12.1: Introduction - Welcome to the Anthropocene!

We humans have become so numerous and so powerful, the changes we have wrought on the Earth’s surface so extreme, that a new geological epoch is being named after us, the Anthropocene. It seems we have left the stability of the Holocene epoch, the preceding 10,000 to 12,000 years that followed the last Ice Age, and are now entering a period wherein many planetary parameters are shifting toward values unseen in hundreds of thousands or millions of years, with unknown consequences not only for human civilization but for all highly evolved lifeforms. Paul Crutzen dates its onset to the onset of the Industrial Revolution in the late 1700s, heralded by the invention of the steam engine and, coincidently, the beginning of the anthropogenic increase in atmospheric carbon dioxide and methane (Crutzen, 2002). Representative of the emerging field of Earth System Science, ^[1] Will Steffen and colleagues (2011) present a series of graphs, all reflecting the general outline of a J-curve, starting out slowly and rising to very high values rapidly near the end–the paradigm case being our human population, holding at less than one billion for all our previous existence prior to 1800 and then beginning a slow rise followed by a sharp upturn around 1950, coinciding with the onset of the “Great Acceleration” of “just about everything” else, from motor vehicles, telephones and McDonald’s restaurants to water use, fertilizer consumption, and species extinctions—and attempt to consider the effects of the changes in all these variables and their interactions with one another on the state of the biogeophysical system as a whole. Johan Rockstrom and associates (2009) delineate nine planetary boundaries that must not be crossed if we are to stay within “a safe operating space for humanity,” of which three have already been exceeded: rate of biodiversity loss, climate change, and interference with the nitrogen cycle, primarily in the form of massive amounts of reactive nitrogen created in the manufacture of fertilizer. Anthony Barnosky and co-authors (2012), meanwhile, focus specifically on the possibility of a “planetary-scale tipping point” that could trigger an irreversible shift from the present state of the Earth System into another, largely unknown one. As they explain, “biological ‘states’ are neither steady nor in equilibrium; rather, they are characterized by a defined range of deviations from a mean condition over a prescribed period of time,” and from time to time this “mean condition” can change, either as the result of a “sledgehammer” effect, such as the sudden bulldozing of an ecosystem, or via a “threshold” effect, through the accumulation of incremental changes over time, the actual threshold being unknown to us before the shift occurs. These authors list the global-scale “forcings” pushing us away from our present state, including habitat transformation, energy production and consumption, and climate change—all of which “far exceed,” in rate and magnitude, the forcings that drove the last global-scale state shift, the transition from the last ice age into the Holocene epoch, a transition that occurred over more than 3,000 years. They note, however, that “human population growth and per-capita consumption rate underlie all of the other present drivers of global change,” and so these ultimate drivers of Earth System change will be considered in more detail later in this chapter.

Steffen and colleagues (2018) recently explored the “Trajectories of the Earth System in the Anthropocene,” depicting the “limit cycle” traced by the Earth when it was following its glacial-interglacial oscillation and, since many parameters are now departing from earlier values, projecting a possible alternative path that reaches a state they term “Hothouse Earth,” the impacts of which “would likely be massive, sometimes abrupt, and undoubtedly disruptive.” Analyzing the Anthropocene “from a complex systems perspective,” they illustrate our present precarious position, perched upon a “stability landscape” between two stable states, by asking the reader to visualize a marble rolling along a ridge between two valleys, representing two different “basins of attraction”–complex interactions among various parameters can trap the system in either of these two different states, should something trigger its rolling down into one or the other valley. While feedbacks in the complex relationships among many variables (greenhouse gas concentrations, ice sheet reflectivity, etc) have kept us in the relatively stable Holocene “valley” for thousands of years, anthropogenic changes are lifting us out of that valley and could potentially push us over the “hilltop” into another, possibly quite different and most likely less hospitable basin of attraction, which they describe as a “geologically long-lived, generally warmer state of the Earth System.”

To avoid the “Hothouse Earth” scenario, they stress the need for “planetary stewardship,” including “resilience-building strategies” to keep the planetary system in a “Stabilized Earth” state, noting that the current trends of our collective human activities, which tend to focus on enhancing economic efficiency rather than biogeophysical stability, “will likely not be adequate” for doing so. Carl Folke (2016) advocates seeing our human societies coupled with natural processes as interdependent social-ecological systems that need to focus on developing resilience, “the capacity to change in order to sustain identity” by “reorganizing in the face of disturbance.” He explains, “adaptation refers to human actions that sustain development on current pathways, while transformation is about shifting development into other emergent pathways and even creating new ones.” Engaging in “resilience thinking” in confrontation with our planetary boundaries, it becomes obvious that a transformation of our collective human actions is required, so as to become “in tune with the resilience of the biosphere” (2016). However, as he and his colleagues remark, “alas, resilience of behavioral patterns in society is notoriously large and a serious impediment for preventing loss of Earth System resilience” (Folke et al., 2010). Perhaps propagating awareness of the ontological difference between our socially constructed economic and political institutions and the complex systems that sustain the Biosphere—which we did not create and which we destabilize at our peril—could help foster such a transformation.