Saturday, July 7, 2018

Welcome to the Narcisscene



Returning Humans to the Center of the Cosmos
     
Echo and Narcissus (1903) by John William Waterhouse

 The Breakthrough Institute  Summer 2018 via  | Mark Sagoff

At a conference in Amsterdam in 2001, the International Geosphere–Biosphere Programme (IGBP) and affiliated scientific groups issued what its authors called “the historic Amsterdam Declaration on Earth System Science.” According to this historic declaration, “A new system of global environmental science is required.”1 Although the IGBP eventually closed in response to changes in the funding landscape, its most historic act was to propose the concept of the Anthropocene, a new geologic epoch that would emphasize and draw public attention to the degree to which humanity has altered the “Earth system.” Paul Crutzen, who then served as IGBP vice chair and had earlier won a Nobel Prize in atmospheric science, is credited (along with Eugene Stoermer) with introducing the concept of the Anthropocene and advocating its adoption by the International Commission on Stratigraphy (ICS), which is responsible for naming and dating geologic periods, eras, and epochs. 

In view of the glacial pace of geologic events and the time it takes for things to turn into rock or become encased in it, you might think there would be no hurry to name a new geologic epoch, especially because the current one, the Holocene, started only about 11,500 years ago. You would be wrong. In 2002, Crutzen published an article in Nature magazine, “Geology of Mankind,” which called on geologists “to assign the term ‘Anthropocene’ to the present, in many ways human-dominated, geological epoch, supplementing the Holocene — the warm period of the past 10–12 millennia” and the beginning of which roughly coincided with the advent of human agriculture.2 The idea of the Anthropocene, which Earth system scientists initiated and advocated, landed like a meteor, setting off a stampede among academics. Nature followed with an editorial that urged that the Anthropocene be added to the geologic timescale. “The first step is to recognize,” Nature editorialized, “that we are in the driver’s seat.”3

In response to the clamor, the ICS convened an eclectic Anthropocene Working Group (AWG), including Crutzen and many other Earth system scientists, to present a recommendation. The working group struggled to agree on a demarcation between the Anthropocene and the current Holocene: for example, the Columbian Exchange, the industrial revolution, or the detonation of the first atomic device. But the outcome of AWG deliberations — to declare a new epoch pour rendre hommage à l’Homme — was never in doubt. “We’re not so puny, after all,” one climate scientist remarked. “We are becoming players in geologic time.”4      
      
If the ICS declares the Anthropocene as a new epoch, it will reverse at one stroke three great humiliations science has inflicted on humanity. First, it will restore humanity to the self-importance it knew when people believed that the Earth and humanity were created at about the same time. The Anthropocene, as Erle Ellis and colleagues have written, “will divide Earth’s story into two parts: one in which humans are a geological superpower — an epoch called the Anthropocene — and the other encompassing all that came before our species had a major influence on Earth’s functioning.”5
Second, it will redress the humiliation imposed by Darwin, who saw humanity as a minor twig on the tree of life, by recognizing Homo sapiens as a colossus so powerful that it is relocating tens of thousands of species and causing as many extinctions as the world has ever known. Third, it will return the Earth to its Ptolemaic position. Ancient astronomers thought of the cosmos as an orderly system that revolved around the Earth, which they saw as tempestuous, turbulent, intemperate, violent, ferocious, and capricious. Earth system science turns the Earth into the cosmos — an orderly, self-regulating system that revolves around a capricious humanity. It accomplishes a counter-Copernican revolution.6

The Anthropocene makes humanity great again. 

1.

In the 17th century, James Ussher published The Annals of the World (1658), which, on the basis of scriptural and other evidence, set the creation of the Earth at 4004 BC, or roughly six thousand years ago. Toward the end of the 18th century, Scottish natural philosopher James Hutton challenged the widely held “young Earth” theory. Later geologists (most importantly Charles Lyell, whose Principles of Geology (1830) became the standard text) argued on the basis of fossil and stratigraphic evidence that the Earth was much older than human beings could possibly imagine.

