulator based on climate data from a state-of-the-art climate model. We use the emulator to model changes in temperature and precipitation over the late Pliocene (3.3–2.8 million years before present) and the next 200 thousand years. The impact of the Earth's orbit and the atmospheric carbon dioxide concentration on climate is assessed, and the data for the late Pliocene are compared to proxy temperature data.
Gary Shaffer, Esteban Fernández Villanueva, Roberto Rondanelli, Jens Olaf Pepke Pedersen, Steffen Malskær Olsen, and Matthew Huber
Geosci. Model Dev., 10, 4081–4103, https://doi.org/10.5194/gmd-10-4081-2017, https://doi.org/10.5194/gmd-10-4081-2017, 2017
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We include methane cycling in the simplified but well-tested Danish Center for Earth System Science model. We now can deal with very large methane inputs to the Earth system that can lead to more methane in the atmosphere, extreme warming and ocean dead zones. We can now study ancient global warming events, probably forced by methane inputs. Some such events were accompanied by mass extinctions. We wish to understand such events, both for learning about the past and for looking into the future.
Bette L. Otto-Bliesner, Pascale Braconnot, Sandy P. Harrison, Daniel J. Lunt, Ayako Abe-Ouchi, Samuel Albani, Patrick J. Bartlein, Emilie Capron, Anders E. Carlson, Andrea Dutton, Hubertus Fischer, Heiko Goelzer, Aline Govin, Alan Haywood, Fortunat Joos, Allegra N. LeGrande, William H. Lipscomb, Gerrit Lohmann, Natalie Mahowald, Christoph Nehrbass-Ahles, Francesco S. R. Pausata, Jean-Yves Peterschmitt, Steven J. Phipps, Hans Renssen, and Qiong Zhang
Geosci. Model Dev., 10, 3979–4003, https://doi.org/10.5194/gmd-10-3979-2017, https://doi.org/10.5194/gmd-10-3979-2017, 2017
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The PMIP4 and CMIP6 mid-Holocene and Last Interglacial simulations provide an opportunity to examine the impact of two different changes in insolation forcing on climate at times when other forcings were relatively similar to present. This will allow exploration of the role of feedbacks relevant to future projections. Evaluating these simulations using paleoenvironmental data will provide direct out-of-sample tests of the reliability of state-of-the-art models to simulate climate changes.
Masa Kageyama, Samuel Albani, Pascale Braconnot, Sandy P. Harrison, Peter O. Hopcroft, Ruza F. Ivanovic, Fabrice Lambert, Olivier Marti, W. Richard Peltier, Jean-Yves Peterschmitt, Didier M. Roche, Lev Tarasov, Xu Zhang, Esther C. Brady, Alan M. Haywood, Allegra N. LeGrande, Daniel J. Lunt, Natalie M. Mahowald, Uwe Mikolajewicz, Kerim H. Nisancioglu, Bette L. Otto-Bliesner, Hans Renssen, Robert A. Tomas, Qiong Zhang, Ayako Abe-Ouchi, Patrick J. Bartlein, Jian Cao, Qiang Li, Gerrit Lohmann, Rumi Ohgaito, Xiaoxu Shi, Evgeny Volodin, Kohei Yoshida, Xiao Zhang, and Weipeng Zheng
Geosci. Model Dev., 10, 4035–4055, https://doi.org/10.5194/gmd-10-4035-2017, https://doi.org/10.5194/gmd-10-4035-2017, 2017
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The Last Glacial Maximum (LGM, 21000 years ago) is an interval when global ice volume was at a maximum, eustatic sea level close to a minimum, greenhouse gas concentrations were lower, atmospheric aerosol loadings were higher than today, and vegetation and land-surface characteristics were different from today. This paper describes the implementation of the LGM numerical experiment for the PMIP4-CMIP6 modelling intercomparison projects and the associated sensitivity experiments.
