The Triassic was the dawn of the dinosaurs. The Paleogene saw the rise of mammals. The Pleistocene included the last ice ages.
Is it time to mark humanity’s transformation on the planet with its own chapter in Earth history, the “Anthropocene” or human age?
Not yet, scientists have decided after a debate spanning nearly 15 years. Or in the blink of an eye, depending on how you look at it.
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A committee of nearly two dozen scientists overwhelmingly rejected a proposal to declare the beginning of the Anthropocene, a newly created period of geological time, according to an internal announcement of the voting results seen by The New York Times.
According to geologists’ current timeline of Earth’s 4.6 billion-year history, our world is currently in the Holocene, which began with the last retreat of the great glaciers 11,700 years ago. Changing the chronology to say that we have moved into the Anthropocene would represent an acknowledgment that recent human-caused changes in geological conditions are profound enough to end the Holocene.
The declaration will shape terminology in textbooks, research papers and museums around the world. It will guide scientists in understanding our present, which is still evolving for future generations, perhaps even millennia.
But in the end, the committee members who voted for the Anthropocene last month weren’t just weighing how important this period is for the planet. They also had to consider exactly when this started.
By definition, which an earlier expert panel spent nearly fifteen years debating and crafting, the Anthropocene began in the mid-20th century, when nuclear bomb tests spread radioactive fallout across our world. That definition, according to some members of the scientific committee that evaluated the panel’s proposal in recent weeks, was too limited and strangely new to be an appropriate signpost for Homo sapiens’ reshaping of planet Earth.
“It restricts, limits and narrows down the entire significance of the Anthropocene,” said Jan A. Piotrowski, a committee member and geologist at Aarhus University in Denmark. “What was happening when agriculture started? How would the Industrial Revolution happen? “How about the colonization of the American continent and Australia?”
“Human impact goes much deeper into geological time,” said another committee member, Mike Walker, a geoscientist and professor emeritus at the University of Wales Trinity Saint David. “If we ignore this, we ignore the real impact, the real impact that humans have on our planet.”
A few hours after the voting results were circulated in committee early Tuesday, some members said they were surprised by the margin of votes against the Anthropocene proposal compared with those in favour: 12 to 4, with two abstentions. (The other three committee members neither voted nor formally abstained.)
However, it was unclear Tuesday morning whether the results meant a definitive rejection or whether they would still be contested or appealed. Committee chairman Jan A. Zalasiewicz said in an email to the Times that there were “some procedural issues that need to be considered” but declined to discuss them further. Zalasiewicz, a geologist from the University of Leicester, expressed his support for the sanctification of the Anthropocene.
This question of how to position our time in the narrative arc of Earth history has brought the rarefied world of geological timekeepers into an unusual spotlight.
The grandiosely named chapters of our planet’s history are managed by a society of scientists called the International Union of Geological Sciences. The organization uses strict criteria to decide when each episode begins and what characteristics define it. The aim is to promote common global standards for expressing the history of the planet.
Geologists do not deny that our age stands out in this long history. Radionuclides from nuclear testing. Plastics and industrial ash. Concrete and metal contaminants. Fast greenhouse heating. Species extinction has increased sharply. These and other products of modern civilization leave unmistakable traces in the mineral record, especially since the mid-20th century.
However, in order to take its place on the geological time scale, the Anthropocene must be defined in a very specific way; This will not only meet the needs of anthropologists, artists, and others who already use this method, but also the needs of geologists. period.
Therefore, many experts who have expressed doubts about the canonization of the Anthropocene have emphasized that votes against it should not be read as a referendum among scientists on the general state of the Earth. “This was mostly a narrow, technical issue for geologists,” said environmental scientist Erle C. Ellis of the University of Maryland, Baltimore County, one of those skeptics. “This has nothing to do with the evidence that humans are changing the planet,” Ellis said. “The evidence is mounting.”
St. Francine MG McCarthy, a micropaleontologist at Brock University in St. Catharines, Ontario, is the opposite of a skeptic: She helped produce some research to support confirmation of the new age.
“Regardless of the line in time scale, we are in the Anthropocene,” McCarthy said. “And acting accordingly is our only path forward.”
The Anthropocene proposal began in 2009, when a working group met to investigate whether recent planetary changes deserved a place in the geological timeline. After years of deliberation, the group, which included McCarthy, Ellis and three dozen others, decided to do so. The group also decided that the best start date for the new era was around 1950.
The group then had to choose a physical location that would most clearly demonstrate a definitive break between the Holocene and the Anthropocene. They settled at Crawford Lake, Ontario; Here deep waters preserved detailed records of geochemical change in bottom sediments.
Last fall, the working group presented its Anthropocene proposal to the first of three steering committees within the International Union of Geological Sciences. Sixty percent of each committee must approve the proposal before it can move to the next stage.
Members of the first of these, the Quaternary Stratigraphy Subcommission, submitted their votes from the beginning of February. (Stratigraphy is the branch of geology that deals with rock layers and their relationships over time. The Quaternary is the geological period that began 2.6 million years ago and continues.)
According to the rules of stratigraphy, every interval of Earth time needs a clear, objective starting point that is valid worldwide. The Anthropocene working group suggested the mid-20th century because it bracketed the post-war boom in economic growth, globalization, urbanization, and energy use. But several members of the subcommittee said humanity’s upheaval of the Earth is a much broader story, one that may not even have a single start date across the planet.
This is why Walker, Piotrowski, and others prefer to describe the Anthropocene as an “event” rather than an “epoch.” In the language of geology, events is a looser term. They do not appear on the official timeline and no committee is required to approve start dates.
But many of the most important events on the planet, including mass extinctions between 2.1 billion and 2.4 billion years ago, the rapid expansion of biodiversity, and the filling of Earth’s skies with oxygen, are called events.
Even if the subcommittee’s vote is upheld and the Anthropocene proposal is rejected, the new era could be added to the timeline at a later point. But he would have to reconsider the entire debate and voting process.
Time will move on. Evidence of our civilization’s impact on Earth will continue to accumulate in rocks. The task of interpreting what all this means and how it fits into the grand flow of history may fall to the future heirs of our world.
“Our impact will be permanent and will be recognized in the geological record in the future; there is absolutely no doubt about that,” Piotrowski said. “The people who will come after us will decide how this will be sorted.”
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