Keywords in Anthropocene Research

How Do We Frame Humanity in the Anthropocene?

Understanding humans as a geological agent does not mean to eliminate the differences within humankind—the differences of gender, race, affluence, health, including the inequalities in the access to technology, lifestyles and forms of consumption. It also does not imply a new Anthropocentrism. On the contrary, it means to take into account the dependency of humanity on many non-human entities, ranging from certain species (e.g. bacteria, crops, insects) to landscapes, water cycles, the ozon layer or material resources. The Anthropocene also raises the question of responsibility for the human-made changes of the Earth System. How can we – differentiated into poor and affluent, powerless and powerful, huge and small ecological footprints—take responsibility for the changing state of the planet? How can we—as individuals—account for the cumulative, non-intentional effects of our lifestyles and economical system?

Thinking about the anthropos of the Anthropocene means to think of humans as cultural beings, endowed with rationality and universal rights—thus the “human” that the humanities refer to. However, it also must include humankind as a species among other species. How could humans develop from an ecologically un-specialised and unprotected but highly communicative mammal into the dominant species on the planet? One of the specifically human traits that were decisive on this path is the development of complex technology which today forms a sphere of its own, the technosphere. Humans in the Anthropocene are humans using, building and being serviced, but also caught in, dependent on and maintaining the technosphere. Understanding what it means to be human in the Anthropocene means seeing humans not just as beings changing nature and transforming it into a post-natural environment. It also calls for an assessment of humanity’s place within the technosphere. How can we think of human control and responsibility within this sphere?

Deep Time and Human Time – A Clash of Scales?

Deep time and its interference with human time are key issues in the Anthropocene. What is deep time? And how do we interfere with it today in ways that are characteristic of the Anthropocene? In the history of science, deep time is a relatively recent discovery. Generally, what we mean by deep time is geological time or cosmic time, in other words: billions of years. Astronomers estimate that the big bang happened about 13.8 billion years ago and the Earth to have formed 4.54 billion years ago. This is real deep time. In contrast, according to traditional Christian world views, for example, God created the world—and the plants, animals and humans on it—no more than a few thousand years ago.

There are still religious fundamentalists holding this belief today. 19th- and 20th-century scientific cosmology and geology overturned such views. Modern science has historicized “nature.” It all started with Earth history. With the ice ages that preceded the warming of the Holocene, scientists in the 19th century began to recognize that the Earth’s climate had changed many times, and quite dramatically, since the planet had formed in our solar system. The theory of evolution introduced by Charles Darwin meant that life on Earth also has a history. Plant and animal species are not unchangeable forever. Rather, most of the plants and animals that have been around on Earth in the past have died out or evolved into something different. 

Deep time is key to understanding such evolutionary and geological processes. Their time is different from the processes we experience in human society. The latter operate on an entirely different timescale. For example, the average human life expectancy is still below a hundred years. The cultural memory of oral traditions extends two to three generations (though some elements of such a tradition may go significantly deeper than that). Cultures based on writing generally create longer traditions. Think of Judaic, Christian, Islamic and Buddhist religious traditions which go back a few thousand of years. However, this is still a long way from geological timescales. So, what does it mean to state that human time interferes with geological time in the Anthropocene? We are only beginning to explore this question. What seems clear enough is that, as humanity has become a geophysical force in the Anthropocene, the changes are beginning to show on the huge scales of geological deep time. For example, according to some recent model calculations, anthropogenic climate change has already delayed the next ice age by at least 100,000 years. In other words, our emissions of greenhouse gases in the last 150 years—which equals five generations—are causing an effect we can expect to last 3333 generations, or roughly half the time our species (homo sapiens) has been around on Earth.

