The Anthropocene by B. L. Turner II (introduction, Q2 and Q3)

THE ANTHROPOCENE

101 Questions and Answers for Understanding the Human Impact on the Global Environment

B. L. TURNER II

INTRODUCTION

Our species, Homo sapiens (or wise human!), evolved during the last two seconds of Earth’s geological clock (Fig. 0.1), which, in our case, started ticking about 4.6 billion years ago. In those two seconds we have risen to become the dominant species on Earth, reaching the capacity during the last one- tenth of a second to rival the forces of nature in our influence on the Earth system. This ascendancy is a chronicle of evolving human–environment relationships. For our purposes, it begins during the Late Palaeolithic (or Late Stone Age, about 100,000 to 70,000 years ago) as migrations of modern humans out of Africa ultimately reached the far corners of all the continents, apart from Antarctica. That chronicle continues today through rapidly advancing technological capacities that supply the demands of nearly eight billion people whose material consumption, on average, is at an unprecedented per capita level. In the process, we have changed – more often than not degraded – the natural capital and environmental services of the Earth system (nature) that have supported our rise to dominance. For most of this ascent, our environmental impacts were local to regional in scale and our responses to declines in environmental services involved moving to new locations, importing resources from afar, or innovating management and technology to maintain or improve those resources. The human transformation of the planet in the last one- tenth of a second of the clock, however, not only challenges these responses but has become global in scope and threatens the functioning of the Earth system.

This transformation raises serious concerns about the capacity of the Earth system to sustain the biosphere – the very part of our planet that our species occupies. The human–environmental conditions that create these concerns are called the Anthropocene. The implications of the Anthropocene for society and the environment are variously interpreted, however, be they the lessons of human-induced environmental changes in the past to forecasts of the well-being of society and the environment in the future. The differences in these interpretations reside partially in the evidence and significantly in the worldviews and values of the interpreter. Society at large navigates among the interpretations through its day- to-day behaviour and the signals sent (e.g. through voting) to its decision-makers. The signals sent could be informed by the state of the science – both the evidence and interpretations – relevant to understanding past, present and future human–environment relationships.

This book provides a baseline for understanding these relationships. Through a series of interconnected questions and answers, it addresses: (1) the concept of the Anthropocene

Figure 0.1: Earth history in 12 hours

Condensing our planet’s history into a 12-hour period, our species would appear only in the last two seconds, and the Anthropocene perhaps one-tenth of the last second. Different depictions of Earth history clocks as well as different assessments of Earth history apply somewhat different time and date ranges for the appearances of different forms of life.

Source: adapted from Wikimedia Commons (commons.wikimedia.org/wiki/File:Geologic_Clock_with_events_and_periods. svg; accessed 12 February 2022).

and the broad-stroke history of human-induced changes in the environmental conditions of the planet that provide different indicators of the emergence of this period; (2) the major human impacts currently inscribed on the Earth system and their consequences; (3) the different causes and rationales applied to understanding the changes made; and (4) various elements of sustainability science, the field of study that informs society about sustainable development in the Anthropocene.

The connections among the themes, phenomena and processes in this book are expansive and complex, requiring multiple encyclopedias to cover their entirety. Indeed, various collections exist for the Anthropocene, Earth system and sustainability (DellaSala & Goldstein 2017; Meyers 2012; Nierenberg 1992). This work differs from these compendia in several ways.

First, it takes a broad, historical sweep of human impacts on the Earth system, providing insights on the past and present activities and consequences as they affect interpretations of the Anthropocene and sustainability. The topics addressed are those this author finds important to that history, the current human–environment condition, and the science of sustainability. The empirical evidence applied to the topics and the interpretations of this evidence is presented through a science-based lens focused on what was and is, not what ought to be. Moral and philosophical considerations of the topics, as important as they may be, are underemphasized for the most part.

Second, a question-and-answer (Q&A) format attempts to balance the breadth and depth of knowledge of the topics included. A brief answer, typically a sentence or two, follows each question. An elaboration of the brief answer deliberately reduces the complexities of the issues explored, but provides a more complete answer and justifications for it as well as references to support the claims and metrics presented. These references include new evidence or claims in the literature as they appeared up to July 2022. Those that are especially new and novel must be weighed in light of the fact that they have yet to stand the test of subsequent research attention that support or not or alter the observations of the new work (e.g. Clements et al. 2022).

