Articles | Volume 21, issue 11
https://doi.org/10.5194/cp-21-2189-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Special issue:
https://doi.org/10.5194/cp-21-2189-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
12 Nov 2025
Research article |
| 12 Nov 2025
| 12 Nov 2025
Divergent estimates of Miocene to Pleistocene upper ocean temperatures in the South Atlantic Ocean from alkenone and coccolith clumped isotope proxies
Heather M. Stoll
CORRESPONDING AUTHOR
Geological Institute, Department of Earth and Planetary Sciences, ETH Zurich, Zurich, 8092, Switzerland
Invited contribution by Heather M. Stoll, recipient of the EGU Hans Oeschger Medal 2025.
Clara Bolton
Aix Marseille Univ, CNRS, IRD, INRAE, CEREGE, Aix en Provence, France
Madalina Jaggi
Geological Institute, Department of Earth and Planetary Sciences, ETH Zurich, Zurich, 8092, Switzerland
Alfredo Martinez-Garcia
Max Planck Institute fur Chemie, Mainz, Germany
Stefano M. Bernasconi
Geological Institute, Department of Earth and Planetary Sciences, ETH Zurich, Zurich, 8092, Switzerland
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Celia Campa-Bousoño, Miguel Iglesias, Iñaki Vadillo, Lucía Ojeda, Jorge Pisonero, Hai Cheng, R. Lawrence Edwards, and Heather Stoll
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To understand how rainfall changed in southern Iberia during the shift from the Medieval Climate Anomaly to the Little Ice Age, we studied yearly layers preserved in a stalagmite from Ardales Cave, southern Spain. The record shows repeated shifts between wetter and drier periods, including major droughts around 1125, 1250, 1500, and 1560 CE. It also reveals intervals of more variable rainfall, suggesting changing influence from Atlantic and Mediterranean weather patterns.
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In this study, we examined the relationship between surface ocean temperature in the midlatitudes in both the Northern and Southern Hemispheres over a period of major Antarctic ice expansion 24 to 22 million years ago, a period when Antarctica was the only polar ice sheet. We find consistent cooling of the surface ocean in both hemispheres as ice was expanding, indicating a close coupling of global climate and polar ice caps.
Laura Endres, Carlos Pérez-Mejías, Ruza Ivanovic, Lauren Gregoire, Anna L. C. Hughes, Hai Cheng, and Heather Stoll
Clim. Past, 22, 797–824, https://doi.org/10.5194/cp-22-797-2026, https://doi.org/10.5194/cp-22-797-2026, 2026
Short summary
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Stable isotope data of a precisely dated stalagmite from northwestern Iberia indicate gradual North Atlantic meltwater input during the last glacial maximum, followed by abrupt surges early in the last deglaciation. The first abrupt surge was decoupled from first cooling about 810 years later – unlike later events – which reveals that the Atlantic circulation’s sensitivity to meltwater is variable and related to the evolving background climate boundary conditions.
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Photosynthetic organisms leave characteristic carbon isotope fingerprints that help scientists study Earth’s carbon cycle. We developed a simpler laboratory method to measure these isotope effects in Rubisco, the key enzyme fixing CO2. Applying this approach, we obtained the first measurement for Gephyrocapsa oceanica, a widespread marine alga that plays a major role in ocean carbon cycling.
Alexander J. Clark, Alba Gonzalez-Lanchas, Kyra Bachmakova, Madalina Jaggi, and Heather M. Stoll
J. Micropalaeontol., 44, 673–692, https://doi.org/10.5194/jm-44-673-2025, https://doi.org/10.5194/jm-44-673-2025, 2025
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We quantified the thickness of early Eocene calcareous nannofossils and linked it to different depositional environment parameters. Discoasters and placoliths do not respond in the same manner. Carbonate content affects discoasters and induces overgrowth, but palaeowater depth affects placoliths and can induce dissolution. We also find that the ratio of non-overgrown to overgrown Discoaster multiradiatus is a potential quantitative placolith preservation indicator.
