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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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.
Cited articles
Backman, J., Moran, K., McInroy, D. B., Mayer, L. A., and
Expedition-302-Scientists: Proceedings of the Integrated Ocean Drilling
Program, Integrated Ocean Drilling Program Management International,
Inc., Edinburgh, 302, https://doi.org/10.2204/iodp.proc.302.2006, 2006.
Baxter, A. J., Hopmans, E. C., Russell, J. M., and Sinninghe Damsté, J.
S.: Bacterial GMGTs in East African lake sediments: Their potential as
palaeotemperature indicators, Geochim. Cosmochim. Ac., 259, 155–169,
https://doi.org/10.1016/j.gca.2019.05.039, 2019.
Berry, E. W.: A Possible Explanation of Upper Eocene Climates, P. Am. Philos. Soc., 61, 1–14, 1922.
Besseling, M. A., Hopmans, E. C., Bale, N. J., Schouten, S., Damsté, J.
S. S., and Villanueva, L.: The absence of intact polar lipid-derived GDGTs
in marine waters dominated by Marine Group II: Implications for lipid
biosynthesis in Archaea, Sci. Rep.-UK, 10, 294,
https://doi.org/10.1038/s41598-019-57035-0, 2020.
Bijl, P. K., Schouten, S., Sluijs, A., Reichart, G.-J., Zachos, J. C., and
Brinkhuis, H.: Early Palaeogene temperature evolution of the southwest
Pacific Ocean, Nature, 461, 776–779, 2009.
Bijl, P. K., Bendle, J. A. P., Bohaty, S. M., Pross, J., Schouten, S.,
Tauxe, L., Stickley, C. E., McKay, R. M., Rohl, U., Olney, M., Sluijs, A.,
Escutia, C., Brinkhuis, H., and the Expedition 318 Scientists: Eocene
cooling linked to early flow across the Tasmanian Gateway, P. Am. Philos. Soc., 110, 9645–9650, https://doi.org/10.1073/pnas.1220872110, 2013.
Blaga, C. I., Reichart, G.-J., Heiri, O., and Sinninghe Damsté, J. S.:
Tetraether membrane lipid distributions in water-column particulate matter
and sediments: a study of 47 European lakes along a north–south transect,
J. Paleolimnol., 41, 523–540, https://doi.org/10.1007/s10933-008-9242-2, 2009.
Carmichael, M. J., Inglis, G. N., Badger, M. P. S., Naafs, B. D. A., Behrooz, L., Remmelzwaal, S., Monteiro, F. M., Rohrssen, M., Farnsworth, A., Buss, H. L., Dickson, A. J., Valdes, P. J., Lunt, D. J., and Pancost, R. D.: Hydrological and associated biogeochemical consequences of rapid global warming during the Paleocene-Eocene Thermal Maximum, Global Planet. Change, 157, 114–138, https://doi.org/10.1016/j.gloplacha.2017.07.014, 2017.
Carton, J. A., Ding, Y., and Arrigo, K. R.: The seasonal cycle of the Arctic
Ocean under climate change, Geophys. Res. Lett., 42, 7681–7686,
https://doi.org/10.1002/2015GL064514, 2015.
Chepurin, G. A. and Carton, J. A.: Subarctic and Arctic sea surface
temperature and its relation to ocean heat content 1982–2010, J.
Geophys. Res.-Oceans, 117, C06019, https://doi.org/10.1029/2011JC007770, 2012.
Coolen, M. J. L., Abbas, B., v. Bleijswijk, J., Hopmans, E. C., Kuypers, M.
M. M., Wakeham, S. G., and Damsté, J. S. S.: Putative ammonia-oxidizing
Crenarchaeota in suboxic waters of the Black Sea: a basin-wide ecological
study using 16S ribosomal and functional genes and membrane lipids, Environ.
Microbiol., 9, 1001–1016, 2007.
Cramwinckel, M. J., Huber, M., Kocken, I. J., Agnini, C., Bijl, P. K.,
Bohaty, S. M., Frieling, J., Goldner, A., Hilgen, F. J., Kip, E. L.,
Peterse, F., van der Ploeg, R., Röhl, U., Schouten, S., and Sluijs, A.:
Synchronous tropical and polar temperature evolution in the Eocene, Nature,
559, 382–386, https://doi.org/10.1038/s41586-018-0272-2, 2018.
Cui, Y., Kump, L. R., Ridgwell, A. J., Charles, A. J., Junium, C. K.,
Diefendorf, A. F., Freeman, K. H., Urban, N. M., and Harding, I. C.: Slow
release of fossil carbon during the Palaeocene-Eocene Thermal Maximum,
Nat. Geosci., 4, 481–485, 2011.
Dawson, M. R., West, R. M., Langston Jr., W., and Hutchison, J. H.: Paleogene
terrestrial vertebrates: Northernmost occurrence, Ellesmere Island, Canada,
Science, 192, 781–782, 1976.
De Jonge, C., Hopmans, E. C., Zell, C. I., Kim, J.-H., Schouten, S., and
Sinninghe Damsté, J. S.: Occurrence and abundance of 6-methyl branched
glycerol dialkyl glycerol tetraethers in soils: Implications for
palaeoclimate reconstruction, Geochim. Cosmochim. Ac., 141, 97–112,
https://doi.org/10.1016/j.gca.2014.06.013, 2014.
De Jonge, C., Radujković, D., Sigurdsson, B. D., Weedon, J. T.,
Janssens, I., and Peterse, F.: Lipid biomarker temperature proxy responds to
abrupt shift in the bacterial community composition in geothermally heated
soils, Org. Geochem., 137, 103897,
https://doi.org/10.1016/j.orggeochem.2019.07.006, 2019.