A New Way of Conceiving Human-Nature Relations

The Earth System has fundamentally changed our perspective on human-nature relations in the Anthropocene. Older concepts such as “nature” or the “environment” may still have their own particular charm. But they create a dualism between the anthropos and the Earth. The Earth System integrates the atmosphere, hydrosphere, lithosphere, biosphere and cryosphere. Earth System science studies—and models—positive and negative feedbacks between these subsystems. Earth System science is also underlying climate modelling. More than anything else, anthropogenic climate change has created the need to add human activities to the mix. Hence, the study of recent climate change became the driving force to include economic activities that are often at the core of human-climate interactions, particularly land use and the burning of fossil fuels. In the past, integrated assessment has been the dominant approach to make that link between the physical climate and human activities. More recently, modelling attempts are trying to go further to include the socio-cultural sphere and grasp its dynamics.

Earth Systems thinking began in the late 19th century. Eduard Suess (1831-1914) coined the term “biosphere”, which Vladimir Vernadsky (1863-1945) famously developed further in a study that is now often considered a precursor of Anthropocene thinking. In the 1950s and 1960s, general systems theory and the Cold War threat of nuclear destruction became crucial for the advancement of Earth System science. In the 1980s, modelers reached hypothesised nuclear winter, in other words: global cooling that would follow soon after a nuclear firestorm. One of them was Paul Crutzen who, together with Eugene Stoermer, later suggested the term “Anthropocene” for a new geological era.

Rethinking the Dualistic Distinction Between Nature and Culture

In the Anthropocene, the Earth has been “modified by human action” (George Perkins Marsh) to an extent that some have proclaimed “the end of nature” (Bill McKibben), or a complete transformation of nature into culture. About 250 years ago, many Enlightenment philosophers and naturalists contemplated the idea of transforming “first nature” into an improved “second nature” which also became part of the colonial experiment. Some even saw it as history’s final destination. One may wonder in what way the current state of the Earth relates to those ideas, but viewed in this light the Anthropocene looks like an experiment coming close to failure.

However, the continuity suggested by this long view may be illusionary—and the concept of “nature” itself the cause of misguidance in this case. What Enlightenment philosophers called “nature” was a combination of physical laws beyond human control, a few resources that could be accessed through mining, and the biosphere. The latter was the sphere of human influence that 18th-century philosophers, naturalists and colonialists considered transformable. Transforming the biosphere was what creating an improved “second nature” by the means of human effort meant. The environmental changes of the Anthropocene lie far beyond Enlightenment imaginaries of nature’s transformation, mainly because material extractions from the Earth’s crust have vastly expanded the sphere of human influence beyond the biosphere.

“Nature” is a problematic concept for other reasons as well. The nature-culture dualism has been questioned by philosophers and anthropologists alike, such as Bruno Latour and Philippe Descola, among others. This dualism has been reproduced in European traditions of separating the humanities and social sciences from the natural sciences. Some have claimed that dualistic thinking of this kind has its share in causing the environmental disasters we are facing today. It is perhaps equally relevant that the unity suggested by the term “nature” ceased to exist when natural science split up into multiple disciplines. Moreover, if we look at the universe as it is seen by modern astrophysics, the part that is exposed to human transformation is actually so minute that it ridicules holistic claims about humans having transformed “nature.” Therefore, references to nature are at least blurry if not seriously misleading. What we are talking about in the Anthropocene is the Earth (or the Earth System)—that tiny part of the universe that humans are capable of transforming. The problem is that this is the part our own existence depends on.

The Anthropocene Is an Era of Rapidly Changing Risks

At first glance, this may look like nothing new under the sun. Theorists of “risk society”, like Anthony Giddens and Ulrich Beck, have described preoccupation with the future as one of the trademarks of “reflexive modernity”. The notion of risk is a common way of assessing the likelihood of a certain outcome of our future actions. Risk is crucial in understanding technologies and their potential for accidents, for example: the explosion of a nuclear powerplant. Risk has become systemic in the technological settings in which modern societies operate. What does the Anthropocene add to this? The Anthropocene implies that humans are altering the planet. This involves the danger of altering basic functional systems of the Earth in unpredictable ways.

