Constraining the evolution of Neogene ocean carbonate chemistry using the boron isotope pH proxy

Sosdian, Sindia; Greenop, Rosanna; Hain, Mathis P.; Foster, Gavin L.; Pearson, Paul Nicholas; Lear, Caroline H

doi:10.1016/j.epsl.2018.06.017

Cited by 166 publications

(362 citation statements)

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“…At Site 872, we measure T. trilobus from the 300‐ to 350‐μm size fraction and use the calibration of Sanyal et al () with a modified intercept so that it passes through the core top value for the related T. sacculifer (300–355 μm) from ODP 999A (Seki et al, ) to correct for vital effects (Sosdian et al, ):

δ^{11} B_{borate} = ((), δ^{11} B_{normalT . trilobus} - 2.69) ∕ 0.833 .

…”

Section: Methods and Site Informationmentioning

confidence: 99%

“…Instead, we use the calibration for the symbiotic foraminifera T. sacculifer . In the absence of a T. sacculifer calibration for the 250‐ to 300‐μm size fraction, we apply the same calibration as at Site 872 from Sosdian et al (). We then use the close temporal overlap between the data from our two sites and with the different species to examine the validity of these vital effect assumptions.…”

Section: Methods and Site Informationmentioning

confidence: 99%

“…Both sites are currently located in regions where surface water is close to equilibrium (±25 ppm) with the atmosphere with respect to CO 2 (Figure 2; Takahashi et al, 2009). Age models for Sites 926 and 872 are from Pälike, Frazier, and Zachos (2006; and references therein) and Sosdian et al (2018) updated to GTS2012 (Gradstein et al, 2012), respectively. Samples from ODP Site 926 were taken from between 469 and 522 meters composite depth (mcd) and between 110 and 117 mcd at ODP Site 872.…”

Section: Site Location and Informationmentioning

confidence: 99%

“…To define atmospheric CO 2 , a second carbonate system parameter, in addition to pH, is required. We use the regression of the Neogene dissolved inorganic carbon (DIC) estimates from Sosdian et al (2018), where deep-ocean DIC is calculated from benthic δ 11 B derived estimates of bottom water pH and deep-ocean carbonate ion concentration ([CO 3 2− ]) constrained by the calcite compensation depth and [Ca] sw . A linear regression is fitted through the deep-ocean DIC estimates and used to estimate changes in surface DIC relative to the modern value of 2,000 μmol/kg ( Figure S3).…”

Section: Estimating Absolute Comentioning

confidence: 99%

“…Data are fromTakahashi et al (2009). Plotted using Ocean Data View(Schlitzer, 2017). same calibration as at Site 872 fromSosdian et al (2018). We then use the close temporal overlap between the data from our two sites and with the different species to examine the validity of these vital effect assumptions.…”

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confidence: 99%

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Orbital Forcing, Ice Volume, and CO₂ Across the Oligocene‐Miocene Transition

Greenop

Sosdian

Henehan

et al. 2019

Paleoceanog and Paleoclimatol

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Paleoclimate records suggest that a rapid major transient Antarctic glaciation occurred across the Oligocene‐Miocene transition (OMT; ca. 23 Ma; ~50‐m sea level equivalent in 200–300 kyr). Orbital forcing has long been cited as an important factor determining the timing of the OMT glacial event. A similar orbital configuration occurred 1.2 Myr prior to the OMT, however, and was not associated with a major climate event, suggesting that additional mechanisms play an important role in ice sheet growth and decay. To improve our understanding of the OMT, we present a boron isotope‐based CO2 record between 22 and 24 Ma. This new record shows that δ11B/CO2 was comparatively stable in the million years prior to the OMT glaciation and decreased by 0.7‰ (equivalent to a CO2 increase of ~65 ppm) over ~300 kyr during the subsequent deglaciation. More data are needed, but we propose that the OMT glaciation was triggered by the same forces that initiated sustained Antarctic glaciation at the Eocene‐Oligocene transition: long‐term decline in CO2 to a critical threshold and a superimposed orbital configuration favorable to glaciation (an eccentricity minimum and low‐amplitude obliquity change). When comparing the reconstructed CO2 increase with estimates of δ18Osw during the deglaciation phase of the OMT, we find that the sensitivity of the cryosphere to CO2 forcing is consistent with recent ice sheet modeling studies that incorporate retreat into subglacial basins via ice cliff collapse with modest CO2 increase, with clear implications for future sea level rise.

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δ^{11} B_{borate} = ((), δ^{11} B_{normalT . trilobus} - 2.69) ∕ 0.833 .