Paul J. Valdes, Edward Armstrong, Marcus P. S. Badger, Catherine D. Bradshaw, Fran Bragg, Michel Crucifix, Taraka Davies-Barnard, Jonathan J. Day, Alex Farnsworth, Chris Gordon, Peter O. Hopcroft, Alan T. Kennedy, Natalie S. Lord, Dan J. Lunt, Alice Marzocchi, Louise M. Parry, Vicky Pope, William H. G. Roberts, Emma J. Stone, Gregory J. L. Tourte, and Jonny H. T. Williams
Geosci. Model Dev., 10, 3715–3743, https://doi.org/10.5194/gmd-10-3715-2017, https://doi.org/10.5194/gmd-10-3715-2017, 2017
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In this paper we describe the family of climate models used by the BRIDGE research group at the University of Bristol as well as by various other institutions. These models are based on the UK Met Office HadCM3 models and here we describe the various modifications which have been made as well as the key features of a number of configurations in use.
Lennert B. Stap, Roderik S. W. van de Wal, Bas de Boer, Richard Bintanja, and Lucas J. Lourens
Clim. Past, 13, 1243–1257, https://doi.org/10.5194/cp-13-1243-2017, https://doi.org/10.5194/cp-13-1243-2017, 2017
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We show the results of transient simulations with a coupled climate–ice sheet model over the past 38 million years. The CO2 forcing of the model is inversely obtained from a benthic δ18O stack. These simulations enable us to study the influence of ice sheet variability on climate change on long timescales. We find that ice sheet–climate interaction strongly enhances Earth system sensitivity and polar amplification.
Thomas Westerhold, Ursula Röhl, Thomas Frederichs, Claudia Agnini, Isabella Raffi, James C. Zachos, and Roy H. Wilkens
Clim. Past, 13, 1129–1152, https://doi.org/10.5194/cp-13-1129-2017, https://doi.org/10.5194/cp-13-1129-2017, 2017
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We assembled a very accurate geological timescale from the interval 47.8 to 56.0 million years ago, also known as the Ypresian stage. We used cyclic variations in the data caused by periodic changes in Earthäs orbit around the sun as a metronome for timescale construction. Our new data compilation provides the first geological evidence for chaos in the long-term behavior of planetary orbits in the solar system, as postulated almost 30 years ago, and a possible link to plate tectonics events.
Stefanie Kaboth, Patrick Grunert, and Lucas Lourens
Clim. Past, 13, 1023–1035, https://doi.org/10.5194/cp-13-1023-2017, https://doi.org/10.5194/cp-13-1023-2017, 2017
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This study is devoted to reconstructing Mediterranean Outflow Water (MOW) variability and the interplay between the Mediterranean and North Atlantic climate systems during the Early Pleistocene. We find indication that the increasing production of MOW aligns with the intensification of the North Atlantic overturning circulation, highlighting the potential of MOW to modulate the North Atlantic salt budget. Our results are based on new stable isotope and grain-size data from IODP 339 Site U1389.
Jack Longman, Daniel Veres, Vasile Ersek, Ulrich Salzmann, Katalin Hubay, Marc Bormann, Volker Wennrich, and Frank Schäbitz
Clim. Past, 13, 897–917, https://doi.org/10.5194/cp-13-897-2017, https://doi.org/10.5194/cp-13-897-2017, 2017
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We present the first record of dust input into an eastern European bog over the past 10 800 years. We find significant changes in past dust deposition, with large inputs related to both natural and human influences. We show evidence that Saharan desertification has had a significant impact on dust deposition in eastern Europe for the past 6100 years.
Michael J. Henehan, David Evans, Madison Shankle, Janet E. Burke, Gavin L. Foster, Eleni Anagnostou, Thomas B. Chalk, Joseph A. Stewart, Claudia H. S. Alt, Joseph Durrant, and Pincelli M. Hull
Biogeosciences, 14, 3287–3308, https://doi.org/10.5194/bg-14-3287-2017, https://doi.org/10.5194/bg-14-3287-2017, 2017
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It is still unclear whether foraminifera (calcifying plankton that play an important role in cycling carbon) will have difficulty in making their shells in more acidic oceans, with different studies often reporting apparently conflicting results. We used live lab cultures, mathematical models, and fossil measurements to test this question, and found low pH does reduce calcification. However, we find this response is likely size-dependent, which may have obscured this response in other studies.