Nicolas Tapia, Laura Endres, Madalina Jaggi, and Heather Stoll
Biogeosciences, 22, 6861–6875, https://doi.org/10.5194/bg-22-6861-2025, https://doi.org/10.5194/bg-22-6861-2025, 2025
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We use stalagmites to study past changes in the terrestrial P cycle. Our P records from multiple, coeval stalagmites from Northwest Spain show that the onsets of past abrupt cooling events are characterized by multi-century reproducible peaks in stalagmite P which reflect higher groundwater P/Ca concentrations and enhanced P export, potentially resulting from increased freeze-thaw frequency and more intense infiltration from snowmelt.
José Guitián, Samuel Phelps, Reto S. Wijker, Pratigya J. Polissar, Laura Arnold, and Heather M. Stoll
Clim. Past, 21, 2115–2132, https://doi.org/10.5194/cp-21-2115-2025, https://doi.org/10.5194/cp-21-2115-2025, 2025
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We reconstructed from sediments of different ocean sites phytoplankton carbon isotopic fractionation (εp), mainly linked to CO2 variations, during the Oligocene to early Miocene. Data confirm Cenozoic long-term CO2 record but show contrasting relationships with the sea surface temperatures evolution. We evaluate the role of non-CO2 environmental factors such as temperature and nutrients at each site εp, highlighting the complexity of interpreting climate dynamics and CO2 reconstructions.
Nikita Kaushal, Carlos Pérez-Mejías, and Heather M. Stoll
Clim. Past, 21, 1633–1660, https://doi.org/10.5194/cp-21-1633-2025, https://doi.org/10.5194/cp-21-1633-2025, 2025
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Terminations are large-magnitude rapid events triggered in the North Atlantic region that manifest across the global climate system. They provide key examples of climatic teleconnections and dynamics. In this study, we use the SISAL global speleothem database and find that there are sufficient climatic records from key locations to make speleothems a valuable archive for studying terminations and provide instances for more targeted work on speleothem research.
Judit Torner, Isabel Cacho, Heather Stoll, Ana Moreno, Joan O. Grimalt, Francisco J. Sierro, Joan J. Fornós, Hai Cheng, and R. Lawrence Edwards
Clim. Past, 21, 465–487, https://doi.org/10.5194/cp-21-465-2025, https://doi.org/10.5194/cp-21-465-2025, 2025
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We offer a clearer view of the timing of three relevant past glacial terminations. By analyzing the climatic signal recorded in stalagmite and linking it with marine records, we revealed differences in the intensity and duration of the ice melting associated with these three key deglaciations. This study shows that some deglaciations began earlier than previously thought; this improves our understanding of natural climate processes, helping us to contextualize current climate change.
Alexander J. Clark, Ismael Torres-Romero, Madalina Jaggi, Stefano M. Bernasconi, and Heather M. Stoll
Clim. Past, 20, 2081–2101, https://doi.org/10.5194/cp-20-2081-2024, https://doi.org/10.5194/cp-20-2081-2024, 2024
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Coccoliths are abundant in sediments across the world’s oceans, yet it is difficult to apply traditional carbon or oxygen isotope methodologies for temperature reconstructions. We show that our coccolith clumped isotope temperature calibration with well-constrained temperatures systematically differs from inorganic carbonate calibrations. We suggest the use of our well-constrained calibration for future coccolith carbonate temperature reconstructions.
Nikita Kaushal, Franziska A. Lechleitner, Micah Wilhelm, Khalil Azennoud, Janica C. Bühler, Kerstin Braun, Yassine Ait Brahim, Andy Baker, Yuval Burstyn, Laia Comas-Bru, Jens Fohlmeister, Yonaton Goldsmith, Sandy P. Harrison, István G. Hatvani, Kira Rehfeld, Magdalena Ritzau, Vanessa Skiba, Heather M. Stoll, József G. Szűcs, Péter Tanos, Pauline C. Treble, Vitor Azevedo, Jonathan L. Baker, Andrea Borsato, Sakonvan Chawchai, Andrea Columbu, Laura Endres, Jun Hu, Zoltán Kern, Alena Kimbrough, Koray Koç, Monika Markowska, Belen Martrat, Syed Masood Ahmad, Carole Nehme, Valdir Felipe Novello, Carlos Pérez-Mejías, Jiaoyang Ruan, Natasha Sekhon, Nitesh Sinha, Carol V. Tadros, Benjamin H. Tiger, Sophie Warken, Annabel Wolf, Haiwei Zhang, and SISAL Working Group members
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Reconstructing past temperatures at regional scales during the Common Era is necessary to place the current warming in the context of natural climate variability. We present a climate reconstruction based on eight stalagmites from four caves in the Pyrenees, NE Spain. These stalagmites were dated precisely and analysed for their oxygen isotopes, which appear dominated by temperature changes. Solar variability and major volcanic eruptions are the two main drivers of observed climate variability.
