Nuclear Winter and the Anthropocene

Abstract

In 2019, the Anthropocene Working Group proposed the creation of an Anthropocene chronostratigraphic time unit to follow the Holocene Epoch. The Anthropocene time period would begin in the mid-twentieth century, coincident with rapid acceleration of multiple, ongoing anthropogenic changes to Earth’s surface and environments. Radioactive isotopes dispersed during the 1952– 1962 period of atmospheric thermonuclear-bomb tests form a proposed global marker for the beginning of the Anthropocene. This marker is proposed for purely geological rea-sons as it is reasonably precise and global in scope. These isotopes are also a marker for the initiation of a new human capacity to trigger global environmental change in a period of hours. The possibility of a global, multiyear nuclear winter following a nuclear war between North Atlantic Treaty Organization nations and Russia is suggested by recent studies of wildfires that injected sunlight-blocking smoke into the stratosphere, and by increasingly sophisticated numerical simulations of global climate following a major nuclear war. Although the proposal for an Anthropocene time period was made without consideration of the consequences of nuclear war or nuclear winter, designating the period of thermonuclear weapon tests as initiating an Anthropocene time period is supported here specifically because it indicates a new human capability for rapid and destructive environmental change on a global scale.