Articles | Volume 9, issue 2
https://doi.org/10.5194/cp-9-859-2013
© Author(s) 2013. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
https://doi.org/10.5194/cp-9-859-2013
© Author(s) 2013. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
Research article
| 
22 Mar 2013
Research article |
| 22 Mar 2013
Mismatch between the depth habitat of planktonic foraminifera and the calibration depth of SST transfer functions may bias reconstructions
R. J. Telford
Department of Biology, University of Bergen, Thormøhlensgate 53A, 5006 Bergen, Norway
Bjerknes Centre for Climate Research, Allégaten 55, 5007 Bergen, Norway
Bjerknes Centre for Climate Research, Allégaten 55, 5007 Bergen, Norway
Geophysical Institute, University of Bergen, Allégaten 70, 5008 Bergen, Norway
M. Kucera
MARUM & Fachbereich Geowissenschaften, Universität Bremen, Leobener Strasse, 28359 Bremen, Germany
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J. Micropalaeontol., 37, 519–534, https://doi.org/10.5194/jm-37-519-2018, https://doi.org/10.5194/jm-37-519-2018, 2018
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In this study we investigate consistency in species-level identifications and whether disagreements are predictable. Overall, 21 researchers from across the globe identified sets of 300 specimens or digital images of planktonic foraminifera. Digital identifications tended to be more disparate. Participants trained by the same person often had more similar identifications. Disagreements hardly affected transfer-function temperature estimates but produced larger differences in diversity metrics.
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Strong disagreement exists in the scientific community over the role of Arctic sea ice in shaping wintertime Eurasian cooling. The observed Eurasian cooling can arise naturally without sea-ice loss but is expected to be a rare event. We propose a framework that incorporates sea-ice retreat and natural variability as contributing factors. A helpful analogy is of a dice roll that may result in cooling, warming, or anything in between, with sea-ice loss acting to load the dice in favour of cooling.
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Weather Clim. Dynam., 4, 61–80, https://doi.org/10.5194/wcd-4-61-2023, https://doi.org/10.5194/wcd-4-61-2023, 2023
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To aid researchers working with living planktonic foraminifera, we provide a comprehensive review of names that we consider appropriate for extant species. We discuss the reasons for the decisions we made and provide a list of species and genus-level names as well as other names that have been used in the past but are considered inappropriate for living taxa, stating the reasons.
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Lukas Jonkers, Olivier Cartapanis, Michael Langner, Nick McKay, Stefan Mulitza, Anne Strack, and Michal Kucera
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Anna Jentzen, Joachim Schönfeld, Agnes K. M. Weiner, Manuel F. G. Weinkauf, Dirk Nürnberg, and Michal Kučera
J. Micropalaeontol., 38, 231–247, https://doi.org/10.5194/jm-38-231-2019, https://doi.org/10.5194/jm-38-231-2019, 2019
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The study assessed the population dynamics of living planktic foraminifers on a weekly, seasonal, and interannual timescale off the coast of Puerto Rico to improve our understanding of short- and long-term variations. The results indicate a seasonal change of the faunal composition, and over the last decades. Lower standing stocks and lower stable carbon isotope values of foraminifers in shallow waters can be linked to the hurricane Sandy, which passed the Greater Antilles during autumn 2012.
Lise S. Graff, Trond Iversen, Ingo Bethke, Jens B. Debernard, Øyvind Seland, Mats Bentsen, Alf Kirkevåg, Camille Li, and Dirk J. L. Olivié
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Differences between a 1.5 and a 2.0 °C warmer global climate than 1850 conditions are discussed based on a suite of global atmosphere-only, fully coupled, and slab-ocean runs with the Norwegian Earth System Model. Responses, such as the Arctic amplification of global warming, are stronger with the fully coupled and slab-ocean configurations. While ice-free Arctic summers are rare under 1.5 °C warming in the slab-ocean runs, they are estimated to occur 18 % of the time under 2.0 °C warming.