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Stalagmites formed in caves provide valuable information about past changes in climate and vegetation conditions. In this contribution, we present a new method to better estimate past changes in soil and vegetation productivity using carbon isotopes and trace elements measured in stalagmites. Applying this method to other stalagmites should provide a better indication of past vegetation feedbacks to climate change.
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Based on the analysis of the response of coccolithophores’ morphological attributes in a laboratory dissolution experiment and surface sediment samples from the South China Sea, we proposed that the thickness shape (ks) factor of fossil coccoliths together with the normalized ks variation, which is the ratio of the standard deviation of ks (σ) over the mean ks (σ/ks), is a robust and novel proxy to reconstruct past changes in deep ocean carbon chemistry.
Jessica G. M. Crumpton-Banks, Thomas Tanner, Ivan Hernández Almeida, James W. B. Rae, and Heather Stoll
Biogeosciences, 19, 5633–5644, https://doi.org/10.5194/bg-19-5633-2022, https://doi.org/10.5194/bg-19-5633-2022, 2022
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Past ocean carbon is reconstructed using proxies, but it is unknown whether preparing ocean sediment for one proxy might damage the data given by another. We have tested whether the extraction of an organic proxy archive from sediment samples impacts the geochemistry of tiny shells also within the sediment. We find no difference in shell geochemistry between samples which come from treated and untreated sediment. This will help us to maximize scientific return from valuable sediment samples.
José Guitián, Miguel Ángel Fuertes, José-Abel Flores, Iván Hernández-Almeida, and Heather Stoll
Biogeosciences, 19, 5007–5019, https://doi.org/10.5194/bg-19-5007-2022, https://doi.org/10.5194/bg-19-5007-2022, 2022
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The effect of environmental conditions on the degree of calcification of marine phytoplankton remains unclear. This study implements a new microscopic approach to quantify the calcification of ancient coccolithophores, using North Atlantic sediments. Results show significant differences in the thickness and shape factor of coccoliths for samples with minimum dissolution, providing the first evaluation of phytoplankton physiology adaptation to million-year-scale variable environmental conditions.
Franziska A. Lechleitner, Christopher C. Day, Oliver Kost, Micah Wilhelm, Negar Haghipour, Gideon M. Henderson, and Heather M. Stoll
Clim. Past, 17, 1903–1918, https://doi.org/10.5194/cp-17-1903-2021, https://doi.org/10.5194/cp-17-1903-2021, 2021
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Soil respiration is a critical but poorly constrained component of the global carbon cycle. We analyse the effect of changing soil respiration rates on the stable carbon isotope ratio of speleothems from northern Spain covering the last deglaciation. Using geochemical analysis and forward modelling we quantify the processes affecting speleothem stable carbon isotope ratios and extract a signature of increasing soil respiration synchronous with deglacial warming.
Joseph B. Novak, Rocío P. Caballero-Gill, Timothy D. Herbert, Harry J. Dowsett, and Alfredo Martínez-García
Clim. Past, 22, 1277–1290, https://doi.org/10.5194/cp-22-1277-2026, https://doi.org/10.5194/cp-22-1277-2026, 2026
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Accurate information about the surface ocean temperatures are important for understanding Earth's climate history. Here, we correct a sea surface temperature record from the critical subarctic North Pacific region for systematic biases introduced into the algal-biomarker-based geologic temperature estimates by the analytical method used by the original study.
Celia Campa-Bousoño, Miguel Iglesias, Iñaki Vadillo, Lucía Ojeda, Jorge Pisonero, Hai Cheng, R. Lawrence Edwards, and Heather Stoll
EGUsphere, https://doi.org/10.5194/egusphere-2026-3717, https://doi.org/10.5194/egusphere-2026-3717, 2026
This preprint is open for discussion and under review for Climate of the Past (CP).
