When Did the Anthropocene Begin?

Mark Altaweel

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Usually, geological timescales move slowly, even if the world around us changes rapidly. For the last 12,000 years, we have lived in the Holocene Epoch. This is a time defined by the end of glacial expansion and changes to the Earth’s climate that led to wide temporal regions around the Earth that facilitated human settlement.

Now, however, scientists say we have entered the Anthropocene Epoch. This could spell new environmental changes to come while also showing we have begun to affect global-scale natural systems in a much more significant way.

What is the Anthropocene?

The Anthropocene is described as a geological epoch; the division of time affecting epochs usually relate to geological deposits that can be reasonably dated and measured.

Epochs represent the second shortest geochronological unit that geologists use. For instance, in many parts of the world, topsoil that we see around us has often been deposited during the Holocene with the previous epoch being the Pleistocene often evident in the form of bedrock.


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Side by side comparison of black and white photo from 1899 showing glaciers and a color photo from 2003 showing a bay with water.
One impact of the Anthropocene and the resulting accelerated climate change is the retreat of glaciers. Scientists are using repeat photography to understand changes to local environments. Reid Glacier in Glacier Bay, Alaska filled all of Reid Inlet in 1899. The glacier has retreated substantially as seen in this photo from 2003 and continues to retreat at a rate of about 30 – 50 feet per year. Photos: G.K. Gilbert, 1899 and Bruce Molnia/USGS, 2003.

More recently, scientists have been debating if human activity has now affected geological deposits and, if so, then would this represent a transition away from the Holocene Epoch that was affected by post-glacial deposits?

For a number of years, there has been a working scientific group (Anthropocene Working Group) that has been working on the concept of the Anthropocene and when it began. Since around the 2000s scientists have been debating about the onset of the Anthropocene, although the concept of the Anthropocene goes back even further to the 1980s.

Nobel laureate Paul Crutzen and Eugene F. Stoermer popularized the argument that humanity has driven the world into a new geological time. They wondered if this started around the end of the 18th century, when the Industrial Revolution began, although they were aware that this was debatable.[1]

When did the Anthropocene begin?

The time ranges of when the Anthropocene began vary from decades to hundreds or thousands of years ago; some scientists argue that when human activity became significant enough to affect geological time and deposits should be when we date the beginning of the Anthropocene to.

Ground zero for the the Anthropocene

In what has been called the ‘golden spike’, the site and time used as the type example of when the Anthropocene becomes clearly evident is argued for.

Crawford Lake in southern Ontario, Canada demonstrates the transition from more natural to human-evident deposits that become clearly measurable at around the mid-twentieth century.

A shaded relief map showing the location of Crawford Lake in Ontario Canada.
Crawford Lake, located in the province of Ontario in Canada is a meromictic lake. This means the layers of the lake don’t intermix which make the lake an idea location to study geological epochs by studying the layers of sediments. Map: Caitlin Dempsey.

In Crawford Lake, you can see evidence for industrialization and atomic activity from deposits around 1950. Carbon and plutonium isotopes are present that vary from the natural background. These are from the various atomic activities tested or used as well as the increasing rate of fossil fuel burning. While industrialization began much earlier, the level of activity only becomes clearly noticeable in the atmosphere by the mid-twentieth century when such activity accelerates tremendously.

Although Crawford Lake is far from atomic use sites and major factories, the high presence of atmospheric particles that demonstrate human activity at Crawford Lake makes it clear to some scientists that we can now clearly distinguish this new epoch, even if other sites or places demonstrate the Anthropocene more clearly.[2]

Scientists disagree over defining the Anthropocene

Not all scientists are happy by what they call a ‘narrow definition’ of what defines the Anthropocene. Many scientists argue that human activity could be found to have affected the Earth clearly and substantially for hundreds or thousands of years. In fact, many landscapes and what we see around us in different parts of the world have been shaped over many generations.

The development of agriculture, for instance, has been seen as a clear defining moment in human history that began to significantly shape the natural environment.[3] This may show that the timing of the Anthropocene is not in clear agreement; however, there is nearly no dispute among scientists that we are now living at a time of clear human activity affecting virtually all ecosystems.

Others have argued discussion and debate about when the Anthropocene began is not relevant to us today, but how the Anthropocene ends might be more impactful. The fact that now human activity can affect geological deposits or vastly alter our atmosphere and landscapes should be cause for concern and a warning to rapidly adapt.[4]

Debating the exact start of the Anthropocene seems somewhat esoteric to some, as the main interest is how do we limit human impact on the natural environment. However, the timing of when human activity becomes significantly measurable at a geological timescale around the world is of interest to many because it demonstrates how long we have been altering our planet from what might have been its natural evolution.

The Anthropocene will be a time of great change and likely adaptation, but its longer-term impact will only become evident in the decades ahead. 

References

[1]    For more on how the Anthropocene discussion became popular with scientists, see: http://www.igbp.net/globalchange/anthropocene.4.1b8ae20512db692f2a680009238.html.

[2]    For a recent story on the Anthropocene and the ‘golden spike’, see:  https://boingboing.net/2023/07/15/the-anthropocene-working-group-has-chosen-crawford-lake-as-a-golden-spike-that-can-help-scientists-understand-this-new-geological-epoch.html.

[3]    For indication of disagreement about the Anthropocene’s definition, see:  https://anthroecology.org/why-i-resigned-from-the-anthropocene-working-group/.

[4]    For more on what should concern us about the Anthropocene, see:  https://www.economist.com/leaders/2023/07/13/what-matters-about-the-anthropocene-is-not-when-it-began-but-how-it-might-end.

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About the author
Mark Altaweel
Mark Altaweel is a Reader in Near Eastern Archaeology at the Institute of Archaeology, University College London, having held previous appointments and joint appointments at the University of Chicago, University of Alaska, and Argonne National Laboratory. Mark has an undergraduate degree in Anthropology and Masters and PhD degrees from the University of Chicago’s Department of Near Eastern Languages and Civilizations.