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Anthropocene: The Uncertain Age of Humans

A book review of “Anthropocene: A very short introduction” by Erle C. Ellis (2018)

By Bopi Biddanda, Jasmine Mancuso, Rachel Ratliff, Katie Knapp, Tony Weinke, Annis Water Resources Institute, Grand Valley State University, USA, and Manuel Villar-Argaiz, Instituto del Agua and Departamento de Ecologia, University of Granada, Spain

“The future ain’t what it used to be.”
– Lawrence Peter “Yogi” Berra.

Ancient and recent human-driven biological, chemical, and physical changes to the Earth system are world-wide, profound, distinct, and rapidly increasing. Today, multiple lines of evidence of globally-distributed anthropogenic signals suggest that we are now living in a radically new human-dominated geologic period on Earth called the Anthropocene. Herein, we review a new book that discusses the meaning of the Anthropocene, how humans became a force of nature and now dominate the planet – and the responsibilities this realization brings with it.

Today, there is little doubt that we are living on a greatly changed planet. In just the last 10,000 years, the human population has grown from 5-10 million to over 7 billion. During this very brief period – a relative “blink” in the 3.5 billion years of history of the biosphere – great forests of the past have been mowed down to make room for hulking skyscrapers and strip malls. Roaring rivers have been subdued to create electricity. Fertile estuaries and bays have been over-exploited and built upon. Even distant oceans, highest mountain tops, and the polar regions have been modified by us. Collectively, we are massively engineering and exploiting our planet’s resources to suit our over-consumptive lifestyles. Until now, no single species has had the ability to manipulate forces of nature to their advantage with such a global reach – but now we do. However, we are now caught in a classic “progress trap” – a condition that arises from the very causes that enabled the progress of human civilization in the first place. For example, the progress enabled by mining minerals and fossil fuels in our rocks has become unsustainable. The resulting environmental changes now endanger civilization itself by threatening the stable climate conditions over the past several thousand years that sustained our stepwise progression from ancient hunter-gather and agrarian societies to the modern industrialized and globalized world. This realization has spurred arguments regarding the role of humans in nature.

Making their first appearance 300,000 years ago, the Homo sapiens was just one of several species in the genus Homo, barely distinguishable from their other hominid counterparts. It wasn’t until about 200,000 years into their existence that they began to display ‘modern’ human behaviors such as cooperative hunting, agriculture, and culture, that enabled Homo sapiens to succeed where others failed. Within a relatively short period of time (~50,000 years), Homo sapiens took over the world. Recent anthropogenic manipulations of the Earth are leading to some drastic changes in its sub-systems, affecting global climate, altering various global elemental cycles, disturbing biological life cycles, inducing habitat transformation, and promoting myriad forms of pollution – threatening the very stability of the interglacial climate of the past several thousand years under which the human civilization flourished.

The Anthropocene is not a new concept: George Marsh – a US minister to Italy in the 19th century who visited the sites of many extinct civilizations in the Mediterranean and realized that they were all victims of self-destruction – wrote the book Man and Nature in 1864 about the influence man had on the world at the time through cutting forests and changing vegetation in the Mediterranean. Following him in 1873, Antonio Stoppani defined this era of humans changing the environment as the ‘Anthropozoic era’. Svante Arrhenius, who discovered that carbon dioxide and water vapor can trap heat energy in 1895, suggested that increases in these gases would create the greenhouse gas effect. With the industrial age underway, the environment was changing at an accelerated rate. Half a century later, scientists began to warn of global warming and its consequences. In 1972, the United Nations Environmental Program (UNEP) was formed in an effort to stem environmental damage and address the ‘human environment’. By 1988, enough evidence of catastrophic global change had accumulated to inspire the formation of a new scientific institution, the Intergovernmental Panel on Climate Change (IPCC), which served to join activists, institutions, and intellectuals in assessing the risks of global warming. Subsequently, Paul Crutzen (a Dutch atmospheric chemist) and Eugene Stoermer (a University of Michigan ecologist) popularized the term “Anthropocene” to describe a planet dominated by humans (2000).  In 2009, the Anthropocene Working Group (AWG) formed to propose formalizing “The Anthropocene” as a new geologic period of time. The proposal to rename this time period to reflect the influence of mankind has sparked intense debates across many disciplines and arguments regarding the specifics of this proposed geologic time period abound. Is this re-naming long over-due, or unprecedented? While there is much empirical evidence supporting the existence of this new time, there are equally as many questions. When did this change begin? What does it mean to be human? Is there a way to reverse or moderate our influence? Does it even matter?