One way of looking at this would be to describe this as the next step in the expansion of the modern “risk society”—an expansion that reaches out from the technological systems we have created into natural systems. Another way of looking at this is that it goes beyond the familiar framework of a risk society precisely because Earth itself cannot be guaranteed to provide a safe operating space for human action. In the latter case, we would have to recognise that the Earth of the Anthropocene is still bigger than modern society, despite modern societies now being a major geophysical force. One way to describe what that means is what climate scientists call uncertainty. Statistically, uncertainty means that likelihoods cannot be calculated based on the information available. Once the warming of the Earth’s climate has reached 2° above pre-industrial levels, it crosses a threshold beyond which many processes become unpredictable. Hence the question: Are we still living in the era of “risk societies”? Or should we describe the Anthropocene as an age of uncertainty? For social scientists and scholars from the humanities this implies another set of questions: What is the relationship between the Anthropocene and modernity? Is the Anthropocene just another step in the history of modernity? Or is it a rupture—a discontinuity? Is it perhaps even a reversal of the trends that defined modernity, as the Indian novelist Amitav Ghosh suggests?

What Marks the Beginning of the Anthropocene?

Starting dates of the Anthropocene induced an extremely diverse discussion across academic disciplines, from the natural sciences to history, sociology and politics. This discussion centres on the question when human impact on the Earth System, and especially on geological processes, started to be significant and fundamental enough to substantiate the definition of a new geological time unit that terminates or even replaces the Holocene. Originally, Paul Crutzen suggested the start of the Industrial Revolution, i.e. the invention of the steam engine in 1783, as a possible start date of the Anthropocene.

In an initial paper, members of the stratigraphic Anthropocene Working Group (AWG) proposed the world's first nuclear bomb explosion (on July 16th 1945 at Alamogordo, New Mexico, USA) instead. This event spread globally a sequence of significant artificial radionuclides which may be used as the primary stratigraphic marker for the base of the Anthropocene. Later on, the AWG introduced a potential and pragmatic base in the 1950s with the first appearance of plutonium 239/240 from radiogenic bomb test fallout. The mid-20th century placement is related to the Great Acceleration concept, the exponential increase in rates of changes in various human-influenced Earth System trends leading to critical tipping points—the Planetary Boundaries in a new state of the Earth System. 

Slightly earlier potential definitions and markers for the base of the Anthropocene include the increase of greenhouse gases during the Industrial Revolution and the Columbian Exchange, the widespread transfer of animals, culture, diseases, human populations, ideas, plants and technology between the Americas and the Old World. This relatively young historic placement of the start date of the Anthropocene concurs with mainly archaeological and geo-ecological arguments about a long lasting, significant and steadily increasing human influence on the Earth since thousands of years, the Early Anthropocene hypothesis. Assuming such a gradually increasing influence, no real starting point can be defined, thus a transitional phase into the Anthropocene is favoured by some scientists. Major events in this Early Anthropocene provide diachronous steps in human cultural evolution and interaction with the Earth System such as the advent of agriculture or first widespread environmental pollution due to metal mining and smelting. However, these early events so far do not provide a synchronous start date of the Anthropocene.

The Defining System of the Anthropocene

The technosphere is the realm of technology—machines, factories, computers, cars, buildings, the railway, mobility infrastructure. Today we use technology to produce food, to extract material resources, to convert and distribute energy so it can be used in society, to enable other than mere face-to-face communication, and for many other purposes. The totality of technological infrastructures is what we call the “technosphere”. The term was introduced to General Systems Theory by the Canadian control engineer John H. Milsum (1925-2008) in the late 1960s. Milsum argued that the technosphere is distinct from other spheres of the Earth System, including the social sphere formed by all human beings. While the technosphere has been created by humans and serves human purposes, there is some controversy about its independence: Is the technosphere still controlled by humans? Or is it exceedingly escaping control? Does it, perhaps, even operate “according to a quasi-autonomous dynamics”, as Peter Haff (2014) has argued? Already back in the 1970s, the philosopher Günther Anders assessed that technological development has conquered the role of dominant “subject of history”, reducing the anthropos to a mere bystander.

