Scientists take new step to announce Anthropocene – 12/26/2022 – Science

The official timeline of Earth’s history–from the earliest rocks to the dinosaurs and rise of primates, from the Paleozoic to the Jurassic and every point before and after–could soon include the age of nuclear weapons, weather changes Caused by man and The spread of plasticAnd garbage and concrete all over the planet.

In short, the present.

Ten thousand years after our species began forming primitive agricultural societies, a panel of scientists took a big step on the last day 17 to announce a new time period of geological time: Anthropocenethe age of mankind.

Our current geological era, the Holocene, began 11,700 years ago with the end of the last great ice age. The 35 or so researchers on the panel seem close to certifying that we have indeed spent the past few decades in an entirely new unit of time, characterized by patchy but ongoing man-made planetary-scale changes.

said Colin Waters, a geologist and chair of the Anthropocene Working Group, a panel that has debated the issue since 2009. The past century has changed that thinking, Waters said. “It was a shocking event, a bit like an asteroid hitting the planet.”

Last week, members of the working group completed their first internal vote on details, including exactly when they think The Anthropocene has begun🇧🇷 Once those votes are finished, which could be in the next quarter, the committee will present its final proposal to three other geological committees whose votes will either make the Anthropocene responsible or reject it.

Sixty percent of each committee will have to agree to the group’s proposal in order to move on to the next. If it fails at any of these, the Anthropocene may not have another chance to be ratified for years.

However, if he makes it to the end, the changing timeline of geology will officially acknowledge that mankind’s impacts on the planet were so significant that they closed the previous chapter in Earth’s history. I’d like to realize that these effects will be noticeable in rocks for thousands of years.

“I teach history science “You know, Copernicus and Kepler and Galileo,” said Francine McCarthy, an earth scientist at Brock University in Canadaand a member of the Working Group. “We really do,” she said. We live in the history of science.

However, there are still criticisms of the Anthropocene, even though we all have first-hand knowledge of it, or perhaps because of it.

Stanley C. Finney, secretary general of the International Union of Geosciences, worries that the Anthropocene has become a way for geologists to make a “political statement.”

He notes that in the vast expanse of geological time, the Anthropocene will be just a small picture. other units of geological time They are useful because they direct scholars to periods of deep time that left no written records, only scattered scientific notes. On the other hand, the Anthropocene would be a time in Earth’s history that humans have documented extensively already.

“For human transformation, we don’t need those terms, we have the exact years,” said Finney, whose committee will be the last to vote on the working group’s proposal if it goes this far.

Martin J. Head, a member of the working group and geoscientist at Brock University, argues that refusing to acknowledge the Anthropocene would also have political ramifications.

“People will say, ‘Well, does this mean the geological community is in denial that we have fundamentally changed the planet?’” he said. We have to justify our decision anyway.

Philip L. Gibbard, a geologist at the University of Cambridge, is the general secretary of the other committees that will vote on the working group’s proposal. He has serious concerns about how the proposal will shape up, concerns that are shared by the broader geological community, in his opinion.

“It won’t be easy,” he said.

“ Messy and controversial work “

Like zoologists curating the names of animal species or astronomers deciding what counts as a planet, time-keepers in geology operate conservatively by default. They establish classifications that will be reflected in academic studies, museums, and textbooks for generations to come.

“Everyone is criticizing the Anthropocene Working Group for taking so long,” said Lucy Edwards, a retired USGS scientist. we🇧🇷 “In geological time, that’s not much.”

Drawing lines in Earth’s time has never been so easy. The rock record is full of holes, “a jigsaw puzzle with many missing pieces”, in Gibbard’s words. And most changes on a global scale happen gradually, making it difficult to know when one season ends and the next begins. There weren’t many times when the whole planet changed at once.

“If a meteor hits the Yucatan Peninsula, that’s a good sign,” Edwards said. “But other than that, nothing in the geological world is the best line.”

beginning of the Of course time Cambrian, about 540 million years ago, saw the Earth explode with an astonishing diversity of animal life, but the exact starting point has been disputed for decades. The long-running controversy led to a redesign of the current geological period, the Quaternary, in 2009.

Jean A. Zalasiewicz, a geologist at the University of Leicester, “It’s a messy and controversial piece of work.” “And, of course, the Anthropocene brings a whole new range of dimensions to confusion and conflict.”

Humanity footprint

It took a decade of discussion—in emails, academic articles, and meetings at the London🇧🇷 Berlin🇧🇷 Oslo and beyond – to the Anthropocene Working Group for defining a key aspect of its proposal.

In a vote of 29 to 4 in 2019, the group agreed with the recommendation that the Anthropocene should begin in the mid-20th century. Greenhouse gas emissions A fire started all over the world, leaving indelible traces: plutonium isotopes from nuclear explosions, nitrogen from fertilizers, ash from power plants.

The Anthropocene, like almost all other geological time intervals, needed to mark a specific physical location, known as a “golden peg,” in which the rock record clearly distinguishes it from the earlier period.

After years of research, the working group concluded on the 17th by voting on nine candidate sites for the Anthropocene. They represent a range of environments in which human influences are recorded: a peat bog in Poland, a glacier Antarctic Peninsulabay in Japancoral reefs off the coast of Louisiana (USA).

Many scholars remain unsure whether the mid-twentieth century boundary makes sense. It’s embarrassingly recent, especially for archaeologists and anthropologists who will have to start pointing to artifacts from World War II as the “pre-anthropocene”.

And using nuclear bombs to pinpoint a geological gap seems distasteful to some scientists, or at least irrelevant. A radionuclide is a convenient global marker, said University of Maryland ecologist Earl C. Ellis, but it says nothing about climate change or other human impacts.

Using the Industrial Revolution might help, but this definition still leaves out thousands of years of changes wrought on the planet through agriculture and deforestation.

called for attention

Legalizing the Anthropocene is a wake-up call, said Naomi Oreskes, a member of the working group. For geology, but also for the rest of the world.

“I grew up in a generation where we were taught that geology ended when people showed up,” said Oreskes, a historian of science at Harvard University. The Anthropocene foreshadows, she said, that “human influence is actually part of geology as a science.” It takes us to realize that our impact on the planet goes beyond the surface level.

But Cambridge’s Gibbard worries that by trying to add the Anthropocene to the geologic time scale, the working group may be underestimating the concept. Strict schedule rules force the group to impose a single starting point on a sprawling story, which unfolded at different times in different places.

He and others argue that the Anthropocene deserves a looser geological designation: an event. Events do not appear in the timeline; No bureaucracy of scholars regulates them. But it was transformative for the planet.

Translated by Luis Roberto M. Gonsalves