book cover

Erle C. Ellis, author

Figure 1The Book Under Review: Cover of “Anthropocene: A very short introduction” by Erle C. Ellis (Oxford University Press, 2018. 180 p, ~$12; left) and Erle C. Ellis (right). Dr. Ellis is a professor of Geography and Environmental Systems at the University of Maryland and a member of the Anthropocene Working Group (AWG).

Geographer Erle Ellis is a member of the AWG, a committee of researchers working to more sharply define the Anthropocene. His expertise comes through in the book titled “Anthropocene: A Very Short Introduction” published by Oxford University Press. Ellis neatly compartmentalizes an entire epoch of time into evidence, impacts, and social consequences, and states his goal as providing the reader with background about the proposed idea of the Anthropocene to explain why it has become both influential and controversial. Few small books grapple with such huge concepts. Fewer still deliver such a clear and comprehensive synthesis. As we discuss below, it gives readers plenty of information to spur additional questions. 

Up until the Renaissance period, humans believed that the Earth was the center of the universe, and that a divine being created and controlled the universe with the benefits of mankind in mind. It was not until Nicolaus Copernicus and Charles Darwin challenged these thoughts with heliocentric (Sun as the center) ideas in which we are not the center of the universe and evolutionary theories in which humans are simply another animal on an evolving biosphere. These revelations sparked controversy and confusion in a world that relied on biblical ideals revolving around a geocentric (Earth as the center) viewpoint. By the late 17th century, following the revolutionary ideas of famous thinkers and, ultimately Isaac Newton, it was widely accepted that Earth is not the center of the universe, and a new origin story was needed. These revolutionary concepts demanded an adjustment of perspective from mankind, but the battle to untangle age-old worldviews and contemporary debates is still not over. Nevertheless, as the world changes under human influence, we must once more face the questions of what the role of humans in nature is and what it even means to be human.

In 2004, the International Geosphere-Biosphere Programme (IGBP) published their report Global Change and the Earth System: A Planet Under Pressure. This report depicted a dramatic jump in the rate of human-driven and environmental changes starting in the middle of the 20th century – the still ongoing event that became ubiquitously known as ‘The Great Acceleration’, making the case for a new interval of Earth history. However, in order for these significant anthropogenic changes to be recognized, it was necessary to demonstrate that humans have forced Earth system processes to change beyond their natural range of variability. Ellis then dives into a detailed explanation of how anthropogenic forces have altered land, the hydrosphere, the biosphere, elemental cycles, the atmosphere, and climate.

In order to discuss significant Earth changes, one must define what exactly is being affected by change. Ellis outlines the four natural spheres of the Earth’s system: atmosphere (air), lithosphere (earth), hydrosphere (water), and biosphere (life). These spheres are constantly interacting to maintain the overall Earth system. These systems go through natural cycles of acceleration and deceleration, but how does the rate of natural change stack up against change enacted by the human species? In many cases, human presence has accelerated the rate of change beyond natural patterns. Of particular importance are the closely coupled oxygen and carbon cycles of the Earth. For example, the publishing of the Keeling’s Curve of increasing atmospheric CO2 levels ( along with depletion of stratospheric Ozone since the Industrial Revolution has sparked long-overdue concern about how humans are greatly altering Earth’s atmosphere, lithosphere, hydrosphere, biosphere, and climate. Whereas we have been able to conserve the protective Ozone layer in the atmosphere through the introduction of the Montreal Protocol that banned the production and use of Ozone-destroying Chlorofluorocarbons, we have been less successful – despite many attempts – in bringing under control the emission of Greenhouse gas CO2 from fossil fuel consumption.  In order to properly assess the rates and consequences of anthropogenic change, Ellis proposes the “anthroposphere”, or human activity, as the fifth sphere of influence. What qualifies as a human activity can range from agricultural practices to recreational activities to travel patterns. Ellis stresses the importance of a robust understanding of the functioning of Earth’s systems and its underlying cycles, as their natural behavior can be used as a yardstick by which to measure anthropogenic influences.

