EARTH SYSTEM MODELING CONSTRAINTS ON THE RATE OF PETM CARBON INJECTION (Invited Presentation)

Carbon injection triggering the Paleocene-Eocene Thermal Maximum (PETM, ~56 Ma) is variously thought to have occurred over a geologic instant to tens of thousands of years. Typically, these estimates of the onset duration rely on conventional sedimentary age models that are not ideal for resolving rapid events. Yet, knowledge of the PETM onset duration is crucial for making comparisons with future CO₂ release and warming. Different durations of carbon input (or the rate of carbon injection if constraint is placed on the total mass of PETM carbon emissions) should, however, result in distinct records of environmental change. Here we use the Earth system model cGENIE to quantify the consequences of differing carbon input durations on the isotopic and temperature record of different carbon reservoirs. We trace how the isotopic signal and temperature rise is differentially imprinted within the atmosphere and ocean, and focus on patterns and causes of spatial and depth-dependent variation in the carbon isotopic anomaly and warming in the ocean. From this, we identify a characteristic relationship between the difference in carbon isotope excursion size between atmospheric CO₂ and dissolved inorganic carbon (DIC) and the duration of carbon emissions. To the extent that available isotopic data spanning the PETM constrain the size of the marine and atmospheric carbon isotopic excursions, applying this empirical relationship suggests the component of carbon emissions that dominates the isotopic signal could be less than 3000 years.