Bogs, lakebeds, and sea floors compete to become Anthropocene’s ‘golden spike’
Excerpt: If you had to pick one spot that best reflects when human activity became an Earth-shaping force, where would it be? Geoscientists will consider the question this month when they meet to evaluate 12 sites, only one of which can serve as the “golden spike” for the Anthropocene, a proposed geological age beginning in the 1950s amid the fire of nuclear bomb tests and the fumes of surging fossil fuel use. Although the idea of the Anthropocene has gained wide traction, it still lacks a formal geological definition. In 2016, the Anthropocene Working Group (AWG), a group of several dozen geoscientists convened by the International Commission on Stratigraphy (ICS), settled on the early 1950s as its starting point. But the ICS still needs a formal proposal with an ideal geologic sample recording these global changes—a golden spike—to mark the end of the Holocene epoch, which began 11,700 years ago, and the beginning of the Anthropocene. To find that sample, teams of earth scientists spent several years analyzing sites that contain promising markers, such as spikes in plutonium and other radionuclides that settled after atmospheric nuclear tests, spherical ash particles from unchecked industrial emissions, microplastics, and perturbations to carbon and nitrogen chemistry from greenhouse gas emissions and urban smog.…