The debate around Anthropocene Epoch

Anthropocene Epoch is an unofficial interval of time, based on the claim that human activities have changed the Earth so much that we've started a new geological epoch. This idea has stirred up a lot of discussion among scientists, policymakers, and the public. Recently, a key scientific group decided against officially recognising the Anthropocene as a distinct epoch, despite, what some argue, are clear signs of our significant impact on the planet's ecosystems and geology. Regardless of this decision, evidence of human influence on Earth's ecosystems and geology is undeniable and continues to mount, sparking discussions about how we recognise and respond to human-driven environmental changes.

👉 In this article, we delve into the debate over the Anthropocene Epoch, examining what this term means, why it's controversial, and what it reveals about our impact on the planet.

The term 'Anthropocene' derives from the Greek words 'anthropos,' meaning human, and 'cene,' meaning new. It suggests a new epoch in Earth's history, one dominated by human influence. In geological terms, an epoch represents a significant time span that is shorter than a period but longer than an age, marking distinct phases in Earth's geological and climatic history.

💡 Did you know? 

In geology, the divisions of time - like ages, periods, epochs, eras, and eons - are not strictly defined by a specific number of years, instead, they’re characterised by significant geological or paleontological events.

• Eon - The largest unit of geological time, eons are divided into eras. The current eon, the Phanerozoic, began about 541 million years ago and encompasses nearly all of the significant developments in complex life on Earth.
• Era - An era encompasses multiple periods and is marked by major shifts in the Earth's crust, climate, and biological diversity. For example, we are currently in the Cenozoic Era, which started around 66 million years ago following the mass extinction that ended the age of dinosaurs.
• Period - A division within an era consisting of several epochs, periods can last from tens of millions to over a hundred million years. The current period is the Quaternary, which started about 2.58 million years ago and is noted for its ice ages and the evolution of humans.
• Epoch - An epoch is a smaller division within a period, characterised by distinct climatic changes and evolutionary developments. We are currently in the Holocene Epoch, which began about 11,700 years ago after the last major ice age.
• Age - The smallest unit on the geologic time scale, an age can vary widely in its duration. The current age is the Meghalayan, which started approximately 4,200 years ago and was marked by a severe drought in low-latitude regions and increased precipitation in high latitudes.

The proposed Anthropocene Epoch marks a time when human activities have started to have a profound and lasting impact on Earth’s ecosystems and geology. The idea of a new epoch emerged as scientists noticed that human actions - like burning fossil fuels, massive deforestation, and widespread pollution - are leaving a clear mark on the world. These changes are so significant that they can be seen in the layers of the Earth itself, from altered sediment formations to unique chemical residues left by nuclear tests or plastics.

The Anthropocene Epoch is not just about recognising these impacts but also understanding that humans have become the main force shaping the planet's future. This epoch would start when these human effects became globally noticeable and would be defined by clear signs in the geological record.

The idea of officially recognising the Anthropocene Epoch hinges on whether recent human impacts can be distinctly observed in the Earth’s geological layers. Geologists and scientists have set rigorous criteria for defining any new epoch. These criteria include clear, globally identifiable markers in the Earth's strata (layers of sedimentary rock) - evidence that is unmistakable even millions of years into the future.

Criteria for a new epoch

To declare a new epoch, geologists typically look for:

• Global stratotype section and point (GSSP), often referred to as a ‘golden spike’. This is a physical reference point in the geological record. This is a physical reference point in the geological record that must clearly exhibit the onset of distinctive geochemical markers.
• Global environmental changes preserved in the rock, ice, or sediment records. This criterion ensures that when scientists examine rocks from various locations around the world, they can align the geochemical markers found to determine the age of the formations.
  

Evidence of a new epoch

Supporters of the Anthropocene argue that human activities have left such markers. Examples of geochemical markers used to support their argument include:

• Radionuclides from nuclear bomb tests, which are globally distributed and provide a clear signal that can be dated precisely.
• Technofossils, such as plastics and metals, which are durable and widespread enough to leave a lasting record.
• Changes in sediment layers resulting from urbanisation, agriculture, and other land use changes.
• Biological changes like mass extinctions and the widespread movement of species across continents due to human activity.

Despite compelling evidence, the challenge in declaring a new epoch lies in proving that these changes are both global and profound, matching the scale and uniformity of geological events that have defined past epochs. Critics argue that while human impact on the planet is undeniable, it may not yet meet the strict geological criteria required to define a new epoch. They point out that many human impacts, such as climate change and biodiversity loss, are ongoing and may not yet be fully reflected in the Earth’s geological record.

👉 A recent vote by the International Union of Geological Sciences reflects this view. The highest governing body in geology rejected the proposal to officially recognise the Anthropocene as a new epoch. The vote concluded a nearly 15-year-long discussion, with opponents arguing that the evidence, while clear, does not yet demonstrate the permanent global changes typically required to define a new epoch.