cosmic calendar

Cosmic Calendar

Figure 2. The Cosmic Calendar: Carl Sagan-inspired sequential history of the cosmos, Earth and humans represented within the passage of a single year (modified from Figure 1 in Ellis, 2018). If we could compare the age of the universe to a year, then the beginning of life would have started in September, and it is only on the very last day of December that hominids showed up. Humans have been around for such little time – but have had such a huge impact on Earth. Kya = Thousands of years ago.

In creating the Geologic Time Scale (GTS), stratigraphers have been challenged with the task of examining the layers of Earth’s crust to determine when a time period begins and ends. The formal study of stratigraphy began in the late 17th century with Nicholas Steno, who coined the “law of superposition”, describing the way the layers of Earth are organized such that the uppermost layers represent more recent deposition periods than those below it. Stratigraphy is useful to understanding the early evolution of life, and scientists rely on radiometric dating with either carbon or uranium to determine the age of each layer. With this technology and biostratigraphic signatures, stratigraphers were able to divide the dates of Earth into different chronostratigraphic units. Distinctions between each new unit must go through a rigorous validation process in order to be officially recognized. Boundaries defined by an agreed age are termed a Global Standard Stratigraphic Age (GSSA). Once a new marker is found, this must be also found at various other locations around the world to avoid confusing with diachronous markers – apparently similar sediments that vary in age from place to place.

Here the author goes into detail on some of the more recent major events that could provide biostratigraphic evidence to denote the beginning of the “Anthropocene” and focuses on stratigraphy as the main tool to denote these events using Global Boundary Stratotype Sections and Points (GSSP; informally, ‘golden spikes’) within the Geologic Time Scale. In 2009, the AWG was formed and tasked with identifying a new GSSP based on anthropogenic influences within the Holocene Epoch (beginning ~12,000 years since the end of the last ice age) that would effectively subdivide it and include the new Anthropocene Epoch. The beginning of the Anthropocene is debated among scientists and, more recently, among social scientists and politicians. Some insist the Anthropocene began long ago when humans began using fire and farming to alter ecosystems, while others argue that it began more recently with the Industrial Revolution or the Great Acceleration of the mid 20th century. In 2016, the AWG sanctioned The Great Acceleration as the main scientific tale explaining Earth’s transition into the Anthropocene; however, the search for a definitive stratigraphic signature and GSSP to describe the beginning of the Anthropocene still continues.

anthropocene milestones

Anthropocence milestones

Figure 3.  Humanity’s March of Progress: Schematic common curve of the coupled increase in human population size (in billions of people; note non-linear axis) and the change in global atmospheric composition (carbon di-oxide in parts per million) since the last glacial retreat, highlighting major milestones in humanity’s recent history that have had significant and globally distributed anthropogenic impacts.  Although humans have altered the surface of the Earth over the last 80,000 years beginning with hunter-gatherers, globally wide-spread human impact is clearly discernible only since the beginning of advanced agriculture about 6,000 years ago and the industrial revolution about 250 years ago – both of which enabled rapid and unprecedented increases in food production and population.  While it is commonly accepted that we are in the Anthropocene today, it has been a challenge to determine its exact start date (brown arrows under the X-axis and black arrows along the population-CO2 curve).  Possible proposed start dates for the Anthropocene range from 6,000 years ago when large-scale agriculture began, 500 years ago with the discovery and exploitation of the Americas (Columbian Exchange), ~250 years ago when the Industrial Revolution began (the Agroindustrial Revolution that gave rise to the city-state, factory system and industrial-scale production of food), to as recent as mid 20th century when atom bomb tests left global signatures of their radioactive fallout throughout the planet – in sediments and the ocean water masses.  GHG=Green House Gasses such as CO2, CH4 and N2O.  Note that the X-axis is also non-linear.  For additional information, see table in appendix of the book titled “Chronology: Potential Anthropocene beginnings” going as far back in time as 2.3 Million years ago to the Stone Age marking the advent of stone tools (Ellis, 2018).

