Articles | Volume 16, issue 6
https://doi.org/10.5194/cp-16-2381-2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/cp-16-2381-2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
28 Nov 2020
Research article |
| 28 Nov 2020
| 28 Nov 2020
Late Paleocene–early Eocene Arctic Ocean sea surface temperatures: reassessing biomarker paleothermometry at Lomonosov Ridge
Department of Earth Sciences, Faculty of Geosciences, Utrecht
University, Princetonlaan 8a, 3584 CB Utrecht, the Netherlands
Joost Frieling
Department of Earth Sciences, Faculty of Geosciences, Utrecht
University, Princetonlaan 8a, 3584 CB Utrecht, the Netherlands
Gordon N. Inglis
Organic Geochemistry Unit, School of Chemistry, School of Earth
Sciences, University of Bristol, Bristol, UK
present address: School of Ocean and Earth Science, National
Oceanography Centre Southampton, University of Southampton, Southampton, UK
Klaas G. J. Nierop
Department of Earth Sciences, Faculty of Geosciences, Utrecht
University, Princetonlaan 8a, 3584 CB Utrecht, the Netherlands
Francien Peterse
Department of Earth Sciences, Faculty of Geosciences, Utrecht
University, Princetonlaan 8a, 3584 CB Utrecht, the Netherlands
Francesca Sangiorgi
Department of Earth Sciences, Faculty of Geosciences, Utrecht
University, Princetonlaan 8a, 3584 CB Utrecht, the Netherlands
Stefan Schouten
Department of Earth Sciences, Faculty of Geosciences, Utrecht
University, Princetonlaan 8a, 3584 CB Utrecht, the Netherlands
NIOZ Royal Institute for Sea Research, Department of Microbiology and Biogeochemistry, P.O. Box 59, 1790 AB Den Burg, the Netherlands
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Allix J. Baxter, Francien Peterse, Dirk Verschuren, Aihemaiti Maitituerdi, Nicolas Waldmann, and Jaap S. Sinninghe Damsté
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Chris D. Fokkema, Tobias Agterhuis, Danielle Gerritsma, Myrthe de Goeij, Xiaoqing Liu, Pauline de Regt, Addison Rice, Laurens Vennema, Claudia Agnini, Peter K. Bijl, Joost Frieling, Matthew Huber, Francien Peterse, and Appy Sluijs
Clim. Past, 20, 1303–1325, https://doi.org/10.5194/cp-20-1303-2024, https://doi.org/10.5194/cp-20-1303-2024, 2024
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Marci M. Robinson, Kenneth G. Miller, Tali L. Babila, Timothy J. Bralower, James V. Browning, Marlow J. Cramwinckel, Monika Doubrawa, Gavin L. Foster, Megan K. Fung, Sean Kinney, Maria Makarova, Peter P. McLaughlin, Paul N. Pearson, Ursula Röhl, Morgan F. Schaller, Jean M. Self-Trail, Appy Sluijs, Thomas Westerhold, James D. Wright, and James C. Zachos
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The climatic factors sustaining vegetation in the Sahara during the African humid period (AHP) are still not fully understood. Using biomarkers in a marine sediment core from the eastern Mediterranean, we infer variations in Mediterranean (winter) and monsoonal (summer) rainfall in the Nile river watershed around the AHP. We find that winter and summer rain enhanced during the AHP, suggesting that Mediterranean moisture supported the monsoon in sustaining the “green Sahara”.
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
Biogeosciences, 21, 531–556, https://doi.org/10.5194/bg-21-531-2024, https://doi.org/10.5194/bg-21-531-2024, 2024
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Many important processes within the global mercury (Hg) cycle operate over thousands of years. Here, we explore the timing, magnitude, and expression of Hg signals retained in sediments of lakes Prespa and Ohrid over the past ∼90 000 years. Divergent signals suggest that local differences in sediment composition, lake structure, and water balance influence the local Hg cycle and determine the extent to which sedimentary Hg signals reflect local- or global-scale environmental changes.