Mattia Greco, Lukas Jonkers, Kerstin Kretschmer, Jelle Bijma, and Michal Kucera
Biogeosciences, 16, 3425–3437, https://doi.org/10.5194/bg-16-3425-2019, https://doi.org/10.5194/bg-16-3425-2019, 2019
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To be able to interpret the paleoecological signal contained in N. pachyderma's shells, its habitat depth must be known. Our investigation on 104 density profiles of this species from the Arctic and North Atlantic shows that specimens reside closer to the surface when sea-ice and/or surface chlorophyll concentrations are high. This is in contrast with previous investigations that pointed at the position of the deep chlorophyll maximum as the main driver of N. pachyderma vertical distribution.
Haruka Takagi, Katsunori Kimoto, Tetsuichi Fujiki, Hiroaki Saito, Christiane Schmidt, Michal Kucera, and Kazuyoshi Moriya
Biogeosciences, 16, 3377–3396, https://doi.org/10.5194/bg-16-3377-2019, https://doi.org/10.5194/bg-16-3377-2019, 2019
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Photosymbiosis (endosymbiosis with algae) is an evolutionary important ecology for many marine organisms but has poorly been identified among planktonic foraminifera. In this study, we identified and characterized photosymbiosis of various species of planktonic foraminifera by focusing on their photosynthesis–related features. We finally proposed a new framework showing a potential strength of photosymbiosis, which will serve as a basis for future ecological studies of planktonic foraminifera.
Andreia Rebotim, Antje Helga Luise Voelker, Lukas Jonkers, Joanna J. Waniek, Michael Schulz, and Michal Kucera
J. Micropalaeontol., 38, 113–131, https://doi.org/10.5194/jm-38-113-2019, https://doi.org/10.5194/jm-38-113-2019, 2019
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To reconstruct subsurface water conditions using deep-dwelling planktonic foraminifera, we must fully understand how the oxygen isotope signal incorporates into their shell. We report δ18O in four species sampled in the eastern North Atlantic with plankton tows. We assess the size and crust effect on the isotopic δ18O and compared them with predictions from two equations. We reveal different patterns of calcite addition with depth, highlighting the need to perform species-specific calibrations.
Lukas Jonkers and Michal Kučera
Clim. Past, 15, 881–891, https://doi.org/10.5194/cp-15-881-2019, https://doi.org/10.5194/cp-15-881-2019, 2019
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Fossil plankton assemblages have been widely used to reconstruct SST. In such approaches, full taxonomic resolution is often used. We assess whether this is required for reliable reconstructions as some species may not respond to SST. We find that only a few species are needed for low reconstruction errors but that species selection has a pronounced effect on reconstructions. We suggest that the sensitivity of a reconstruction to species pruning can be used as a measure of its robustness.
Nadia Al-Sabouni, Isabel S. Fenton, Richard J. Telford, and Michal Kučera
J. Micropalaeontol., 37, 519–534, https://doi.org/10.5194/jm-37-519-2018, https://doi.org/10.5194/jm-37-519-2018, 2018
Short summary
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In this study we investigate consistency in species-level identifications and whether disagreements are predictable. Overall, 21 researchers from across the globe identified sets of 300 specimens or digital images of planktonic foraminifera. Digital identifications tended to be more disparate. Participants trained by the same person often had more similar identifications. Disagreements hardly affected transfer-function temperature estimates but produced larger differences in diversity metrics.
Kerstin Kretschmer, Lukas Jonkers, Michal Kucera, and Michael Schulz
Biogeosciences, 15, 4405–4429, https://doi.org/10.5194/bg-15-4405-2018, https://doi.org/10.5194/bg-15-4405-2018, 2018
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The fossil shells of planktonic foraminifera are widely used to reconstruct past climate conditions. To do so, information about their seasonal and vertical habitat is needed. Here we present an updated version of a planktonic foraminifera model to better understand species-specific habitat dynamics under climate change. This model produces spatially and temporally coherent distribution patterns, which agree well with available observations, and can thus aid the interpretation of proxy records.