In any case, there is little doubt that the technosphere has expanded in human history, and particularly rapidly since the dawn of industrialisation. It leaped forward once again during the Great Acceleration after World War II, which saw an unprecedented generation and globalisation of novel technologies. Since industrialisation, the technosphere has also emerged as the “control center” of material flows. Most of the materials extracted from the environment stay within the technosphere to further expand and maintain it. This explains why the expansion of the technosphere is key to understanding anthropogenic changes in the Earth System. The current total mass of the technosphere has been estimated to weigh approximately 30 trillion tons, roughly five orders of magnitude larger than the biomass of all human beings living on Earth. These dimensions explain why the technosphere has been called the “defining system of the Anthropocene” (Haff 2017). Geologists already detect its traces in recent sediments, for example in urban stratigraphy. Its enormous diversity is well-reflected in the variety of technofossils found in these most recent sediments, which provides the Anthropocene Working Group (AWG) with evidence to define the lower boundary of this new geological epoch.

Planetary Dimensions of Environmental Change

In the Anthropocene, human beings are altering the Earth collectively. Of course, there are differences: some have a much greater impact than others (ecological footprint). But as the “human web” (John & William McNeill) spans around the globe, the sum of anthropogenic changes has become a dominating geophysical force altering the planet. This planetary dimension of environmental change is new in the Anthropocene. Before we boosted our economies by burning coal, oil and natural gas, environmental change caused by humans predominantly affected the biosphere—the sphere of life on the surface of the Earth which consists of plants and animals.

What exactly is this planetary scale about? — Planets are astronomical bodies orbiting a star. Only planets can become the hosts of life as we know it. In recent years, astronomers have found quite a few candidates among other planets that might provide living conditions similar to those on Earth. But Earth is still the only planet that we know for sure has life crawling on its surface. There is no other “Earth” we can escape to in case something goes wrong. The only “spaceship” we have to survive on is Earth itself. A thin layer of gas, which we call the atmosphere, protects us from outer space which is hostile to any form of life. The boundary between the atmosphere and outer space has been defined at an altitude of 100 km. However, earthly life has expanded no more than a few kilometers up into the stratosphere, the lowest layer of the atmosphere, directly above the Earth’s surface. The stratosphere provides sufficient amounts of oxygen for breathing and carbon dioxide for photosynthesis. Its ozone shield absorbs most of the sun’s ultraviolet radiation which causes skin cancer.

Changing the atmosphere as we have done by burning enormous amounts of fossil fuels is a dangerous experiment. Although unlikely, runaway warming due to unchecked accumulation of greenhouse gases is a possible and very dangerous scenario. Astronomers believe that this is what happened to Venus, our closest planetary neighbour, at some point in its history. Today, its atmosphere has more than 90% carbon dioxide and its temperature is estimated at being close to 500° Celsius. Protecting Earth from uncontrollable change caused by humanity is equivalent to protecting the planetary conditions for life. It is an open question how we translate this planetary dimension of the Anthropocene into policies that protect the Earth and the complex forms of life that have evolved on it. Clearly, “the Planetary” is no longer just an astronomical or scientific category—it has become a political and socio-economic category as well.

The Basis of Life on Earth as We Know It

The Anthropocene is characterised by unprecedented changes to the environment caused by human actions that affect ecosystems and the natural world. Anthropogenic drivers severely accelerate climate change and biodiversity loss, such that scientists have identified the massive decline of biological diversity as a major cause for concern in the 21st century. Their warnings should not be taken lightly since biodiversity—the biological variety of all living species on Earth—provides the basis of life as we know it. Diversity of plants and insects ensures our global food supply, marine biodiversity keeps oceanic ecosystems stable and healthy, just as species variety of land-dwelling animals and plants in grasslands, forests, wetlands and other habitats maintains these diverse ecosystems by keeping them in balance.