Following Lyell, geologists offered estimates of the age of the Earth but accepted the idea that the planet was inconceivably and awesomely old. John Playfair, a geologist who in the early 1800s popularized Hutton’s views, wrote, “The mind seemed to grow giddy by looking so far into the abyss of time.” From Hutton “we became sensible how much farther reason may sometimes go than imagination can venture to follow.”7

The human imagination cannot in any way reckon or fathom the depth of geologic time; in relation to that scale, human beings are unable to comprehend how vanishingly insignificant and epiphenomenal their tenure on the planet has been. Instructors often use a teaching aid titled the “Geologic Drive” to illustrate geologic time. The Earth is about 4,560 million years old. If one thinks of each million-year interval as a kilometer, a road trip the length of 4,560 million years would traverse 4,560 kilometers, or approximately 2,800 miles, roughly the distance between Washington, DC, and the campus of the University of Washington in Seattle. You are halfway across Washington State when you see dinosaurs, and about 50 miles outside Seattle when they disappear. You are in Seattle when you begin to see lots of plants and animals. You are already on campus looking for parking when the first humans appear. You better have found it because the distance between the assassination of Julius Caesar and today would be about six feet, that is, less than the length of the car. The mid-20th century boundary that the AWG has proposed would give the Anthropocene about three inches in this 2,800-mile road trip, negligible in relation to the length of the car or even the driver’s seat.

Geologic epochs typically last around three million years. In establishing them, the ICS has historically proceeded by first identifying a stratum or “chronostratigraphic unit,” which is usually categorized in terms of the fossils it contains. By figuring out how long fossil layers took to accumulate, geologists date them and derive the geologic time scale, which is used to estimate the age of the Earth.

By contrast, in convening the AWG to determine the onset of the Anthropocene, the ICS apparently abandoned this practice, instead presuming that the new epoch had already begun and then casting about for a fossil record or other stratigraphic evidence of the existence of the Anthropocene and of when exactly it began.

The chairman of the AWG, Jan Zalasiewicz of the University of Leicester, writing with the majority of members of the committee, noted that “technofossils such as ball-point pens, CDs, or mobile phones” had “spread rapidly around the world from the time of their first use” and provided “stratigraphic criteria that can be used to identify deposits that post-date the mid-20th century, and this, on current evidence, we consider to be the optimal position for an Anthropocene boundary.”8 More recently, Zalasiewicz and more than 20 coauthors pointed out that “mobile phones, commercially available since 1983, and with ~6.8 billion unique mobile phone connections made by 2014,” have “good fossilization potential.”9 The phonal layer of the Anthropocene (not to be confused with the faunal layer of the Mesozoic) could provide ample stratigraphic evidence that the Earth has entered a new geologic epoch.

In 2016 the AWG returned its verdict as expected: “The majority opinion within the AWG holds the Anthropocene to be stratigraphically real, and recommends formalization at epoch/series rank based on a mid-20th century boundary.”10 In so doing, the ICS will render its decision (still to be finalized) on the basis of a kind of evidence that is entirely foreign to its epistemic conventions and in response to a kind of pressure and attention it has never known.

William Whewell, a 19th-century British philoso­pher and polymath, described geology, paleontology, and evolution as “palaetiological sciences” because they interpret the present to construct the past. The Anthropocene, instead, constructs the future to interpret the present: a future in which humanity either takes responsibility for the Earth system or is responsible for its collapse. It then interprets the present in terms of humanity’s role in causing this calamity or in averting it, which humanity can do if it responds to the warnings of Earth system science.

Because one cannot conceive of the length of geologic time, one cannot comprehend the brevity of the past 75 years in relation to it. The Anthropocene, if officially recognized, would be inconceivably ephemeral, momentary — indeed, instantaneous — existing only in real time. But it will endure until the Götterdämmerung, that is, until humans go extinct; it will run to the end of recorded history — turning the hourglass of geologic time upside down.

