The Temperature of the Deep Ocean Is a Robust Proxy for Global Mean Surface Temperature During the Cenozoic

Paleoceanography and Paleoclimatology, Journal Year: 2024, Volume and Issue: 39(5)

Published: May 1, 2024

Abstract Reconstructing global mean surface temperature (GMST) is one of the key contributions that paleoclimate science can make in addressing societally relevant questions and required to determine equilibrium climate sensitivity (ECS). GMST has been derived from deep ocean (T d ), with previous work suggesting a simple T ‐GMST scaling factor 1 prior Pliocene. However, this lacks robust mechanistic basis, indeed, intuitively difficult envisage given polar amplification ubiquitous feature past warm states water overwhelmingly forms at high latitudes. Here, we interrogate whether crucially, why, relationship exists using suite curated data compilations two sets model simulations. We show models are full agreement 1:1 good approximation. Taken together, suggest (a) lower SST season formation than latitude annual response forcing, moreover (b) greater degree land versus warming processes act counterbalance possible amplification‐derived bias on ‐derived GMST. Using knowledge, provide new Cenozoic record Our estimates substantially warmer similar efforts for much Paleogene thus consistent higher‐than‐modern ECS during deep‐time CO 2 states.

Language: Английский

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No detectable influence of the carbonate ion effect on changes in stable carbon isotope ratios (δ¹³C) of shallow dwelling planktic foraminifera over the past 160 kyr

Climate of the past, Journal Year: 2024, Volume and Issue: 20(4), P. 991 - 1015

Published: April 25, 2024

Abstract. Laboratory experiments showed that the isotopic fractionation of δ13C and δ18O during calcite formation planktic foraminifera are species-specific functions ambient CO32- concentration. This effect became known as carbonate ion (CIE), whose role for interpretation marine sediment data will be investigated here in an in-depth analysis 13C cycle. For this investigation, we constructed new 160 kyr long mono-specific stacks changes both from either Globigerinoides ruber (rub) or Trilobatus sacculifer (sac) 112 40 records, respectively, wider tropics (latitudes below 38°). Both time series Δ(δ13Crub) Δ(δ13Csac) very similar to each other, a linear regression through scatter plot sets has slope ∼ 0.99 – although laboratory-based CIE species differs by factor nearly 2, implying they should record distinctly different δ13C, if accept concentration on glacial–interglacial timescales. deeper understanding cycle, use Solid Earth version Box model Isotopic Carbon cYCLE (BICYLE-SE) calculate how surface-ocean have varied over order able potential offsets which would caused quantified culture experiments. Our simulations forced with atmospheric reconstructions CO2 δ13CO2 derived ice cores obtain carbon cycle at least surface ocean close possible expected conditions deep largely agrees isotope ratio dissolved inorganic (DIC), δ13CDIC, reconstructed benthic foraminifera. We find agree better simulated δ13CDIC when ignoring than those were corrected CIE. The combination data- model-based evidence lack suggests measured laboratory is not directly transferable records. much smaller CIE-to-glacial–interglacial-signal δ18O, compared prevents us drawing robust conclusions recorded hard shells species. However, theories propose depends pH surrounding water, suggesting detectable neither isotopes. Whether paleo-data general feature restricted two needs checked further other foraminiferal

Language: Английский

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Exploring macroevolutionary links in multi-species planktonic foraminiferal Mg∕Ca and δ¹⁸O from 15 Ma to recent

Biogeosciences, Journal Year: 2025, Volume and Issue: 22(4), P. 1095 - 1113

Published: Feb. 28, 2025

Abstract. The ratio of the trace element Mg over Ca (Mg/Ca) and oxygen isotopic composition (δ18O) foraminiferal calcite are widely employed for reconstructing past ocean temperatures, although geochemical signals also influenced by several other factors that vary temporally spatially. Here, we analyse a global dataset Mg/Ca δ18O data 59 middle Miocene to recent species planktonic foraminifera from wide range depth habitats, many which have never been analysed before Mg/Ca. We investigate extent covary through time space identify sources mismatch between two proxies. Once adjusted long-term non-thermal factors, overall positively correlated in way consistent with temperature being dominant controller both across different species, including deep dwellers. However, systematic offsets values, multispecies calibrations should be applied caution. can track appearance such ancestor-descendent last 15 Myr propose emergence these may expression evolutionary innovations. find virtually all Mg/Ca- δ18O-derived temperatures commonly used genera Globigerinoides Trilobatus within uncertainty each other, highlighting utility paleoceanographic reconstructions. Our results highlight potential leveraging information lineages improve sea surface reconstruction Cenozoic.

Language: Английский

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Spatial biases in oxygen-based Phanerozoic seawater temperature reconstructions

Earth and Planetary Science Letters, Journal Year: 2025, Volume and Issue: 663, P. 119418 - 119418

Published: May 9, 2025

Language: Английский

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Omnivariant Generalized Least Squares regression: Theory, geochronological applications, and making the case for reconciled Δ47 calibrations

Chemical Geology, Journal Year: 2023, Volume and Issue: 647, P. 121881 - 121881

Published: Dec. 18, 2023

Language: Английский

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The Ostracod Clumped‐Isotope Thermometer: A Novel Tool to Accurately Quantify Continental Climate Changes

Geophysical Research Letters, Journal Year: 2024, Volume and Issue: 51(4)

Published: Feb. 19, 2024

Abstract This study presents a methodological advancement in the field of clumped‐isotope (∆ 47 ) thermometry, specifically tailored for application to freshwater ostracods. The novel ostracod clumped isotope approach enables quantitative temperature and hydrological reconstruction lacustrine records. relationship between ∆ at which shell mineralized is determined by measuring on different species grown under controlled temperatures, ranging from 4 ± 0.8 23 0.5ºC. excellent agreement presented data monitored temperatures confirms that can be applied shells vital effect absent outside uncertainty measurements. Results are consistent with carbonate unified calibration (Anderson et al., 2021, https://doi.org/10.1029/2020gl092069 ), therefore, an ostracod‐specific not needed. thermometer represents powerful tool terrestrial paleoclimate studies all around world, as lakes ostracods found climatic belts.