Third, in most cases, the Q&As are expected to be read as needed and not necessarily in their numerical order. As such, the questions are cross-listed in the text based on their relevance with one another. For example, Question 94 asks if it is possible to place a monetary value on the Earth system. Part of the answer resides in the economic value of environmental services, a core concept used throughout the book. In Question 94 and elsewhere among other answers, these services are coded to the original question addressing them, in this case Q7, guiding the reader to the elaboration of the phenomenon which is not found in Q94.

Fourth, the Q&As are organized in sections, as noted below, to provide coherence. Each section introduces the rationale for the Q&As within it and provides insights of relevance to the section theme not otherwise found in the Q&As. Such insights are especially important for those sections addressing the human impacts on the different spheres of the Earth system (Sections III–VI) relative to natural drivers of change. These sections, therefore, briefly introduce the natural drivers, identifying those dimensions that differ from humaninduced changes.

The framing of the Q&As could be arranged in various ways. The approach adopted takes us from the meaning of the Anthropocene, through the changes in the Earth system created by societies past and present, the broader, science-based means of understanding these changes, and the emerging field seeking to address a more sustainable human–environment relationship.

Section I. identifies the meaning of the human–environmental relationships of the Anthropocene, the Earth system and global environmental change. Attention is given to the roles of the Anthropocene as a concept and, possibly, a geological time unit or event.

Section II. The exact timing of the start of the Anthropocene is variously interpreted. Arguments and evidence about its antiquity and recency exist. A broad-stroke history identifies the commonalities and distinctions of past and current human-induced environmental change. This history provides a basis from which to interpret the emergence of the Anthropocene, including those dimensions involved in considerations of the Anthropocene as a formal geological unit. Major human impacts on the stocks and flows of the Earth system are identified for different periods of human history, including the evidence, often contested, that the impacts in question were the outcome of natural forcing or drivers in the Earth system or some combination of them and human activities.

Sections III–VI. What are the major human impacts on environments globally and what Earth system consequences have followed from these impacts? These four sections explore the nature and scale of current human changes through the different “spheres” comprising the Earth system: land cover of the lithosphere, hydrosphere, atmosphere and biosphere – or the land surface, water, air and life, respectively. Each sphere is essential to functioning of the Earth system and has been changed variously by human activities. The spheres differ, however, in the discreteness of their geographic boundaries and, as may be expected in a system, the environmental processes interact among the spheres, many flowing across them. Notably, the land surface per se is not considered a sphere, although it covers the lithosphere. The atmosphere is distinctive in its position relative to the lithosphere. In contrast, the hydrosphere and biosphere physically cross-cut one another and the other two spheres. In addition, biogeochemical cycles, a critical dimension of the Earth system, flow through the spheres.

These dimensions require decisions about which phenomena and processes to treat in which section. With a few exceptions, the decision lies in the sphere space in which the phenomenon physically exists or the process takes place, or in which the phenomenon or process receive the most research attention. For example, carbon cycling is the centrepiece of climate warming; it and other greenhouse gas Q&As are addressed primarily in the atmosphere section, despite their cross-sphere flows. The most abundant human-induced change to the terrestrial surface of the Earth – part of the lithosphere – is that of land cover, captured largely by vegetation changes in terms of spatial dimensions. As such, land-cover/ vegetation change is placed in the lithosphere/land cover section, despite biota constituting life and, hence, the biosphere. The hydrosphere flows through the other spheres in different forms (i.e. liquid, solid, gas), but all dimensions of water are treated within the context of the hydrological cycle, regardless of their spatial location. Given the vegetative link to land cover, the biosphere section focuses on the biological kingdom of Animalia, both terrestrial or marine, and microorganisms.

Section VII. How do we explain the underlying human drivers that generate the environmental outcomes? Human innovations to overcome the vagaries of the biophysical environment to improve the provisioning of food, fibre, fuel and shelter and to reduce environmental hazards, such as floods and droughts, mark the history of human–environment

relationships. In some cases, the technologies and strategies employed in these efforts enhance environmental services and attenuate hazards. In others, however, they degrade the environment and/or lead to unintentional Earth system consequences. This section examines the driving forces that have been advanced for the changes in question, ranging from the demands on nature from the growth in the global population of our species to differing values and norms of societies. The various roles and supporting evidence proposed for each cause and the challenges to it are addressed.