Dearing Crampton-Flood, E., Peterse, F., Munsterman, D., and Sinninghe
Damsté, J. S.: Using tetraether lipids archived in North Sea Basin
sediments to extract North Western European Pliocene continental air
temperatures, Earth Planet. Sci. Lett., 490, 193–205,
https://doi.org/10.1016/j.epsl.2018.03.030, 2018.
Dearing Crampton-Flood, E., Tierney, J. E., Peterse, F., Kirkels, F. M. S.
A., and Sinninghe Damsté, J. S.: BayMBT: A Bayesian calibration model
for branched glycerol dialkyl glycerol tetraethers in soils and peats,
Geochim. Cosmochim. Ac., 268, 142–159,
https://doi.org/10.1016/j.gca.2019.09.043, 2020.
De Rosa, M., Esposito, E., Gambacorta, A., Nicolaus, B., and Bu'Lock, J. D.:
Effects of temperature on ether lipid composition of Caldariella acidophila,
Phytochemistry, 19, 827–831, https://doi.org/10.1016/0031-9422(80)85120-X,
1980.
Dong, L., Li, Z., and Jia, G.: Archaeal ammonia oxidation plays a part in
late Quaternary nitrogen cycling in the South China Sea, Earth Planet.
Sci. Lett., 509, 38–46, https://doi.org/10.1016/j.epsl.2018.12.023,
2019.
Douglas, P. M. J., Affek, H. P., Ivany, L. C., Houben, A. J. P., Sijp, W.
P., Sluijs, A., Schouten, S., and Pagani, M.: Pronounced zonal heterogeneity
in Eocene southern high-latitude sea surface temperatures, P. Natl. Acad. Sci. USA, 111, 6582–6587, 2014.
Eberle, J. J. and Greenwood, D. R.: Life at the top of the greenhouse
Eocene world–A review of the Eocene flora and vertebrate fauna from
Canada's High Arctic, Geol. Soc. Am. Bull., 124, 3–23, https://doi.org/10.1130/B30571.1, 2012.
Elling, F. J., Könneke, M., Lipp, J. S., Becker, K. W., Gagen, E. J.,
and Hinrichs, K.-U.: Effects of growth phase on the membrane lipid
composition of the thaumarchaeon Nitrosopumilus maritimus and their
implications for archaeal lipid distributions in the marine environment,
Geochim. Cosmochim. Ac., 141, 579–597,
https://doi.org/10.1016/j.gca.2014.07.005, 2014.
Elling, F. J., Könneke, M., Mußmann, M., Greve, A., and Hinrichs,
K.-U.: Influence of temperature, pH, and salinity on membrane lipid
composition and TEX86 of marine planktonic thaumarchaeal isolates, Geochim.
Cosmochim. Ac., 171, 238–255, https://doi.org/10.1016/j.gca.2015.09.004, 2015.
Estes, R. and Hutchinson, J. H.: Eocene Lower Vertebrates from Ellesmere
Island, Canadian Arctic Archipelago, Palaeogeogr. Palaeocl., 30, 325–347, 1980.
Evans, D., Sagoo, N., Renema, W., Cotton, L. J., Müller, W., Todd, J.
A., Saraswati, P. K., Stassen, P., Ziegler, M., Pearson, P. N., Valdes, P.
J., and Affek, H. P.: Eocene greenhouse climate revealed by coupled clumped
isotope-Mg/Ca thermometry, P. Natl. Acad. Sci. USA,
115, 1174–1179, https://doi.org/10.1073/pnas.1714744115, 2018.
Frieling, J. and Sluijs, A.: Towards quantitative environmental
reconstructions from ancient non-analogue microfossil assemblages:
Ecological preferences of Paleocene – Eocene dinoflagellates, Earth-Sci.
Rev., 185, 956–973, https://doi.org/10.1016/j.earscirev.2018.08.014,
2018.
Frieling, J., Iakovleva, A. I., Reichart, G. J., Aleksandrova, G. N.,
Gnibidenko, Z. N., Schouten, S., and Sluijs, A.: Paleocene-Eocene warming
and biotic response in the epicontinental West Siberian Sea, Geology, 42,
767–770, 2014.
Frieling, J., Gebhardt, H., Huber, M., Adekeye, O. A., Akande, S. O.,
Reichart, G.-J., Middelburg, J. J., Schouten, S., and Sluijs, A.: Extreme
warmth and heat-stressed plankton in the tropics during the Paleocene-Eocene
Thermal Maximum, Sci. Adv., 3, e1600891, https://doi.org/10.1126/sciadv.1600891,
2017.
Greenwood, D. R. and Wing, S. L.: Eocene continental climates and
latitudinal temperature gradients, Geology, 23, 1044–1048, 1995.
Greenwood, D. R., Basinger, J. F., and Smith, R. Y.: How wet was the Arctic
Eocene rain forest? Estimates of precipitation from Paleogene Arctic
macrofloras, Geology, 38, 15–18, https://doi.org/10.1130/G30218.1, 2010.
Harding, I. C., Charles, A. J., Marshall, J. E. A., Pälike, H., Roberts,
A. P., Wilson, P. A., Jarvis, E., Thorne, R., Morris, E., Moremon, R.,
Pearce, R. B., and Akbari, S.: Sea-level and salinity fluctuations during
the Paleocene-Eocene thermal maximum in Arctic Spitsbergen, Earth Planet. Sci. Lett., 303, 97–107, 2011.
Heer, O.: Flora fossilis Arctica, Kongliga Swenska Wetenskaps Academiens
Handlingar, 4, Stockholm, Sweden, 41 pp., 1869.
Ho, S. L. and Laepple, T.: Flat meridional temperature gradient in the
early Eocene in the subsurface rather than surface ocean, Nat. Geosci.,
9, 606–610, https://doi.org/10.1038/ngeo2763, 2016.