Roy H. Wilkens, Thomas Westerhold, Anna J. Drury, Mitchell Lyle, Thomas Gorgas, and Jun Tian
Clim. Past, 13, 779–793, https://doi.org/10.5194/cp-13-779-2017, https://doi.org/10.5194/cp-13-779-2017, 2017
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Here we introduce the Code for Ocean Drilling Data (CODD), a unified and consistent system for integrating disparate data streams such as micropaleontology, physical properties, core images, geochemistry, and borehole logging. As a test case, data from Ocean Drilling Program Leg 154 (Ceara Rise – western equatorial Atlantic) were assembled into a new regional composite benthic stable isotope record covering the last 5 million years.
Clint M. Miller, Gerald R. Dickens, Martin Jakobsson, Carina Johansson, Andrey Koshurnikov, Matt O'Regan, Francesco Muschitiello, Christian Stranne, and Carl-Magnus Mörth
Biogeosciences, 14, 2929–2953, https://doi.org/10.5194/bg-14-2929-2017, https://doi.org/10.5194/bg-14-2929-2017, 2017
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Continental slopes north of the East Siberian Sea are assumed to hold large amounts of methane. We present pore water chemistry from the 2014 SWERUS-C3 expedition. These are among the first results generated from this vast climatically sensitive region, and they imply that abundant methane, including gas hydrates, do not characterize the East Siberian Sea slope or rise. This contradicts previous modeling and discussions, which due to the lack of data are almost entirely based assumption.
Stephanie L. Strother, Ulrich Salzmann, Francesca Sangiorgi, Peter K. Bijl, Jörg Pross, Carlota Escutia, Ariadna Salabarnada, Matthew J. Pound, Jochen Voss, and John Woodward
Biogeosciences, 14, 2089–2100, https://doi.org/10.5194/bg-14-2089-2017, https://doi.org/10.5194/bg-14-2089-2017, 2017
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One of the main challenges in Antarctic vegetation reconstructions is the uncertainty in unambiguously identifying reworked pollen and spore assemblages in marine sedimentary records influenced by waxing and waning ice sheets. This study uses red fluorescence and digital imaging as a new tool to identify reworking in a marine sediment core from circum-Antarctic waters to reconstruct Cenozoic climate change and vegetation with high confidence.
Johan Vellekoop, Lineke Woelders, Sanem Açikalin, Jan Smit, Bas van de Schootbrugge, Ismail Ö. Yilmaz, Henk Brinkhuis, and Robert P. Speijer
Biogeosciences, 14, 885–900, https://doi.org/10.5194/bg-14-885-2017, https://doi.org/10.5194/bg-14-885-2017, 2017
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The Cretaceous–Paleogene boundary, ~ 66 Ma, is characterized by a mass extinction. We studied groups of both surface-dwelling and bottom-dwelling organisms to unravel the oceanographic consequences of these extinctions. Our integrated records indicate that a reduction of the transport of organic matter to the sea floor resulted in enhanced recycling of nutrients in the upper water column and decreased food supply at the sea floor in the first tens of thousands of years after the extinctions.
Rosanna Greenop, Mathis P. Hain, Sindia M. Sosdian, Kevin I. C. Oliver, Philip Goodwin, Thomas B. Chalk, Caroline H. Lear, Paul A. Wilson, and Gavin L. Foster
Clim. Past, 13, 149–170, https://doi.org/10.5194/cp-13-149-2017, https://doi.org/10.5194/cp-13-149-2017, 2017
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Understanding the boron isotopic composition of seawater (δ11Bsw) is key to calculating absolute estimates of CO2 using the boron isotope pH proxy. Here we use the boron isotope gradient, along with an estimate of pH gradient, between the surface and deep ocean to show that the δ11Bsw varies by ~ 2 ‰ over the past 23 million years. This new record has implications for both δ11Bsw and CO2 records and understanding changes in the ocean isotope composition of a number of ions through time.
