Three flaws in defining a formal ‘Anthropocene’

Abstract

The Anthropocene Working Group (AWG) of the Subcommission of Quaternary Stratigraphy of the International Commission on Stratigraphy is moving toward recommending that the start of a formally designated ‘Anthropocene’ epoch be placed in the middle-to-late 1900s. This article summarizes three objections to this possible action. First, major human alterations of Earth’s environment long preceded the 1900s: extinction of most Australian and American mammals; extensive deforestation of arable regions around the globe; creation of extensive anthropogenic wetlands for rice irrigation; and, in recent centuries, plowing of prairies and steppes for conversion to croplands. Second, the formal chronostratigraphic rules followed by the AWG reject any recognition of these early changes a priori: the very rapid pulse-like extinctions because they were ‘merely’ continent-wide, and forest clearance, rice irrigation, and prairie plowing because they developed time-transgressively. Third, the classical approach the AWG follows – adding subdivisions to the standard Geologic Column – is largely disregarded today among scientists working in the younger geologic record, as is apparent from the rare mention of the Pleistocene subdivisions in paleoclimate textbooks. For these reasons, the use of an informal, flexible ‘anthropocene’ is preferable to the constraints that would be imposed by defining a formal ‘Anthropocene’.