Paleocene–Eocene Thermal Maximum

The Paleocene–Eocene Thermal Maximum was a brief global warming event about 56 million years ago, marked by rapid carbon release, a large carbon-isotope shift, and widespread ocean acidification.

Carbon isotope excursion: A marked shift in the ratio of carbon isotopes recorded in geological materials. Its large negative shift is the defining geochemical signal of the event.
North Atlantic Igneous Province: A large region of volcanic rocks formed during the opening of the North Atlantic Ocean. Its magmatism may have heated carbon-rich sediments and released greenhouse gases.
Benthic foraminifera: Single-celled protists that live on or within seafloor sediments and often build carbonate shells. Their shells record the carbon-isotope excursion and a sharp loss of deep-sea species.
Benthic extinction: The widespread loss of deep-sea organisms during the Paleocene–Eocene Thermal Maximum. The extinction reflects severe disruption of deep-ocean habitats during the event.
Anthropogenic climate change: Climate change caused by human activities, especially greenhouse-gas emissions and land-use change. Both involve rapid carbon release, but modern emissions are occurring far faster.
Ocean acidification: A decrease in seawater pH, commonly caused by uptake of atmospheric carbon dioxide. Rapid carbon input lowered ocean pH and impaired carbonate-producing organisms.
Thermogenic methane: Methane produced when buried organic matter is altered by heat over geological time. Intrusions associated with North Atlantic volcanism could have generated this carbon source.
Foraminifera: A group of mostly marine single-celled organisms, many of which build mineral shells. Their abundant fossil shells preserve marine chemistry across the event.
Mammalian dispersal: The movement of mammal groups between regions as geographic and environmental conditions change. Rapid warming coincided with major mammal migrations and range shifts across high-latitude routes.
Cretaceous–Paleogene extinction event: A mass extinction about 66 million years ago associated with an asteroid impact and major ecological change. Unlike the PETM, this abrupt crisis was driven principally by impact-related catastrophe.

Linked from 22 pages