Section VIII. Experts differ in their interpretations of the dynamics of human–environment relationships and the future consequences of dynamics now under way. These differences have as much to do with worldviews of the interpreter as they do with the evidence. This section addresses those worldviews as entertained by experts committed to perspectives grounded in mainstream science. It begins with Q&As about the character of the integrative science addressing the Anthropocene, followed by considerations of opposing worldviews, with examples.

Section IX. How do we deal with the conditions of the Anthropocene? Is it possible to create a sustainable human–environment relationship and what would that relationship entail? These are the questions of sustainability science, the emergence of which is examined. The goals and content of sustainability science are identified, followed by considerations of its various dimensions, including issues such as the vulnerability and resilience of human–environmental systems and the capacity to measure sustainable development.

Strategies to address sustainable human–environment conditions are limited to the broader themes for which consensus exists among the expert community, such as the need for adaptive management. Specific strategies and the technologies associated with them are not discussed. There are several reasons for this omission. Many of the strategies proposed to mitigate climate warming, for example, involve controversial approaches, such as placing aerosols in the atmosphere to block solar radiation. Furthermore, the means of assessing the costs of mitigating strategies versus subsequent adaptations to the changes as they occur involve significant disagreements among the expert communities, such as the appropriate discount rates to apply in assessments of the costs. These two examples alone would require expansive text to treat adequately, let alone address the other issues at play, such as the means to calculate environmental services that are not part of the market system.

The text includes a large range of metrics and measures dealing with environmental changes and associated drivers of those changes. The International System of Units (SI) is used in most cases. Some literature, however, uses the term “ton” in United States-based sources without reference to a US spelling of tonne or to the use of the imperial system. If ton is used in context of all other measures in the metric system or if the cited reference for the measure comes from a source that invariably employs metric measures, such as the United Nations, this text assumes that the US spelling of tonne has been employed and the metric spelling used. If neither of these options proves viable, the imperial/US figures are provided as reported in the source from which they were taken. In addition, scientific

notations of metrics and measures are used throughout. As an example, 10 tonnes per hectare is noted as 10 tha−1, not 10 t/ha. In some complex cases, however, measures use the per sign (/) as in gC/m2/y. The notations are listed in the section on metrics and measures.

As noted, the sources of the data and claims for each answer elaboration are referenced, providing a starting point for those readers seeking more in-depth discussion of the topic. In almost all cases, references involve research articles appearing in English language journals and available online through their DOIs and Google Scholar or other scholarly search engines. Books, encyclopedias and non- journal internet sources are sparingly referenced, with the exception of major reports, largely from international agencies, such as the Intergovernmental Panel on Climate Change and the United Nations. Numerous figures are drawn from digital sources, however. Note that figure and table references are treated as reference material and placed in the reference section of the individual Questions and Answers unless inappropriate to do so. In addition, research articles overwhelmingly focus on those that have appeared after 2000. Older articles are sparingly cited, but are referenced if they were seminal to a particular issue and a more recent article does not fully cover the original base theme. For each Q&A, references that provide reviews and syntheses or constitute a starting point for exploration are identified in bold print in the reference list.

The text uses a large number of abbreviations and acronyms, be they for elements and compounds in the Earth system or various metrics, time periods, and so forth. These are listed in the Metric and Measures section at the beginning of the book. Definitions of the phenomena, processes and concepts referred to in the book are listed in the Glossary at the end of the book. With a few exceptions, the text does not refer to the international science programmes or activities associated with changes in the Earth system or sustainability interests. A list and brief description of those that are mentioned can be found in the Appendix.

References

Clements, J. C. et al. (2022). “Meta-analysis reveals an extreme ‘decline effect’ in the impacts of ocean acidification on fish behavior”. PLoS Biol 20 (2): e3001511. doi.org/10.1371/journal. pbio.3001511.

DellaSala, D. & M. Goldstein (eds) (2017). Encyclopedia of the Anthropocene. Amsterdam: Elsevier. Meyers, R. (ed.) (2012). Encyclopedia of Sustainability Science and Technology. Berlin: Springer. Nierenberg, W. (ed.) (1992). Encyclopedia of Earth System Science. San Diego, CA: Academic Press.