Zhongshi Zhang, Qing Yan, Elizabeth J. Farmer, Camille Li, Gilles Ramstein, Terence Hughes, Martin Jakobsson, Matt O'Regan, Ran Zhang, Ning Tan, Camille Contoux, Christophe Dumas, and Chuncheng Guo
Clim. Past Discuss., https://doi.org/10.5194/cp-2018-79, https://doi.org/10.5194/cp-2018-79, 2018
Revised manuscript not accepted
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Our study challenges the widely accepted idea that the Laurentide-Eurasian ice sheets gradually extended across North America and Northwest Eurasia, and suggests the growth of the NH ice sheets is much more complicated. We find climate feedbacks regulate the distribution of the NH ice sheets, producing swings between two distinct ice sheet configurations: the Laurentide-Eurasian and a circum-Arctic configuration, where large ice sheets existed over Northeast Siberia and the Canadian Rockies.
Camille Li, Clio Michel, Lise Seland Graff, Ingo Bethke, Giuseppe Zappa, Thomas J. Bracegirdle, Erich Fischer, Ben J. Harvey, Trond Iversen, Martin P. King, Harinarayan Krishnan, Ludwig Lierhammer, Daniel Mitchell, John Scinocca, Hideo Shiogama, Dáithí A. Stone, and Justin J. Wettstein
Earth Syst. Dynam., 9, 359–382, https://doi.org/10.5194/esd-9-359-2018, https://doi.org/10.5194/esd-9-359-2018, 2018
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This study investigates the midlatitude atmospheric circulation response to 1.5°C and 2.0°C of warming using modelling experiments run for the HAPPI project (Half a degree Additional warming, Prognosis & Projected Impacts). While the chaotic nature of the atmospheric flow dominates in these low-end warming scenarios, some local changes emerge. Case studies explore precipitation impacts both for regions that dry (Mediterranean) and regions that get wetter (Europe, North American west coast).
Raphaël Morard, Franck Lejzerowicz, Kate F. Darling, Béatrice Lecroq-Bennet, Mikkel Winther Pedersen, Ludovic Orlando, Jan Pawlowski, Stefan Mulitza, Colomban de Vargas, and Michal Kucera
Biogeosciences, 14, 2741–2754, https://doi.org/10.5194/bg-14-2741-2017, https://doi.org/10.5194/bg-14-2741-2017, 2017
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The exploitation of deep-sea sedimentary archive relies on the recovery of mineralized skeletons of pelagic organisms. Planktonic groups leaving preserved remains represent only a fraction of the total marine diversity. Environmental DNA left by non-fossil organisms is a promising source of information for paleo-reconstructions. Here we show how planktonic-derived environmental DNA preserves ecological structure of planktonic communities. We use planktonic foraminifera as a case study.
Lukas Jonkers and Michal Kučera
Clim. Past, 13, 573–586, https://doi.org/10.5194/cp-13-573-2017, https://doi.org/10.5194/cp-13-573-2017, 2017
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Planktonic foraminifera – the most important proxy carriers in palaeoceanography – adjust their seasonal and vertical habitat. They are thought to do so in a way that minimises the change in their environment, implying that proxy records based on these organisms may not capture the full amplitude of past climate change. Here we demonstrate that they indeed track a particular thermal habitat and suggest that this could lead to a 40 % underestimation of reconstructed temperature change.
Philipp M. Munz, Stephan Steinke, Anna Böll, Andreas Lückge, Jeroen Groeneveld, Michal Kucera, and Hartmut Schulz
Clim. Past, 13, 491–509, https://doi.org/10.5194/cp-13-491-2017, https://doi.org/10.5194/cp-13-491-2017, 2017
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We present the results of several independent proxies of summer SST and upwelling SST from the Oman margin indicative of monsoon strength during the early Holocene. In combination with indices of carbonate preservation and bottom water redox conditions, we demonstrate that a persistent solar influence was modulating summer monsoon intensity. Furthermore, bottom water conditions are linked to atmospheric forcing, rather than changes of intermediate water masses.