Daniel J. Lunt, Matthew Huber, Eleni Anagnostou, Michiel L. J. Baatsen, Rodrigo Caballero, Rob DeConto, Henk A. Dijkstra, Yannick Donnadieu, David Evans, Ran Feng, Gavin L. Foster, Ed Gasson, Anna S. von der Heydt, Chris J. Hollis, Gordon N. Inglis, Stephen M. Jones, Jeff Kiehl, Sandy Kirtland Turner, Robert L. Korty, Reinhardt Kozdon, Srinath Krishnan, Jean-Baptiste Ladant, Petra Langebroek, Caroline H. Lear, Allegra N. LeGrande, Kate Littler, Paul Markwick, Bette Otto-Bliesner, Paul Pearson, Christopher J. Poulsen, Ulrich Salzmann, Christine Shields, Kathryn Snell, Michael Stärz, James Super, Clay Tabor, Jessica E. Tierney, Gregory J. L. Tourte, Aradhna Tripati, Garland R. Upchurch, Bridget S. Wade, Scott L. Wing, Arne M. E. Winguth, Nicky M. Wright, James C. Zachos, and Richard E. Zeebe
Geosci. Model Dev., 10, 889–901, https://doi.org/10.5194/gmd-10-889-2017, https://doi.org/10.5194/gmd-10-889-2017, 2017
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In this paper we describe the experimental design for a set of simulations which will be carried out by a range of climate models, all investigating the climate of the Eocene, about 50 million years ago. The intercomparison of model results is called 'DeepMIP', and we anticipate that we will contribute to the next IPCC report through an analysis of these simulations and the geological data to which we will compare them.
Bette L. Otto-Bliesner, Pascale Braconnot, Sandy P. Harrison, Daniel J. Lunt, Ayako Abe-Ouchi, Samuel Albani, Patrick J. Bartlein, Emilie Capron, Anders E. Carlson, Andrea Dutton, Hubertus Fischer, Heiko Goelzer, Aline Govin, Alan Haywood, Fortunat Joos, Allegra N. Legrande, William H. Lipscomb, Gerrit Lohmann, Natalie Mahowald, Christoph Nehrbass-Ahles, Jean-Yves Peterschmidt, Francesco S.-R. Pausata, Steven Phipps, and Hans Renssen
Clim. Past Discuss., https://doi.org/10.5194/cp-2016-106, https://doi.org/10.5194/cp-2016-106, 2016
Preprint retracted
Emma J. Stone, Emilie Capron, Daniel J. Lunt, Antony J. Payne, Joy S. Singarayer, Paul J. Valdes, and Eric W. Wolff
Clim. Past, 12, 1919–1932, https://doi.org/10.5194/cp-12-1919-2016, https://doi.org/10.5194/cp-12-1919-2016, 2016
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Climate models forced only with greenhouse gas concentrations and orbital parameters representative of the early Last Interglacial are unable to reproduce the observed colder-than-present temperatures in the North Atlantic and the warmer-than-present temperatures in the Southern Hemisphere. Using a climate model forced also with a freshwater amount derived from data representing melting from the remnant Northern Hemisphere ice sheets accounts for this response via the bipolar seesaw mechanism.
Mathieu Martinez, Sergey Kotov, David De Vleeschouwer, Damien Pas, and Heiko Pälike
Clim. Past, 12, 1765–1783, https://doi.org/10.5194/cp-12-1765-2016, https://doi.org/10.5194/cp-12-1765-2016, 2016
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Identification of Milankovitch cycles within the sedimentary record depends on spectral analyses, but these can be biased because there are always slight uncertainties in the sample position within a sedimentary column. Here, we simulate uncertainties in the sample position and show that a tight control on the inter-sample distance together with a density of 6–12 samples per precession cycle are needed to accurately reconstruct the contribution of the orbital forcing on past climate changes.
Michiel Baatsen, Douwe J. J. van Hinsbergen, Anna S. von der Heydt, Henk A. Dijkstra, Appy Sluijs, Hemmo A. Abels, and Peter K. Bijl
Clim. Past, 12, 1635–1644, https://doi.org/10.5194/cp-12-1635-2016, https://doi.org/10.5194/cp-12-1635-2016, 2016
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One of the major difficulties in modelling palaeoclimate is constricting the boundary conditions, causing significant discrepancies between different studies. Here, a new method is presented to automate much of the process of generating the necessary geographical reconstructions. The latter can be made using various rotational frameworks and topography/bathymetry input, allowing for easy inter-comparisons and the incorporation of the latest insights from geoscientific research.