…”

Section: Methods and Site Informationmentioning

confidence: 99%

Section: Methods and Site Informationmentioning

confidence: 99%

Section: Site Location and Informationmentioning

confidence: 99%

Section: Estimating Absolute Comentioning

confidence: 99%

mentioning

confidence: 99%

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Orbital Forcing, Ice Volume, and CO₂ Across the Oligocene‐Miocene Transition

Greenop

Sosdian

Henehan

et al. 2019

Paleoceanog and Paleoclimatol

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The Monterey Event and the Paleocene‐Eocene Thermal Maximum

Babila

Foster

2021

Large Igneous Provinces

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The Columbia River Flood Basalts and the North Atlantic Igneous Province are two of the youngest Large Igneous Provinces (LIPs) and both are associated with perturbations of the global carbon-cycle. Here we explore the link between the emplacement and eruption of LIPs and their associated carbon-cycle and climatic responses. The emplacement of both LIPs are associated with two well-known climate events: the Monterey Carbon Isotope Excursion (MCIE; ~17-13.5 Ma) and the Paleocene-Eocene Thermal Maximum (PETM; ~56 Ma) characterized by a positive 1‰ and negative 3-5‰ carbon isotope excursion, respectively. Both are also associated with signifi cant global warming. However, despite these contrasting timescales and carbon isotope trends, boron-based proxy records indicate a similar surface ocean carbonate system response. In both cases, elevated LIP derived carbon dioxide emissions led to oceanic absorption of the carbon released causing a decline of surface ocean pH and an increase in dissolved inorganic carbon. We conclude that, although similar underlying carbon-cycle processes are at play during both events, their specific behavior is somewhat different as the magnitude, carbon emissions rate (slow vs. fast), and background climate state (icehouse vs. greenhouse) conspire to cause distinct carbon isotope expressions in the sedimentary record and variable climatic responses to each LIP emplacement.

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Tropical Sea Surface Temperatures following the Middle Miocene Climate Transition from Laser-Ablation ICP-MS analysis of glassy foraminifera

Nairn

Lear

Sosdian

et al. 2021

Preprint

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The mid-late Miocene is an important interval in the evolution of global climate through the Cenozoic, representing a key period in the transition out of the warm, dynamic climate state of the Miocene Climatic Optimum (MCO) into a more stable unipolar icehouse world (Badger et al., 2013;Foster et al., 2012;Greenop et al., 2014;Sosdian et al., 2018). Despite being characterized by similar to modern day atmospheric CO 2 concentrations (Foster et al., 2012;Sosdian et al., 2018;Super et al., 2018), middle Miocene mean global temperatures were likely significantly warmer than the modern day (Pound et al., 2011;Rousselle et al., 2013). This has been used to suggest a decoupling of global temperature and atmospheric CO 2 forcing (LaRiviere et al., 2012;Pagani et al., 1999), a characteristic which general circulation models struggle to simulate (Knorr et al., 2011;von der Heydt & Dijkstra, 2006). It has also been suggested that the late Miocene was an additional important key step in the transition to our modern climate state, as high latitudes cooled more than low latitudes, leading to a marked steepening of latitudinal temperature gradients (Herbert et al., 2016).The late Miocene Cooling (LMC) between ∼ 7.5 and 5.5 Ma was a global phenomenon (Herbert et al., 2016) perhaps associated with decreasing atmospheric pCO 2 (Stoll et al., 2019). The increase in the equator to pole surface temperature gradients was not associated with an increase in the benthic foraminiferal oxygen isotope record, implying that it occurred in the absence of a large increase in continental ice volume (Herbert et al., 2016). Polar amplification in the LMC is consistent with estimates for other time intervals (e.g., Cramwinckel et al., 2018). However, the LMC was also preceded by a significant cooling of mid to high southern and northern latitudes, a heterogenous cooling at high northern latitudes, and a muted, limited cooling in the tropics (Herbert et al., 2016). This heterogenous cooling perhaps suggests an unusually high polar amplification factor for the interval immediately preceding the LMC. Potential changes in the Earth System that could impact the magnitude of polar amplification include sea ice extent, vegetation induced changes in albedo, cloud cover, or ocean-atmosphere heat transport. Constraining the magnitude and timing of the

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Constraining the evolution of Neogene ocean carbonate chemistry using the boron isotope pH proxy

Cited by 166 publications

References 109 publications

Orbital Forcing, Ice Volume, and CO₂ Across the Oligocene‐Miocene Transition

Orbital Forcing, Ice Volume, and CO₂ Across the Oligocene‐Miocene Transition

The Monterey Event and the Paleocene‐Eocene Thermal Maximum

Tropical Sea Surface Temperatures following the Middle Miocene Climate Transition from Laser-Ablation ICP-MS analysis of glassy foraminifera

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Constraining the evolution of Neogene ocean carbonate chemistry using the boron isotope pH proxy

Cited by 166 publications

References 109 publications

Orbital Forcing, Ice Volume, and CO2 Across the Oligocene‐Miocene Transition

Orbital Forcing, Ice Volume, and CO2 Across the Oligocene‐Miocene Transition

The Monterey Event and the Paleocene‐Eocene Thermal Maximum

Tropical Sea Surface Temperatures following the Middle Miocene Climate Transition from Laser-Ablation ICP-MS analysis of glassy foraminifera

Contact Info

Product

Resources

About

Orbital Forcing, Ice Volume, and CO₂ Across the Oligocene‐Miocene Transition

Orbital Forcing, Ice Volume, and CO₂ Across the Oligocene‐Miocene Transition