Biodiversity is key to all the wonders of planet Earth and, yet, it has become increasingly threatened since humans have entered the stage. Recognising this threat, nations worldwide responded by founding initiatives to focus their efforts on monitoring and protecting global biodiversity, such as the Convention on Biological Diversity (CBD, 1993) and the IPBES (Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services) established in 2012. The IPBES publishes regular assessment reports on the biodiversity crisis in different parts of the world. Most recently, the UN Sustainable Development Goals (SDGs) clearly articulated the need to protect and sustain biodiversity, especially Goals 14 and 15 that centre on ‘Life Below Water’ and ‘Life On Land’.  These calls for action testify to the “anthropogenic biodiversity crisis” (Rull 2022) that we are currently witnessing due to global warming, habitat loss, overexploitation and several other interlinked factors. Rates of biodiversity loss far exceed the threshold of a 'safe operating space for humanity' as originally proposed in Rockström et al's Planetary Boundary model (2009). Refined since then in attempts to specify how genetic and functional diversity contribute to ‘biosphere integrity’ (Steffen et al 2015; Mace et al 2014), the model highlights the vital importance of biodiversity from an Earth System perspective.

With more than 40.000 species threatened with extinction according to the IUCN Red List, the current biodiversity crisis has been likened to the five documented mass extinctions in Earth’s history which occurred over the last 540 million years. Scientists, policy makers and journalists who refer to anthropogenic biodiversity loss as the “sixth (mass) extinction” acknowledge that it is enormous in scale and might result in the annihilation of more than 75 percent of all species on the planet. Latest research findings indeed confirm that the continuing decline of biodiversity across the world has set the Earth on a “sad trajectory towards a Sixth Mass Extinction” (Cowie, Bouchet & Fontaine 2022). All is not yet lost, however, and examples of successful conservation projects and reintroductions of species give reasons for hope. It remains to be seen if deliberate human action taken against the unintended ecological consequences of human interference may still reverse the world’s worrying course towards extinction and planetary crisis.

One of the Major Challenges in the Anthropocene

Climate change is a key issue in the Anthropocene and helps illustrating what it means that humans have become a “geophysical force” and a “geological agent” in our time. Anthropogenic climate change was what Paul Crutzen had in mind, more than anything else, when he proposed the term “Anthropocene” back in 2000. Global warming today is due to a dominance of human influences over natural forces in the climate system. Since the dawn of industrialisation, excessive burning of fossil fuels and the expansion of food production for rapidly growing numbers of people have released greenhouse gasses such as carbon dioxide, methane and nitrogen oxide into the atmosphere. This has caused significant changes in the chemical composition of the atmosphere, so that the anthropogenic greenhouse effect now overrules natural drivers of climate change such as fluctuations in solar radiation or volcanism. This is unique in Earth history, even though there have been changes of the planet’s climate in its estimated 4.54 billion years of existence. In the last 200,000 years, since anatomically modern humans (Homo sapiens) have been around, climatic changes came about in cycles between cold periods with lots of ice on Earth, and warmer periods with less ice.

The last 11,700 years, which geologists call the Holocene, were a warm period. With natural forces still undisturbed as they used to be, the Holocene would end not too long from now in another cold period. The glacial masses around the poles would be expanding slowly. But the opposite is happening, since the anthropogenic greenhouse effect has reversed this long-term cooling trend. Instead, Earth is now warming at an unprecedented rate. Even if we could instantly stop releasing more greenhouse gases into the atmosphere, climate models have shown that the next ice age will still be delayed by at least 100,000 years. What could be a better illustration of what it means that humans collectively have become a geological force? Anthropogenic climate change may be most prominent in public awareness. And yet it is only one aspect among others that show how humans have changed the state of the planet. The ratio and speed of loss in variety of biological species, for example, is equally alarming as climate change. It is, of course, also due to anthropogenic climate change that many species who have lived on Earth for millions of years are now being threatened or have already gone extinct. Other control variables that are used to assess the state of the planet are either reaching or crossing thresholds which have been defined in the Planetary Boundaries framework, beyond which irreversible rapid environmental change is most likely to occur.