Ho, S. L., Mollenhauer, G., Fietz, S., Martínez-Garcia, A., Lamy, F.,
Rueda, G., Schipper, K., Méheust, M., Rosell-Melé, A., Stein, R.,
and Tiedemann, R.: Appraisal of TEX86 and TEX86L thermometries in subpolar
and polar regions, Geochim. Cosmochim. Ac., 131, 213–226,
https://doi.org/10.1016/j.gca.2014.01.001, 2014.
Hollis, C. J., Dunkley Jones, T., Anagnostou, E., Bijl, P. K., Cramwinckel, M. J., Cui, Y., Dickens, G. R., Edgar, K. M., Eley, Y., Evans, D., Foster, G. L., Frieling, J., Inglis, G. N., Kennedy, E. M., Kozdon, R., Lauretano, V., Lear, C. H., Littler, K., Lourens, L., Meckler, A. N., Naafs, B. D. A., Pälike, H., Pancost, R. D., Pearson, P. N., Röhl, U., Royer, D. L., Salzmann, U., Schubert, B. A., Seebeck, H., Sluijs, A., Speijer, R. P., Stassen, P., Tierney, J., Tripati, A., Wade, B., Westerhold, T., Witkowski, C., Zachos, J. C., Zhang, Y. G., Huber, M., and Lunt, D. J.: 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, Geosci. Model Dev., 12, 3149–3206, https://doi.org/10.5194/gmd-12-3149-2019, 2019.
Hopmans, E. C., Schouten, S., Pancost, R. D., van der Meer, M. T. J., and
Damsté, J. S. S.: Analysis of intact tetraether lipids in archaeal cell
material and sediments by high performance liquid chromatography/atmospheric
pressure chemical ionization mass spectrometry, Rapid. Commun. Mass. Sp., 14, 585–589, 2000.
Hopmans, E. C., Weijers, J. W. H., Schefuß, E., Herfort, L., Sinninghe
Damsté, J. S., and Schouten, S.: A novel proxy for terrestrial organic
matter in sediments based on branched and isoprenoid tetraether lipids,
Earth Planet. Sci. Lett., 224, 107–116, 2004.
Hopmans, E. C., Schouten, S., and Sinninghe Damsté, J. S.: The effect of
improved chromatography on GDGT-based palaeoproxies, Org. Geochem., 93, 1–6,
https://doi.org/10.1016/j.orggeochem.2015.12.006, 2016.
Hurley, S. J., Elling, F. J., Könneke, M., Buchwald, C., Wankel, S. D.,
Santoro, A. E., Lipp, J. S., Hinrichs, K.-U., and Pearson, A.: Influence of
ammonia oxidation rate on thaumarchaeal lipid composition and the TEX86
temperature proxy, P. Natl. Acad. Sci. USA, 113,
7762–7767, https://doi.org/10.1073/pnas.1518534113, 2016.
Inglis, G. N., Farnsworth, A., Lunt, D., Foster, G. L., Hollis, C. J.,
Pagani, M., Jardine, P. E., Pearson, P. N., Markwick, P., Galsworthy, A. M.
J., Raynham, L., Taylor, K. W. R., and Pancost, R. D.: Descent toward the
Icehouse: Eocene sea surface cooling inferred from GDGT distributions,
Paleoceanography, 30, 1000–1020, https://doi.org/10.1002/2014PA002723, 2015.
Inglis, G. N., Farnsworth, A., Collinson, M. E., Carmichael, M. J., Naafs,
B. D. A., Lunt, D. J., Valdes, P. J., and Pancost, R. D.: Terrestrial
environmental change across the onset of the PETM and the associated impact
on biomarker proxies: A cautionary tale, Global Planet. Change, 181,
102991, https://doi.org/10.1016/j.gloplacha.2019.102991, 2019.
Jaeschke, A., Jørgensen, S. L., Bernasconi, S. M., Pedersen, R. B.,
Thorseth, I. H., and Früh-Green, G. L.: Microbial diversity of Loki's
Castle black smokers at the Arctic Mid-Ocean Ridge, Geobiology, 10, 548–561,
https://doi.org/10.1111/gbi.12009, 2012
Karner, M. B., DeLong, E. F., and Karl, D. M.: Archaeal dominance in the
mesopelagic zone of the Pacific Ocean, Nature, 409, 507–510,
https://doi.org/10.1038/35054051, 2001.
Kim, J.-H., Schouten, S., Hopmans, E. C., Donner, B., and Sinninghe Damste,
J. S.: Global sediment core-top calibration of the TEX86 paleothermometer in
the ocean, Geochim. Cosmochim. Ac., 72, 1154–1173, 2008.
Kim, J.-H., van der Meer, J., Schouten, S., Helmke, P., Willmott, V.,
Sangiorgi, F., Koç, N., Hopmans, E. C., and Sinninghe Damsté, J. S.:
New indices and calibrations derived from the distribution of crenarchaeal
isoprenoid tetraether lipids: Implications for past sea surface temperature
reconstructions, Geochim. Cosmochim. Ac., 74, 4639–4654, 2010.
Kim, J.-H., Schouten, S., Rodrigo-Gámiz, M., Rampen, S., Marino, G.,
Huguet, C., Helmke, P., Buscail, R., Hopmans, E. C., Pross, J., Sangiorgi,
F., Middelburg, J. B. M., and Sinninghe Damsté, J. S.: Influence of
deep-water derived isoprenoid tetraether lipids on the paleothermometer in
the Mediterranean Sea, Geochim. Cosmochim. Ac., 150, 125–141,
https://doi.org/10.1016/j.gca.2014.11.017, 2015.