SECTION I

THE ANTHROPOCENE AND THE EARTH SYSTEM: FOUNDATIONAL CONCEPTS

Q1 What is the Anthropocene? 9

Q2 Is the Anthropocene a geological time unit? 11

Q3 What is the Earth system? 15

Q4 What are biogeochemical cycles? 18

Q5 What is albedo? 21

Q6 What are ecosystems, landscapes and biomes? 24

Q7 What are environmental (ecosystem) services? 26

Q8 Are global environmental change and climate change different? 30

Q9 Are the totality of human impacts on the Earth system novel? 32

Never before has humankind dominated the planet Earth as it does today, provisioning, if inequitably, 7.8 billion people, at the historically highest level of material life on a per capita average (Fig. I.1). This achievement has relied on advances in technologies and strategies, accompanied by changing political economies, that, in general, have increasingly stressed natural resources, local to regional environments, and the functioning of the Earth system. The Anthropocene emerges from the resulting human–environment conditions (Q1), a period challenging the capacity of the Earth system to maintain itself suitable for life. Securing a more equitable provisioning of material life for the nearly 10 billion people expected to exist by the middle of the twenty-first century raises concerns (Clark & Harley 2019). This provisioning is desired without reducing the capacity of the Earth system to provide the resources and environmental conditions which humankind expects (Griggs et al. 2013). As such, the conditions of the Anthropocene and Earth system, linked to ways in which we seek to understand them, provide a means by which questions of more sustainable human–environment relationships (Section IX) may be addressed. This section introduces foundational concepts and the key phenomena and process critical to the concepts of the Anthropocene and Earth systems, including several important dimensions of the Earth system that cross multiple thematic sections of the book.

Figure I.1 Global population and per capita gross domestic product (GDP) over 1,000 years 1 international dollar would purchase an amount of goods and services comparable to that of 1 US$ in the United States.

Source: Šlaus & Jacobs (2011).

References

Clark, W. & A. Harley (2019). “Sustainability science: towards a synthesis”. Annual Reviews in Environment and Resources 45: 331–86. doi.org/10,1146/annurev-environ-012420-043621.

Griggs, D. et al. (2013). “Sustainable development goals for people and planet”. Nature 495(7441): 305–307. doi.org/10.1038/495305a.

Šlaus, I. & G. Jacobs (2011). “Human capital and sustainability”. Sustainability 3(1): 97–154. doi.org/ 10.3390/su3010097.

WHAT IS THE ANTHROPOCENE?

Short answer: the current human– environment condition in which human activity matches and, in some cases, exceeds nature as a force of change in the Earth system

While not the first to use the term, the late Nobel laureate, Paul Crutzen, advanced the concept of the Anthropocene through a series of publications beginning in 2002 (Crutzen 2002). The term refers to a new human–environmental relationship in which humankind has become a force that equals or exceeds the natural forcings shaping the Earth system (Q3), such as human-induced climate change. This force derives from our actions that change the states or stocks of phenomena comprising the Earth system and the biogeochemical cycles or flows (Q4) that maintain those conditions. The subsequent changes, in turn, improve or degrade environmental services (Q7) and the functioning of the biosphere, which support humankind and life in general (Crutzen & Steffen 2003; Steffen, Crutzen & McNeill 2007).

Each new technological phase in the advancement of our species, associated with increasing global population, has amplified existing demands and generated new pressures on the states and flows of the Earth system. The human footprint of today (Q96) is sufficiently large to warrant the Anthropocene identity (Q9), although debate exists over how distant in the past the concept is applicable (Q15). Especially since the “Great Acceleration” (Monastersky 2015; Steffen et al. 2015) in population and affluence arising in the mid- twentieth century (Q62 , Q63, Q64), the complexity and pace of changes are such that there are few, if any, analogues in our planet’s history to guide the anticipation of the consequences (Steffen, Crutzen & McNeill 2007; Zalasiewicz et al. 2015). Owing to the conditions prevailing in this new relationship, various arguments declare that perhaps the Anthropocene constitutes a new geological time unit, an epoch or stage (Q2). Regardless of this proposal, the Anthropocene has become the moniker for contemporary human–environmental relationships (Zalasiewicz et al. 2021). It is conceptually powerful and a useful heuristic to examine those relationships.

References

Crutzen, P. (2002). “The ‘anthropocene’”. Journal de Physique IV (Proceedings) 12(10): 1–5. doi.org/ 10.1051/jp4:20020447.

Crutzen P. & W. Steffen (2003). “How long have we been in the Anthropocene?” Climatic Change 62(3): 251–7. doi:10.1023/B:CLIM.0000004708.74871.62.

Monastersky, R. (2015). “Anthropocene: the human age”. Nature News 519(7542): 144–7. doi.org/ 10.1038/519144a.

