Slow release of fossil carbon during the Palaeocene–Eocene Thermal Maximum

Cui, Ying; Kump, Lee R.; Ridgwell, Andy; Charles, Adam J.; Junium, Christopher K.; Diefendorf, Aaron F.; Freeman, Katherine H.; Urban, Nathan M.; Harding, Ian C.

doi:10.1038/ngeo1179

Cited by 226 publications

(266 citation statements)

References 37 publications

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“…However, initial estimates with very low carbon input mass may have underestimated the magnitude of the CIE and hence the total carbon input [47]. The highend scenarios with very large carbon input mass require certain assumptions about the CCD before the event and/or predict deep-sea carbonate dissolution patterns during the event that seem difficult to reconcile with the sediment record [31,34,35,43]. Moreover, the mechanism (i.e.…”

Section: Ocean Acidificationmentioning

confidence: 99%

“…Alternatively, carbon isotope data for populations of individual shells from closely spaced samples across the boundary throughout the ocean yield clear bimodal distributions of shells recording pre-excursion and excursion carbon isotope values, but with no transitional values, suggestive of an abrupt shift in surface water δ 13 C [22,54], though this also could be an artefact of dissolution. Expanded shallow marine, siliciclastic sections, on the other hand, lack the needed stratigraphic control to constrain rapid changes in sediment accumulation, and thus yield conflicting results for the initial onset of the CIE, with estimates ranging from just a few thousand years to as long as 20 kyr [19,33,50,55]. In sum, the Effect of releasing 3000 Pg C over various time intervals during the PETM [11,31].…”

Section: Massive Carbon Releasementioning

confidence: 99%

“…For the PETM, a number of carbon input scenarios have been proposed with masses ranging from 1100 to more than 10 000 Pg C over durations of a few thousand to tens of thousands of years [30,31,33,47]. However, initial estimates with very low carbon input mass may have underestimated the magnitude of the CIE and hence the total carbon input [47].…”

Section: Ocean Acidificationmentioning

confidence: 99%

“…One critical element for a comparison between the Anthropocene and the PETM is the time scale of carbon input. While it is clear that the carbon input during the PETM was rapid on geological time scales (a few thousand years), establishing the approximate rate of emissions has proved difficult using conventional stratigraphic methods [33,34].…”

Section: Massive Carbon Releasementioning

confidence: 99%

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Long-term legacy of massive carbon input to the Earth system: Anthropocene versus Eocene

Zeebe

Zachos

2013

Phil. Trans. R. Soc. A.

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Over the next few centuries, with unabated emissions of anthropogenic carbon dioxide (CO 2 ), a total of 5000 Pg C may enter the atmosphere, causing CO 2 concentrations to rise to approximately 2000 ppmv, global temperature to warm by more than 8 ° C and surface ocean pH to decline by approximately 0.7 units. A carbon release of this magnitude is unprecedented during the past 56 million years—and the outcome accordingly difficult to predict. In this regard, the geological record may provide foresight to how the Earth system will respond in the future. Here, we discuss the long-term legacy of massive carbon release into the Earth's surface reservoirs, comparing the Anthropocene with a past analogue, the Palaeocene–Eocene Thermal Maximum (PETM, approx. 56 Ma). We examine the natural processes and time scales of CO 2 neutralization that determine the atmospheric lifetime of CO 2 in response to carbon release. We compare the duration of carbon release during the Anthropocene versus PETM and the ensuing effects on ocean acidification and marine calcifying organisms. We also discuss the conundrum that the observed duration of the PETM appears to be much longer than predicted by models that use first-order assumptions. Finally, we comment on past and future mass extinctions and recovery times of biotic diversity.

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Section: Ocean Acidificationmentioning

confidence: 99%

Section: Massive Carbon Releasementioning

confidence: 99%

Section: Ocean Acidificationmentioning

confidence: 99%

Section: Massive Carbon Releasementioning

confidence: 99%

See 2 more Smart Citations

Long-term legacy of massive carbon input to the Earth system: Anthropocene versus Eocene

Zeebe

Zachos

2013

Phil. Trans. R. Soc. A.