Kirkels, F. M. S. A., Ponton, C., Galy, V., West, A. J., Feakins, S. J., and
Peterse, F.: From Andes to Amazon: Assessing Branched Tetraether Lipids as
Tracers for Soil Organic Carbon in the Madre de Dios River System, J. Geophys. Res.-Biogeo., 125, e2019JG005270,
https://doi.org/10.1029/2019jg005270, 2020.
Knies, J., Mann, U., Popp, B. N., Stein, R., and Brumsack, H.-J.: Surface
water productivity and paleoceanographic implications in the Cenozoic Arctic
Ocean, Paleoceanography, 23, PA1S16, https://doi.org/10.1029/2007pa001455, 2008.
Könneke, M., Bernhard, A. E., de la Torre, J. R., Walker, C. B.,
Waterbury, J. B., and Stahl, D. A.: Isolation of an autotrophic
ammonia-oxidizing marine archaeon, Nature, 437, 543–546,
https://doi.org/10.1038/nature03911, 2005.
Liu, X.-L., Summons, R. E., and Hinrichs, K.-U.: Extending the known range
of glycerol ether lipids in the environment: structural assignments based on
tandem mass spectral fragmentation patterns, Rapid. Commun. Mass. Sp., 26, 2295–2302, https://doi.org/10.1002/rcm.6355, 2012.
Liu, Z., Pagani, M., Zinniker, D., DeConto, R., Huber, M., Brinkhuis, H.,
Shah, S. R., Leckie, R. M., and Pearson, A.: Global Cooling During the
Eocene-Oligocene Climate Transition, Science, 323, 1187–1190,
https://doi.org/10.1126/science.1166368, 2009.
Lunt, D. J., Dunkley Jones, T., Heinemann, M., Huber, M., LeGrande, A., Winguth, A., Loptson, C., Marotzke, J., Roberts, C. D., Tindall, J., Valdes, P., and Winguth, C.: A model–data comparison for a multi-model ensemble of early Eocene atmosphere–ocean simulations: EoMIP, Clim. Past, 8, 1717–1736, https://doi.org/10.5194/cp-8-1717-2012, 2012.
März, C., Schnetger, B., and Brumsack, H. J.: Paleoenvironmental
implications of Cenozoic sediments from the central Arctic Ocean (IODP
Expedition 302) using inorganic geochemistry, Paleoceanography, 25, PA3206,
https://doi.org/10.1029/2009pa001860, 2010.
Menzel, D., Hopmans, E. C., Schouten, S., and Sinninghe Damsté, J. S.:
Membrane tetraether lipids of planktonic Crenarchaeota in Pliocene sapropels
of the eastern Mediterranean Sea, Palaeogeogr. Palaeocl., 239, 1–15, 2006.
Mollenhauer, G., Basse, A., Kim, J.-H., Sinninghe Damsté, J. S., and
Fischer, G.: A four-year record of UK′37- and TEX86-derived sea
surface temperature estimates from sinking particles in the filamentous
upwelling region off Cape Blanc, Mauritania, Deep Sea Res. Pt. I, 97, 67–79,
https://doi.org/10.1016/j.dsr.2014.11.015, 2015.
Morales, C., Rogov, M., Wierzbowski, H., Ershova, V., Suan, G., Adatte, T.,
Föllmi, K. B., Tegelaar, E., Reichart, G.-J., de Lange, G. J.,
Middelburg, J. J., and van de Schootbrugge, B.: Glendonites track methane
seepage in Mesozoic polar seas, Geology, 45, 503–506, https://doi.org/10.1130/g38967.1,
2017.
Müller, R. D., Cannon, J., Qin, X., Watson, R. J., Gurnis, M., Williams,
S., Pfaffelmoser, T., Seton, M., Russell, S. H. J., and Zahirovic, S.:
GPlates: Building a Virtual Earth Through Deep Time, Geochem.,
Geophys., Geosys., 19, 2243–2261, https://doi.org/10.1029/2018gc007584, 2018.
Naafs, B. D. A., Inglis, G. N., Zheng, Y., Amesbury, M. J., Biester, H.,
Bindler, R., Blewett, J., Burrows, M. A., del Castillo Torres, D., Chambers,
F. M., Cohen, A. D., Evershed, R. P., Feakins, S. J., Gałka, M.,
Gallego-Sala, A., Gandois, L., Gray, D. M., Hatcher, P. G., Honorio
Coronado, E. N., Hughes, P. D. M., Huguet, A., Könönen, M.,
Laggoun-Défarge, F., Lähteenoja, O., Lamentowicz, M., Marchant, R.,
McClymont, E., Pontevedra-Pombal, X., Ponton, C., Pourmand, A., Rizzuti, A.
M., Rochefort, L., Schellekens, J., De Vleeschouwer, F., and Pancost, R. D.:
Introducing global peat-specific temperature and pH calibrations based on
brGDGT bacterial lipids, Geochim. Cosmochim. Ac., 208, 285–301,
https://doi.org/10.1016/j.gca.2017.01.038, 2017.
Naafs, B. D. A., McCormick, D., Inglis, G. N., and Pancost, R. D.: Archaeal
and bacterial H-GDGTs are abundant in peat and their relative abundance is
positively correlated with temperature, Geochim. Cosmochim. Ac., 227, 156–170,
https://doi.org/10.1016/j.gca.2018.02.025, 2018a.
Naafs, B. D. A., Rohrssen, M., Inglis, G. N., Lähteenoja, O., Feakins,
S. J., Collinson, M. E., Kennedy, E. M., Singh, P. K., Singh, M. P., Lunt,
D. J., and Pancost, R. D.: High temperatures in the terrestrial
mid-latitudes during the early Palaeogene, Nat. Geosci., 11, 766–771,
https://doi.org/10.1038/s41561-018-0199-0, 2018b.
