Defining the Anthropocene using precise geological evidence

Abstract

The Geological Time Scale provides a global framework for correlating major Earth system changes over geological history. The Anthropocene term is widely used to describe transformative human impacts on the environment but lacks a formal Geological Time Scale definition, and hence is applied and interpreted inconsistently. In this Perspective, we summarize multi-proxy evidence from 12 globally distributed stratigraphic records to show that mid-twentieth century Earth system changes are abrupt, globally synchronous, and stratigraphically distinct, providing a basis for precisely defining the Anthropocene as a series and epoch. Accelerated fossil fuel combustion, industrial pollution and biosphere transformation have caused extensive climate, environmental and ecosystem disruptions that are recorded in stratigraphic successions. Atmospheric carbon dioxide and methane concentrations at 51% and 157% above Holocene levels have driven global temperatures to 1.5 °C above pre-industrial levels, marking a substantial departure from earlier relatively stable climatic conditions. A sharp global plutonium increase in 1952, related to above-ground thermonuclear detonations, provides the most suitable primary marker for establishing the Anthropocene’s base, supported by an array of proxies, many unique to the Anthropocene. Formal recognition of the Anthropocene on the Geological Time Scale would communicate the scale and abruptness of human-driven Earth system change, distinct from the less pronounced human impacts during the Holocene. The Anthropocene is widely used without fixed definition. This Perspective argues for its base to be defined in 1952 by a sharp plutonium upturn coinciding with changes in multiple proxies, providing a globally correlatable horizon reflecting substantial human-driven Earth system disruption.