If hunting only partly accounts for the megafauna extinctions, what else was involved? According to Koch & Barnosky (2006, p. 239):
Taken as a whole, recent studies suggest that humans precipitated the extinction in many parts of the globe through combined direct (hunting) and perhaps indirect (competition [for food or habitat], habitat alteration and fragmentation) impacts, but that … environmental change influenced the timing, geography, and perhaps magnitude of extinction. Put another way, absent the various impacts of Homo sapiens … it is highly unlikely global ecosystems would have experienced a mass extinction of large, slow‐breeding animals in the late Quaternary. But, absent concurrent rapid climatic change evident in many parts of the globe, some species may have persisted longer.
In other words, it is likely that it was the interaction of human hunting and climate change that eliminated or fragmented the environmental conditions necessary to maintain the megafauna, leading to their extinction.
Without question, the vast majority (99 percent) of species that have ever lived are now extinct (Novacek 2001). Human presence on the planet is not guaranteed; indeed, like all species, and despite our comparatively big brains and powerful technologies, we are dependent upon our fragile relationship with the environment. Failure to fully appreciate this simple truth and move with determination to more sustainable socioeconomic systems will place our near future at grave risk. This idea touches on a broader question about lifeforms elsewhere in our galaxy: namely, why, with all of our searching (e.g., NASA probes, monitoring of electromagnetic radiation, the work of the SETI Institute), have we not encountered signs of alien civilizations? One explanation, known as the Great Filter theory, is that extraterrestrial civilizations may emerge, develop, and destroy their environments, and hence themselves, too quickly for us to find them, or vice versa. In other words, the Milky Way may be sprinkled with extinct alien civilizations that were wiped out by self‐induced environmental destruction.
1.9 How did things get this bad?
Promoting the vital need to develop a deeper awareness of our relationship with the environment and assisting students to make informed decisions for action are the ultimate objectives of this book. While there is mounting concern over the ways anthropogenic environmental change is putting human health at risk, the specific rationale for this volume is the inadequate consideration given to the special risk of ecocrises interaction in the existing environmental literature.
The following chapters trace the history of that risk, beginning with the sweeping environmental and social changes launched by the Industrial Revolution. These changes were so immense that many environmental scientists see them as constituting a new geological epoch, one that highlights the dominant role now played by human activity in shaping the very geology and ecology of Earth. Referred to as the Anthropocene, it was triggered in the late eighteenth century with the invention of the steam engine, followed in relatively short order by the production and use of fossil fuels, which contributed to an intense rise in the amount of carbon dioxide and other pollutants in the atmosphere and the oceans. Industrial production, in turn, contributed to an array of other environmental crises, including fuel spills, waste dumping and leakages (Fig. 1.4), deforestation, the spread of infectious diseases, loss of biodiversity, and the devastation of marine life.
Fig. 1.4 Toxic waste barrel.
Source: EliasSch/Pixabay.
But how did all of this come about? What steps along the way pushed our arrival at this troublesome destination? Having come to this point, how can we avoid catastrophe? To adequately address these urgent questions, it is necessary to tease apart and rigorously examine a linked set of environmental, biological, social, political, and economic issues in historic context. This is the approach taken in explicating the health perils of ecocrises interaction in this volume.
1.10 Age of the Anthropocene
The term “Anthropocene” unites the word anthropo, ancient Greek for “humankind”, with the root ‐cene, the standard suffix to denote an epoch in geologic time. Another Greek term of relevance is kairos, which signifies a “moment of transition.” As Moore (2016) remarks, “the Anthropocene concept [is] the most influential concept in environmental studies over the past decade.” But the Anthropocene is more than a concept: it also increasingly constitutes a major influence on the lived experience of Earthlings of all species (Kelly & McDonald 2018), including playing a role in the ending of such experience through species extinction.
While “global‐scale human influence on the environment has been recognized since the 1800s, the term Anthropocene … has only recently [during the 21st century] become widely, but informally, used in the global change research community” (Steffen et al. 2011). It was first introduced by the Nobel Prize‐winning atmospheric chemist Paul Crutzen and the biologist Eugene Stoermer (Crutzen & Stoermer 2000; Crutzen 2002). A primary driver of its acceptance as a meaningful and needed concept is the multiple Earth‐changing effects of climate change. But “climate change is only the tip of the iceberg” (Steffen et al. 2011). Human actions have also changed the life‐sustaining cycles of key elements such as nitrogen, phosphorus, and sulfur. The nitrogen cycle has been altered through the production and use of fertilizer, deforestation, and the burning of fossil fuels. The massive amounts of nitrogen that humans produce—they at their highest level today for 2.5 billion years—are reshaping the world’s ecosystems (Lewis & Maslin 2015). The phosphorous cycle has been changed by fertilizer use and the rearing of livestock (especially hogs), as well as by the use of detergents containing sodium tripolyphoshate. The sulfur cycle has been changed by the burning of fossil fuels, which increases the amount of sulfur in both the atmosphere and the oceans. Moreover, human activities have altered the terrestrial water cycle via dam building, river course modification, and the elimination of riverside wetlands, as well as through changes in land cover that modify the flow of water vapor from the land to the atmosphere. Another human impact is an acceleration of species extinctions to such a degree that it has raised questions about whether we are on the threshold of a mass extermination on par with the one that nearly eliminated the dinosaurs (nearly, and not totally, because the dinosaur ancestors of modern birds survived). In short, human activities are so widespread and so profound in the ways they are changing Earth that they have begun to threaten the very life‐support systems upon which we and all other species depend (Steffen et al. 2005; Waters et al. 2016). The concept of the Anthropocene was developed to call attention to this human‐driven quantitative shift in the geochronology of the planet. As Meyer (2018) comments, “[i]t is a stirring idea: that humans are not a momentary blip in the long procession of Earth’s history, but a new and fundamental driver of planetary change, equal in stature to volcanoes and tectonic plates.” In terms of the actual effects we are having on the planet, it also is a disturbing one.
How do earth scientists determine geochronology? The process involves ongoing data collection, international expert discussion, and committee consensus. Critical components occur within the International Union of Geological Sciences (IUGS), an international nongovernmental organization concerned with promoting international cooperation in the scientific field of geology. The Union manages six international commissions, including the International Commission on Stratigraphy (ICS), which is responsible for setting the stages and boundary markers of the geochronology of Earth history and for naming geological eras. In the language of the ICS, a historical epoch is defined as a subdivision of the geologic timescale that is longer than an age but shorter than a period. By way of analogy, in measuring the dimension of length, a foot is longer than an inch but shorter than a yard.
The establishment of an epochal