2.

Against the belief that humans are a special creation of God, Charles Darwin held that human beings descended from apelike creatures. “The main conclusion arrived at in this work, namely, that man is descended from some lowly organised form, will, I regret to think, be highly distasteful to many,” he wrote in The Descent of Man (1871). “But there can hardly be a doubt that we are descended from barbarians.”11 It was the biblical view outlined in Psalm 8 that Darwin specifically contradicted, namely, that God elevated human beings above the rest of creation:

You made them rulers over the works of your hands;
you put everything under their feet:
all flocks and herds,
and the animals of the wild . . .

An official acknowledgment of the Anthropocene would, like the Psalmist, recognize Homo sapiens as a force so powerful that it is causing as many extinctions as the world has ever known. The Anthropocene reclaims the power and dominance of human beings who, pace Darwin, far from acting like siblings of the apes, so rule over the plants and animals of the wild that they will soon kill off most of them.

That humanity is driving a “sixth mass extinction” on a par with five previous extinction events during the past half-billion years, each of which led to a loss of more than 75 percent of estimated species, has been known to science for many decades.12 In 1979, Norman Myers, a British biologist, predicted in The Sinking Ark that by 2000, one million species would go extinct.13 In 1981, an article in Science magazine began, “By the end of the century, up to a million species of plants and animals will disappear from the face of the earth.”14  In 1993, Harvard biologist E. O. Wilson estimated that Earth was losing an estimated 30,000 species a year.15 In 1995, Richard Leakey and Roger Lewin, in their influential book The Sixth Extinction, settled on an extinction rate between 17,000 and 100,000 species per year.16 Peter Raven, then director of the Missouri Botanical Garden, in a paper titled “The Politics of Preserving Biodiversity,” wrote in 1990, “I estimate the extinction of perhaps 65,000 species of plants, a quarter of the world total, within the next several decades.”17 In 1998, the American Museum of Natural History published a survey of 400 experts in the biological sciences which revealed “that seven out of ten biologists believe that we are in the midst of a mass extinction of living things.”

In the top scientific journals, hundreds of papers have confirmed the dire reality of the sixth mass extinction. A 2011 analysis published in Nature responding affirmatively to the question “Has the Earth’s Sixth Mass Extinction Already Arrived?” has been cited by more than 1,750 scientific publications.18 In 2017, three biologists, including Paul Ehrlich, described the situation as a “biological annihilation” in order “to highlight the current magnitude of Earth’s ongoing sixth major extinction event.”19

What better evidence than a mass extinction could there be of the power, dominance, and evolutionary supremacy of Homo sapiens over all living things? The problem is that the body count is missing.20 There is no evidence that extinctions have occurred at a magnitude that would even remotely bear out the predictions of the 1990s or the claim that we are in the midst of a mass extinction event.21

The International Union for Conservation of Nature (IUCN), a highly respected scientific organization, keeps tabs on the number of species that have gone extinct. The IUCN Red List database of 2017, which looks at around 24,230 plant species, lists about 118 of them as disappearing since 1500, while another 35 are extinct in the wild but survive in cultivation. A mass extinction among the 24,230 plant species surveyed would require the loss of 18,000 of them. Given observed extinctions, at the current rate, the extinction of these 18,000 plants would take more than 70,000 years. 

Or take insects, by far the largest faunal group in nature. Entomologists have good information on butterflies, tiger beetles, dragonflies, and damselflies. Over 25,250 of these species have been evaluated; only three are known to have become extinct in the past 500 years.22 A mass extinction will therefore take three million years, although some data are hard to assess. 