The Anthropocene Is Marked by Intensive Human Energy Consumption

The material culture of the Anthropocene is based on the burning of fossil fuels. Which of your daily activities does not, in one way or another, involve the burning of fossil fuels? Mobility and transport are based on it. Using your car to go to work in the morning is an obvious case: burning fossil fuel is what your engine does. Public transport does not necessarily solve the problem as long as, for example, most of the electricity needed to run the railway, trams and the metro still originates from the burning of fossil fuels. Mobility and transport are by no means the only sectors involved in most people’s everyday activities. Construction is another. And just like mobility it is energy-intensive and, hence, releases a lot of carbon into the atmosphere. The built infrastructure that emerges from construction uses heat and electricity. That is what we all do at home or in our workplaces. By and large that energy is also generated from the burning of fossil fuels.

More than thirty years after the Intergovernmental Panel on Climate Change (IPCC) was founded in 1988 and after the signing of the United Nations Framework Convention on Climate Change (UNFCCC) during the Rio Earth Summit in 1992, the global energy regime continues to rely on the burning of fossil fuels. In the course of the 20th century, we can see shifts in primary energy consumption from one resource to another becoming (temporarily) dominant: from coal, to oil, to gas. Renewables are still lagging a long way behind. They have come nowhere near to replacing fossil fuels. This means that energy consumption world-wide continues to produce enormous amounts of CO₂ and other greenhouse gas emissions that drive climate change. Equally, air pollution continues to threaten the health of millions of people. This dual effect is the source of further ambiguity. Greenhouse gases are warming the planet while air pollution has a cooling effect (aerosols block some of the incoming sunlight). However, the latter does not fully compensate for the first. Because aerosols are heavier and more quickly washed out from the air than carbon dioxide, the anthropogenic greenhouse effect will continue to increase even after we stop burning fossil fuels entirely. This problem will only increase over time. The sustainable energy transformation is more urgent than ever, and climate change demands that most of the remaining fossil reserves will stay underground. Our energy regimes require decarbonisation—which would also decouple Anthropocene material culture(s) from fossil fuels.

An Expression of Growing Anthropocene Conscience

Environmental history is a relatively young field of study within the spectrum of historical disciplines. It has emerged along with growing environmental concerns and the environmental movement since the late 1960s. The contours of environmental history first shaped in the United States, before it drew attention in Europe. Today it is a global field of study with scholars from all parts of the world participating in it. Many first-generation environmental historians were environmental activists who shared concerns about nuclear confrontation during the Cold War, the use of nuclear energy and human health issues caused by industrial pollution. They had various disciplinary backgrounds, often in the natural sciences.

Environmental history expanded rapidly after the turn of the millennium as it became organised in the frameworks of international societies. Compared with the 1970s or 1980s, environmental historians are nowadays less outspoken than environmentalists or activists. However, they are more involved in cross-disciplinary cooperation than ever before and as scientific advisors in political processes. Environmental historians also contribute to the activities of the Anthropocene Working Group (AWG). If the Anthropocene was formally defined as a geological epoch, its starting point would most likely be during the Great Acceleration after World War II—a definition preferred by a majority within the AWG. Thus, we may well regard the emergence of environmental history as an expression of growing Anthropocene conscience.

What Is the Anthropocene’s Political Potential?

