Jan Zalasiewicz

Human activity is transforming the shape, size, and resilience of Earth’s biosphere, degrading and augmenting Holocene baseline conditions at various scales, and replacing the wild biosphere with an anthropogenically modified one. We evaluate episodes of biosphere change throughout Earth history and compare them with contemporary and near-future anthropogenic changes, developing the concept of biosphere disruptors – agents that force global-scale macroevolutionary change. Transient disruptors are short-lived agents (mean 8.0×10 ⁵ years), including massive volcanism and asteroid impacts. Persistent disruptors , including atmospheric and ocean oxygenation and land plant evolution, remain in the Earth System over long timescales (mean 1.6×10 ⁸ years). In the geological record, transient disruptors are associated with temporary but sometimes massive biosphere degradation, whereas persistent disruptors are associated with sustained biosphere enhancement. Most anthropogenic biosphere impacts resemble those of past transient disruptors , globally degrading wild biomass and biodiversity. Humanity is driving the second highest rate of biosphere degradation in Earth history after the Cretaceous-Palaeogene bolide impact. However, humanity is the first disrupting agent capable of reflecting on and potentially transforming its impact on planetary habitability. If we can achieve this, humanity could drive the greatest rate of increase in planetary habitability in Earth history on centennial to millennial timescales.

The Anthropocene was introduced to denote a dramatic, ongoing, planetary shift from prolonged relative Holocene stability, driving the Earth system into a new functional state outside its natural variability. Now stratigraphically‐grounded, the Anthropocene is de facto a new epoch, not the subjective filtering of all anthropogenic impacts in Earth history.

The Anthropocene represents a wholly changed, and still rapidly evolving, Earth state: one where human patterns of consumption of the Earth's resources are essentially out of control, and as a result risk degrading the very life support systems that sustain humans and all other organisms on this planet. This entry explores the development of the Anthropocene and outlines its relevance for Critical Management Studies.

An erratic chert pebble discovered on an exposure of the Lowestoft Till (Anglian Stage, Pleistocene) of North Lopham, Norfolk, UK, contains graptolites preserved three-dimensionally in silica in a mode not known in the UK. The graptolites are Monograptus parapriodon , Monograptus priodon , Monoclimacis linnarssoni and an undetermined retiolitid that indicate an Oktavites spiralis Biozone (mid-late Telychian, Late Llandovery, Silurian) age. The graptolites are associated with organic-walled microfossils, some containing internal bodies. The combination of lithology, preservation and low thermal maturity seem to exclude a British origin. The closest comparison is with Silurian chert pebbles in Miocene and Pleistocene gravels in central Germany, thought to be derived from bedrock in the Frankenwald region of Thuringia. A conjectured natural transport vector for this pebble involves drainage along the proto-Rhine system flowing into early/mid Pleistocene North Sea deltaic/marine deposits, with subsequent glacial transport to Norfolk. The possibility of an anthropogenic vector is also considered, but dismissed.

The Anthropocene was introduced to denote a dramatic, ongoing, planetary shift from prolonged Holocene stability, driving the Earth system into a new functional state outside its natural variability. Now stratigraphically-grounded, the Anthropocene is de facto a new epoch, not an encapsulation of all anthropogenic impacts in Earth history.

Jan Zalasiewicz, Martin J. Head , Colin N. Waters, Simon D. Turner, Peter K. Haff , Colin Summerhayes, Mark Williams, Alejandro Cearreta, Michael Wagreich, Ian Fairchild , Neil L. Rose, Yoshiki Saito, Reinhold Leinfelder, Barbara Fiałkiewicz-Kozieł, Zhisheng An, Jaia Syvitski, Agnieszka Gałuszka, Francine M. G. McCarthy, Juliana Ivar do Sul, Anthony Barnosky, Andrew B. Cundy, J. R. McNeill, Jens Zinke. Episodes -0001;0:. https://doi.org/10.18814/epiiugs/2023/023025