Michiel Baatsen, Peter Bijl, Anna von der Heydt, Appy Sluijs, and Henk Dijkstra
Clim. Past, 20, 77–90, https://doi.org/10.5194/cp-20-77-2024, https://doi.org/10.5194/cp-20-77-2024, 2024
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This work introduces the possibility and consequences of monsoons on Antarctica in the warm Eocene climate. We suggest that such a monsoonal climate can be important to understand conditions in Antarctica prior to large-scale glaciation. We can explain seemingly contradictory indications of ice and vegetation on the continent through regional variability. In addition, we provide a new mechanism through which most of Antarctica remained ice-free through a wide range of global climatic changes.
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
Clim. Past, 20, 1–23, https://doi.org/10.5194/cp-20-1-2024, https://doi.org/10.5194/cp-20-1-2024, 2024
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The discovery of cold-water glendonite pseudomorphs in sediments deposited during the hottest part of the Cenozoic poses an apparent climate paradox. This study examines their occurrence, association with volcanic sediments, and speculates on the timing and extent of cooling, fitting this with current understanding of global climate during this period. We propose that volcanic activity was key to both physical and chemical conditions that enabled the formation of glendonites in these sediments.
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.
Yord W. Yedema, Timme Donders, Francien Peterse, and Francesca Sangiorgi
J. Micropalaeontol., 42, 257–276, https://doi.org/10.5194/jm-42-257-2023, https://doi.org/10.5194/jm-42-257-2023, 2023
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The pollen and dinoflagellate cyst content of 21 surface sediments from the northern Gulf of Mexico is used to test the applicability of three palynological ratios (heterotroph/autotroph, pollen/dinocyst, and pollen/bisaccate ratio) as proxies for marine productivity and distance to the coast/river. Redundancy analysis confirms the suitability of these three ratios, where the H/A ratio can be used as an indicator of primary production, and the P/B ratio best tracks the distance to the coast.
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.
Katrin Hättig, Devika Varma, Stefan Schouten, and Marcel T. J. van der Meer
Clim. Past, 19, 1919–1930, https://doi.org/10.5194/cp-19-1919-2023, https://doi.org/10.5194/cp-19-1919-2023, 2023
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Water isotopes, both hydrogen and oxygen, correlate with the salinity of the sea. Here we reconstruct the surface seawater isotopic composition during the last deglaciation based on the measured hydrogen isotopic composition of alkenones, organic compounds derived from haptophyte algae, and compared it to oxygen isotopes of calcite shells produced in the bottom water. Our results suggest that surface seawater experienced more freshening during the last 20 000 years than the bottom seawater.
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.
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.
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.
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.
Kasia K. Śliwińska, Helen K. Coxall, David K. Hutchinson, Diederik Liebrand, Stefan Schouten, and Agatha M. de Boer
Clim. Past, 19, 123–140, https://doi.org/10.5194/cp-19-123-2023, https://doi.org/10.5194/cp-19-123-2023, 2023
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We provide a sea surface temperature record from the Labrador Sea (ODP Site 647) based on organic geochemical proxies across the late Eocene and early Oligocene. Our study reveals heterogenic cooling of the Atlantic. The cooling of the North Atlantic is difficult to reconcile with the active Atlantic Meridional Overturning Circulation (AMOC). We discuss possible explanations like uncertainty in the data, paleogeography and atmospheric CO2 boundary conditions, model weaknesses, and AMOC activity.
Frédérique M. S. A. Kirkels, Hugo J. de Boer, Paulina Concha Hernández, Chris R. T. Martes, Marcel T. J. van der Meer, Sayak Basu, Muhammed O. Usman, and Francien Peterse
Biogeosciences, 19, 4107–4127, https://doi.org/10.5194/bg-19-4107-2022, https://doi.org/10.5194/bg-19-4107-2022, 2022
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The distinct carbon isotopic values of C3 and C4 plants are widely used to reconstruct past hydroclimate, where more C3 plants reflect wetter and C4 plants drier conditions. Here we examine the impact of regional hydroclimatic conditions on plant isotopic values in the Godavari River basin, India. We find that it is crucial to identify regional plant isotopic values and consider drought stress, which introduces a bias in C3 / C4 plant estimates and associated hydroclimate reconstructions.
