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I wrote Facing the Anthropocene to help bridge the gap between Earth System science and ecosocialism-to show socialists why they must understand the Anthropocene, and to show Earth System scientists why they must understand ecological Marxism.
When Facing the Anthropocene was published in 2016, it reflected, to the best of my ability, the state of scientific knowledge and debate at the time. But the world does not stand still, so it may be helpful to outline some important recent developments in Anthropocene science in the two main fields involved: geology, which has mainly been concerned with formally defining the new epoch; and Earth System science, which studies the global biological, chemical, and physical changes that are reshaping the conditions of life on this planet.
Formalization
Geologists have divided Earth's 4.5 billion years into a hierarchy of eons, eras, periods, epochs, and ages-divisions that reflect major changes in the dominant conditions and forms of life on Earth, as revealed in geological strata. The procedures for changing the Geological Time Scale, developed over two centuries, are rigorous and time consuming: it is not unusual for a proposed change to be investigated and debated for decades before a decision is made.
By 2016, a clear majority in the Anthropocene Working Group favored recognizing a new epoch, but they needed more specifically stratigraphic evidence before a formal proposal could be made to geology's governing bodies, where a required 60 percent majority vote is required to approve any change to the Geological Time Scale. Subsequent research has focused on two questions.
When did the Anthropocene begin? In May 2019, after extensive evaluation of multiple possibilities, 88 percent of Anthropocene Working Group members voted that a new epoch began in the mid-twentieth century. That was a binding vote, so other possibilities are now off the table.
What physical evidence in the geological strata -known informally as a "golden spike"-is the best indicator for the new beginning of the new epoch? Many pos sibilities are being considered, each with advantages and disadvantages. For example, a 2018 study discusses multiple examples of "Anthropocene deposits" in England alone, including radioactive fallout, plastics, ash from fossil fuels, concrete, and various chemical pollutants that leave long-lasting and readily identifiable traces. All were rare or nonexistent before...