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“…We used the following mass balance equation modified from McInerney and Wing 11 to quantify DpCO 2 for each of the proposed sources (vertical, coloured lines in Fig. 3: green ¼ methane hydrate 14 , d 13 C source ¼ À 60%; purple ¼ thermogenic methane 54 or permafrost thawing 50 12,27,57). We calculated the value for CIE marine ( À 2.6%) as the average of the CIEs measured in benthic forams ( À 2.5 ± 1.0%, n ¼ 36), planktic forams ( À 2.7±1.0%, n ¼ 36) and bulk marine carbonate ( À 2.7±1.1%, n ¼ 33) as listed in Table 1 of McInerney and Wing 11 .…”

Section: Methodsmentioning

confidence: 99%

Reconciliation of marine and terrestrial carbon isotope excursions based on changing atmospheric CO2 levels

Schubert

Jahren

2013

Nat Commun

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Negative carbon isotope excursions measured in marine and terrestrial substrates indicate large-scale changes in the global carbon cycle, yet terrestrial substrates characteristically record a larger-amplitude carbon isotope excursion than marine substrates for a single event.Here we reconcile this difference by accounting for the fundamental increase in carbon isotope fractionation by land plants in response to increasing atmospheric CO 2 concentration (pCO 2 ). We show that for any change in pCO 2 concentration (DpCO 2 ), terrestrial and marine records can be used together to reconstruct background and maximum pCO 2 levels across the carbon isotope excursion. When applied to the carbon isotope excursion at the Palaeocene-Eocene boundary, we calculate pCO 2 ¼ 674-1,034 p.p.m.v. during the Late Palaeocene and 1,384-3,342 p.p.m.v. during the height of the carbon isotope excursion across all sources postulated for the carbon release. This analysis demonstrates the need to account for changing pCO 2 concentration when analysing large-scale changes in the carbon isotope composition of terrestrial substrates.

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Recovering the true size of an Eocene hyperthermal from the marine sedimentary record

Turner

Ridgwell

2013

Paleoceanography

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[1] Hyperthermals-episodes of abrupt global warming associated with the massive injection of carbon into the oceans and atmosphere-represent possible analogs for future climate change. However, uncertainties in their magnitude, rate, and duration arising as a result of mixing processes and changes in carbonate preservation as the sediment record is formed complicate their use in constraining climate sensitivity and the role of carbon cycle feedbacks. Here, we use cGENIE, an Earth system model of intermediate complexity, to assess likely magnitude and rate of carbon input, taking a small hyperthermal event from the early-middle Eocene, C22nH3 (~49.2 Ma) as a case study. We develop an iterative method combined with a sediment model simulating the formation and mixing of deep-sea sediments to converge on an estimate for the "true" magnitude of the carbon cycle perturbation in the atmosphere and ocean that drives the event. In inverting the À0.95‰ benthic δ 13 C excursion recorded at Ocean Drilling Program Site 1258, we obtain an estimate of at least À1.45‰ for the atmospheric CO 2 δ 13 C excursion that drove event C22nH3. We also assess controls on intersite variation of event shape in model sediments and find that sedimentation rate is the strongest determinant of modeled event size, with higher sedimentation rate sites recording the atmospheric signal more accurately. Our revised estimate for the size of C22nH3 implies a total carbon input almost two-thirds higher than would be deduced if the recorded δ 13 C excursion magnitude was taken at face value.Citation: Kirtland Turner, S., and A. , Recovering the true size of an Eocene hyperthermal from the marine sedimentary record, Paleoceanography, 28, 700-712,

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Slow release of fossil carbon during the Palaeocene–Eocene Thermal Maximum

Cited by 226 publications

References 37 publications

Long-term legacy of massive carbon input to the Earth system: Anthropocene versus Eocene

Long-term legacy of massive carbon input to the Earth system: Anthropocene versus Eocene

Reconciliation of marine and terrestrial carbon isotope excursions based on changing atmospheric CO2 levels

Recovering the true size of an Eocene hyperthermal from the marine sedimentary record

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