Williams, M., et al. March 14, 2016. The Anthropocene: a conspicuous stratigraphical signal of anthropogenic changes in production and consumption across the biosphere. Earth’s Future.
Humans are producing and consuming resources at a geologically unprecedented rate – a rate that needs to be maintained to continue the high level and complexity of the current [fossil-fuel based] civilization. This high consumption has formed a ‘striking new pattern’ in the planet’s global energy flow.
Humans now consume between 25 and 38% of net primary production of the planet. Human modification and appropriation of NPP, and the production of energy over and above NPP, has been developing over thousands of years, but accelerated markedly from the mid-20th century onward (Figure 1).Figure 1. Produced energy and the pattern of human population growth from 1750.
Professor Zalasiewicz at the University of Lecister said the last times such huge effects were seen happened 2.5 billion years ago when photosynthesis appeared, and again half a billion years ago when the food web grew more complex. Although the 5 major extinction events were also huge, “ even measured against these events, human-driven changes to production and consumption are distinctly new.”
Co-author Dr Carys Bennett added: “It is without precedent to have a single species appropriating something like one quarter of the net primary biological production of the planet and to become effectively the top predator both on land and at sea.”
Some of the massive effects humans are having on the planet include mining phosphorus and fixing nitrogen to make fertilizer, burning hundreds of millions of years of fossil fuels, and directing this increased productivity that is well beyond natural levels towards animals re-engineered for our consumption.
According to Professor Zalasiewicz: “This refashioning of the relationship between Earth’s production and consumption is leaving signals in strata now forming, and this helps characterize the Anthropocene as a geological time unit. It also has wider and more fundamental importance in signaling a new biological stage in this planet’s evolution.”
Dr Colin Waters of the British Geological Survey said: “Modern human society is structured around economic production and consumption and our recent perturbation of the balance between the two, notably since the mid-20th century, will leave a signal that will provide a lasting legacy of our existence on this planet.”
Also see ScienceDaily.com’s March 23, 2016 Human impact forms ‘striking new pattern’ in Earth’s global energy flow.
Some excerpts from the paper
The human impact on production and consumption in the biosphere is recognizably different from all previous patterns. Humans appropriate a major component of NPP that is augmented by their use of fossil fuels: the combined energy use now approaches that available to the entire terrestrial biosphere prior to human intervention. In addition, humans are poor at recycling compared to the unmodified biosphere, a clear example being the geologically unprecedented rapid increase of carbon in the atmosphere from the consumption of fossil fuels, and concomitant accumulations of plastics—made from hydrocarbons—at the surface.
The influence of humans on mammal populations during the late Pleistocene represents a global, though diachronous, signal of growing human impact. This potentially had an ecosystem engineering effect, as the climax forests of several areas throughout North America may be the result of the removal of megafauna (mammoths and mastodons) in the late Pleistocene, animals that were effective in forest clearance.
However, a key transition in the human remodeling of production and consumption was the origin of farming, moving primary productivity to annual crop plants and shifting primary consumption to domesticated animals. These innovations, which mark the end of the Epi-Paleolithic and the beginning of the Neolithic culture, include the domestication of cattle (pigs, cows, goats, sheep etc.) and development of agriculture from about 10,000 years ago. Once adopted, agriculture sustained a greater population (and standing biomass) of people, and provided the environment in which human specialist activities unrelated to food production could evolve.
The eventual transfer of labor from agriculture to non-agricultural activities is the central component of industrialization, and has led to even greater appropriation of primary production by humans, and to the use of fossil fuels to augment energy supplies to the global ecosystem, with the concomitant rise of humans and their domesticated animals as the principal component of standing terrestrial large-animal biomass. From the 17th- to mid-20th century technological advances in farming, in their initial stages focused on England, the Low Countries and northern Italy, and then spreading globally, helped facilitate increasing appropriation of primary production. These included: improvements in drainage and restoration systems; the development of the Dutch plough in the early 17th century; the mechanization of farming in the early 18th century; developments in breeding and genetic manipulation, scientifically explained by Gregor Mendel in the mid-19th century; and the use of fertilizers, with the discovery that ammonia could be synthesized by a chemical reaction from nitrogen, first demonstrated by Fritz Haber in 1909, representing perhaps the most significant step. This paved the way for overcoming a major natural limiting force on agricultural production—the rate at which plants fix atmospheric nitrogen into soils—in the early 20th century by the German scientists Fritz Haber and Carl Bosch, who used Haber’s earlier discovery to develop the Haber-Bosch process. Their process took atmospheric nitrogen to make nitrogen fertilizers [some 90 million tons of nitrogen-based fertilizer now being produced each year. Through enhancing food production, this single innovation is estimated to sustain some 40% of global human population today. The process is energy-intensive, and is directly supported by the consumption of fossil fuels (fossil NPP). The widespread use of fossil energy to make processing of land (e.g., ploughing) quicker and more efficient, to support a greater number of humans and their domesticated animals, to enable rapid national/international transfer of produce, and to enable more efficient harvesting of the sea and sea floor has further amplified the impact of humans on both production and consumption in the biosphere.