This development suggests that while the term Anthropocene may continue to be used informally to describe the current influence of humans on Earth's systems, it will not, for now, be recognised as a distinct epoch within the official geological time scale. 

The debate therefore continues and the question remains: Are we in the midst of a significant enough shift to mark the start of a new epoch, or are these changes just a brief moment in geological time? The ongoing discussions among scientists highlight not only the complexities of Earth’s geological history but also the significant influence humans now wield over it.

Many credible scientists argue that the push to recognise the Anthropocene Epoch is supported by tangible scientific evidence that clearly points to a distinct new period in Earth's history. Key indicators include:

• Radionuclides - These are distinct markers left by nuclear bomb tests that began in the mid-20th century and are globally detectable in the Earth’s geological record. Their widespread presence provides a precise timestamp that many argue marks the beginning of the Anthropocene.
• Plastics - Found in oceans, soils, and even airborne dust, plastics have become a significant and permanent part of the planet's sedimentary layers. Some argue that their durability and persistence make them a clear sign of human impact.
• Sharp rise in CO2 levels - The exponential increase in atmospheric CO2 since the Industrial Revolution, primarily due to burning fossil fuels, is a major geochemical change that has led to global climate shifts, directly linked to human activity.
  

Crawford Lake as a potential GSSP site

Crawford Lake in Ontario, Canada, has been proposed as a potential Global Stratotype Section and Point (GSSP) for the Anthropocene due to its well-preserved sediments that clearly show annual layers and contain significant Anthropocene markers like radionuclides and heavy metals from the post-World War II industrial boom.

The lake was chosen by the Anthropocene Working Group, set up in 2009 by the International Commission on Stratigraphy. The group identified Crawford Lake as the ideal reference site due to its sedimentary record that captures the global impacts of human activity starting in the mid-20th century, often referred to as the ‘Great Acceleration’.

If the Anthropocene is officially recognised as a new epoch, Crawford Lake would serve as a critical reference point for global geological studies and could become a key site for education and policy-making, highlighting the significant influence that humans have on the planet.

While the idea of the Anthropocene has its supporters there are also critics within the geological community. They raise the following issues: 

• Lack of clear global changes - Critics argue that while human impacts are evident, they do not yet show the global uniformity typically required for geological epochs. This lack of uniform global markers makes it challenging to define a precise start time for the Anthropocene across all regions.
• Recentness and duration - Some geologists contend that the proposed epoch is too recent and brief to be distinguished in the geological record effectively. Geological epochs generally encompass more substantial periods.

There are also concerns about the broader implications of designating a new epoch. One major issue is the impact on geological understanding. Recognising the Anthropocene could complicate our understanding of Earth’s geological history by introducing human influence as a defining factor, which is unprecedented in geology. 

Official recognition of the Anthropocene as a distinct geological epoch is not just a matter of scientific categorisation, it's a wake-up call to how deeply human activities like industrialisation and pollution have changed our planet. This recognition could help the world realise just how urgent issues like climate change and pollution are.

Such a step could also help shape our environmental policies, leading to stricter regulations and stronger efforts to protect nature. It might change education too, by bringing the impact of human activities into school curriculums and driving research across various scientific fields. Moreover, it could inspire action at both global and local levels, encouraging communities to rethink their impact on the environment and adopt greener practices.

👉 The declaration of the Anthropocene as a new epoch would mark a significant milestone in our planetary history. It would not only reshape our understanding of the past but also push us to tackle the significant challenges arising from human impacts on Earth. Whether or not the Anthropocene is formally recognised, the concept itself acts as a call to action.

The process of declaring a new epoch involves rigorous scientific scrutiny and multiple rounds of voting by relevant geological bodies. Following the recent vote that decided against recognising the Anthropocene as a new epoch, the scientific community will likely now take additional time to gather more evidence and refine their arguments. Future votes could be scheduled as more data becomes available and as methodologies for measuring human impact on the geological record are improved.

For the Anthropocene to be officially declared, the criteria used to define geological epochs may need to be revisited and refined. This could involve developing a clearer understanding of what constitutes a significant and global marker in the geological record. The community will need to agree on specific indicators that are both reflective of widespread human impact and observable in a consistent manner across different parts of the world.

Continued research and the gathering of new evidence is also essential. This includes identifying other potential Global Stratotype Section and Point (GSSP) candidates like Crawford Lake, which can serve as the primary reference points marking the beginning of the Anthropocene. Researchers will need to compile compelling evidence that these sites show clear and consistent global signals of human impact starting from a specific point in time.

Achieving a consensus among geologists and other scientific experts is also essential. The debate over the Anthropocene is not just about scientific evidence but also about the interpretation of this evidence within the context of Earth's natural variability. Engaging more of the scientific community in discussions, presenting findings at conferences, and publishing detailed studies can help build a broader consensus.

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