Steffen, W., P. Crutzen, & J. McNeill (2007). “The Anthropocene: are humans now overwhelming the great forces of nature?” Ambio 36(8): 614–21. doi.org/10.1579/0044-7447(2007)36[614:TAAHN O]2.0.CO;2.

Steffen, W. et al. (2015). “The trajectory of the Anthropocene: the great acceleration”. Anthropocene Review 2(1): 81–98. doi.org/10.1177/2053019614564785.

Zalasiewicz, J. et al. (2015). “When did the Anthropocene begin? A mid-twentieth century boundary level is stratigraphically optimal”. Quaternary International 383: 196–203. doi. org/10.1016/j.quaint.2014.11.045.

Zalasiewicz, J. et al. (2021). “The Anthropocene: comparing its meaning in geology (chronostratigraphy) with conceptual approaches arising in other disciplines”. Earth’s Future 9(3): e2020EF001896. doi.org/10.1002/2016EF000379.

IS THE ANTHROPOCENE A GEOLOGICAL

TIME UNIT?

Short answer: the process is under way to determine the formalization or not of the Anthropocene as a geological epoch or stage.

Geological time units refer to events that change conditions of the Earth system as registered in the stratigraphy of the Earth, such as a mass extinction of biota and the emergence of new organisms, identified by distinguishing markers or “golden spikes” found in the geological (or stratigraphic) record. The markers or Global Boundary Stratotype Sections and Points (GSSPs), include, for example, the absence of specific fossil sets, changes in the magnetic polarity of minerals in rock, and various indicators of climatic change. Until recently, the current geological time unit was recognized as part of the Cenozoic era, Quaternary period and the Holocene epoch (Fig. 2.1 A). The Holocene epoch began about 11,650 years ago at the end of the last glaciation and the beginning of an interglacial period. Recognition of the Anthropocene as an epoch was initially proposed as either the second epoch of the Quaternary period (Fig. 2.1 B), rendering the Holocene as the shortest epoch on record, or shifting the Holocene to the last stage of the Pleistocene epoch (Fig. 2.1 C), making the Anthropocene the first epoch beyond the Pleistocene (Lewis & Maslin 2015).

Heretofore, identification of geological time units has begun with notable distinctions found in stratigraphy, largely associated with a GSSP. The rationale for the Anthropocene epoch, however, is based on the profound and rapid changes in the Earth system created by human activity – those that reside beyond the conditions marking the Holocene – with a major case made for human impacts on biogeochemical cycles (Q4), such as humaninduced carbon emitted to the atmosphere, triggering climate change (Q46). In this case, the time unit is in search of a GSSP. A large number of other indicators suggest that currently the Earth system is functionally and stratigraphically different from that of the Holocene (Waters et al. 2016), perhaps marked by the appearance of radionuclides (i.e. unstable nuclear atoms) from nuclear activities, providing a date beginning about 1950 (Fig. 2.2). Formal recognition of the Anthropocene, however, rests with the International Commission on Stratigraphy (ICS), which appointed a working group to consider the case and make a recommendation (Monastersky 2015; Zalasiewicz et al. 2017). A final vote on the formal recognition of the Anthropocene is projected to take place in 2024.

Figure 2.1 Geological time units and possible changes to include the Anthropocene Figures for boundary start dates are in millions of years. [?] refers to the uncertain date given to the Anthropocene if it is accepted as an epoch. Option 1 would create an extremely abbreviated Holocene, whereas Option 2 moves the Holocene to a stage rather than an epoch.

Source: simplified and altered from Lewis & Maslin (2015). Reprinted by permission from Springer Nature. © (2019).

Various arguments against the new unit exist, however, owing to the identity of its golden spike or the clarity of its dating. For example, epochs and their markers need identification in “deep geologic” time, not that of the short-lived period of the Anthropocene. Humankind’s marks on the Earth are, at best, too transient, perhaps constituting a geological event but not yet an epoch (Brannen 2019). Others advance that the Anthropocene emerged over a long period of time with multiple markers but no definitive one (Q11) (Ruddiman 2018). Yet others recognize the Anthropocene as an ongoing geological event. Interestingly, in 2018 the ICS divided the Holocene epoch into three stages, the last beginning 2250 bce (Walker et al. 2018) (Fig. 2.3), generating serious challenges from palaeoenvironmentalists (Middleton 2018). How this designation will affect the Anthropocene decision is not yet clear: a new stage or a new epoch starting at 1950 or some other configuration, or an ongoing geological event?