If plants and insects don’t suffice, consider animals. IUCN manages data on 67,222 animals. It lists 748 as extinct since 1500 and an additional 34 as extinct in the wild. For a mass extinction to overtake 67,222 animals, 50,000 of them would need to disappear, which would take more than 25,000 years. All told, IUCN estimates that about 900 plant and animal species — 150 plants and 750 animals — have gone extinct since the year 1500. If one “ballparks” these numbers, 1,000 species went extinct at a rate of approximately two species per year during the past 500 years in a sample of roughly 100,000 species. A “mass extinction” at this rate will take 34,250 years.23

Nonetheless, a Google Scholar search of the phrase “sixth mass extinction” generates almost 6,000 hits, nearly all of which concur that such an extinction event is well under way. Within this vast scientific consensus, it is difficult to find even a single article that questions the extinction predictions of the 1990s. Contrarian papers are often denied publication, biologists Peter Kareiva and Michelle Marvier have found, because reviewers worry “as much about political fallout and potential misinterpretation by the public as they do about the validity and rigor of the science.”24
3.
The belief that the world has embarked on a sixth mass extinction, it turns out, is based on theory, not data. The first model, which most ecologists defend, originates from the theory of island biogeography presented in 1967 by Robert MacArthur and E. O. Wilson.25 MacArthur and Wilson argued that the number of species that will come to an island (the “immigration rate”) will fall over time “because as more species become established, fewer immigrants will belong to new species.” Conversely, “the extinction curve must on the other hand rise,” they reasoned, since the more species colonize, “the more there are to become extinct” and the more likely each will succumb to “ecological and genetical accident.” The theory of island biogeography, although centered on islands, is often used to model fragments of natural biodiversity surrounded by human development on the mainland as well.

On the basis of this theory, it is not a stretch to derive predictions that half the world’s species have gone extinct in the past century or two. In the wake of global commerce, species introduced to oceanic islands have at least equaled the number of species established on those islands.26 The theory demonstrates mathematically that before these introductions occurred, the number of species the island could sustain was already in equilibrium and saturated.27 It follows conceptually that the number of extinctions, either of native or of introduced species, must therefore offset the number of introductions. As native species are often endemic and introduced species are cosmopolitan, virtually all island species but weedy ones will either have gone extinct or fall somewhere along the trajectory toward extinction.

A few ecologists have demurred, finding, for instance, that empirical evidence “overwhelm­ingly supports the openness of communities to new species, even at the small spatial scales where species interact and the influences of competition and resource supply should be strongest.”28 In a letter published in Nature in 2011, the distinguished ecologist Stephen Hubbell questioned the reliability of the equilibrium theory of island biogeography as the basis for estimating extinction rates and as the pillar of conservation science. “Extinction rates estimated from the SAR [species–area relationship] are all overestimates,” he and coauthor Fangliang He wrote.­­29

But any contrarian argument based on empirical evidence is quickly dismissed. “They’re either venal or stupid,” Stuart Pimm, a prominent extinction expert, said of those who dared question the higher estimates for species losses.30 A temporary increase in the number of species in an island-like environment, no matter how long it lasts, represents not an increase in species richness but instead a “lag time to extinction” or an “extinction debt.” Ecosystems, the theory’s many defenders aver, “may take a long time to equilibrate.”31 As a result, no evidence could ever disconfirm the theory of island biogeography, just as no evidence has ever confirmed it.

The second theory that purports to show that the world is caught in the midst of a sixth mass extinction argues that current extinction rates — say, since 1500 — are far greater than the “normal” rates that prevailed between previous mass extinctions. On this approach, what matters is not the current extinction rate (which may be negligible and dwarfed by speciation) but the difference between it and the “normal” or “background” rate of extinction, the measurement of which has received enormous attention in the literature. The current extinction rate is thought to exceed by 100 to 1,000 times the “background” rate of extinction.32

Suppose this were true. So what? At current rates (say, two per 100,000 species, or 20 per million species per year), a mass extinction will take roughly 37,500 years, assuming no new species evolve to take their places. Scientists say that we are in the midst of that catastrophic event. Why? That a massive extinction event would take even longer than 37,500 years at “normal” or “background” rates is irrelevant.

