Galinkin, Ryan Alexander. Evaluating the impact trigger hypothesis for the onset of the Paleocene-Eocene thermal maximum. Retrieved from https://doi.org/doi:10.7282/t3-5pmq-0966
DescriptionWe investigate whether an extraterrestrial impact could produce changes in atmospheric chemistry sufficient to produce the 5°C global temperature rise observed at the onset of the Paleocene-Eocene Thermal Maximum (PETM), a major global warming event in Earth history that occurred approximately 55.8 million years ago (Ma) [Charles et al., 2014]. We calculated greenhouse gas production stemming from both asteroidal and cometary impacts for impactors with radii of 2.5 km or 5 km, and impact angles perpendicular to the surface. We examined a range of processes such as fireball-induced combustion and associated release of biogenic carbon, the deposition of carbon and water directly from the impactor, the massive vaporization of water due to a deep oceanic impact, and the production of NO via a hypervelocity impactor's path through the atmosphere and subsequent O_3 production. We then convert the global warming potential (GWP) of the greenhouse gases produced in our calculations into GWP equivalent of CO_2 and use the resulting values to compute the estimated global increase in temperature for each hypothetical impact. Our most powerful impacts could potentially increase the global temperature by up to 4.69°C. This amount of warming is very close to what is inferred from paleoclimate records. We suggest that a purely perpendicular impact in our modeled size range is unlikely, yet plausible, to produce the required GWP equivalent of CO_2 to result in a 5°C rise in global temperatures. However, future work may be conducted to study whether changes in impact angle may produce higher amounts of greenhouse gases and potentially be responsible for the abrupt warming experienced at the PETM boundary.