During the 20th century (between 1910 and 2005) the Human Appropriation of Net Primary Productivity doubled from 13 to 25% of the NPP of potential vegetation. These changes involved a doubling of reactive nitrogen and phosphorus in the environment, and the use of vast amounts of fossil energy focused on agricultural production. In 2014 humans extracted 225 million tons of fossil phosphates, and this is projected to rise to 258 million tons by 2018. Phosphates are a limited resource, but nevertheless annual human addition to the phosphorus cycle exceeds the amount of available phosphorus from natural recycling. Future projections, dependent on land-use, suggest between 27 and 44% of NPP might be appropriated by humans by 2050. While it is likely a geologically unique situation for a single species to co-opt or consume such a large percentage of NPP, perhaps more significant from a biosphere perspective is the technology and landscape modification that humans have used to achieve this. This leads to a complex relationship whereby the ultimate biophysical limit to the amount of NPP that humans might appropriate is dependent on the interplay of many parameters in the landscape, a relationship that needs to evolve rapidly to provide stability between production and consumption in the Anthropocene biosphere.
Viewed from another perspective, the large-scale integration of humans and technology has led to a new terrestrial “sphere,” the technosphere, a novel Earth system of global extent, which is characterized by a total mass approaching that of the biosphere, significant rate of energy dissipation (17 TW), and high average density of infrastructure links such as roads [circa 0.4 km of roadway per km2 of land area, CIA, 2015] and of links between mobile communication devices [circa 50 such devices per km2 of land area, PR Newswire, 2014] that help connect together most humans and most in-use technological artifacts. An emergent system, the technosphere comprises the world’s humans, cultures, and technological components and systems, and maintains itself quasi-autonomously via feedback loops that deliver goods and services desired by humans (e.g., entertainment), or essential for their survival (e.g., food and water), in return for human participation in its continued function. There are no analogs for the technosphere in the geological history of life on Earth. Therefore, its myriad ramifications are truly unprecedented.
Human Impact Measured Against Geological Events
Throughout geological history the coupling between the production of biomass and the consumption of that biomass in the biosphere has typically maintained stability, with periods such as the Ordovician and Cretaceous showing patterns of fauna and flora that indicate persistent stable ecosystems over long time frames. Intervals where this stability may have been temporarily disrupted include the mass extinction events of the Neoproterozoic Era and Phanerozoic Eon [there being six of these following the definition of Benton, 2012, of which five were within the Phanerozoic Eon], with many small-scale extinctions operating at intervals of perhaps hundreds of thousands of year timescales or less. More fundamental changes to the functioning of the biosphere are associated with: its expansion to cover much of the globe (with increasing primary production) during the evolution of photosynthesis at circa 2.7 billion years ago [Nisbet and Fowler, 2014; see Figure 2] linked to the development of an oxygenated atmosphere during the Great Oxygenation Event beginning circa 2.5 billion years ago [Pufahl and Hiatt, 2012]; the construction of complex trophic structures between primary producers (e.g., marine phytoplankton), primary consumers (e.g., herbivorous zooplankton), and secondary consumers (e.g., tertiary and apex arthropod predators) during the Cambrian Period [Butterfield, 2011; Perrier et al., 2015], which led to animals typically forming the largest standing biomass in marine ecosystems; and the construction of complex terrestrial ecosystems with plants forming the largest standing biomass, with an increasing impact on the carbon-cycle and climate during the mid-Paleozoic [Kansou et al., 2013] and later. Measured against these changing geological-scale patterns, is the human impact on the biosphere significant?
Certain characteristics of current production and consumption in the biosphere appear entirely unique from a geological perspective, not least in being driven by a single species (Homo sapiens) within a time frame that is dramatically accelerated (decades versus millions of years) relative to past events. These changes have been characterized as defining a new biosphere state [Behrensmeyer et al., 1992; Williams et al., 2015]. They include the widespread transportation of animals and plants around the planet (the “neobiota”), the human-directed evolution of biology and ecosystems, the extraction of energy and material resources from deep in the Earth’s crust, and the huge appropriation of production by humans, which will leave a fossil record in, for example, both the physical and chemical signatures of biomineralized materials [bones, shells, reefs, etc., see Kidwell, 2015].