Frédérique M. S. A. Kirkels, Huub M. Zwart, Muhammed O. Usman, Suning Hou, Camilo Ponton, Liviu Giosan, Timothy I. Eglinton, and Francien Peterse
Biogeosciences, 19, 3979–4010, https://doi.org/10.5194/bg-19-3979-2022, https://doi.org/10.5194/bg-19-3979-2022, 2022
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Soil organic carbon (SOC) that is transferred to the ocean by rivers forms a long-term sink of atmospheric CO2 upon burial on the ocean floor. We here test if certain bacterial membrane lipids can be used to trace SOC through the monsoon-fed Godavari River basin in India. We find that these lipids trace the mobilisation and transport of SOC in the wet season but that these lipids are not transferred far into the sea. This suggests that the burial of SOC on the sea floor is limited here.
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.
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.
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.
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.
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.
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.
Charlotte L. Spencer-Jones, Erin L. McClymont, Nicole J. Bale, Ellen C. Hopmans, Stefan Schouten, Juliane Müller, E. Povl Abrahamsen, Claire Allen, Torsten Bickert, Claus-Dieter Hillenbrand, Elaine Mawbey, Victoria Peck, Aleksandra Svalova, and James A. Smith
Biogeosciences, 18, 3485–3504, https://doi.org/10.5194/bg-18-3485-2021, https://doi.org/10.5194/bg-18-3485-2021, 2021
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Long-term ocean temperature records are needed to fully understand the impact of West Antarctic Ice Sheet collapse. Glycerol dialkyl glycerol tetraethers (GDGTs) are powerful tools for reconstructing ocean temperature but can be difficult to apply to the Southern Ocean. Our results show active GDGT synthesis in relatively warm depths of the ocean. This research improves the application of GDGT palaeoceanographic proxies in the Southern Ocean.
Cécile L. Blanchet, Rik Tjallingii, Anja M. Schleicher, Stefan Schouten, Martin Frank, and Achim Brauer
Clim. Past, 17, 1025–1050, https://doi.org/10.5194/cp-17-1025-2021, https://doi.org/10.5194/cp-17-1025-2021, 2021
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The Mediterranean Sea turned repeatedly into an oxygen-deprived basin during the geological past, as evidenced by distinct sediment layers called sapropels. We use here records of the last sapropel S1 retrieved in front of the Nile River to explore the relationships between riverine input and seawater oxygenation. We decipher the seasonal cycle of fluvial input and seawater chemistry as well as the decisive influence of primary productivity on deoxygenation at millennial timescales.
Nadine T. Smit, Laura Villanueva, Darci Rush, Fausto Grassa, Caitlyn R. Witkowski, Mira Holzheimer, Adriaan J. Minnaard, Jaap S. Sinninghe Damsté, and Stefan Schouten
Biogeosciences, 18, 1463–1479, https://doi.org/10.5194/bg-18-1463-2021, https://doi.org/10.5194/bg-18-1463-2021, 2021
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Soils from an everlasting fire (gas seep) in Sicily, Italy, reveal high relative abundances of novel uncultivated mycobacteria and unique 13C-depleted mycocerosic acids (multi-methyl branched fatty acids) close to the main gas seep. Our results imply that mycocerosic acids in combination with their depleted δ13C values offer a new biomarker tool to study the role of soil mycobacteria as hydrocarbon consumers in the modern and past global carbon cycle.
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.
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.
Loes G. J. van Bree, Francien Peterse, Allix J. Baxter, Wannes De Crop, Sigrid van Grinsven, Laura Villanueva, Dirk Verschuren, and Jaap S. Sinninghe Damsté
Biogeosciences, 17, 5443–5463, https://doi.org/10.5194/bg-17-5443-2020, https://doi.org/10.5194/bg-17-5443-2020, 2020
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Branched glycerol dialkyl glycerol tetraethers (brGDGTs) are used as a paleothermometer based on their temperature dependence in global soils, but aquatic production complicates their use in lakes. BrGDGTs in the water column of Lake Chala, East Africa, respond to oxygen conditions and mixing. Changes in their signal can be linked to bacterial community composition rather than membrane adaptation to changing conditions. Their integrated signal in the sediment reflects mean air temperature.
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.
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Short summary
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.
We revisit 15-year-old reconstructions of sea surface temperatures in the Arctic Ocean for the...
