News FocusGeology

A Sign of Our Times

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Science  07 Oct 2011:
Vol. 334, Issue 6052, pp. 37
DOI: 10.1126/science.334.6052.37

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If we are living in a new geological phase called the Anthropocene, when did it begin? Many human-driven planetary changes have their roots in the industrial revolution, when the human population reached 1 billion. Atmospheric carbon dioxide from fossil fuels started to build from around 1800, a change that could mark the beginning of the Anthropocene. But the scale of our impact accelerated rapidly after 1945 when population doubled (from 3 billion in 1950 to 6 billion by 2000). As a result, some think the "golden spike" should be set around 1945, which handily provides a marker that's sudden, distinctive, and global: the introduction of radioactive nuclei into the environment from the first atomic-bomb tests in Alamogordo, New Mexico.