In the later chapters, Ellis discusses the political and social implications of defining this most recent geologic period. The Anthropocene focuses on how humans have changed a planet, but the change has not been equally created by all members of humanity. When it comes to the more recent system changes like anthropogenic climate change, does it make sense to hold all humans equally accountable? Basic economics have shown us that wealthy nations and wealthy individuals use far more energy than their less fortunate neighbors. The idea of a Capitalocene was proposed by three researchers: Adreas Malm, Jason Moore, and Alf Hornborg. Our current system of economics separates humans from nature by commodifying natural resources and humans as mere consumers. Rivers are potential electricity, vast fields and wetlands are potential housing developments, and fossil carbon in rock formations are potential drilling sites for mining non-renewable riches. Decisions about these kinds of large-scale developments are promoted by wealthy business-owners and global industry names. Moreover, all such world-changing decisions are made by adults who are business and political leaders – without consulting our children about their needs and wishes for a future world. As humanity looks for ways to lessen their environmental impact, it is important to keep the consequences of a consumerism-centric view and the rights of future generations in perspective to truly slow down our ever-accelerating use of natural resources.

Today, the human society is collectively acting as force of nature transforming the entire planet at an unprecedented intensity – and Ellis refers to us frequently as “Earth Engineers”. There is societal realization that much of these transformations are to the detriment of both humans and our other planetary co-inhabitants that form the life-sustaining web of life on Earth and constitute a safe operating biosphere conducive to human civilization. Coral reefs and the species they support are suffering; Earth is experiencing a sixth mass extinction; plastics, synthetic hormones, and pharmaceuticals plague our oceans; more than 85,000 industrial chemicals are in active use with unknown consequences; and the effects of global climate change are extensive. The emergence of the Anthropocene crisis demands concerted societal action for immediate course-correction.

book cover

back cover

Figure 4.  Images from cover (left) and content (right) of the book “The Cartoon Guide to the Environment” by Gonik and Outwater (1996) showing an extreme scenario of the human predicament:  Balancing human needs with the rights of other biospheric residents and ensuring a sustainable future – because there is only one Earth. 

Although there are many “wicked problems” to deal with in the anthropocene, the future is not hopeless. The first step in solving a problem is to identify the problem, and considering that we have identified many potential ways we are altering the Earth, we should be now on our way to solving them. The author points out that we should not be too quick to come up with solutions that will simply create secondary issues in the future, such as pumping sulfate into the atmosphere to reflect the sun’s rays, thereby cooling the planet. Although out-of-control consumerism is partially to blame for where we stand now, a new type of market is open for potentially planet-saving sustainable technologies, none more obvious than solar and wind power and electric cars to replace fossil fuel sources like coal and oil. Along the same lines, the “dangerous” nuclear age that started with the development of atom bombs now allows us to use that technology safely in replacing coal-fired power plants for much longer-lasting and less-polluting nuclear fuel sources. And these are just the solutions we have now, not counting future technological developments.