Figure 2.2 Key indicators for the Anthropocene

See Metrics and measures for various symbols.

Source: Waters et al. (2016).

Figure 2.3 2018 Holocene reconfiguration by the International Commission on Stratigraphy

The colour coding matches that of Fig. 2.1 for visual insertion of the 2018 additions to the time units.

References

Brannen, P. (2019). “The Anthropocene is a joke”. The Atlantic, 13 August. www.theatlantic.com/scie nce/archive/2019/08/arrogance-anthropocene/595795/.

Lewis, S. & M. Maslin (2015). “Defining the Anthropocene”. Nature 519(7542): 171–80. doi:10.1038/ nature14258.

Middleton, G. (2018). “Bang or whimper?” Science 361(6408): 1204–05. doi:10.1126/science. aau8834.

Monastersky, R. (2015). “Anthropocene: the human age”. Nature News 519(7542): 144–7. doi:10.1038/519144a.

Ruddiman, W. (2018). “Three flaws in defining a formal ‘Anthropocene’ ” . Progress in Physical Geography: Earth and Environment 42(4): 451–61. doi.org/10.1177/ 0309133318783142.

Walker, M. et al. (2018). “Formal ratification of the subdivision of the Holocene Series/Epoch (Quaternary System/Period): two new Global Boundary Stratotype Sections and Points (GSSPs) and three new stages/subseries”. Episodes 41(4): 213–23. doi.org/10.18814/epiiugs/2018/018016.

Waters, C. et al. (2016). “The Anthropocene is functionally and stratigraphically distinct from the Holocene”. Science 351(6269): 137. doi:10.1126/science.aad2622.

Zalasiewicz, J. et al. (2017). “The working group on the Anthropocene: summary of evidence and interim recommendations”. Anthropocene 19: 55–60. doi.org/10.1016/ j.ancene.2017.09.001.

WHAT IS THE EARTH SYSTEM?

Short answer: the interacting physical, chemical and biological processes operating through the spheres of the planet that generate its biogeophysical conditions.

The Earth system, sometimes referred to as the geosphere (which also includes the interior of the Earth), is composed of interacting subsystems or spheres (Fig. 3.1). The most common set of spheres used to describe the Earth system are the lithosphere (solid mineral earth, including the deep Earth; addressed via land cover in this text as explained in Section III); hydrosphere (water, water vapour, ice; the latter sometimes identified separately as the cryosphere); atmosphere, and biosphere (life) (Sections III–VI). Stocks and states reference the components or phenomena comprising these spheres, such as the amount of fresh surface water and the average temperature of the Earth. These stocks and states affect and are affected by biogeochemical cycles or the flow of physical, chemical and biological elements among the spheres, such as that of water and carbon, including the energy (heat) that elements and compounds carry (Q4) (Reid et al. 2010). The stocks/states and cycles/flows interact, creating the Earth system. Figure 3.2 illustrates a simplified version of the subsystems and their linkages comprising the Earth system (Rosswall et al. 2015). Together, the functioning of the Earth system generates the environmental services (Q7) and disservices confronting humankind. Recognition of this system has given rise to the field of Earth system science (Steffen et al. 2020).

Biogeophysical drivers or forcings of our planetary and Earth system, all of which continue to operate in the Anthropocene, influence the longer-term conditions of the biosphere. These drivers include: the great tectonic forces within the Earth (i.e. plate tectonics, Section III); variations in incoming solar radiation (i.e. Milankovitch cycles, Section V); waxing and waning of ocean currents (Section IV); occasional large meteorites (Section V); and periods of intensive volcanic activity (Petersen, Dutton & Lohmann 2016; Shen et al. 2019) (Section III). The Anthropocene (Q1) is marked by the ascendency of human activities as a new driver or forcing (Fig. 3.2, far right) that amplifies and attenuates the stocks/ states and cycles/flows within the Earth system and, thus, the dynamics of the subsystems.

Figure 3.1 The spheres of the Earth system

While other spheres are recognized, the four shown here tend to be the more common set used to identify the Earth system. Each sphere is comprised of many interacting phenomena with changing conditions or states; some phenomena cycle or flow (arrows) through the Earth system.

Source: adapted from Hamilton (2016).

