The Anthropocene: When exactly did humans begin changing Earth?

We’re living in the Anthropocene, a new geological epoch that shows just how big an impact humans have had on our planet. From changing the climate to reshaping landscapes, our influence is now on par with natural forces in driving Earth’s systems.

Industrial activities, urbanization, and deforestation have left their mark, pushing ecosystems to their limits and driving species to extinction at alarming rates.

The Anthropocene isn’t just a time of change; it’s a crucial moment in Earth’s history that prompts us to rethink how we relate to the natural world and our role in its future.

Defining the start of the Anthropocene

A team of Earth scientists led by the Center for Marine Environmental Studies has identified the 1950s as the most likely starting point for the Anthropocene.

Proposals regarding when humanity began to significantly change the Earth system have included several milestones:

• Development of agricultural societies approximately 8,000 years ago

• Development of irrigated rice cultivation approximately 6,500 to 5,000 years ago

• Arrival of Europeans in the “New World” between 1492 and 1800, the Industrial Revolution, and the Great Acceleration

“However, to date, no report has pinpointed the time at which humankind began to disrupt much of the operation of the Earth system based on global datasets of diverse proxy records with high-precision chronology,” noted the study authors.

New era in the mid-20th century 

In their comprehensive analysis, published in the journal Proceedings of the National Academy of Sciences, the researchers evaluated three leading contenders for the beginning of the Anthropocene and concluded that the mid-20th century stands out as the strongest candidate. 

This new study adds significant weight to the ongoing debate about when human activities began to leave a profound and lasting mark on our planet.

Concept of the Anthropocene 

The concept of the Anthropocene was first proposed in 2002 by Nobel laureate Paul Crutzen, who suggested that the Holocene – the current geological epoch – had ended and been succeeded by a new era dominated by human-induced changes. 

Since Crutzen’s proposal, scientists have debated whether sufficient evidence exists to formally recognize the Anthropocene and pinpoint its exact start date.

Globally significant human impact

Believing that the evidence is indeed compelling enough to declare the Anthropocene, the research team set out to determine the precise moment when human impact became globally significant. They examined a range of indicators across three potential start dates:

• Late 1800s: Marked by the onset of the Industrial Revolution, this period saw the widespread distribution of lead across major land surfaces, alterations in stable isotope ratios, and shifts in nutrient balances.
  
• Early 1900s: Characterized by global changes in pollen distribution, significant increases in black carbon, and widespread alterations in stable isotopes.
  
• Mid-20th Century (1950s): This era witnessed the proliferation of organic pollutants, the emergence of plastics and microplastics, the beginning of the nuclear age with test blasts leaving evidence worldwide, and the onset of major impacts from global warming.

Enduring changes to Earth’s systems

After meticulously comparing the global impacts of these periods, the researchers found that the 1950s best encapsulated the most measurable and enduring changes to the Earth’s systems. 

These changes are likely to persist for thousands, if not millions, of years, making them a clear marker of a new geological epoch.

The team emphasized that the mid-20th century introduced changes that are both easily observable and irreversible on geological timescales. 

True start of the Anthropocene 

By comparing the global impact of all three periods, the scientists concluded it was the third one that should be considered as the true start of the Anthropocene, being characterized by the most easily seen and measured global changes.

“This study reveals the dates of rapid increases in anthropogenic fingerprints in the strata of the Antarctica, Arctic, East Asia, Europe, North America, Oceania, and other regions,” noted the researchers.

“This leads to the identification of an unprecedented surge in diverse anthropogenic fingerprints throughout all regions, which began in 1952 ± 3 CE, corresponding to the onset of the Great Acceleration.”

The Great Acceleration

According to the study authors, this demonstrates that an overwhelming force with global influence can now be associated with human activities during the Great Acceleration, rapidly and fundamentally transforming diverse natural processes and cycles in the Earth system.

The experts further noted that the global upsurge in anthropogenic fingerprints suggests that humans have become a geological and planetary force capable of inscribing abundant and diverse anthropogenic fingerprints in strata worldwide. 

“This period marked the start of profound planetary-wide changes, such as climate deviations from the Holocene conditions, the transformation of the nitrogen cycle, and intercontinental invasions and colonization of alien species.” 

“Thus, the nearly simultaneous and unprecedented surges in anthropogenic signals worldwide suggest that human influences began to profoundly change the Earth system around 1952 CE.”

Human impacts on Earth

This research not only solidifies the argument for the Anthropocene but also provides a clear timeframe that can guide future scientific and policy discussions about human impacts on the Earth. 

By identifying the 1950s as the starting point, the study highlights the profound and rapid changes initiated during this period, underscoring the significant role human activities have played in shaping the planet’s future.

The research included contributions from experts at the University of Tokyo, the Australian National University, Matsuyama University, Kyoto University, and Shimane University.

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