From nuclear fallout to microplastics, the Earth enters the Anthropocene

Paris, France:

As scientists argue that humans have radically transformed the planet enough to account for our geological epoch, another question arises: Is there anything that hasn’t been touched by humanity’s presence?

The soaring greenhouse gases, ubiquitous microplastics, pervasive “forever chemicals”, global animal upheaval, even old cell phones and chicken bones – all have been presented as evidence that the world has entered the Anthropocene. , or era of humans, in the mid-20th century.

Jan Zalasiewicz, a British geologist who has chaired the Anthropocene Working Group for over a decade, paused for a moment when asked if there was any place on Earth free from signs of human influence.

“It’s hard to think of a place more remote” than Antarctica’s Pine Island glacier, Zalasiewicz told AFP.

However, when scientists drilled deep beneath the glacier ice a few years ago, they found traces of plutonium.

It was a persistent fallout from nuclear weapons tests that began in 1945, leaving behind a radioactive presence unlike anything before.

Zalasiewicz said these radionuclides represent perhaps “the sharpest signal” to mark the start of the Anthropocene epoch 70 years ago.

But “there’s a lot to choose from,” he added.

On Tuesday, the Anthropocene Working Group is expected to announce its pick for the location of the “golden tip” of the era, selecting the site that most clearly represents the many ways humans have changed the world.

However, the announcement still won’t make the Anthropocene an official geological time unit, as geologists around the world continue to sift through the evidence.

– The weight of humanity –

Another major calling card of the Anthropocene will probably come as no surprise: the rapid rise of carbon dioxide and other greenhouse gases that are warming the world.

A lot changed “once humans developed the technology to extract fossilized sunlight — in the form of oil, coal and gas — from the ground,” Zalasiewicz said.

Humans have consumed more energy since 1950 than was used in the previous 11,700 years of the Holocene epoch, Anthropocene scientists have shown.

This new power was used to dominate the world in a way that was not possible before. Both land and animals were used to feed the exploding human population.

Humans and their livestock make up 96 percent of the biomass of all land mammals on the planet, with wild mammals accounting for just four percent, according to researchers’ estimates in 2018.

Supermarket chickens, raised by humans to grow much larger than natural, account for two-thirds of the biomass of all birds, Zalasiewicz said.

Humans have also reshuffled species across the globe, introducing invasive species like rats to even the most remote Pacific islands.

– Technofossils, chemicals forever –

In 2020, researchers estimated that the mass of all objects made by humans now exceeded the weight of all living things on the planet.

Anthropocene researchers have called these objects “technofossils.”

Subsequent generations of cell phones, which have become obsolete so quickly, were just one example of a technofossil that “will be part of the Anthropocene record,” Zalasiewicz said.

Tiny pieces of plastic called microplastics have been found on the planet’s highest peaks and at the bottom of the deepest oceans.

Substances called PFAS or “forever chemicals”, created for products such as non-stick cookware, are also increasingly being identified around the world.

Pesticides, fertilizers, rising levels of nitrogen or phosphorus, even buried skeletons of humans – the list of potential Anthropocene markers goes on and on.

Scientists say that hundreds of thousands of years into the future, all of these markers will clearly be preserved to give our future ancestors — or any being who cares to look — a glimpse into this human era.

But what will this future geologist see happen?

“One of the signs you’d like to see from the Anthropocene is that humanity is responding in a positive way,” said Mark Williams, a British paleontologist and member of the Anthropocene Working Group.

The fossil record doesn’t yet show a mass extinction, but one “is now very likely,” he told AFP.

“We go two directions from here,” he added.

So is there anywhere left on Earth that doesn’t bear a human footprint?

Scientists agreed that the only such place was probably somewhere under the ice in Antarctica.

But if nothing changes, these ice caps will be steadily melted by global warming, Zalasiewicz warned.

(Except for the title, this story has not been edited by NDTV staff and is published from a syndicated feed.)