Short summary
Short summary
To understand how rainfall changed in southern Iberia during the shift from the Medieval Climate Anomaly to the Little Ice Age, we studied yearly layers preserved in a stalagmite from Ardales Cave, southern Spain. The record shows repeated shifts between wetter and drier periods, including major droughts around 1125, 1250, 1500, and 1560 CE. It also reveals intervals of more variable rainfall, suggesting changing influence from Atlantic and Mediterranean weather patterns.
Thomas Tanner, Ivan Hernandez-Almeida, Reto Wijker, Andrea K. Manirajan, Madeleine Santos, Peter Bijl, Tim van Peer, and Heather Stoll
EGUsphere, https://doi.org/10.5194/egusphere-2026-3415, https://doi.org/10.5194/egusphere-2026-3415, 2026
This preprint is open for discussion and under review for Climate of the Past (CP).
Short summary
Short summary
In this study, we examined the relationship between surface ocean temperature in the midlatitudes in both the Northern and Southern Hemispheres over a period of major Antarctic ice expansion 24 to 22 million years ago, a period when Antarctica was the only polar ice sheet. We find consistent cooling of the surface ocean in both hemispheres as ice was expanding, indicating a close coupling of global climate and polar ice caps.
Yohan Lichterfeld, Guillaume Leduc, Kaustubh Thirumalai, Laurence Vidal, Thibault de Garidel-Thoron, Corinne Sonzogni, and Clara Bolton
EGUsphere, https://doi.org/10.5194/egusphere-2026-2343, https://doi.org/10.5194/egusphere-2026-2343, 2026
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The Indian Ocean regulates global climate through heat and moisture exchanges. To understand past climate variability, we analyzed oxygen isotopes in individual fossil shells of tiny marine organisms. Combining numerical simulations, we show that shell chemistry reflects seasonal temperature changes driven by both the monsoon and the Indian Ocean Dipole. This opens new perspectives for reconstructing past climate extreme events.
Laura Endres, Carlos Pérez-Mejías, Ruza Ivanovic, Lauren Gregoire, Anna L. C. Hughes, Hai Cheng, and Heather Stoll
Clim. Past, 22, 797–824, https://doi.org/10.5194/cp-22-797-2026, https://doi.org/10.5194/cp-22-797-2026, 2026
Short summary
Short summary
Stable isotope data of a precisely dated stalagmite from northwestern Iberia indicate gradual North Atlantic meltwater input during the last glacial maximum, followed by abrupt surges early in the last deglaciation. The first abrupt surge was decoupled from first cooling about 810 years later – unlike later events – which reveals that the Atlantic circulation’s sensitivity to meltwater is variable and related to the evolving background climate boundary conditions.
Reto S. Wijker, Pere Aguiló-Nicolau, Madalina Jaggi, Jeroni Galmés, and Heather M. Stoll
Biogeosciences, 23, 1591–1608, https://doi.org/10.5194/bg-23-1591-2026, https://doi.org/10.5194/bg-23-1591-2026, 2026
Short summary
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Photosynthetic organisms leave characteristic carbon isotope fingerprints that help scientists study Earth’s carbon cycle. We developed a simpler laboratory method to measure these isotope effects in Rubisco, the key enzyme fixing CO2. Applying this approach, we obtained the first measurement for Gephyrocapsa oceanica, a widespread marine alga that plays a major role in ocean carbon cycling.
Alexander J. Clark, Alba Gonzalez-Lanchas, Kyra Bachmakova, Madalina Jaggi, and Heather M. Stoll
J. Micropalaeontol., 44, 673–692, https://doi.org/10.5194/jm-44-673-2025, https://doi.org/10.5194/jm-44-673-2025, 2025
Short summary
Short summary
We quantified the thickness of early Eocene calcareous nannofossils and linked it to different depositional environment parameters. Discoasters and placoliths do not respond in the same manner. Carbonate content affects discoasters and induces overgrowth, but palaeowater depth affects placoliths and can induce dissolution. We also find that the ratio of non-overgrown to overgrown Discoaster multiradiatus is a potential quantitative placolith preservation indicator.
Medhavi Srivastava, Clara T. Bolton, Luc Beaufort, Franck Bassinot, and Katarína Holcová
J. Micropalaeontol., 44, 555–571, https://doi.org/10.5194/jm-44-555-2025, https://doi.org/10.5194/jm-44-555-2025, 2025
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The Bay of Bengal is a unique region influenced by the Asian monsoon. We present a record of past ocean productivity and carbonate flux based on the fossil remains of calcifying algae over the last 279 000 years from a core in the northern Bay of Bengal. We used AI microscopy to count and measure plankton fossils and identify species. Results show that coccolith export, including of the species Florisphaera profunda, is highest when the monsoon is weak and the water column is more mixed.
