We live in a time where humanity’s impact on the world around us is clearly visible. From the neverending barrage of information about climate change, to extinction and habitat loss, the consequences of our actions are impossible to avoid. There’s no denying that the world around us is changing, but what if there are deeper implications? What if our impact on the planet will be apparent thousands, even millions of years into the future? Have we changed our planet’s system to such an extent that the birth of our species defined a new geological epoch?

The geological timescale is how we understand the relative timing of past events. From the advent of life, to mass extinctions, all of it is documented in the rock record. Our geological past is divided into formalised time periods: eons, eras, periods, epochs and ages. These time periods are generally divided by major changes visible in the rock record, such as mass extinctions, major climate shifts, or changes in magnetic polarity, with absolute ages determined by radioactive dating (1). Currently, we are formally sitting in the Holocene Epoch, which began around 11.7 thousand years ago, with the end of the last glacial maximum and beginning of the subsequent warmer interglacial phase (2). However, due to the enormity of impact on earth systems that humanity has had, especially since the dawn of the industrial revolution, some scientists are pushing for the formalisation of a new epoch: the Anthropocene. 

The concept of the Anthropocene was first officially coined by Paul Crutzen and Eugene Stoermer in 2002 (3). Initially, it was used to recognise the exploitation of earth’s resources by humankind, including the emission of greenhouse gases, urbanisation of land, and increase in species extinction rates. Crutzen and Stoermer suggested the beginning of the Anthropocene to be in the late 18th century, as, in the last 200 years, the “global effects of human activities have become clearly noticeable” (3). The concept, at its core, has remained the same since then, but there have been some changes and debate around formal definitions and informal uses of the term. The Anthropocene has been adopted in popular culture, with its broad use encompassing humanity’s interactions with the earth, but there is ongoing debate about its formal use. Furthermore, although the theory traces its origins to earth system science, efforts to formalise the Anthropocene  have been multidisciplinary, involving not only stratigraphers and palaeontologists, but also experts from various scientific backgrounds (4). 

Formalising the Anthropocene as an epoch distinct from the Holocene relies on being able to find stratal evidence in the rock record for where this transition took place (4). There are countless pieces of evidence for our impact on Earth’s systems.Yet, there is still debate around which ones can be used to define the Anthropocene. The Anthropocene Working Group identified as potential evidence for the beginning of the Anthropocene: the increase in sedimentation and erosion rates; changes to carbon, nitrogen and phosphorus cycles; climate change and increase in sea level, and; biotic changes such as unprecedented spread of species across Earth (4). Many of these impacts will leave permanent evidence in the geological record, indicating our existence long after our civilisations have crumbled. 

There are many potential ways to define the beginning of the Anthropocene. Crutzen suggested this crucial moment to be the invention of the steam engine, which led to the industrial revolution, often used as a baseline to compare our current climate to (3). However, evidence of industrialisation from this time is really only visible in Europe, with sediments from the Southern Hemisphere showing no change (5).  More recently, it has been posited that the detonation of the first atomic bomb in 1945 should be the official marker of the Anthropocene, as it deposited a thin stratal layer of radionuclides, which do not naturally occur in the environment (6).

While it’s clear that humans are a major source of change on Earth, some say that it does not necessarily mean we’ve entered a new epoch. Although geological time periods are often delineated based on environmental change, not every environmental change necessitates the creation of a new epoch. There have been past periods of (relatively) rapid climate change that are not associated with new time periods. An example of this is the Palaeocene-Eocene Thermal Maximum (PETM). During this time, there was significant global warming, change in habitats, and migration in species. This warm period lasted for approximately 100,000 years, but there were no mass extinctions. Once temperatures returned to normal, ecosystems essentially returned to how they were before the event (7).  

Geologically speaking, the proposed Anthropocene is a minuscule amount of time. Although the effects are extreme, if we stopped all emissions right now, it is possible that within 5000 years the climate could return to pre-industrial levels (8). Another argument presented by some authors is that the stratigraphic basis for the Anthropocene doesn’t exist yet, and is merely expected to exist in the future. Many structures which have an anthropogenic origin, such as excavation, boreholes and mine dumps, are not yet geological strata. Additionally, in strata that have recorded anthropogenic change, such as speleothems, marshes, lake and ocean floor sediments, the layers representing the Anthropocene would be so thin as to be difficult to distinguish from the underlying Holocene sediments (6). Without the gift of hindsight that has allowed scientists to examine previous epochs, it is difficult to say whether or not the change we currently see will be significant enough on a geological scale to officially move us into a new epoch. 