O'Brien, C. L., Robinson, S. A., Pancost, R. D., Sinninghe Damsté, J.
S., Schouten, S., Lunt, D. J., Alsenz, H., Bornemann, A., Bottini, C.,
Brassell, S. C., Farnsworth, A., Forster, A., Huber, B. T., Inglis, G. N.,
Jenkyns, H. C., Linnert, C., Littler, K., Markwick, P., McAnena, A.,
Mutterlose, J., Naafs, B. D. A., Püttmann, W., Sluijs, A., van Helmond,
N. A. G. M., Vellekoop, J., Wagner, T., and Wrobel, N. E.: Cretaceous
sea-surface temperature evolution: Constraints from TEX86 and planktonic
foraminiferal oxygen isotopes, Earth-Sci. Rev., 172, 224–247,
https://doi.org/10.1016/j.earscirev.2017.07.012, 2017.
O'Regan, M., Moran, K., Sangiorgi, F., Brinkhuis, H., Backman, J.,
Jakobsson, M., Stickley, C. E., Koc, N., Brumsack, H., Willard, D.,
Pockalny, R., and Skelton, A.: Mid-Cenozoic Tectonic and Paleoenvironmental
setting of the Central Arctic Ocean, Paleoceanography, 23, PA1S20,
https://doi.org/10.1029/2007PA001559, 2008.
Pagani, M., Pedentchouk, N., Huber, M., Sluijs, A., Schouten, S., Brinkhuis,
H., Sinninghe Damsté, J. S., Dickens, G. R., and Expedition 302
Scientists, T.: Arctic hydrology during global warming at the
Palaeocene-Eocene thermal maximum, Nature, 442, 671–675, 2006.
Pancost, R. D., Hopmans, E. C., and Sinninghe Damsté, J. S.: Archaeal
lipids in mediterranean cold seeps: Molecular proxies for anaerobic methane
oxidation, Geochim. Cosmochim. Ac., 65, 1611–1627, 2001.
Park, E., Hefter, J., Fischer, G., Iversen, M. H., Ramondenc, S., Nöthig, E.-M., and Mollenhauer, G.: Seasonality of archaeal lipid flux and GDGT-based thermometry in sinking particles of high-latitude oceans: Fram Strait (79∘ N) and Antarctic Polar Front (50∘ S), Biogeosciences, 16, 2247–2268, https://doi.org/10.5194/bg-16-2247-2019, 2019.
Pierrehumbert, R. T.: The hydrologic cycle in deep-time climate problems,
Nature, 419, 191–198, 2002.
Pitcher, A., Hopmans, E. C., Mosier, A. C., Park, S.-J., Rhee, S.-K.,
Francis, C. A., Schouten, S., and Sinninghe Damsté, J. S.: Core and
Intact Polar Glycerol Dibiphytanyl Glycerol Tetraether Lipids of
Ammonia-Oxidizing Archaea Enriched from Marine and Estuarine Sediments,
Appl. Environ. Microbiol., 77, 3468–3477, https://doi.org/10.1128/aem.02758-10,
2011a.
Pitcher, A., Wuchter, C., Siedenberg, K., Schouten, S., and Sinninghe
Damsté, J. S.: Crenarchaeol tracks winter blooms of ammonia-oxidizing
Thaumarchaeota in the coastal North Sea, Limnol. Oceanogr., 56, 2308–2318,
https://doi.org/10.4319/lo.2011.56.6.2308, 2011b.
Qin, W., Amin, S. A., Martens-Habbena, W., Walker, C. B., Urakawa, H.,
Devol, A. H., Ingalls, A. E., Moffett, J. W., Armbrust, E. V., and Stahl, D.
A.: Marine ammonia-oxidizing archaeal isolates display obligate mixotrophy
and wide ecotypic variation, P. Natl. Acad. Sci. USA, 111, 12504–12509, https://doi.org/10.1073/pnas.1324115111, 2014.
Qin, W., Carlson, L. T., Armbrust, E. V., Devol, A. H., Moffett, J. W.,
Stahl, D. A., and Ingalls, A. E.: Confounding effects of oxygen and
temperature on the TEX86 signature of marine Thaumarchaeota,
P. Natl. Acad. Sci. USA, 112, 10979–10984,
https://doi.org/10.1073/pnas.1501568112, 2015.
Reichgelt, T., West, C. K., and Greenwood, D. R.: The relation between
global palm distribution and climate, Sci. Rep.-UK, 8, 4721,
https://doi.org/10.1038/s41598-018-23147-2, 2018.
Richey, J. N. and Tierney, J. E.: GDGT and alkenone flux in the northern
Gulf of Mexico: Implications for the TEX86 and UK'37 paleothermometers,
Paleoceanography, 31, 1547–1561, https://doi.org/10.1002/2016pa003032, 2016.
Sangiorgi, F., van Soelen, E. E., Spofforth, D. J. A., Pälike, H.,
Stickley, C. E., St. John, K., Koç, N., Schouten, S., Sinninghe
Damsté, J. S., and Brinkhuis, H.: Cyclicity in the middle Eocene central
Arctic Ocean sediment record: Orbital forcing and environmental response,
Paleoceanography, 23, PA1S08, https://doi.org/10.1029/2007PA001487, 2008.
Schouten, S., Hopmans, E. C., Schefuß, E., and Sinninghe Damsté, J.
S.: Distributional variations in marine crenarchaeotal membrane lipids: a
new tool for reconstructing ancient sea water temperatures?, Earth
Planet. Sci. Lett., 204, 265–274, 2002.
Schouten, S., Hopmans, E. C., Forster, A., Breugel, Y. V., Kuypers, M. M.