Nicolas Tapia, Laura Endres, Madalina Jaggi, and Heather Stoll
Biogeosciences, 22, 6861–6875, https://doi.org/10.5194/bg-22-6861-2025, https://doi.org/10.5194/bg-22-6861-2025, 2025
Short summary
Short summary
We use stalagmites to study past changes in the terrestrial P cycle. Our P records from multiple, coeval stalagmites from Northwest Spain show that the onsets of past abrupt cooling events are characterized by multi-century reproducible peaks in stalagmite P which reflect higher groundwater P/Ca concentrations and enhanced P export, potentially resulting from increased freeze-thaw frequency and more intense infiltration from snowmelt.
José Guitián, Samuel Phelps, Reto S. Wijker, Pratigya J. Polissar, Laura Arnold, and Heather M. Stoll
Clim. Past, 21, 2115–2132, https://doi.org/10.5194/cp-21-2115-2025, https://doi.org/10.5194/cp-21-2115-2025, 2025
Short summary
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We reconstructed from sediments of different ocean sites phytoplankton carbon isotopic fractionation (εp), mainly linked to CO2 variations, during the Oligocene to early Miocene. Data confirm Cenozoic long-term CO2 record but show contrasting relationships with the sea surface temperatures evolution. We evaluate the role of non-CO2 environmental factors such as temperature and nutrients at each site εp, highlighting the complexity of interpreting climate dynamics and CO2 reconstructions.
Jasmine S. Berg, Paula C. Rodriguez, Cara Magnabosco, Longhui Deng, Stefano M. Bernasconi, Hendrik Vogel, Marina Morlock, and Mark A. Lever
Biogeosciences, 22, 5483–5496, https://doi.org/10.5194/bg-22-5483-2025, https://doi.org/10.5194/bg-22-5483-2025, 2025
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Our research explores microbial sulfur cycling in the 13 500-year-old sediment record of a sulfate-rich alpine lake. We present evidence for active sulfur cycling across sediment layers, even in sulfate-depleted zones, driven by uncultivated microorganisms. In addition, rapid organic matter sulfurization could contribute to its preservation. These findings enhance our understanding of the role of sulfur in organic matter preservation and deep biosphere processes.
Nikita Kaushal, Carlos Pérez-Mejías, and Heather M. Stoll
Clim. Past, 21, 1633–1660, https://doi.org/10.5194/cp-21-1633-2025, https://doi.org/10.5194/cp-21-1633-2025, 2025
Short summary
Short summary
Terminations are large-magnitude rapid events triggered in the North Atlantic region that manifest across the global climate system. They provide key examples of climatic teleconnections and dynamics. In this study, we use the SISAL global speleothem database and find that there are sufficient climatic records from key locations to make speleothems a valuable archive for studying terminations and provide instances for more targeted work on speleothem research.
Alexandra Auderset, Sandi M. Smart, Yeongjun Ryu, Dario Marconi, Haojia Abby Ren, Lena Heins, Hubert Vonhof, Ralf Schiebel, Janne Repschläger, Daniel M. Sigman, Gerald H. Haug, and Alfredo Martínez-García
Biogeosciences, 22, 1887–1905, https://doi.org/10.5194/bg-22-1887-2025, https://doi.org/10.5194/bg-22-1887-2025, 2025
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This study uses foraminifera-bound nitrogen isotopes (FB-δ15N) to investigate photosymbiosis in planktic foraminifera. The analysis of South Atlantic shells, compared to a global dataset, shows that FB-δ15N distinguishes species with certain algal symbionts (dinoflagellates), likely due to internal ammonium recycling. However, the studied site stands out with its larger-than-expected FB-δ15N offsets, highlighting influences on FB-δ15N signatures in regions with strong environmental gradients.
