The geography of the Anthropocene

Through a range of activities and impacts, humanity now plays a dominant role in transforming the global environment. This dominance can be seen in varied physical and societal processes, including global climate change, land degradation, urbanisation, species extinction, pollution, and habitat fragmentation, which are often encapsulated in the term “the Great Acceleration” and are represented by physical and socioeconomic environmental measures that span from 1950 CE (Steffen et al., 2015, 2018). The spatial and temporal scales of these transformational processes have resulted in the development of a proposed new geological unit called the Anthropocene that is being used to highlight human impacts on the Earth System and to develop actions to address these significant global issues (Boivin & Crowther, 2021; Crutzen, 2002). Currently, there is a debate about the benefits of formalising the Anthropocene as a geological unit, and this commentary will examine that debate and consider the key role that geography and geographers play in understanding the Anthropocene.

The concept of the Great Acceleration was first presented in 2004 and highlighted a range of physical, environmental, and socioeconomic data from 1750 to 2004 presented in a graphical format that encompassed an upward trajectory and focused on a global scale (Steffen et al., 2005). Socioeconomic trends included human population, real gross domestic production, foreign direct investment, urban population, primary energy use, fertiliser consumption, large dams, water use, paper production, transportation, telecommunications, and international tourism. Physical environmental (or Earth System) trends included atmospheric carbon dioxide concentrations, atmospheric nitrous oxide concentrations, atmospheric methane concentrations, stratospheric ozone loss, earth surface temperature, ocean acidification (pH of ocean water), marine fish capture, shrimp aquaculture production, nitrogen coastal zone input, tropical forest loss, percentage of domesticated land, and terrestrial biosphere degradation (mean species loss) (Steffen et al., 2005). The 1750 CE date was selected to encompass the beginning of the Industrial Revolution in western Europe, which was thought to be an appropriate starting point.

However, more recent arguments have put forward the view that the beginning of the Great Acceleration should commence at 1950 CE, when the most rapid increase in many of the indicators are apparent in the original 2004 graphs (Steffen et al., 2015). In addition, to capture the different rate of acceleration between developed and developing nations, there have been suggestions that socioeconomic indicators should separate OECD (Organisation for Economic Co-operation and Development) countries, BRICS nations (Brazil, Russia, India, China, South Africa, Egypt, Ethiopia, Iran, and the United Arab Emirates), and the rest of the world (Steffen et al., 2015). In terms of the Anthropocene, the key aspect of the Great Acceleration is that it closely aligns with the 1952 CE commencement data for the formal geological time unit definition of the term (Head et al., 2022).

The term Anthropocene was initially developed at the start of the 21st century to highlight the scale of human impact on the Earth System (Crutzen, 2002; Crutzen & Stoermer, 2000). It was suggested that, as highlighted by the Great Acceleration, this impact would define a new geological unit within the geological time scale (Steffen et al., 2018). This time scale was developed by the International Commission on Stratigraphy (ICS) (https://stratigraphy.org), which periodically updates the geological time scale based on new research across the span of Earth’s geological history.

Boundaries between geological units are defined by Global Boundary Stratotype Section and Points (GSSPs), colloquially known as “Golden Spikes,” which are distinct changes in life forms, geochemical data, and/or other factors that separate geological units and which can be dated by absolute techniques and linked to a distinct geographic location (https://stratigraphy.org/gssps). For instance, the Cretaceous/Paleogene Event—associated with dinosaur extinction and the rise of mammals—is defined by the Iridium layer, which is linked to the asteroid impact on the Yucatan peninsula, Mexico, at 66 million years ago (Goderis et al., 2021) and associated with a specific location in Tunisia (Molina et al., 2006).

The same process to define the Anthropocene is currently underway through the Anthropocene Working Group (AWG), which is a component of the Sub-commission on Quaternary Stratigraphy—the current geological epoch. It, in turn, is a constituent body of the ICS (http://quaternary.stratigraphy.org/working-groups/anthropocene). A key aspect of the puzzle on which the AWG is focusing is when the Anthropocene commenced. Most arguments are for the period between 7000 and 5500 years ago (Ruddiman et al., 2020), the period since the Industrial Revolution (Crutzen & Stoermer, 2000), or the period since 1950 (Zalasiewicz et al., 2017).

Other elements of the AWG’s focus include deliberations on what dataset the periodisation should be based on and which geographic location should be used to define its onset (Lewis & Maslin, 2015). A proposal has been put forward for the Anthropocene to commence in 1952 CE, based on radionuclides generated by atmospheric nuclear testing, and for the “Golden Spike” to be based on a sediment core from Lake Crawford, Ontario, Canada, which records this geochemical alteration (McCarthy et al., 2023). In February 2024, the proposal to ratify the Anthropocene as a distinct geological time unit was rejected by the ICS (12 votes rejecting and four votes in favour), although the decision is being challenged at the time of writing (Witze, 2024).

The Anthropocene concept plays a key role in raising awareness of the scale of human impacts on the global environment and highlighting potential solutions to global problems, particularly those linked to the Great Acceleration. As outlined above, there are efforts to develop a formal geological definition for the Anthropocene, but there are significant debates about whether this is a suitable approach. Swindles et al. (2023) have argued that the term needs to be flexible because it is not just a physical science concept but also cuts across the social sciences—and to develop a formal geological unit may affect the broader conceptual outline and importance of the concept. Therefore, Swindles et al. (2023) have also argued for an informal definition that can be used in a range of disciplines.

Geography is well placed to be a discipline central to the work involved in understanding and defining the Anthropocene—particularly because geographers are focused on space and time, which are core components of the formal definition of the Anthropocene as a geological unit. In addition, a central tenet of geography is bringing together both physical and social Earth Systems in physical and human geography and at their interfaces. Indeed, geographers regularly examine a range of datasets that incorporate the key physical environment and socioeconomic factors associated with the Great Acceleration. In fact, the Anthropocene concept can act as a vehicle to bring together human and physical geographers and those in associated disciplines to address major problems that humanity is facing in the current century and beyond. This actual and potential collaborative work is possible both in terms of providing key conceptual frameworks and in data analysis and presentation using, for example, Geographic Information Sciences. In this journal, responses to the Covid-19 pandemic are a template for geographical approaches to scholarly engagement with the Great Acceleration (see Commentaries on Covid Special, Volume 62, Issue 2 Geographical Research), and we invite colleagues to work with us on such matters.

Finally, while definitions and conceptual frameworks are important in relation to the Anthropocene, they can also lead to solutions. For example, consider a paper by Boivin and Crowther (2021), which was developed as a model underpinned by archaeology about why understanding past environments can provide context and solutions for addressing the pressing issues we face this century. Similar papers should be developed for geography, and I encourage authors to consider such approaches that not only help with conceptualisation of the Anthropocene but also offer solutions and fresh contexts.

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