Figure 3.2 Simplified components and linkages comprising the Earth system

The Earth system is a coupling of the subsystems of the physical climate system and biogeochemical cycles (brown) driven by external forcing, such as solar radiation and volcanism, and human activities, such as fossil fuel burning and deforestation (blue).

Source: IGBP (2015).

What is the e arth syste M?

References

Hamilton, C. (2016). “The Anthropocene belongs to Earth system science”. The Conversation. theconversation.com/the-anthropocene-belongs- to-earth-system-science-64105.

IGBP (International Geosphere-Biosphere Programme) (2015). “Reflections on Earth-system science”. www.igbp.net/news/features/features/reflectionsonearthsystemscience.5.950c2fa149 5db7081ecdc.html.

Petersen, S., A. Dutton & K. Lohmann (2016). “End-Cretaceous extinction in Antarctica linked to both Deccan volcanism and meteorite impact via climate change”. Nature Communications 7(1): 1–9. doi.org/10.1038/ncomms12079.

Reid, W. et al. (2010). “Earth system science for global sustainability: grand challenges”. Science 330(6006): 916–17. doi:10.1126/science.1196263.

Rosswall, T. et al. (2015). “Reflections on Earth-system science”. Global Change 64: www.igbp.net/ download/18.950c2fa1495db7081e1754b/1446110005354/NL84-reflections ES_science.pdf.

Shen, J. et al. (2019). “Evidence for a prolonged Permian–Triassic extinction interval from global marine mercury records”. Nature Communications 10(1): 1–9. doi.org/10.1038/ s41467-019-09620-0.

Steffen, W. et al. (2020). “The emergence and evolution of Earth System Science”. Nature Reviews Earth & Environment 1(1): 54–63. doi.org/10.1038/s43017-019-0005-6.

“Stunning in its breadth and rigour while simultaneously being immensely readable. This will be my go-to reference for teaching about human impact on the environment through time and across space.”

Elena M. Bennett, McGill University

“An authoritative guide to the Anthropocene that readily puts a broad range of information at your fingertips, while prompting deeper exploration of this complex topic. A book filled with thoughtful answers.”

Glen MacDonald, University of California, Los Angeles

“This book’s enumerated Q&A format provides unique opportunities to both explore the big picture of Earth’s transformation by humanity and to drill down into the details and original source materials that back it all up with solid science. This is a book that should be on the desktops of everyone interested in human transformation of this planet.”

Erle Ellis, University of Maryland, Baltimore County

“By providing concise answers to complex questions, The Anthropocene allows students to explore and understand the complex human–environment relationships that shape our changing environment.”

Marc Metzger, University of Edinburgh

“A must-have for anyone interested in understanding the state of the planet and our collective role in shaping current conditions. This will be in the canon of human–environment interactions and should be on everyone’s bookshelves.”

Karen C. Seto, Yale University

“Turner’s remarkable book poses the most important questions that arise in explorations of the Anthropocene and provides short, balanced and accessible syntheses of what scholars have come up with as answers.”

William C. Clark, Harvard University

“A highly accessible and balanced review of the key facts, concepts and ideas that are essential to understand today’s global environmental crisis in all its dimensions.”

Eric Lambin, Stanford University

“An encyclopedic tour de force! Will be immensely useful to students, professionals and the public for years to come.”

Emilio F. Moran, Michigan State University

“Turner’s new book helps us understand the nature of the Anthropocene reality and the profound challenges it presents for civilization. Highly recommended.”

Stockholm University

The Anthropocene is an authoritative desk-top reference work for students of geography, the environment and sustainability. Through a series of 101 interconnected questions and answers spanning nine thematic sections, the book provides a comprehensive survey of humankind’s impact on the global environment from the Late Stone Age to the present day.

Unrivalled in scope, the book distills the latest research findings and scholarship across a remarkable range of topics concerning the evolving human–environment relationship. These include the broad history of human-induced changes in the environmental conditions of the planet, the major human impacts on the Earth and their consequences, and the different causes and rationales applied to understanding these environmental changes. All questions are answered succinctly and rigorously and draw on a wealth of contemporary evidence and scientific theories. The book is colour illustrated throughout, answers are fully cross-referenced and further readings are provided for those wishing to delve deeper. For anyone seeking to understand the human-induced changes to our planet and the challenges these pose for sustainability, this book is an invaluable resource. It provides a masterly presentation of the human footprint on the Earth system.

agenda publishing www.agendapub.com