Pedro Alejandro Ruiz-Ortiz, José Manuel Castro, Ginés Alfonso de Gea, Ian Jarvis, José Miguel Molina, Luis Miguel Nieto, Richard David Pancost, María Luisa Quijano, Matías Reolid, Peter William Skelton, and Helmut Jürg Weissert
Sci. Dril., 21, 41–46, https://doi.org/10.5194/sd-21-41-2016, https://doi.org/10.5194/sd-21-41-2016, 2016
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The Cretaceous was punctuated by several episodes of accelerated global change, defined as Oceanic Anoxic Events (OAE), that reflect abrupt changes in global carbon cycling. In this progress report, we present a new drill core recovering an Aptian section spanning OAE1a in southern Spain. The Cau section is located in the easternmost part of the Prebetic Zone (Betic Cordillera). All the studies performed reveal that the Cau section represents an excellent site to further investigate OAE1a.
Harry Dowsett, Aisling Dolan, David Rowley, Robert Moucha, Alessandro M. Forte, Jerry X. Mitrovica, Matthew Pound, Ulrich Salzmann, Marci Robinson, Mark Chandler, Kevin Foley, and Alan Haywood
Clim. Past, 12, 1519–1538, https://doi.org/10.5194/cp-12-1519-2016, https://doi.org/10.5194/cp-12-1519-2016, 2016
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Past intervals in Earth history provide unique windows into conditions much different than those observed today. We investigated the paleoenvironments of a past warm interval (~ 3 million years ago). Our reconstruction includes data sets for surface temperature, vegetation, soils, lakes, ice sheets, topography, and bathymetry. These data are being used along with global climate models to expand our understanding of the climate system and to help us prepare for future changes.
Daniel J. Lunt, Alex Farnsworth, Claire Loptson, Gavin L. Foster, Paul Markwick, Charlotte L. O'Brien, Richard D. Pancost, Stuart A. Robinson, and Neil Wrobel
Clim. Past, 12, 1181–1198, https://doi.org/10.5194/cp-12-1181-2016, https://doi.org/10.5194/cp-12-1181-2016, 2016
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We explore the influence of changing geography from the period ~ 150 million years ago to ~ 35 million years ago, using a set of 19 climate model simulations. We find that without any CO2 change, the global mean temperature is remarkably constant, but that regionally there are significant changes in temperature which we link back to changes in ocean circulation. Finally, we explore the implications of our findings for the interpretation of geological indicators of past temperatures.
Oliver Friedrich, Sietske J. Batenburg, Kazuyoshi Moriya, Silke Voigt, Cécile Cournède, Iris Möbius, Peter Blum, André Bornemann, Jens Fiebig, Takashi Hasegawa, Pincelli M. Hull, Richard D. Norris, Ursula Röhl, Thomas Westerhold, Paul A. Wilson, and IODP Expedition
Clim. Past Discuss., https://doi.org/10.5194/cp-2016-51, https://doi.org/10.5194/cp-2016-51, 2016
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A lack of knowledge on the timing of Late Cretaceous climatic change inhibits our understanding of underlying causal mechanisms. Therefore, we used an expanded deep ocean record from the North Atlantic that shows distinct sedimentary cyclicity suggesting orbital forcing. A high-resolution carbon-isotope record from bulk carbonates allows to identify global trends in the carbon cycle. Our new carbon isotope record and the established cyclostratigraphy may serve as a future reference site.
Hemmo A. Abels, Vittoria Lauretano, Anna E. van Yperen, Tarek Hopman, James C. Zachos, Lucas J. Lourens, Philip D. Gingerich, and Gabriel J. Bowen
Clim. Past, 12, 1151–1163, https://doi.org/10.5194/cp-12-1151-2016, https://doi.org/10.5194/cp-12-1151-2016, 2016
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Ancient greenhouse warming episodes are studied in river floodplain sediments in the western interior of the USA. Paleohydrological changes of four smaller warming episodes are revealed to be the opposite of those of the largest, most-studied event. Carbon cycle tracers are used to ascertain whether the largest event was a similar event but proportional to the smaller ones or whether this event was distinct in size as well as in carbon sourcing, a question the current work cannot answer.