M., and Sinninghe Damsté, J. S.: Extremely high sea-surface temperatures
at low latitudes during the middle Cretaceous as revealed by archaeal
membrane lipids, Geology, 31, 1069–1072, 2003.
Schouten, S., Forster, A., Panoto, F. E., and Sinninghe Damste, J. S.:
Towards calibration of the TEX86 palaeothermometer for tropical sea surface
temperatures in ancient greenhouse worlds, Org. Geochem., 38, 1537–1546,
2007.
Schouten, S., Baas, M., Hopmans, E. C., and Sinninghe Damsté, J. S.: An
unusual isoprenoid tetraether lipid in marine and lacustrine sediments, Org.
Geochem., 39, 1033–1038, 2008.
Schouten, S., Hopmans, E. C., van der Meer, J., Mets, A., Bard, E., Bianchi,
T. S., Diefendorf, A., Escala, M., Freeman, K. H., Furukawa, Y., Ingalls, C.
H. a. A., Ménot-Combes, G., Nederbragt, A. J., Oba, M., Pearson, A.,
Pearson, E. J., Rosell-Melé, A., Schaeffer, P., Shah, S. R., Shanahan,
T. M., Smith, R. W., Smittenberg, R., Talbot, H. M., Uchida, M., Mooy, B. A.
S. V., Yamamoto, M., Zhang, Z., and Sinninghe Damsté, J. S.: An
interlaboratory study of TEX86 and BIT analysis using high-performance
liquid chromatography–mass spectrometry, Geochem. Geophys.
Geosys., 10, Q03012, https://doi.org/10.1029/2008GC002221, 2009.
Schouten, S., Hopmans, E. C., and Sinninghe Damsté, J. S.: The organic
geochemistry of glycerol dialkyl glycerol tetraether lipids: A review, Org.
Geochem., 54, 19–61, https://doi.org/10.1016/j.orggeochem.2012.09.006,
2013.
Schweitzer, H.-J.: Environment and climate in the early Tertiary of
Spitsbergen, Palaeogeogr. Palaeocl., 30, 297–311,
1980.
Seton, M., Müller, R. D., Zahirovic, S., Gaina, C., Torsvik, T.,
Shephard, G., Talsma, A., Gurnis, M., Turner, M., Maus, S., and Chandler,
M.: Global continental and ocean basin reconstructions since 200Ma,
Earth-Sci. Rev., 113, 212–270,
https://doi.org/10.1016/j.earscirev.2012.03.002, 2012.
Shah, S. R., Mollenhauer, G., Ohkouchi, N., Eglinton, T. I., and Pearson,
A.: Origins of archaeal tetraether lipids in sediments: Insights from
radiocarbon analysis, Geochim. Cosmochim. Ac., 72, 4577–4594,
https://doi.org/10.1016/j.gca.2008.06.021, 2008.
Sinninghe Damsté, J. S., Wakeham, S. G., Kohnen, M. E. L., Hayes, J. M.,
and de Leeuw, J. W.: A 6,000-year sedimentary molecular record of chemocline
excursions in the Black Sea, Nature, 362, 827–829, 1993.
Sinninghe Damsté, J. S., Rijpstra, W. I. C., Hopmans, E. C., Weijers, J.
W. H., Foesel, B. U., Overmann, J., and Dedysh, S. N.: 13,16-Dimethyl
Octacosanedioic Acid (iso-Diabolic Acid), a Common Membrane-Spanning Lipid of Acidobacteria Subdivisions 1 and 3, Appl. Environ. Microbiol.,
77, 4147–4154, https://doi.org/10.1128/aem.00466-11, 2011.
Sinninghe Damsté, J. S.: Spatial heterogeneity of sources of branched
tetraethers in shelf systems: The geochemistry of tetraethers in the Berau
River delta (Kalimantan, Indonesia), Geochim. Cosmochim. Ac., 186, 13–31,
https://doi.org/10.1016/j.gca.2016.04.033, 2016.
Sinninghe Damsté, J. S., Rijpstra, W. I. C., Foesel, B. U., Huber, K.
J., Overmann, J., Nakagawa, S., Kim, J. J., Dunfield, P. F., Dedysh, S. N.,
and Villanueva, L.: An overview of the occurrence of ether- and ester-linked
iso-diabolic acid membrane lipids in microbial cultures of the
Acidobacteria: Implications for brGDGT paleoproxies for temperature and pH,
Org. Geochem., 124, 63–76, https://doi.org/10.1016/j.orggeochem.2018.07.006,
2018a.
Sinninghe Damsté, J. S., Rijpstra, W. I. C., Hopmans, E. C., den Uijl,
M. J., Weijers, J. W. H., and Schouten, S.: The enigmatic structure of the
crenarchaeol isomer, Org. Geochem., 124, 22–28,
https://doi.org/10.1016/j.orggeochem.2018.06.005, 2018b.
Sluijs, A.: GDGT and GMGT data, PANGAEA, https://doi.org/10.1594/PANGAEA.924854, 2020.
Sluijs, A. and Dickens, G. R.: Assessing offsets between the δ13C
of sedimentary components and the global exogenic carbon pool across Early
Paleogene carbon cycle perturbations, Global Biogeochem. Cy., 26,
GB4005, https://doi.org/10.1029/2011GB004224, 2012.
Sluijs, A., Schouten, S., Pagani, M., Woltering, M., Brinkhuis, H.,
Sinninghe Damsté, J. S., Dickens, G. R., Huber, M., Reichart, G.-J.,
Stein, R., Matthiessen, J., Lourens, L. J., Pedentchouk, N., Backman, J.,
Moran, K., and The Expedition 302 Scientists: Subtropical Arctic Ocean
temperatures during the Palaeocene/Eocene thermal maximum, Nature, 441,
610–613, 2006.