Andreia Rebotim, Antje H. L. Voelker, Lukas Jonkers, Joanna J. Waniek, Helge Meggers, Ralf Schiebel, Igaratza Fraile, Michael Schulz, and Michal Kucera
Biogeosciences, 14, 827–859, https://doi.org/10.5194/bg-14-827-2017, https://doi.org/10.5194/bg-14-827-2017, 2017
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Planktonic foraminifera species depth habitat remains poorly constrained and the existing conceptual models are not sufficiently tested by observational data. Here we present a synthesis of living planktonic foraminifera abundance data in the subtropical eastern North Atlantic from vertical plankton tows. We also test potential environmental factors influencing the species depth habitat and investigate yearly or lunar migration cycles. These findings may impact paleoceanographic studies.
Kira Rehfeld, Mathias Trachsel, Richard J. Telford, and Thomas Laepple
Clim. Past, 12, 2255–2270, https://doi.org/10.5194/cp-12-2255-2016, https://doi.org/10.5194/cp-12-2255-2016, 2016
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Indirect evidence on past climate comes from the former composition of ecological communities such as plants, preserved as pollen grains in sediments of lakes. Transfer functions convert relative counts of species to a climatologically meaningful scale (e.g. annual mean temperature in degrees C). We show that the fundamental assumptions in the algorithms impact the reconstruction results in he idealized model world, in particular if the reconstructed variables were not ecologically relevant.
Mathias Trachsel and Richard J. Telford
Clim. Past, 12, 1215–1223, https://doi.org/10.5194/cp-12-1215-2016, https://doi.org/10.5194/cp-12-1215-2016, 2016
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In spatially structured environments, conventional cross validation results in over-optimistic transfer function performance estimates. H-block cross validation, where all samples within h kilometres of the test samples are omitted is a method for obtaining unbiased transfer function performance estimates. We assess three methods for determining the optimal h using simulated data and published transfer functions. Some transfer functions perform notably worse when h-block cross validation is used.
L. Jonkers and M. Kučera
Biogeosciences, 12, 2207–2226, https://doi.org/10.5194/bg-12-2207-2015, https://doi.org/10.5194/bg-12-2207-2015, 2015
I. Hessler, S. P. Harrison, M. Kucera, C. Waelbroeck, M.-T. Chen, C. Anderson, A. de Vernal, B. Fréchette, A. Cloke-Hayes, G. Leduc, and L. Londeix
Clim. Past, 10, 2237–2252, https://doi.org/10.5194/cp-10-2237-2014, https://doi.org/10.5194/cp-10-2237-2014, 2014
A. J. Enge, U. Witte, M. Kucera, and P. Heinz
Biogeosciences, 11, 2017–2026, https://doi.org/10.5194/bg-11-2017-2014, https://doi.org/10.5194/bg-11-2017-2014, 2014
M. F. G. Weinkauf, T. Moller, M. C. Koch, and M. Kučera
Biogeosciences, 10, 6639–6655, https://doi.org/10.5194/bg-10-6639-2013, https://doi.org/10.5194/bg-10-6639-2013, 2013
Y. Milker, R. Rachmayani, M. F. G. Weinkauf, M. Prange, M. Raitzsch, M. Schulz, and M. Kučera
Clim. Past, 9, 2231–2252, https://doi.org/10.5194/cp-9-2231-2013, https://doi.org/10.5194/cp-9-2231-2013, 2013
Related subject area
Subject: Proxy Use-Development-Validation | Archive: Marine Archives | Timescale: Pleistocene
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Contrasting late-glacial paleoceanographic evolution between the upper and lower continental slope of the western South Atlantic
Modal shift in North Atlantic seasonality during the last deglaciation
Technical note: PaleoDataView – a software toolbox for the collection, homogenization and visualization of marine proxy data
Sensitivity to species selection indicates the effect of nuisance variables on marine microfossil transfer functions
Insensitivity of alkenone carbon isotopes to atmospheric CO2 at low to moderate CO2 levels
Extreme lowering of deglacial seawater radiocarbon recorded by both epifaunal and infaunal benthic foraminifera in a wood-dated sediment core