There has been suggestion that instead of a new epoch, the Anthropocene could be a Sub-Age, or an Age within the Holocene Epoch (4); acknowledging our profound impact on the earth, but believing that the earth’s system will eventually return to pre-industrial levels. 

Further complicating the matter, there are suggestions that humans have been altering the earth’s climate since long before the industrial revolution. Evidence shows that a rise in CO2 occurred with the advent of farming by early humans, 7000 years ago. Around the same time, there was also a rise in atmospheric methane, which has been attributed to rice paddies and livestock (9). With the increase in human population happening at this time, there was likewise an increase in land clearance, both to accommodate dwellings and farming. Even though these emissions and land clearing are tiny by today’s standards, they may have been enough to push our climate away from heading into its next glacial period, priming the warmer conditions we experience today. Some arguments have even been made that irreversible impact by humans stretches back even further, to the Pleistocene extinctions of megafauna across multiple continents (10). 

There is no doubt that humans have had, and are having, a massive impact on the environment. The atmosphere and oceans will take thousands of years to recover from their current level of warming. However, these massive changes do not necessarily mean that we have entered a new epoch. Although it appears there will be ample stratigraphic records of our impacts on this planet, without hindsight, it is difficult to see just how much change we have created. In the context of geological time, humans have been around for a minutely short period. Although what’s happening today might seem dramatic to us, it is possible that millions of years in the future all we will have left behind is a few centimetres of ocean floor sediment. Either way, the Anthropocene as an informal term for our current time period is valuable for acknowledging the consequences of our actions, and a reminder of the permanence of our record.

References

1.University of Calgary. Geologic time scale. Energy Education. 2024. Accessed October 21, 2025. https://energyeducation.ca/encyclopedia/Geologic_time_scale#cite_note-GTS-3

2. Walker M, Johnsen S, Rasmussen SO, Popp T, Steffensen JP, Gibbard P, et al. Formal definition and dating of the GSSP (Global Stratotype Section and Point) for the base of the Holocene using the Greenland NGRIP ice core, and selected auxiliary records. J. Quaternary Sci. 2009;24(1):3–17. doi: 10.1002/jqs.1227 

3. Crutzen PJ, Stoermer EF. The ‘Anthropocene’ (2000) [Internet]. Benner S, Lax G, Crutzen PJ, Pöschl U, Lelieveld J, Brauch HG, editors. Cham: Springer International Publishing; 2021. 3 p. (Paul J. Crutzen and the Anthropocene: A New Epoch in Earth’s History). Available from: https://doi.org/10.1007/978-3-030-82202-6_2     

4. Zalasiewicz J, Waters CN, Summerhayes CP, Wolfe AP, Barnosky AD, Cearreta A, et al. The Working Group on the Anthropocene: Summary of evidence and interim recommendations. Anthropocene. 2017;19:55–60. doi: 10.1016/j.ancene.2017.09.001      

5. Pare S. Nuclear bombs set off new geological epoch in the 1950s, scientists say. Live Science. 2023. Accessed October 21, 2025. https://www.livescience.com/planet-earth/nuclear-bombs-set-off-new-geological-epoch-in-the-1950s-scientists-say       

6.  Finney S, Edwards L. The “Anthropocene” epoch: Scientific decision or political statement? GSA Today.  2016;26:4–10. doi: 10.1130/GSATG270A.1

7.  The Editors of Encyclopaedia Britannica. Paleocene-Eocene Thermal Maximum (PETM). Britannica. 2023. Accessed October 21, 2025. https://www.britannica.com/science/Paleocene-Eocene-Thermal-Maximum

8. The Royal Society. If emissions of greenhouse gases were stopped, would the climate return to the conditions of 200 years ago? The Royal Society. 2020. Accessed October 21, 2025. https://royalsociety.org/news-resources/projects/climate-change-evidence-causes/question-20/

9.  Ruddiman WF, He F, Vavrus SJ, Kutzbach JE. The early anthropogenic hypothesis: A review. Quaternary Science Reviews. 2020;240:106386. doi: 10.1016/j.quascirev.2020.106386

10.   Doughty CE, Wolf A, Field CB. Biophysical feedbacks between the Pleistocene megafauna extinction and climate: The first human-induced global warming? Geophys. Res. Lett. 2010;37(15). doi:10.1029/2010GL043985