Sluijs, A., Brinkhuis, H., Crouch, E. M., John, C. M., Handley, L.,
Munsterman, D., Bohaty, S., M., Zachos, J. C., Reichart, G.-J., Schouten,
S., Pancost, R. D., Sinninghe Damsté, J. S., Welters, N. L. D., Lotter,
A. F., and Dickens, G. R.: Eustatic variations during the Paleocene-Eocene
greenhouse world, Paleoceanography, 23, PA4216, https://doi.org/10.1029/2008PA001615,
2008a.
Sluijs, A., Röhl, U., Schouten, S., Brumsack, H.-J., Sangiorgi, F.,
Sinninghe Damsté, J. S., and Brinkhuis, H.: Arctic late Paleocene–early
Eocene paleoenvironments with special emphasis on the Paleocene-Eocene
thermal maximum (Lomonosov Ridge, Integrated Ocean Drilling Program
Expedition 302), Paleoceanography, 23, PA1S11, https://doi.org/10.1029/2007PA001495,
2008b.
Sluijs, A., Schouten, S., Donders, T. H., Schoon, P. L., Röhl, U.,
Reichart, G. J., Sangiorgi, F., Kim, J.-H., Sinninghe Damsté, J. S., and
Brinkhuis, H.: Warm and Wet Conditions in the Arctic Region during Eocene
Thermal Maximum 2, Nat. Geosci., 2, 777–780, 2009.
Sollich, M., Yoshinaga, M. Y., Häusler, S., Price, R. E., Hinrichs,
K.-U., and Bühring, S. I.: Heat Stress Dictates Microbial Lipid
Composition along a Thermal Gradient in Marine Sediments, Front.
Microbiol., 8, 1550, https://doi.org/10.3389/fmicb.2017.01550, 2017.
Spielhagen, R. F. and Tripati, A.: Evidence from Svalbard for near-freezing
temperatures and climate oscillations in the Arctic during the Paleocene and
Eocene, Palaeogeogr. Palaeocl., 278, 48–56,
https://doi.org/10.1016/j.palaeo.2009.04.012, 2009.
Stein, R.: Upper Cretaceous/lower Tertiary black shales near the North Pole:
Organic-carbon origin and source-rock potential, Mar. Petrol.
Geol., 24, 67–73, 2007.
Stein, R., Boucsein, B., and Meyer, H.: Anoxia and high primary production
in the Paleogene central Arctic Ocean: First detailed records from Lomonosov
Ridge, Geophys. Res. Lett., 33, L18606, https://doi.org/10.1029/2006GL026776,
2006.
Suan, G., Popescu, S.-M., Yoon, D., Baudin, F., Suc, J.-P., Schnyder, J.,
Labrousse, L., Fauquette, S., Piepjohn, K., and Sobolev, N. N.: Subtropical
climate conditions and mangrove growth in Arctic Siberia during the early
Eocene, Geology, 45, 539–542, https://doi.org/10.1130/g38547.1, 2017.
Taylor, K. W. R., Huber, M., Hollis, C. J., Hernandez-Sanchez, M. T., and
Pancost, R. D.: Re-evaluating modern and Palaeogene GDGT distributions:
Implications for SST reconstructions, Global Planet. Change, 108,
158–174, https://doi.org/10.1016/j.gloplacha.2013.06.011, 2013.
Teichert, B. M. A. and Luppold, F. W.: Glendonites from an Early Jurassic
methane seep – Climate or methane indicators?, Palaeogeogr. Palaeocl., 390, 81–93,
https://doi.org/10.1016/j.palaeo.2013.03.001, 2013.
Tierney, J. E. and Tingley, M. P.: A Bayesian, spatially-varying
calibration model for the TEX86 proxy, Geochim. Cosmochim. Ac., 127, 83–106,
https://doi.org/10.1016/j.gca.2013.11.026, 2014.
Tierney, J. E., Sinninghe Damsté, J. S., Pancost, R. D., Sluijs, A., and
Zachos, J. C.: Eocene temperature gradients, Nat. Geosci., 10, 538–539,
https://doi.org/10.1038/ngeo2997, 2017.
Torsvik, T. H., Van der Voo, R., Preeden, U., Mac Niocaill, C., Steinberger,
B., Doubrovine, P. V., van Hinsbergen, D. J. J., Domeier, M., Gaina, C.,
Tohver, E., Meert, J. G., McCausland, P. J. A., and Cocks, L. R. M.:
Phanerozoic polar wander, palaeogeography and dynamics, Earth-Sci.
Rev., 114, 325–368, https://doi.org/10.1016/j.earscirev.2012.06.007,
2012.
Trommer, G., Siccha, M., van der Meer, M. T. J., Schouten, S., Sinninghe
Damsté, J. S., Schulz, H., Hemleben, C., and Kucera, M.: Distribution of
Crenarchaeota tetraether membrane lipids in surface sediments from the Red
Sea, Org. Geochem., 40, 724–731,
https://doi.org/10.1016/j.orggeochem.2009.03.001, 2009.
Uhl, D., Traiser, C., Griesser, U., and Denk, T.: Fossil leaves as
palaeoclimate proxies in the Palaeogene of Spitsbergen (Svalbard), Acta
Palaeobotanica, 47, 89–107, 2007.
Van der Burgh, J.: Some palms in the Miocene of the lower Rhenish Plain,
Rev. Palaebot. Palyno., 40, 359–374, 1984.
Van Hinsbergen, D. J. J., de Groot, L. V., van Schaik, S. J., Spakman, W.,
Bijl, P. K., Sluijs, A., Langereis, C. G., and Brinkhuis, H.: A
Paleolatitude Calculator for Paleoclimate Studies, Plos One, 10, e0126946,
https://doi.org/10.1371/journal.pone.0126946, 2015.
