Deciphering the Palaeocene-Eocene thermal maximum by Granger causality test

The Palaeocene-Eocene thermal maximum is a global warming period (∼56 Ma), which marked by sharp negative carbon isotope excursion (CIE) that caused the injection of massive isotopically-light into ocean-atmosphere. It generally considered warming. However, several studies have suggested and environmental perturbations precede onset CIE. Here we present Granger test to investigate detailed mechanisms this event. We show shift from climate-warming driving carbon-emission scenario scheme in carbon-injection causing global-warming during initial emission might be methane hydrates dissociation and/or permafrost thawing, possibly linked with astronomical paced This change causal direction may result feedback emitted additional other sources, such as volcanism, bolide impact, oxidation marine organic matter, wildfires burning peatlands.