A profound example of these changing patterns is the Green Revolution of the mid-20th century. This translation of technologies that originated from technological breakthroughs in developed countries, which were transported and adapted to the developing world, included the transfer of technology for fertilizers (principally nitrogen-, phosphate- and potassium-based), new crop varieties, insecticides, pesticides, herbicides and irrigation. The Green Revolution spread across the world from the 1950s onward, dovetailing with the Great Economic Acceleration in industrialized nations [Steffen et al., 2007, 2015]. It led to the doubling of appropriation of NPP by humans through the 20th century [Krausmann et al., 2013] and a concomitant rise in the consumption of fossil NPP to support that. This redirection of resources along different biological paths has led to humans and their domesticated animals comprising 175 million tons of carbon (estimates based on dry mass of 45% carbon) at the end of the 20th century, whilst wild terrestrial mammals represent just 5 million tons of carbon [Smil, 2011]; the total standing biomass of large terrestrial vertebrates in itself has been increased by about an order of magnitude over a “natural” baseline level by the tightly controlled and directed hyper-fertilization of terrestrial primary production [Barnosky, 2008].
Analyses suggest that human influence on the Earth’s biota is promulgating a contemporary mass extinction event [Barnosky et al., 2011, 2012, 2014; Kolbert, 2014; Pimm et al., 2014; Ceballos et al., 2015] comparable to the five most significant events of the Phanerozoic Eon. This potential Anthropocene mass extinction event, if it continues to unfold, would thus immediately succeed (stratigraphically) a major perturbation of the nitrogen cycle (from the Haber-Bosch process) that is leaving a geochemical signal in sedimentary deposits worldwide, and it would also be associated with changes in carbon isotope ratios in marine carbonates as a result of the anthropogenic CO2 emitted from the burning of hydrocarbons (a characteristically depleted 13C signature). These signatures would resemble in magnitude, though not in environmental forcing, patterns of chemical change in the physico-chemical stratigraphic record, in part suggesting changes in the make-up of primary producer versus consumer organisms, and which are features of earlier extinction events such as in the latest Proterozoic [reduced acritarch phytoplankton diversity as a result of surface ocean eutrophication, Nagy et al., 2009], or at the Precambrian-Cambrian boundary [perhaps reflecting changes to surface-ocean primary production as a result of acritarch extinction, see Zhu et al., 2006 for a summary].
The human impact is not restricted to the land. The scale of appropriation of marine biological production by a single species (Homo sapiens) is almost certainly unique in Earth history, far exceeding the grazing of mainly coastal waters by, for example, seabirds (and, before them, flying reptiles), or pinnipeds. The rates of domestication of marine plants and animals are rising rapidly [Duarte et al., 2007]. Although fish farming dates back over 2000 years [e.g., McCann, 1979], with early examples in Australia, East Asia and Europe, it was quantitatively trivial, except locally, until 1970. Since that time aquaculture has become a significant component of fish consumption [Naylor et al., 2002], and this is sometimes referred to as the “blue revolution”: in 2012 total world fisheries amounted to 158 million tons, of which 42% was aquaculture [FAO, 2014]. Having removed most top predators from the oceans, including by some estimates 90% of the largest predatory fish stocks [Jackson, 2008], humans are steadily fishing down the food chain [Pauly et al., 1998; WBGU, 2013]—in aggregate, 38% of marine fish have been lost, and the decline in certain baleen whales is up to 90% [McCauley et al., 2015]. At the same time, humans are continually harvesting, via a massive extension of bottom trawling powered by fossil fuels, the majority of the continental shelf, ranging now down onto parts of the continental slope [Puig et al., 2012]. Regions of the ocean undergoing fishery collapses are incapable of providing a full complement of ecosystem services, including those necessary to sustaining ever-growing human coastal populations [Worm et al., 2006].
Thus, it can be argued that the scale of human change to the biosphere with its transformation of terrestrial and marine ecologies, its use of fossil fuels to elevate the energy available to the global ecosystem, its impact on the standing biomass of terrestrial vertebrates, and its displacement of apex predators in both terrestrial and marine foodwebs, is of the magnitude of past major changes in the biosphere as shown in Figure 2.
Original paper: Mark Williams, Jan Zalasiewicz, Colin N. Waters, Matt Edgeworth, Carys Bennett, Anthony D. Barnosky, Erle C. Ellis, Michael A. Ellis, Alejandro Cearreta, Peter K. Haff, Juliana A. Ivar do Sul, Reinhold Leinfelder, John R. McNeill, Eric Odada, Naomi Oreskes, Andrew Revkin, Daniel deB Richter, Will Steffen, Colin Summerhayes, James P. Syvitski, Davor Vidas, Michael Wagreich, Scott L. Wing, Alexander P. Wolfe, An Zhisheng. The Anthropocene: a conspicuous stratigraphical signal of anthropogenic changes in production and consumption across the biosphere. Earth’s Future, 2016; DOI: 10.1002/2015EF000339