lecture: Welcome to the Anthropocene?

(Did) We Accidentally a New Geological Epoch(?)

Event large

The Anthropocene is widely understood to mean the current "period of Earth's history during which humans have a decisive influence on the state, dynamics and future" of this planet. For several years, scientists in the Working Group on the 'Anthropocene' (AWG) have worked (and voted!) on defining the beginning of the Anthropocene in geochemical terms. The mid-20th century provides an obvious geochemical 'timestamp': fallout from nuclear weapons detonations. Which other chemicals and timestamps are being considered for marking the Anthropocene's start? How is 'define-by-committee' even working out for geological epochs? This talk boils the scientific background of the Anthropocene debate down for non-stratigraphers.

Stratigraphers are geologists, who focus on sediment, rock or ice layers, etc. These 'strata' form by deposition of organic or inorganic material (such as microorganisms or volcanic ash) and provide a records of the history of our planet's surface. Because gas bubbles, isotopes, etc. are captured in the strata, scientists can analyse the geochemistry of the past, date certain events, and more. That kind of data ultimately underlies xkcd's recent 'Earth Temperature Timeline'. Direct measurements of geochemical signals such as atmospheric CO2 concentration and ocean pH started only in the mid-20th century.

Besides the Intergovernmental Panel on Climate Change, the AWG is possibly the most diverse scientific committee with most public attention currently. Therefore, defining the Anthropocene is a multi-disciplinary, collaborative scientific effort, as well as an inherently political statement. This talk will explain why.