Babette A.A. Hoogakker, Catherine Davis, Yi Wang, Stephanie Kusch, Katrina Nilsson-Kerr, Dalton S. Hardisty, Allison Jacobel, Dharma Reyes Macaya, Nicolaas Glock, Sha Ni, Julio Sepúlveda, Abby Ren, Alexandra Auderset, Anya V. Hess, Katrin J. Meissner, Jorge Cardich, Robert Anderson, Christine Barras, Chandranath Basak, Harold J. Bradbury, Inda Brinkmann, Alexis Castillo, Madelyn Cook, Kassandra Costa, Constance Choquel, Paula Diz, Jonas Donnenfield, Felix J. Elling, Zeynep Erdem, Helena L. Filipsson, Sebastián Garrido, Julia Gottschalk, Anjaly Govindankutty Menon, Jeroen Groeneveld, Christian Hallmann, Ingrid Hendy, Rick Hennekam, Wanyi Lu, Jean Lynch-Stieglitz, Lélia Matos, Alfredo Martínez-García, Giulia Molina, Práxedes Muñoz, Simone Moretti, Jennifer Morford, Sophie Nuber, Svetlana Radionovskaya, Morgan Reed Raven, Christopher J. Somes, Anja S. Studer, Kazuyo Tachikawa, Raúl Tapia, Martin Tetard, Tyler Vollmer, Xingchen Wang, Shuzhuang Wu, Yan Zhang, Xin-Yuan Zheng, and Yuxin Zhou
Biogeosciences, 22, 863–957, https://doi.org/10.5194/bg-22-863-2025, https://doi.org/10.5194/bg-22-863-2025, 2025
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Paleo-oxygen proxies can extend current records, constrain pre-anthropogenic baselines, provide datasets necessary to test climate models under different boundary conditions, and ultimately understand how ocean oxygenation responds on longer timescales. Here we summarize current proxies used for the reconstruction of Cenozoic seawater oxygen levels. This includes an overview of the proxy's history, how it works, resources required, limitations, and future recommendations.
Judit Torner, Isabel Cacho, Heather Stoll, Ana Moreno, Joan O. Grimalt, Francisco J. Sierro, Joan J. Fornós, Hai Cheng, and R. Lawrence Edwards
Clim. Past, 21, 465–487, https://doi.org/10.5194/cp-21-465-2025, https://doi.org/10.5194/cp-21-465-2025, 2025
Short summary
Short summary
We offer a clearer view of the timing of three relevant past glacial terminations. By analyzing the climatic signal recorded in stalagmite and linking it with marine records, we revealed differences in the intensity and duration of the ice melting associated with these three key deglaciations. This study shows that some deglaciations began earlier than previously thought; this improves our understanding of natural climate processes, helping us to contextualize current climate change.
Alexander J. Clark, Ismael Torres-Romero, Madalina Jaggi, Stefano M. Bernasconi, and Heather M. Stoll
Clim. Past, 20, 2081–2101, https://doi.org/10.5194/cp-20-2081-2024, https://doi.org/10.5194/cp-20-2081-2024, 2024
Short summary
Short summary
Coccoliths are abundant in sediments across the world’s oceans, yet it is difficult to apply traditional carbon or oxygen isotope methodologies for temperature reconstructions. We show that our coccolith clumped isotope temperature calibration with well-constrained temperatures systematically differs from inorganic carbonate calibrations. We suggest the use of our well-constrained calibration for future coccolith carbonate temperature reconstructions.
Nikita Kaushal, Franziska A. Lechleitner, Micah Wilhelm, Khalil Azennoud, Janica C. Bühler, Kerstin Braun, Yassine Ait Brahim, Andy Baker, Yuval Burstyn, Laia Comas-Bru, Jens Fohlmeister, Yonaton Goldsmith, Sandy P. Harrison, István G. Hatvani, Kira Rehfeld, Magdalena Ritzau, Vanessa Skiba, Heather M. Stoll, József G. Szűcs, Péter Tanos, Pauline C. Treble, Vitor Azevedo, Jonathan L. Baker, Andrea Borsato, Sakonvan Chawchai, Andrea Columbu, Laura Endres, Jun Hu, Zoltán Kern, Alena Kimbrough, Koray Koç, Monika Markowska, Belen Martrat, Syed Masood Ahmad, Carole Nehme, Valdir Felipe Novello, Carlos Pérez-Mejías, Jiaoyang Ruan, Natasha Sekhon, Nitesh Sinha, Carol V. Tadros, Benjamin H. Tiger, Sophie Warken, Annabel Wolf, Haiwei Zhang, and SISAL Working Group members
Earth Syst. Sci. Data, 16, 1933–1963, https://doi.org/10.5194/essd-16-1933-2024, https://doi.org/10.5194/essd-16-1933-2024, 2024
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Speleothems are a popular, multi-proxy climate archive that provide regional to global insights into past hydroclimate trends with precise chronologies. We present an update to the SISAL (Speleothem Isotopes
Synthesis and AnaLysis) database, SISALv3, which, for the first time, contains speleothem trace element records, in addition to an update to the stable isotope records available in previous versions of the database, cumulatively providing data from 365 globally distributed sites.
