Defining the Anthropocene

This Nature paper by Simon Lewis and Mark Maslin reviews the case for treating the Anthropocene, a proposed new geological epoch marked by humanity's large-scale effect on Earth, as a formal unit of geological time. The authors trace the history of the idea and test several candidate start dates against the formal criteria geologists use to define a new epoch, namely a clear, globally traceable marker in the rock and ice record. Of the dates considered, they identify two that best satisfy those criteria: 1610, tied to a dip in atmospheric carbon dioxide following the population collapse in the Americas after European contact, and 1964, tied to the peak of radioactive fallout from nuclear weapons testing. The paper argues that settling on a start date matters because it shapes how the concept is used, debated and acted on, in science and beyond it. Credits: Lewis, S. y. (2015 vol.519). Defining the Anthropocene. Nature Magazine, 171–180.