Language: Английский

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Reconciling Southern Ocean fronts equatorward migration with minor Antarctic ice volume change during Miocene cooling

Nature Communications, Journal Year: 2023, Volume and Issue: 14(1)

Published: Nov. 9, 2023

Gradual climate cooling and CO2 decline in the Miocene were recently shown not to be associated with major ice volume expansion, challenging a fundamental paradigm functioning of Antarctic cryosphere. Here, we explore ice-ocean-climate interactions by presenting multi-proxy reconstruction subtropical front migration, bottom water temperature global change, using dinoflagellate cyst biogeography, benthic foraminiferal clumped isotopes from offshore Tasmania. We report an equatorward frontal migration strengthening, concurrent surface deep ocean but absence change mid-late-Miocene. To reconcile these counterintuitive findings, argue based on new sheet modelling that progressively lowered height while expanding seawards, maintain stable volume. This can achieved rigorous intervention model precipitation regimes Antarctica ice-induced requires rethinking between ice, climate.

Language: Английский

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A clumped isotope calibration of coccoliths at well-constrained culture temperatures for marine temperature reconstructions

Climate of the past, Journal Year: 2024, Volume and Issue: 20(9), P. 2081 - 2101

Published: Sept. 20, 2024

Abstract. Numerous recent studies have tested the clumped isotope (Δ47) thermometer on a variety of biogenic carbonates such as foraminifera and bivalves showed that most follow common calibration. However, there may be difference between biogenic-carbonate-based calibrations inorganic carbonate are assumed to formed close isotopic equilibrium. Biogenic those based from seafloor sediments suffer uncertainties in determination calcification temperatures. Therefore, well-constrained laboratory cultures without temperature uncertainty can help resolve these discrepancies. Although sample size requirements for reliable Δ47 measurement decreased over years, availability preservation many still limited and/or require substantial time extracted sufficient amounts. Coccoliths, other hand, abundant often well-preserved sediments, they potential interesting target palaeoceanography. We thus determined Δ47–temperature relationship coccoliths due their relative ease growth laboratory. The carbon oxygen compositions coccolith calcite use palaeoenvironmental reconstructions physiological effects cause variability fractionation during mineralization. relatively data available suggest isotopes not significantly influenced by effects. cultured three species coccolithophores under controlled system conditions with CO2(aq) concentrations 5 45 µM, pH 7.9 8.6 units, temperatures 6 27 °C. Our results agree previous culture study no apparent species- or genus-specific vital despite significant deviations equilibrium C O composition. find while varying environmental parameters than does effect Δ47, changing yields within 1.2 ppm. coccolith-specific calibration shows consistent, positive offset 2–3 °C calibrations, which point yet unknown disequilibrium Thus, we our further palaeoceanographic derived laboratory-grown desirable reinforce confidence clumped-isotope-based

Language: Английский

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The temperature of the deep ocean is a robust proxy for global mean surface temperature during the Cenozoic

Authorea (Authorea), Journal Year: 2023, Volume and Issue: unknown

Published: Nov. 8, 2023

Reconstructing past changes in global mean surface temperature (GMST) is one of the key contributions that palaeoclimate science can make addressing societally relevant questions and required to determine equilibrium climate sensitivity (ECS). Previous work has suggested deep ocean (Td) be used GMST with a simple Td-GMST scaling factor 1 prior Pliocene. However, this metric lacks robust mechanistic basis, indeed, such relationship intuitively difficult envisage given polar amplification ubiquitous feature warm states water overwhelmingly forms at high latitudes. Here, we interrogate whether crucially, why, exists using suite curated data compilations generated for deep-time intervals as well two independent sets model simulations. We show models are full agreement 1:1 good approximation. Mechanistically, both suggest i) increasingly seasonally biased formation, ii) faster rate land versus warming processes act counterbalance possible amplification-derived bias on Td-derived GMST. Using knowledge, quality existing datasets provide new Cenozoic record Our estimates substantially warmer than similar previous efforts much Paleogene thus consistent higher-than-modern ECS during CO2 states.

Language: Английский

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Large-scale culturing of the subpolar foraminifera Globigerina bulloides reveals tolerance to a large range of environmental parameters associated to different life-strategies and an extended lifespan

Journal of Plankton Research, Journal Year: 2024, Volume and Issue: 46(4), P. 403 - 420

Published: June 7, 2024

Abstract The subtropical to subpolar planktic foraminifera Globigerina bulloides is a calcifying marine protist, and one of the dominant foraminiferal species Nordic Seas. Previously, relative abundance shell geochemistry fossil G. have been studied for palaeoceanographic reconstructions. There however lack biological observations on poor understanding its ecological tolerances, especially high latitude genotypes. Here, we present from first extensive culturing under conditions, including low temperature (6–13°C) variable salinity (30–38) experiments. Carbonate chemistry (pH [CO32−]) was also manipulated. Experimental conditions were chosen reflect range plausible past future scenarios We found be tolerant environmental well outside their optimal (<10°C, <33, pH <8). Observed life span up three months, which attributed microalgal diet. Two alternative strategies employed, whereby individuals either experienced rapid growth death, or prolonged lifespan with minimal death via slow decay. posit this could help explain differences in geochemical signals recorded different size fractions specimens used

Language: Английский

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