A Late Quaternary climate record based on long-chain diol proxies from the Chilean margin
Moving beyond the age–depth model paradigm in deep-sea palaeoclimate archives: dual radiocarbon and stable isotope analysis on single foraminifera
Quantifying the effect of seasonal and vertical habitat tracking on planktonic foraminifera proxies
Water and carbon stable isotope records from natural archives: a new database and interactive online platform for data browsing, visualizing and downloading
Palaeo-sea-level and palaeo-ice-sheet databases: problems, strategies, and perspectives
Multiproxy reconstruction for Kuroshio responses to northern hemispheric oceanic climate and the Asian Monsoon since Marine Isotope Stage 5.1 (∼88 ka)
Hydrographic changes in the Agulhas Recirculation Region during the late Quaternary
Salinity changes in the Agulhas leakage area recorded by stable hydrogen isotopes of C37 alkenones during Termination I and II
Werner Ehrmann, Paul A. Wilson, Helge W. Arz, Hartmut Schulz, and Gerhard Schmiedl
Clim. Past, 20, 37–52, https://doi.org/10.5194/cp-20-37-2024, https://doi.org/10.5194/cp-20-37-2024, 2024
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Climatic and associated hydrological changes controlled the aeolian versus fluvial transport processes and the composition of the sediments in the central Red Sea through the last ca. 200 kyr. We identify source areas of the mineral dust and pulses of fluvial discharge based on high-resolution grain size, clay mineral, and geochemical data, together with Nd and Sr isotope data. We provide a detailed reconstruction of changes in aridity/humidity.
Elwyn de la Vega, Thomas B. Chalk, Mathis P. Hain, Megan R. Wilding, Daniel Casey, Robin Gledhill, Chongguang Luo, Paul A. Wilson, and Gavin L. Foster
Clim. Past, 19, 2493–2510, https://doi.org/10.5194/cp-19-2493-2023, https://doi.org/10.5194/cp-19-2493-2023, 2023
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We evaluate how faithfully the boron isotope composition of foraminifera records atmospheric CO2 by comparing it to the high-fidelity CO2 record from the Antarctic ice cores. We evaluate potential factors and find that partial dissolution of foraminifera shells, assumptions of seawater chemistry, and the biology of foraminifera all have a negligible effect on reconstructed CO2. This gives confidence in the use of boron isotopes beyond the interval when ice core CO2 is available.
Taehee Lee, Devin Rand, Lorraine E. Lisiecki, Geoffrey Gebbie, and Charles Lawrence
Clim. Past, 19, 1993–2012, https://doi.org/10.5194/cp-19-1993-2023, https://doi.org/10.5194/cp-19-1993-2023, 2023
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Understanding of past climate change depends, in part, on how accurately we can estimate the ages of events recorded in geologic archives. Here we present a new software package, called BIGMACS, to improve age estimates for paleoclimate data from ocean sediment cores. BIGMACS creates multiproxy age estimates that reduce age uncertainty by probabilistically combining information from direct age estimates, such as radiocarbon dates, and the alignment of regional paleoclimate time series.
Jesse R. Farmer, Katherine J. Keller, Robert K. Poirier, Gary S. Dwyer, Morgan F. Schaller, Helen K. Coxall, Matt O'Regan, and Thomas M. Cronin
Clim. Past, 19, 555–578, https://doi.org/10.5194/cp-19-555-2023, https://doi.org/10.5194/cp-19-555-2023, 2023
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Oxygen isotopes are used to date marine sediments via similar large-scale ocean patterns over glacial cycles. However, the Arctic Ocean exhibits a different isotope pattern, creating uncertainty in the timing of past Arctic climate change. We find that the Arctic Ocean experienced large local oxygen isotope changes over glacial cycles. We attribute this to a breakdown of stratification during ice ages that allowed for a unique low isotope value to characterize the ice age Arctic Ocean.
