Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA, 02138, USA.
Lamont-Doherty Earth Observatory, Columbia University of the City of New York, Palisades, NY, 10964, USA.
Nat Commun. 2019 Oct 4;10(1):4519. doi: 10.1038/s41467-019-12553-3.
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.
在古新世-始新世极热事件期间，记录在陆地和海洋档案中的负碳同位素偏移反映了大量的碳被排放到外源碳库中。然而，不同样本类型的碳同位素偏移估计之间的差异导致碳排放的来源、规模和时间存在很大的不确定性。在这里，我们表明海洋浮游古菌的膜脂能够可靠地记录古新世-始新世极热事件期间的碳同位素偏移和表层海洋变暖。新型 crenarchaeol 同位素组成记录约束了全球碳同位素偏移幅度为-4.0±0.4‰，与甲烷水合物分解排放>3000 Pg C 或涉及地热加热或沉积物有机物质氧化排放的>4400 Pg C 一致。crenarchaeol 的同位素组成和海洋温度的先触发偏移突出表明晚古新世碳循环对扰动的敏感性，并表明气候不稳定性先于古新世-始新世极热事件。
