have added ten graphs that display the socioeconomic indicators for the three groups of countries separately. (There was insufficient data for the other two indicators.)
In a section headed “Deconstructing the Socioeconomic Trends: The Equity Issue,” they draw this conclusion: “In 2010 the OECD countries accounted for 74% of global GDP but only 18% of the global population. Insofar as the imprint on the Earth System scales with consumption, most of the human imprint on the Earth System is coming from the OECD world.”14
In the Appendix of this book I consider the claim made by some on the left that Anthropocene scientists have blamed all of humanity for the actions of a small minority. The 2015 update directly contradicts such charges. Steffen and his associates have clearly shown that they understand the importance of including global inequality as a key factor in any discussion of the causes and effects of the Great Acceleration.
Of course, ecosocialists would take the disaggregation further, breaking out inequalities not just between but within countries, stressing the fact that 1 percent of the population owns half of the world’s wealth and that inequality is growing at unprecedented rates. An ecosocialist analysis of the Great Acceleration will build on the decisive issues of class and power that are shaping the Anthropocene and will ultimately determine humanity’s future.
3
When did the Anthropocene Begin?
This was a basic tenet of geological science: that human chronologies were insignificant compared with the vastness of geological time; that human activities were insignificant ompared with the force of geological processes. And once they were. But no more.
—NAOMI ORESKES1
In 2008, Anthropocene was accurately described as “a vivid yet informal metaphor of global environmental change.”2 Although it was proposed as a new interval of geological time, it had not been defined in geological terms. It is noteworthy, for example, that the scientists who used the word described it variously as a new age, epoch, or era, even though those terms have distinct meanings in geology. Some academic papers treated it as little more than an informal label for the period since the Industrial Revolution, without reference to qualitative changes in the Earth System.3 None of the principal authors of Global Change and the Earth System were geologists, and the IGBP does not seem to have formally or informally submitted the concept to geological organizations for consideration.
As long as it remained informal, Anthropocene was convenient shorthand for a wide variety of phenomena, but its scientific usefulness was limited by the lack of a specific definition based on objective criteria. Loosely defined and even undefined words are widely used in casual conversation, but in science lack of clear definitions can cause confusion.
Fortunately, some geologists set out on their own to determine whether a prima facie case could be made for formally defining the Anthropocene as a new geological period, using appropriate geological criteria. And that led to a question that has implications far beyond geology: When did the Anthropocene begin?
The Geological Time Scale
Geologists divide Earth’s 4.5 billion–year history into a hierarchy of time intervals—eons, eras, periods, epochs, and ages—called the geological time scale. We live in the Quaternary Period, the most recent subdivision of the Cenozoic Era, which began 65 million years ago. The Quaternary in turn is divided into two epochs—the Pleistocene, which began 2.58 million years ago, and the Holocene, from 11,700 years ago to the present.
The divisions are not arbitrary: they reflect major changes in the dominant conditions and forms of life on Earth, as revealed in geological strata—layers laid down over time in rock, sediment, and ice. The Cenozoic Era is marked by the rise of mammals, following the mass extinction of dinosaurs and most other plants and animals at the end of the Mesozoic. The Pleistocene Epoch was characterized by the repeated expansions and contractions of continental ice sheets in the Northern Hemisphere that are popularly called Ice Ages. The last glacial retreat marks the beginning of the Holocene, which has been characterized by a stable, relatively warm climate: all human history since shortly before the invention of agriculture has occurred in Holocene conditions.
So for geologists, formally approving the Anthropocene is not like applying a faddish label to a current trend, comparable to the Jazz Age or the Gay Nineties. It would mean declaring, on clear scientific criteria, that the present is as different from the Holocene as the Holocene was from the Pleistocene before it.
The subdiscipline of geology that studies and sets standards for geological strata is stratigraphy, and it was the Stratigraphic Commission of the Geological Society of London, the world’s second-largest organization of geologists, that decided to initiate a review. In late 2007, after a year of investigation, the commission submitted a paper to the journal of the world’s largest geological association, the Geological Society of America, which featured it on the cover of the February 2008 issue. The title was a question: “Are We Now Living in the Anthropocene?”4
Although “increasing levels of human influence” can be seen in thousands of years of Holocene strata, the authors concluded that before the Industrial Revolution, “human activity did not create new, global environmental conditions that could translate into a fundamentally different stratigraphic signal.” Since then, however, “the exploitation of coal, oil, and gas in particular has enabled planet-wide industrialization, construction, and mass transport,” producing a wide range of changes that leave traces in strata around the world. The commission focused on four areas of current and expected change that might leave traces for future geologists.
• Increased erosion now exceeds natural sediment production by an order of magnitude.
• Carbon dioxide and methane levels are significantly higher than at any time in nearly a million years, and are rising much faster than in any previous warming period.
• Mass extinctions, species migrations, and replacement of natural vegetation with agricultural monocultures are changing the nature of the biosphere.
• Sea level rises may reach ten to thirty meters for each 1°C increase in temperature, and acidification of ocean water will have severe effects on coral reefs and plankton.
The combined impact of these changes “makes it likely that we have entered a stratigraphic interval without close parallel” in the Quaternary Period, but “it is too early to state whether or not the Quaternary has come to an end.” The authors conservatively concluded that the Anthropocene should be evaluated as a new epoch, not a new period.
Earth has endured changes sufficient to leave a global stratigraphic signature distinct from that of the Holocene or of previous Pleistocene interglacial phases, encompassing novel biotic, sedimentary, and geochemical change. These changes, although likely only in their initial phases, are sufficiently distinct and robustly established for suggestions of a Holocene-Anthropocene boundary in the recent historical past to be geologically reasonable….
Sufficient evidence has emerged of stratigraphically significant change (both elapsed and imminent) for recognition of the Anthropocene … as a new geological epoch to be considered for formalization by international discussion.
This tentative “yes, there is enough evidence for the subject to be considered” received a remarkably quick response. Within months, the International Commission on Stratigraphy (ICS), the committee of the International Union of Geological Sciences (IUGS) that has responsibility for the geological time scale, asked Jan Zalasiewicz, chair of the London Society’s Stratigraphic Commission, to convene an international Anthropocene Working Group to