Xavier Crosta, Karen E. Kohfeld, Helen C. Bostock, Matthew Chadwick, Alice Du Vivier, Oliver Esper, Johan Etourneau, Jacob Jones, Amy Leventer, Juliane Müller, Rachael H. Rhodes, Claire S. Allen, Pooja Ghadi, Nele Lamping, Carina B. Lange, Kelly-Anne Lawler, David Lund, Alice Marzocchi, Katrin J. Meissner, Laurie Menviel, Abhilash Nair, Molly Patterson, Jennifer Pike, Joseph G. Prebble, Christina Riesselman, Henrik Sadatzki, Louise C. Sime, Sunil K. Shukla, Lena Thöle, Maria-Elena Vorrath, Wenshen Xiao, and Jiao Yang
Clim. Past, 18, 1729–1756, https://doi.org/10.5194/cp-18-1729-2022, https://doi.org/10.5194/cp-18-1729-2022, 2022
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Despite its importance in the global climate, our knowledge of Antarctic sea-ice changes throughout the last glacial–interglacial cycle is extremely limited. As part of the Cycles of Sea Ice Dynamics in the Earth system (C-SIDE) Working Group, we review marine- and ice-core-based sea-ice proxies to provide insights into their applicability and limitations. By compiling published records, we provide information on Antarctic sea-ice dynamics over the past 130 000 years.
Dakota E. Holmes, Tali L. Babila, Ulysses Ninnemann, Gordon Bromley, Shane Tyrrell, Greig A. Paterson, Michelle J. Curran, and Audrey Morley
Clim. Past, 18, 989–1009, https://doi.org/10.5194/cp-18-989-2022, https://doi.org/10.5194/cp-18-989-2022, 2022
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Our proxy-based observations of the glacial inception following MIS 11 advance our mechanistic understanding of (and elucidates antecedent conditions that can lead to) high-magnitude climate instability during low- and intermediate-ice boundary conditions. We find that irrespective of the magnitude of climate variability or boundary conditions, the reorganization between Polar Water and Atlantic Water at subpolar latitudes appears to influence deep-water flow in the Nordic Seas.
Camille Godbillot, Fabrice Minoletti, Franck Bassinot, and Michaël Hermoso
Clim. Past, 18, 449–464, https://doi.org/10.5194/cp-18-449-2022, https://doi.org/10.5194/cp-18-449-2022, 2022
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We test a new method to reconstruct past atmospheric CO2 levels based on the geochemistry of pelagic algal biominerals (coccoliths), which recent culture and numerical experiments have related to ambient CO2 concentrations. By comparing the isotopic composition of fossil coccoliths to the inferred surface ocean CO2 level at the time they calcified, we outline a transfer function and argue that coccolith vital effects can be used to reconstruct geological pCO2 beyond the ice core record.
André Paul, Stefan Mulitza, Rüdiger Stein, and Martin Werner
Clim. Past, 17, 805–824, https://doi.org/10.5194/cp-17-805-2021, https://doi.org/10.5194/cp-17-805-2021, 2021
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Maps and fields of near-sea-surface temperature differences between the past and present can be used to visualize and quantify climate changes and perform simulations with climate models. We used a statistical method to map sparse and scattered data for the Last Glacial Maximum time period (23 000 to 19 000 years before present) to a regular grid. The estimated global and tropical cooling would imply an equilibrium climate sensitivity in the lower to middle part of the currently accepted range.
Leticia G. Luz, Thiago P. Santos, Timothy I. Eglinton, Daniel Montluçon, Blanca Ausin, Negar Haghipour, Silvia M. Sousa, Renata H. Nagai, and Renato S. Carreira
Clim. Past, 16, 1245–1261, https://doi.org/10.5194/cp-16-1245-2020, https://doi.org/10.5194/cp-16-1245-2020, 2020
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Two sediment cores retrieved from the SE Brazilian continental margin were studied using multiple organic (alkenones) and inorganic (oxygen isotopes in carbonate shells and water) proxies to reconstruct the sea surface temperature (SST) over the last 50 000 years. The findings indicate the formation of strong thermal gradients in the region during the last climate transition, a feature that may become more frequent in the future scenario of global water circulation changes.
