Abstract
A negative carbon isotope excursion recorded in terrestrial and marine archives reflects massive carbon emissions into the exogenic carbon reservoir during the Paleocene-Eocene Thermal Maximum. Yet, discrepancies in carbon isotope excursion estimates from different sample types lead to substantial uncertainties in the source, scale, and timing of carbon emissions. Here we show that membrane lipids of marine planktonic archaea reliably record both the carbon isotope excursion and surface ocean warming during the Paleocene-Eocene Thermal Maximum. Novel records of the isotopic composition of crenarchaeol constrain the global carbon isotope excursion magnitude to −4.0 ± 0.4‰, consistent with emission of >3000 Pg C from methane hydrate dissociation or >4400 Pg C for scenarios involving emissions from geothermal heating or oxidation of sedimentary organic matter. A pre-onset excursion in the isotopic composition of crenarchaeol and ocean temperature highlights the susceptibility of the late Paleocene carbon cycle to perturbations and suggests that climate instability preceded the Paleocene-Eocene Thermal Maximum.
Highlights
A negative carbon isotope excursion recorded in terrestrial and marine archives reflects massive carbon emissions into the exogenic carbon reservoir during the Paleocene-Eocene Thermal Maximum
To assess the potential influence of terrigenous input of crenarchaeol on δ13Ccren, records of BIT, a semi-quantitative tracer for input of soil organic matter[44], were generated for the New Jersey core, while literature data were used for the Tasman Sea[36] and Arctic Ocean[43] cores. δ13CTOC records were generated for the Ancora and Arctic Ocean cores and literature data were used for the Tasman Sea site[36]
The effect is inverse to the influence of pCO2 on carbon isotopic fractionation in phytoplankton, resulting in a smaller fractionation factor at high dissolved CO2 concentrations[40,41]
Summary
A negative carbon isotope excursion recorded in terrestrial and marine archives reflects massive carbon emissions into the exogenic carbon reservoir during the Paleocene-Eocene Thermal Maximum. The most intense hyperthermal, the Paleocene-Eocene Thermal Maximum (PETM), was a ~200 ka global climate perturbation[2] associated with increased atmospheric CO2 levels[3,4], ocean warming[5], and ocean acidification[6]. Despite more than 160 published CIE estimates from various sample substrates[16], the true magnitude of the CIE of the exogenic carbon reservoir remains elusive It remains unclear whether the CIE reconstructed from a given sample substrate is representative of the CIE of the entire exogenic carbon reservoir, since equilibration between the exogenic subreservoirs may depend on emission rates and size, carbon isotopic composition and location of the source, and oceanographic changes[19]. The wide range of CIE values has led to a diversity of PETM carbon emission scenarios ranging from 2000–20,000 Pg C
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