Wakeham, S. G., Amann, R., Freeman, K. H., Hopmans, E. C., Jörgensen, B.
B., Putnam, I. F., Schouten, S., Sinninghe Damsté, J. S., Talbot, H. M.,
and Woebken, D.: Microbial ecology of the stratified water column of the
Black Sea as revealed by a comprehensive biomarker stud, Org. Geochem., 38,
2070–2097, 2007.
Weijers, J. W. H., Schouten, S., Spaargaren, O. C., and Sinninghe
Damsté, J. S.: Occurrence and distribution of tetraether membrane lipids
in soils: Implications for the use of the TEX86 proxy and the BIT index, Org.
Geochem., 37, 1680–1693, 2006.
Weijers, J. W. H., Schouten, S., Sluijs, A., Brinkhuis, H., and Sinninghe
Damsté, J. S.: Warm arctic continents during the Palaeocene-Eocene
thermal maximum, Earth Planet. Sci. Lett., 261, 230–238, 2007a.
Weijers, J. W. H., Schouten, S., van den Donker, J. C., Hopmans, E. C., and
Sinninghe Damsté, J. S.: Environmental controls on bacterial tetraether
membrane lipid distribution in soils, Geochim. Cosmochim. Ac., 71, 703–713,
2007b.
Weijers, J. W. H., Lim, K. L. H., Aquilina, A., Sinninghe Damsté, J. S.,
and Pancost, R. D.: Biogeochemical controls on glycerol dialkyl glycerol
tetraether lipid distributions in sediments characterized by diffusive
methane flux, Geochem. Geophys. Geosys., 12, Q10010,
https://doi.org/10.1029/2011GC003724, 2011.
Willard, D. A., Donders, T. H., Reichgelt, T., Greenwood, D. R., Sangiorgi,
F., Peterse, F., Nierop, K. G. J., Frieling, J., Schouten, S., and Sluijs,
A.: Arctic vegetation, temperature, and hydrology during Early Eocene
transient global warming events, Global Planet. Change, 178, 139–152,
https://doi.org/10.1016/j.gloplacha.2019.04.012, 2019.
Wuchter, C., Schouten, S., Coolen, M. J. L., and Sinninghe Damsté, J.
S.: Temperature-dependent variation in the distribution of tetraether
membrane lipids of marine Crenarchaeota: Implications for TEX86
paleothermometry, Paleoceanography, 19, PA402, https://doi.org/10.1029/2004PA001041, 2004.
Wuchter, C., Schouten, S., Wakeham, S. G., and Sinninghe Damste, J. S.:
Temporal and spatial variation in tetraether membrane lipids of marine
Crenarchaeota in particulate organic matter: Implications for TEX86
paleothermometry, Paleoceanography, 20, PA3013, https://doi.org/10.1029/2004PA001110, 2005.
Wuchter, C., Abbas, B., Coolen, M. J. L., Herfort, L., van Bleijswijk, J.,
Timmers, P., Strous, M., Teira, E., Herndl, G. J., Middelburg, J. J.,
Schouten, S., and Damste, J. S. S.: Archaeal nitrification in the ocean,
P. Natl. Acad. Sci. USA, 103, 12317–12322, https://doi.org/10.1073/pnas.0600756103, 2006a.
Wuchter, C., Schouten, S., Wakeham, S. G., and Sinninghe Damsté, J. S.:
Archaeal tetraether membrane lipid fluxes in the northeastern Pacific and
the Arabian Sea: Implications for TEX86 paleothermometry, Paleoceanography,
21, PA4208, 2006b.
Xie, S., Liu, X.-L., Schubotz, F., Wakeham, S. G., and Hinrichs, K.-U.:
Distribution of glycerol ether lipids in the oxygen minimum zone of the
Eastern Tropical North Pacific Ocean, Org. Geochem., 71, 60–71,
https://doi.org/10.1016/j.orggeochem.2014.04.006, 2014.
Yamamoto, M., Shimamoto, A., Fukuhara, T., Tanaka, Y., and Ishizaka, J.:
Glycerol dialkyl glycerol tetraethers and TEX86 index in sinking particles
in the western North Pacific, Org. Geochem., 53, 52–62,
https://doi.org/10.1016/j.orggeochem.2012.04.010, 2012.
Zeng, Z., Liu, X.-L., Farley, K. R., Wei, J. H., Metcalf, W. W., Summons, R.
E., and Welander, P. V.: GDGT cyclization proteins identify the dominant
archaeal sources of tetraether lipids in the ocean, P. Natl. Acad. Sci. USA, 116, 22505–22511, https://doi.org/10.1073/pnas.1909306116,
2019.
Zhang, Y. G. and Liu, X.: Export Depth of the TEX86 Signal,
Paleoceanogr. Paleoclimatol., 33, 666–671, https://doi.org/10.1029/2018pa003337, 2018.
Zhang, Y. G., Zhang, C. L., Liu, X.-L., Li, L., Hinrichs, K.-U., and Noakes,
J. E.: Methane Index: A tetraether archaeal lipid biomarker indicator for
detecting the instability of marine gas hydrates, Earth Planet.
Sci. Lett., 307, 525–534, https://doi.org/10.1016/j.epsl.2011.05.031,
2011.
Zhang, Y. G., Pagani, M., and Wang, Z.: Ring Index: A new strategy to
evaluate the integrity of TEX86 paleothermometry, Paleoceanography, 31,
220–232, https://doi.org/10.1002/2015PA002848, 2016.
Zhu, J., Poulsen, C. J., and Tierney, J. E.: Simulation of Eocene extreme
warmth and high climate sensitivity through cloud feedbacks, Sci.
Adv., 5, eaax1874, https://doi.org/10.1126/sciadv.aax1874, 2019.
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...