Geert-Jan A. Brummer, Brett Metcalfe, Wouter Feldmeijer, Maarten A. Prins, Jasmijn van 't Hoff, and Gerald M. Ganssen
Clim. Past, 16, 265–282, https://doi.org/10.5194/cp-16-265-2020, https://doi.org/10.5194/cp-16-265-2020, 2020
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Here, mid-ocean seasonality is resolved through time, using differences in the oxygen isotope composition between individual shells of the commonly used (sub)polar planktonic foraminifera species in ocean-climate reconstruction, N. pachyderma and G. bulloides. Single-specimen isotope measurements during the deglacial period revealed a surprising bimodality, the cause of which was investigated.
Michael Langner and Stefan Mulitza
Clim. Past, 15, 2067–2072, https://doi.org/10.5194/cp-15-2067-2019, https://doi.org/10.5194/cp-15-2067-2019, 2019
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Collections of paleoclimate data provide valuable information on the functioning of the Earth system but are often difficult to manage due to the inconsistency of data formats and reconstruction methods. We present a software toolbox that combines a simple document-based database with functionality for the visualization and management of marine proxy data. The program allows the efficient homogenization of larger paleoceanographic data sets into quality-controlled and transparent data products.
Lukas Jonkers and Michal Kučera
Clim. Past, 15, 881–891, https://doi.org/10.5194/cp-15-881-2019, https://doi.org/10.5194/cp-15-881-2019, 2019
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Fossil plankton assemblages have been widely used to reconstruct SST. In such approaches, full taxonomic resolution is often used. We assess whether this is required for reliable reconstructions as some species may not respond to SST. We find that only a few species are needed for low reconstruction errors but that species selection has a pronounced effect on reconstructions. We suggest that the sensitivity of a reconstruction to species pruning can be used as a measure of its robustness.
Marcus P. S. Badger, Thomas B. Chalk, Gavin L. Foster, Paul R. Bown, Samantha J. Gibbs, Philip F. Sexton, Daniela N. Schmidt, Heiko Pälike, Andreas Mackensen, and Richard D. Pancost
Clim. Past, 15, 539–554, https://doi.org/10.5194/cp-15-539-2019, https://doi.org/10.5194/cp-15-539-2019, 2019
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Understanding how atmospheric CO2 has affected the climate of the past is an important way of furthering our understanding of how CO2 may affect our climate in the future. There are several ways of determining CO2 in the past; in this paper, we ground-truth one method (based on preserved organic matter from alga) against the record of CO2 preserved as bubbles in ice cores over a glacial–interglacial cycle. We find that there is a discrepancy between the two.
Patrick A. Rafter, Juan-Carlos Herguera, and John R. Southon
Clim. Past, 14, 1977–1989, https://doi.org/10.5194/cp-14-1977-2018, https://doi.org/10.5194/cp-14-1977-2018, 2018
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Carbon’s radioactive isotope (radiocarbon) is a useful tool for oceanographers investigating carbon cycling in the modern ocean and ice age oceans (using foraminifera microfossils). Here we used sediment cores with excellent age constraints and abundant foraminifera microfossils to examine interspecies radiocarbon differences. All species demonstrate the same extreme radiocarbon depletion, and we argue that these observations represent important changes in seawater carbon chemistry.
Marijke W. de Bar, Dave J. Stolwijk, Jerry F. McManus, Jaap S. Sinninghe Damsté, and Stefan Schouten
Clim. Past, 14, 1783–1803, https://doi.org/10.5194/cp-14-1783-2018, https://doi.org/10.5194/cp-14-1783-2018, 2018
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We present a past sea surface temperature and paleoproductivity record over the last 150 000 years for ODP Site 1234 (Chilean margin). We tested the applicability of long-chain diol proxies for the reconstrucion of SST (LDI), past upwelling conditions (diol index), and nutrient concentrations (NDI). The LDI likely reflects past temperature changes, but the diol index and NDI are perhaps more indicative of Proboscia diatom productivity rather than upwelling and/or nutrient conditions.