Synthesis and AnaLysis) database, SISALv3, which, for the first time, contains speleothem trace element records, in addition to an update to the stable isotope records available in previous versions of the database, cumulatively providing data from 365 globally distributed sites.
Paul D. Zander, Daniel Böhl, Frank Sirocko, Alexandra Auderset, Gerald H. Haug, and Alfredo Martínez-García
Clim. Past, 20, 841–864, https://doi.org/10.5194/cp-20-841-2024, https://doi.org/10.5194/cp-20-841-2024, 2024
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Bacterial lipids (branched glycerol dialkyl glycerol tetraethers; brGDGTs) extracted from lake sediments were used to reconstruct warm-season temperatures in central Europe during the past 60 kyr. Modern samples were used to test and correct for bias related to varying sources of brGDGTs. The temperature reconstruction is significantly correlated with other temperature reconstructions but features less millennial-scale variability, which is attributed to the seasonal signal of the proxy.
Miguel Bartolomé, Ana Moreno, Carlos Sancho, Isabel Cacho, Heather Stoll, Negar Haghipour, Ánchel Belmonte, Christoph Spötl, John Hellstrom, R. Lawrence Edwards, and Hai Cheng
Clim. Past, 20, 467–494, https://doi.org/10.5194/cp-20-467-2024, https://doi.org/10.5194/cp-20-467-2024, 2024
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Reconstructing past temperatures at regional scales during the Common Era is necessary to place the current warming in the context of natural climate variability. We present a climate reconstruction based on eight stalagmites from four caves in the Pyrenees, NE Spain. These stalagmites were dated precisely and analysed for their oxygen isotopes, which appear dominated by temperature changes. Solar variability and major volcanic eruptions are the two main drivers of observed climate variability.
Heather M. Stoll, Leopoldo D. Pena, Ivan Hernandez-Almeida, José Guitián, Thomas Tanner, and Heiko Pälike
Clim. Past, 20, 25–36, https://doi.org/10.5194/cp-20-25-2024, https://doi.org/10.5194/cp-20-25-2024, 2024
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The Oligocene and early Miocene periods featured dynamic glacial cycles on Antarctica. In this paper, we use Sr isotopes in marine carbonate sediments to document a change in the location and intensity of continental weathering during short periods of very intense Antarctic glaciation. Potentially, the weathering intensity of old continental rocks on Antarctica was reduced during glaciation. We also show improved age models for correlation of Southern Ocean and North Atlantic sediments.
Heather M. Stoll, Chris Day, Franziska Lechleitner, Oliver Kost, Laura Endres, Jakub Sliwinski, Carlos Pérez-Mejías, Hai Cheng, and Denis Scholz
Clim. Past, 19, 2423–2444, https://doi.org/10.5194/cp-19-2423-2023, https://doi.org/10.5194/cp-19-2423-2023, 2023
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Stalagmites formed in caves provide valuable information about past changes in climate and vegetation conditions. In this contribution, we present a new method to better estimate past changes in soil and vegetation productivity using carbon isotopes and trace elements measured in stalagmites. Applying this method to other stalagmites should provide a better indication of past vegetation feedbacks to climate change.
Oliver Kost, Saúl González-Lemos, Laura Rodríguez-Rodríguez, Jakub Sliwinski, Laura Endres, Negar Haghipour, and Heather Stoll
Hydrol. Earth Syst. Sci., 27, 2227–2255, https://doi.org/10.5194/hess-27-2227-2023, https://doi.org/10.5194/hess-27-2227-2023, 2023
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Cave monitoring studies including cave drip water are unique opportunities to sample water which has percolated through the soil and rock. The change in drip water chemistry is resolved over the course of 16 months, inferring seasonal and hydrological variations in soil and karst processes at the water–air and water–rock interface. Such data sets improve the understanding of hydrological and hydrochemical processes and ultimately advance the interpretation of geochemical stalagmite records.
