Deep ocean carbonate ion increase during mid Miocene CO2 decline

Kender, Sev; Yu, Jimin; Peck, Victoria L

doi:10.1038/srep04187

Cited by 15 publications

(12 citation statements)

References 50 publications

(115 reference statements)

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“…For the latter scenario, paired Mg/Ca and Li/Ca records were used to correct for this effect. While that study demonstrated the potential of using paired trace metal records to correct for changes in carbonate saturation state, it is important to acknowledge that uncertainties remain regarding the species‐specific sensitivities and thresholds to both temperature and saturation state [ Kender et al ., ; Lear et al ., ]. Nevertheless, here we plot the δ 18 O sw calculated for both scenarios by Lear et al .…”

Section: Resultsmentioning

confidence: 99%

Middle Miocene climate instability associated with high‐amplitude CO₂ variability

et al. 2014

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The amplitude of climatic change, as recorded in the benthic oxygen isotope record, has varied throughout geological time. During the late Pleistocene, changes in the atmospheric concentration of carbon dioxide (CO 2 ) are an important control on this amplitude of variability. The contribution of CO 2 to climate variability during the pre-Quaternary however is unknown. Here we present a new boron isotope-based CO 2 record for the transition into the middle Miocene Climatic Optimum (MCO) between 15.5 and 17 Myr that shows pronounced variability between 300 ppm and 500 ppm on a roughly 100 kyr time scale during the MCO. The CO 2 changes reconstructed for the Miocene are~2 times larger in absolute terms (300 to 500 ppm compared to 180 to 280 ppm) than those associated with the late Pleistocene and~15% larger in terms of climate forcing. In contrast, however, variability in the contemporaneous benthic oxygen isotope record (at~1‰) is approximately two thirds the amplitude of that seen during the late Pleistocene. These observations indicate a lower overall sensitivity to CO 2 forcing for Miocene (Antarctic only) ice sheets than their late Pleistocene (Antarctic plus lower latitude northern hemisphere) counterparts. When our Miocene CO 2 record is compared to the estimated changes in contemporaneous δ 18O sw (ice volume), they point to the existence of two reservoirs of ice on Antarctica. One of these reservoirs appears stable, while a second reservoir shows a level of dynamism that contradicts the results of coupled climate-ice sheet model experiments given the CO 2 concentrations that we reconstruct.

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Section: Resultsmentioning

confidence: 99%

Middle Miocene climate instability associated with high‐amplitude CO₂ variability

et al. 2014

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“…2− ] (Kender et al, 2014). To counter both issues, Lear et al (2010Lear et al ( , 2015 used a benthic foraminifer (Oridorsalis umbonatus) which they determined to be less sensitive than other species to changes in seawater Mg/Ca.…”

Section: Introductionmentioning

confidence: 99%

Warm Middle Miocene Indian Ocean Bottom Water Temperatures: Comparison of Clumped Isotope and Mg/Ca‐Based Estimates

Modestou

Leutert

Fernández

et al. 2020

Paleoceanog and Paleoclimatol

102

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The middle Miocene is an important analogue for potential future warm climates. However, few independent deep ocean temperature records exist, though these are important for climate model validation and estimates of changes in ice volume. Existing records, all based on the foraminiferal Mg/Ca proxy, suggest that bottom water temperatures were 5–8°C warmer than present. In order to improve confidence in these bottom water temperature reconstructions, we generated a new record using carbonate clumped isotopes (Δ47) and compared our results with Mg/Ca‐based estimates for the Indian Ocean at ODP Site 761. Our results indicate temperatures of 11.0 ± 1.7°C during the middle Miocene Climatic Optimum (MCO, 14.7–17 Ma) and 8.1 ± 1.9°C after the middle Miocene Climate Transition (MCT, 13.0–14.7 Ma), values 6 to 9°C warmer than present. Our record also indicates cooling across the MCT of 2.9 ± 2.5°C (uncertainties 95% confidence level). The Mg/Ca record derived from the same samples indicates temperatures well within uncertainty of Δ47. As the two proxies are affected by different non‐thermal biases, the good agreement provides confidence in these reconstructed temperatures. Our Δ47 temperature record implies a ~0.6‰ seawater δ18O change over the MCT, in good agreement with previously published values from other sites. Our data furthermore confirm overall high seawater δ18O values across the middle Miocene, at face value suggesting ice volumes exceeding present‐day despite the warm bottom water temperatures. This finding suggests previously underappreciated additional influences on seawater δ18O and/or a decoupling of ice volume and ocean temperature.