Pale blue dot

Solar system

Figure 5.  Earth: A Pale Blue Dot.  Carl Sagan referred to the Earth as a “Pale Blue Dot” in this the photo taken by Voyager I in 1990 from a distance of 6 billion kilometers (left, circled for visibility), and the position of Voyager I on February 14, 1990 (right, vertical bars are spaced one year apart from 1979-1990 to indicate distance above the solar ecliptic – the plane of the yearly path the Sun follows among the stars in the Milky Way Galaxy).  Sagan also made some poignant observations: “Look again at that dot. From this distant vantage point, the Earth might not seem of particular interest. That's home. That's us.  The Earth is a very small stage in a vast cosmic arena.  It is the only world known so far to harbor life.  There is perhaps no better demonstration of the folly of human conceits than this distant image of our tiny world.  Our planet is a lonely speck in the great enveloping cosmic dark. In our obscurity, in all this vastness, there is no hint that help will come from elsewhere to save us from ourselves. It underscores our responsibility to preserve and cherish the pale blue dot, the only home we've ever known”.

The present is certainly not what the past used to be like. And it is unlikely that any concerted future action by humanity to mitigate ongoing climate change and repair altered ecosystems will restore Earth to a desired past state such as the pre-industrial. Fortunately, the story of the Anthropocene has only just begun. There is still time for us to shape a future for the Anthropocene in which human and non-human species thrive for millenia – and thus write a better story into Earth’s rock records.

At the very end of the book, Ellis, advises readers to not give up hope just yet and elucidates the possibility of a “good Anthropocene”. Indeed, lower case “Anthropocene” already exist and range from detrimental in effect to positively beneficial depending on the view of the species interpreting this change. We have found a way to level off populations, use less land, and improve the quality of lives for much of humanity. We have also taken action to prevent major environmental catastrophes, including the Montreal Protocol curbing the production of Ozone-destroying chemicals, banning of DDT and other pollutants, promoting growth of carbon-neutral energy systems and technologies, and expanding parks and protected areas. These examples and myriad other success stories provide hope that the age of humans does not intrinsically usher in the end of nature. But as naturalist Sir David Attenborough declared recently at the December 2018 UN World Climate Conference in Poland, humanity is now at a crossroad: “Human-driven climate change is humanity’s greatest threat in thousands of years. The collapse of our civilization and the extinction of much of the natural world is on the horizon”. Only the future can tell if the Homo sapiens (homo=man, sapiens=wise) was indeed, wise.

Few scholarly works touch on so much that has to do with our collective Earthly past and future – cosmology, history, geology, ecology, biology, physics, chemistry, economics, sociology, culture, philosophy, human rights, and governance – as does Ellis’s “Anthropocene”. Moreover, the emergence of this “accessible to everyone” book could not be more timely – coming out when “humanity is at a crossroad” – and rightfully belongs in our school and college classrooms, university laboratories, industrial workshops, corporation boardrooms and people’s living rooms. Both young and old alike should read this little book so that there is informed participation by all the peoples of the world in humanity’s ongoing big experiment with the only home we know – the pale blue dot. Who knows – the very idea of the “Anthropocene” may seed a dream in someone – and shape our common destiny for the better.

“The visions we offer our children shape the future.  It matters what those visions are. Dreams are maps”
– Carl Sagan.

Other Source Literature:

Crutzen, P. J., Stoermer, E. F.  2000. The “Anthropocene”. Global Change Newsletter. International Geosphere Biosphere Program 41: 17-18.

Gosnik, L., Outwater, A. 1996. The cartoon guide to the environment. Harper Collins, p. 230.

Lewis, S. L., Maslin, M. A. 2015. Defining the Anthropocene.  Nature. 519: 171-179.

Marsh, G. P.  1864.  Man and Nature: Or, Physical Geography as modified by Human Action.  D. Lowenthal (Editor), Weyerhaeuser Environmental Classics, University of Washington Press.

Ruddiman, W. F., and others. 2016. Late Holocene climate: Natural or anthropogenic? Reviews of Geophysics. doi: 10.1002/2015RG000503.

Sagan, C. 1994. Pale Blue Dot: A Vision of the Human Future in Space (1st ed.). Random House, pp. 429. ISBN: 9780679438410

Waters, C. N., and others. 2016. The Anthropocene is functionally and stratigraphically distinct from the Holocene. Science. 351: 137.

Xu, Y., Ramanathan, V., and Victor, D.  2018. Global warming will happen faster than we think. Nature 564: 30-32.