Outside academic circles the Anthropocene is only beginning to enter public awareness. The circle of politicians familiar with the idea and its implications is broadening gradually. For Klaus Töpfer, former executive director of the United Nations Environmental Program (UNEP), the Anthropocene is “essentially a socio-political category” because it has far-reaching implications for a societal transformation toward sustainability. What does the Anthropocene diagnose add to ongoing debates on global environmental governance? Is it more than a new word for the sum total of urgent sustainability issues?

Researchers in philosophy, political science, history, ecology, sustainability studies and other disciplines provide different answers to these questions. Some influential thinkers—Sheila Jasanoff, Dipesh Chakrabarty and Bruno Latour—have expressed discomfort with the term and the idea of global environmental governance because the Anthropocene questions ‘the global’ and ‘globalisation’ which are essentially socio-economic categories. Instead, they prefer other attributes, such as “planet(ary)”, “earth(ly)”, “gaia”, to describe the character and scale of future policies to control anthropogenic changes of the Earth System. Will acknowledging the anthropos as a geophysical force lead to a new form of governance in the Anthropocene? And how will the current political atmosphere influence future planetary governance in the Anthropocene? The recent political shift from anti-globalism to right-wing nationalism in many countries, including some Western democracies with long-standing anti-authoritarian traditions, nourishes concerns that global political cooperation has entered a period of crisis. Will planetary governance in the Anthropocene merely be hampered by these developments? Or will the pressures of dangerous Earth System change push international affairs back towards more, and more effective, cooperation? 

Material Culture Is Changing Dramatically in the Anthropocene

The enormous variety of materials we make use of today is already mirrored in the most recent geological sediments. What high-resolution stratigraphy for the 20th century brings to the fore is a huge number of technofossils which are the signature of fossil material culture. They reflect the evolution of the technosphere and its enormous expansion nurtured by the fossil energy regime of industrialism. Industrial technologies have produced an unprecedented increase in material variety, making it an anomaly in the history of social metabolism. Synthetic materials such as plastics have contributed to it as well as new raw materials for industrial mass production or unprecedented amounts of materials already used centuries or millennia before (e.g. iron ore). As a result, the material culture of the Anthropocene is markedly distinct from anything we find in pre-industrial worlds. We are now living in an “all-metals era” (Martin Held), which means that all metals and semi-metals from the periodical system have become components for building our material world.

The Anthropocene challenges the social sciences and the humanities to expand their study of matter and materiality beyond the cultural sphere. The “material turn” in the humanities and social sciences has ushered in a new consideration of “materiality” in relation to climate, the environment or the Earth System. It can no longer be ignored that the enormous expansion of material flows in industrialised and developing societies is showing the symptoms of environmental disruption on a planetary scale.

Defining the Anthropocene Involves the Scientific Analysis of Geological Layers

The geological subdiscipline of stratigraphy is asked to define the Anthropocene as a new unit of Earth history. Stratigraphy deals with geological layers and beds, with the law of superposition (older layers were deposited below younger ones). A definition for the base of a formally defined Anthropocene as a unit of the Geological Time Scale has to follow stratigraphic rules and the principles and rules of chronostratigraphy. Thus, the ‘chronostratigraphic’ Anthropocene has to be, according to the rules and current usage of geological terms, a time-rock unit that by definition has a synchronous base. Physical rock-unit boundaries are a matter of lithostratigraphy, and may be diachronous.

A diachronous lower physical boundary of the Anthropocene has been suggested by archaeologists and historians, but may not be applied formally to a chronostratigraphic unit. The Anthropocene, if formally defined by the International Commission on Stratigraphy, would be the youngest, shortest and the only still ongoing chronostratigraphic unit of Earth history, in a historic time interval that can be resolved in terms of calendar years and days, and with some events even in seconds such as an atomic bomb test explosion. This challenges the geosciences which, when defining stratigraphic boundaries, deal with millions of years and boundary error bars of several hundred thousand years.