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“…], but this would also lead to an increase in benthic δ 13 C in contradiction to the observed recovery in benthic δ 13 C (Kender et al, 2014). As a result it is clear that, in our simulations, the permanent CCD deepening can be driven by the cooling trend resulting in shelf-basin carbonate fractionation and elevated carbonate weathering after ~15.4 Ma, but as the initial CCD deepening at ~16.0 Ma occurs during a time of relative warmth this suggests that the CRB had a role in deepening the CCD earlier than otherwise would have occurred (Feakins et al, 2012;Passchier et al, 2011).…”

Section: -mentioning

confidence: 78%

“…Ma. A sustained CCD deepening can successfully be simulated through a combination of a shift in carbonate burial to the deep ocean and increased carbonate weathering as a result of ice-sheet growth causing sea-level to fall and shelf carbonate deposits to be exposed after 15.4 Ma or due to elevated continental weathering (simulated as a 30 % shelf burial reduction and a 20 % increase in carbonate weathering) (Barry et al, 2013;Kender et al, 2014;Merico et al, 2008;Passchier et al, 2011;Sandroni and Talarico, 2011;Shevenell et al, 2008) (Fig. 4).…”

Section: The Ccd and The Mid-miocene Climate Transitionmentioning

confidence: 99%

Estimating the impact of the cryptic degassing of Large Igneous Provinces: A mid-Miocene case-study

McKay

Tyrrell

Wilson

et al. 2014

Earth and Planetary Science Letters

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21Large Igneous Provinces (LIPs) have been emplaced throughout Earth's history, erupting that can release significant volumes of carbon into the ocean-atmosphere system (Bryan and , 2008; Coffin and Eldholm, 1994; Courtillot and Renne, 2003; Ernst et al., 2005).47 Ernst 48While the LIPs with the largest volumes (e.g. the Siberian Traps or the Central Atlantic 49Magmatic Province) are widely accepted to have triggered episodes of carbon cycle 50 perturbation, global warmth and ecological crisis (Grard et al., 2005; Sobolev et al., 2011; 51 Wignall, 2005 51 Wignall, , 2001, the case for LIPs with smaller (≤2x10 6 km 3 ) volumes (e.g., the Deccan 52Traps or the Columbia River Basalt), emitting sufficient CO 2 to cause a significant global 53 impact is a subject of debate (Caldeira and Rampino, 1990; Diester-Haass et al., 2009; 54 Kender et al., 2009; Self et al., 2006; Taylor and Lasaga, 1999 2011a; Erwin, 2006; Ganino and Arndt, 2010, 2009; Iacono-Marziano et al., 2012; Retallack 60 and Jahren, 2008; Svensen et al., 2009 Svensen et al., , 2004, and the potential impact of the recycling of 61 mafic crust into the LIP magma source (Sobolev et al., 2011 2013; Barry et al., 2013Barry et al., , 2010 Hooper, 1997 Hooper, , 1988 Reidel et al., 2013b; Wolff and Ramos, 78 2013) (Fig. 2), with the initiation of the CRB eruptions coinciding with the core of both the 79 MCO and the MCIE (Fig. 1). In detail, the peak of the carbon cycle perturbation occurs ca. 8016.0 Ma (Fig. 3) parameters, and the lack of dynamic ocean, atmosphere and terrestrial biosphere components. 119Both models are tuned with estimates for mid-Miocene parameters (Tables S1-3) burial, is also analysed by calculating a sensitivity index using the formula:where S is the sensitivity index, p the parameter value, Y the model results for p, and ' 143denoting the parameter value and model results after the ± 10 % change in p (Haefner, 1996). 144A sensitivity index value of S ≤ ±0. the Siberian Traps) ( Table 2). An EAF of 2.0-6.4 also applies to this crustal-contamination 217 emission scenario. 218An additional source of cryptic degassing beyond magma degassing is the In Figure 4 we compare palaeorecords with model simulations for δ 13 C, CCD and 247 atmospheric CO 2. We find that sub-aerial basalt degassing alone has a negligible effect in our 248 simulations, but that adding cryptic degassing results in excursions similar to those seen in 249 the palaeorecords. In some respects these results are counter-intuitive because they simulate: carbon an isotopic value of -12 ‰ results in a δ 13 C excursion similar to but slightly larger 266 than in our best-fit simulation in MTW08 (Fig. S1), indicating that our main conclusions are 267 not particularly sensitive to uncertainty in this parameter. 268We find that in MTW08 an emission scenario of 1000 Pg C from the Steens and 3000-4000 Pg C of this emitted during just the GRB eruptions, best fits the palaeorecords. 279This emission range falls within the upper end of the range 460-6...

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Deep ocean carbonate ion increase during mid Miocene CO2 decline

Cited by 15 publications

References 50 publications

Middle Miocene climate instability associated with high‐amplitude CO₂ variability

Middle Miocene climate instability associated with high‐amplitude CO₂ variability

Warm Middle Miocene Indian Ocean Bottom Water Temperatures: Comparison of Clumped Isotope and Mg/Ca‐Based Estimates

Estimating the impact of the cryptic degassing of Large Igneous Provinces: A mid-Miocene case-study

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Deep ocean carbonate ion increase during mid Miocene CO2 decline

Cited by 15 publications

References 50 publications

Middle Miocene climate instability associated with high‐amplitude CO2 variability

Middle Miocene climate instability associated with high‐amplitude CO2 variability

Warm Middle Miocene Indian Ocean Bottom Water Temperatures: Comparison of Clumped Isotope and Mg/Ca‐Based Estimates

Estimating the impact of the cryptic degassing of Large Igneous Provinces: A mid-Miocene case-study

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Middle Miocene climate instability associated with high‐amplitude CO₂ variability

Middle Miocene climate instability associated with high‐amplitude CO₂ variability