Amanda Gerotto, Hongrui Zhang, Renata Hanae Nagai, Heather M. Stoll, Rubens César Lopes Figueira, Chuanlian Liu, and Iván Hernández-Almeida
Biogeosciences, 20, 1725–1739, https://doi.org/10.5194/bg-20-1725-2023, https://doi.org/10.5194/bg-20-1725-2023, 2023
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Based on the analysis of the response of coccolithophores’ morphological attributes in a laboratory dissolution experiment and surface sediment samples from the South China Sea, we proposed that the thickness shape (ks) factor of fossil coccoliths together with the normalized ks variation, which is the ratio of the standard deviation of ks (σ) over the mean ks (σ/ks), is a robust and novel proxy to reconstruct past changes in deep ocean carbon chemistry.
Jessica G. M. Crumpton-Banks, Thomas Tanner, Ivan Hernández Almeida, James W. B. Rae, and Heather Stoll
Biogeosciences, 19, 5633–5644, https://doi.org/10.5194/bg-19-5633-2022, https://doi.org/10.5194/bg-19-5633-2022, 2022
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Past ocean carbon is reconstructed using proxies, but it is unknown whether preparing ocean sediment for one proxy might damage the data given by another. We have tested whether the extraction of an organic proxy archive from sediment samples impacts the geochemistry of tiny shells also within the sediment. We find no difference in shell geochemistry between samples which come from treated and untreated sediment. This will help us to maximize scientific return from valuable sediment samples.
José Guitián, Miguel Ángel Fuertes, José-Abel Flores, Iván Hernández-Almeida, and Heather Stoll
Biogeosciences, 19, 5007–5019, https://doi.org/10.5194/bg-19-5007-2022, https://doi.org/10.5194/bg-19-5007-2022, 2022
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The effect of environmental conditions on the degree of calcification of marine phytoplankton remains unclear. This study implements a new microscopic approach to quantify the calcification of ancient coccolithophores, using North Atlantic sediments. Results show significant differences in the thickness and shape factor of coccoliths for samples with minimum dissolution, providing the first evaluation of phytoplankton physiology adaptation to million-year-scale variable environmental conditions.
Clara T. Bolton, Emmeline Gray, Wolfgang Kuhnt, Ann E. Holbourn, Julia Lübbers, Katharine Grant, Kazuyo Tachikawa, Gianluca Marino, Eelco J. Rohling, Anta-Clarisse Sarr, and Nils Andersen
Clim. Past, 18, 713–738, https://doi.org/10.5194/cp-18-713-2022, https://doi.org/10.5194/cp-18-713-2022, 2022
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The timing of the initiation and evolution of the South Asian monsoon in the geological past is a subject of debate. Here, we present a new age model spanning the late Miocene (9 to 5 million years ago) and high-resolution records of past open-ocean biological productivity from the equatorial Indian Ocean that we interpret to reflect monsoon wind strength. Our data show no long-term intensification; however, strong orbital periodicities suggest insolation forcing of monsoon wind strength.
Franziska A. Lechleitner, Christopher C. Day, Oliver Kost, Micah Wilhelm, Negar Haghipour, Gideon M. Henderson, and Heather M. Stoll
Clim. Past, 17, 1903–1918, https://doi.org/10.5194/cp-17-1903-2021, https://doi.org/10.5194/cp-17-1903-2021, 2021
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Soil respiration is a critical but poorly constrained component of the global carbon cycle. We analyse the effect of changing soil respiration rates on the stable carbon isotope ratio of speleothems from northern Spain covering the last deglaciation. Using geochemical analysis and forward modelling we quantify the processes affecting speleothem stable carbon isotope ratios and extract a signature of increasing soil respiration synchronous with deglacial warming.
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Short summary
In periods of high atmospheric CO2 many proxies suggest more extreme past polar warming than is simulated by current coupled climate models. Providing new data on high latitude temperatures in the South Atlantic over the last 15 million years using clumped isotope thermometry, we show that absolute temperatures may not have been as warm as indicated by some biomarker based proxy climate records.
In periods of high atmospheric CO2 many proxies suggest more extreme past polar warming than is...
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