Niels A. G. M. van Helmond, Appy Sluijs, Nina M. Papadomanolaki, A. Guy Plint, Darren R. Gröcke, Martin A. Pearce, James S. Eldrett, João Trabucho-Alexandre, Ireneusz Walaszczyk, Bas van de Schootbrugge, and Henk Brinkhuis
Biogeosciences, 13, 2859–2872, https://doi.org/10.5194/bg-13-2859-2016, https://doi.org/10.5194/bg-13-2859-2016, 2016
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Over the past decades large changes have been observed in the biogeographical dispersion of marine life resulting from climate change. To better understand present and future trends it is important to document and fully understand the biogeographical response of marine life during episodes of environmental change in the geological past.
Here we investigate the response of phytoplankton, the base of the marine food web, to a rapid cold spell, interrupting greenhouse conditions during the Cretaceous.
Kimberley L. Davies, Richard D. Pancost, Mary E. Edwards, Katey M. Walter Anthony, Peter G. Langdon, and Lidia Chaves Torres
Biogeosciences, 13, 2611–2621, https://doi.org/10.5194/bg-13-2611-2016, https://doi.org/10.5194/bg-13-2611-2016, 2016
Sina Panitz, Ulrich Salzmann, Bjørg Risebrobakken, Stijn De Schepper, and Matthew J. Pound
Clim. Past, 12, 1043–1060, https://doi.org/10.5194/cp-12-1043-2016, https://doi.org/10.5194/cp-12-1043-2016, 2016
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This paper presents the first late Pliocene high-resolution pollen record for the Norwegian Arctic, covering the time period 3.60 to 3.14 million years ago (Ma). The climate of the late Pliocene has been widely regarded as relatively stable. Our results suggest a high climate variability with alternating cool temperate forests during warmer-than-presen periods and boreal forests similar to today during cooler intervals. A spread of peatlands at the expense of forest indicates long-term cooling.
Valeria Luciani, Gerald R. Dickens, Jan Backman, Eliana Fornaciari, Luca Giusberti, Claudia Agnini, and Roberta D'Onofrio
Clim. Past, 12, 981–1007, https://doi.org/10.5194/cp-12-981-2016, https://doi.org/10.5194/cp-12-981-2016, 2016
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The symbiont-bearing planktic foraminiferal genera Morozovella and Acarinina were among the most important calcifiers of the early Paleogene tropical and subtropical oceans. However, a remarkable and permanent switch in the relative abundance of these genera happened in the early Eocene. We show that this switch occurred at low-latitude sites near the start of the Early Eocene Climatic Optimum (EECO), a multi-million-year interval when Earth surface temperatures reached their Cenozoic maximum.
Claudia Agnini, David J. A. Spofforth, Gerald R. Dickens, Domenico Rio, Heiko Pälike, Jan Backman, Giovanni Muttoni, and Edoardo Dallanave
Clim. Past, 12, 883–909, https://doi.org/10.5194/cp-12-883-2016, https://doi.org/10.5194/cp-12-883-2016, 2016
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In this paper we present records of stable C and O isotopes, CaCO3 content, and changes in calcareous nannofossil assemblages in a upper Paleocene-lower Eocene rocks now exposed in northeast Italy. Modifications of nannoplankton assemblages and carbon isotopes are strictly linked one to each other and always display the same ranking and spacing. The integration of this two data sets represents a significative improvement in our capacity to correlate different sections at a very high resolution.
David Evans, Bridget S. Wade, Michael Henehan, Jonathan Erez, and Wolfgang Müller
Clim. Past, 12, 819–835, https://doi.org/10.5194/cp-12-819-2016, https://doi.org/10.5194/cp-12-819-2016, 2016
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We show that seawater pH exerts a substantial control on planktic foraminifera Mg / Ca, a widely applied palaeothermometer. As a result, temperature reconstructions based on this proxy are likely inaccurate over climatic events associated with a significant change in pH. We examine the implications of our findings for hydrological and temperature shifts over the Paleocene-Eocene Thermal Maximum and for the degree of surface ocean precursor cooling before the Eocene-Oligocene transition.