Bryan C. Lougheed, Brett Metcalfe, Ulysses S. Ninnemann, and Lukas Wacker
Clim. Past, 14, 515–526, https://doi.org/10.5194/cp-14-515-2018, https://doi.org/10.5194/cp-14-515-2018, 2018
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Palaeoclimate reconstructions from deep-sea sediment archives provide valuable insight into past rapid climate change, but only a small proportion of the ocean is suitable for such reconstructions using the existing state of the art, i.e. the age–depth approach. We use dual radiocarbon (14C) and stable isotope analysis on single foraminifera to bypass the long-standing age–depth approach, thus facilitating past ocean chemistry reconstructions from vast, previously untapped ocean areas.
Lukas Jonkers and Michal Kučera
Clim. Past, 13, 573–586, https://doi.org/10.5194/cp-13-573-2017, https://doi.org/10.5194/cp-13-573-2017, 2017
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Planktonic foraminifera – the most important proxy carriers in palaeoceanography – adjust their seasonal and vertical habitat. They are thought to do so in a way that minimises the change in their environment, implying that proxy records based on these organisms may not capture the full amplitude of past climate change. Here we demonstrate that they indeed track a particular thermal habitat and suggest that this could lead to a 40 % underestimation of reconstructed temperature change.
Timothé Bolliet, Patrick Brockmann, Valérie Masson-Delmotte, Franck Bassinot, Valérie Daux, Dominique Genty, Amaelle Landais, Marlène Lavrieux, Elisabeth Michel, Pablo Ortega, Camille Risi, Didier M. Roche, Françoise Vimeux, and Claire Waelbroeck
Clim. Past, 12, 1693–1719, https://doi.org/10.5194/cp-12-1693-2016, https://doi.org/10.5194/cp-12-1693-2016, 2016
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This paper presents a new database of past climate proxies which aims to facilitate the distribution of data by using a user-friendly interface. Available data from the last 40 years are often fragmented, with lots of different formats, and online libraries are sometimes nonintuitive. We thus built a new dynamic web portal for data browsing, visualizing, and batch downloading of hundreds of datasets presenting a homogeneous format.
André Düsterhus, Alessio Rovere, Anders E. Carlson, Benjamin P. Horton, Volker Klemann, Lev Tarasov, Natasha L. M. Barlow, Tom Bradwell, Jorie Clark, Andrea Dutton, W. Roland Gehrels, Fiona D. Hibbert, Marc P. Hijma, Nicole Khan, Robert E. Kopp, Dorit Sivan, and Torbjörn E. Törnqvist
Clim. Past, 12, 911–921, https://doi.org/10.5194/cp-12-911-2016, https://doi.org/10.5194/cp-12-911-2016, 2016
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This review/position paper addresses problems in creating new interdisciplinary databases for palaeo-climatological sea-level and ice-sheet data and gives an overview on new advances to tackle them. The focus therein is to define and explain strategies and highlight their importance to allow further progress in these fields. It also offers important insights into the general problem of designing competitive databases which are also applicable to other communities within the palaeo-environment.
X. Shi, Y. Wu, J. Zou, Y. Liu, S. Ge, M. Zhao, J. Liu, A. Zhu, X. Meng, Z. Yao, and Y. Han
Clim. Past, 10, 1735–1750, https://doi.org/10.5194/cp-10-1735-2014, https://doi.org/10.5194/cp-10-1735-2014, 2014
D. K. Naik, R. Saraswat, N. Khare, A. C. Pandey, and R. Nigam
Clim. Past, 10, 745–758, https://doi.org/10.5194/cp-10-745-2014, https://doi.org/10.5194/cp-10-745-2014, 2014
S. Kasper, M. T. J. van der Meer, A. Mets, R. Zahn, J. S. Sinninghe Damsté, and S. Schouten
Clim. Past, 10, 251–260, https://doi.org/10.5194/cp-10-251-2014, https://doi.org/10.5194/cp-10-251-2014, 2014
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