Willem P. Sijp, Anna S. von der Heydt, and Peter K. Bijl
Clim. Past, 12, 807–817, https://doi.org/10.5194/cp-12-807-2016, https://doi.org/10.5194/cp-12-807-2016, 2016
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The timing and role in ocean circulation and climate of the opening of Southern Ocean gateways is as yet elusive. Here, we present the first model results specific to the early-to-middle Eocene where, in agreement with the field evidence, a southerly shallow opening of the Tasman Gateway does indeed cause a westward flow across the Tasman Gateway, in agreement with recent micropalaeontological studies.
Alan M. Haywood, Harry J. Dowsett, Aisling M. Dolan, David Rowley, Ayako Abe-Ouchi, Bette Otto-Bliesner, Mark A. Chandler, Stephen J. Hunter, Daniel J. Lunt, Matthew Pound, and Ulrich Salzmann
Clim. Past, 12, 663–675, https://doi.org/10.5194/cp-12-663-2016, https://doi.org/10.5194/cp-12-663-2016, 2016
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Our paper presents the experimental design for the second phase of the Pliocene Model Intercomparison Project (PlioMIP). We outline the way in which climate models should be set up in order to study the Pliocene – a period of global warmth in Earth's history which is relevant for our understanding of future climate change. By conducting a model intercomparison we hope to understand the uncertainty associated with model predictions of a warmer climate.
Matthew J. Carmichael, Daniel J. Lunt, Matthew Huber, Malte Heinemann, Jeffrey Kiehl, Allegra LeGrande, Claire A. Loptson, Chris D. Roberts, Navjit Sagoo, Christine Shields, Paul J. Valdes, Arne Winguth, Cornelia Winguth, and Richard D. Pancost
Clim. Past, 12, 455–481, https://doi.org/10.5194/cp-12-455-2016, https://doi.org/10.5194/cp-12-455-2016, 2016
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In this paper, we assess how well model-simulated precipitation rates compare to those indicated by geological data for the early Eocene, a warm interval 56–49 million years ago. Our results show that a number of models struggle to produce sufficient precipitation at high latitudes, which likely relates to cool simulated temperatures in these regions. However, calculating precipitation rates from plant fossils is highly uncertain, and further data are now required.
K. M. Pascher, C. J. Hollis, S. M. Bohaty, G. Cortese, R. M. McKay, H. Seebeck, N. Suzuki, and K. Chiba
Clim. Past, 11, 1599–1620, https://doi.org/10.5194/cp-11-1599-2015, https://doi.org/10.5194/cp-11-1599-2015, 2015
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Radiolarian taxa with high-latitude affinities are present from at least the middle Eocene in the SW Pacific and become very abundant in the late Eocene at all investigated sites. A short incursion of low-latitude taxa is observed during the MECO and late Eocene warming event at Site 277. Radiolarian abundance, diversity and taxa with high-latitude affinities increase at Site 277 in two steps in the latest Eocene due to climatic cooling and expansion of cold water masses.
J. H. C. Bosmans, F. J. Hilgen, E. Tuenter, and L. J. Lourens
Clim. Past, 11, 1335–1346, https://doi.org/10.5194/cp-11-1335-2015, https://doi.org/10.5194/cp-11-1335-2015, 2015
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Our study shows that the influence of obliquity (the tilt of Earth's rotational axis) can be explained through changes in the insolation gradient across the tropics. This explanation is fundamentally different from high-latitude mechanisms that were previously often inferred to explain obliquity signals in low-latitude paleoclimate records, for instance glacial fluctuations. Our study is based on state-of-the-art climate model experiments.
V. Lauretano, K. Littler, M. Polling, J. C. Zachos, and L. J. Lourens
Clim. Past, 11, 1313–1324, https://doi.org/10.5194/cp-11-1313-2015, https://doi.org/10.5194/cp-11-1313-2015, 2015
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Several episodes of global warming took place during greenhouse conditions in the early Eocene and are recorded in deep-sea sediments. The stable carbon and oxygen isotope records are used to investigate the magnitude of six of these events describing their effects on the global carbon cycle and the associated temperature response. Findings indicate that these events share a common nature and hint to the presence of multiple sources of carbon release.