Despite the great reverence paid to the sixth mass extinction, humanity may be inferior to other species, or at least helpless against them, as is well illustrated by the tens of thousands of plants and animals that cruise around the world on the human dime, catch rides on boats and planes, and establish populations wherever they like, regardless of whether the local human population wants them there or not. Because so many species tag along with human commerce, the number of species, or “species richness,” in ecological communities has remained steady or even increased over the past century or two, as studies have consistently shown. Michael Rosenzweig, an eminent biologist at the University of Arizona, has found that “local diversities are headed for much higher steady states.”33

Consider, for example, Great Britain, the center of Earth system science. In that country, the number of alien plants in the wild equals or exceeds the number of native ones; these groups cannot be distinguished biologically (i.e., in terms of their “functioning”) but only historically. The New Atlas of the British and Irish Flora found 1,407 native plant species and 1,155 “neophytes” or nonnative ones.34  Harvard biologists Richard Lewontin and Richard Levins have found that “no species of vertebrate or flowering plant has become extinct in Britain in the last hundred years.”35 Chris Thomas, a biologist at the University of York, has observed that “more new plant species have come into existence in Europe over the past three centuries than have been documented as becoming extinct over the same period.”36

A similar story is true of oceanic islands generally. Biologist Dov Sax and coauthors have observed a “highly consistent, approximately twofold, increase in the species richness of plants on oceanic islands” owing to plant introductions and invasions.37 Mainland environments show the same trend toward increasing plant biodiversity. According to one study, “In total, 13,168 plant species . . . have become naturalized somewhere on the globe as a result of human activity.”38 Known naturalized plant introductions outnumber known plant extinctions by approximately 100 to one. There is no evidence to show that plant invasions are the sole cause of any plant extinction.39
As Peter Kareiva has suggested, it may be that “nature is more resilient than is generally 
assumed.”40 But another view is that human beings are less omnipotent than is generally assumed. 

We place agency in the wrong quarter — with humans and not with the rest of creation — when we observe the spread of nonnative species around the globe. They are in the driver’s seat. If you want to conceive of humanity’s place in nature, think not of the plants and animals placed under our foot but of the fungus found on it.

4.

The emergence of Earth system science and the declaration of the Anthropocene that goes with it salve and soothe the human ego from the distress of deep time and Darwinian descent. Earth system science also restores humanity to its rightful place at the center of the cosmos. Advances in Earth system analysis, writes one prominent scientist in Nature, will “soon culminate in a second ‘Copernican’ revolution”:

This new revolution will be in a way a reversal of the first: it will enable us to look back on our planet to perceive one single, complex, dissipative, dynamic entity, far from thermodynamic equilibrium — the “Earth system.” It may well be nature’s sole successful attempt at building a robust geosphere–biosphere complex (the ecosphere) in our Galaxy, topped by a life-form that is appropriately tailored for explaining the existence of that complex, and of itself.41

It is the first rule of rationality that reason recognize its limits. That is why Adam Smith warned against “the man of system” who thinks he can know enough about the functioning of an economy to direct or manage it. How much crazier Smith would have thought the pretention of those who believe they can know enough about the functioning of the Earth system, whatever that could mean, to define “planetary boundaries” and a “safe operating space”! 

Earth system science regards the Earth system as a black box that is disturbed or ruptured by human activity. Earth system scientists argue that their discipline is essential if humanity is to understand this box well enough to avoid tipping it over. Earth system scientists empower themselves by citing how much they (and therefore we) do not know about the geosphere and biosphere as these have coevolved as a single, interacting, integrated system. They have yet to find out what these concepts mean; we disregard their ignorance at our peril. 

Over the decades, theoretical ecologists have tried to apply concepts such as “co-evolution,” “complex adaptive systems,” “basins of attraction,” and so forth to local environments, but their efforts were not crowned with empirical results. The genius of these terms lies in their inscrutability. According to ecologist Mark Vellend, “Ecology is widely perceived as being a theoretical and conceptual basket case” with “no known underlying regularities in its basic processes.”42
By understanding “the structure, functioning, and evolution of the Earth’s biosphere as a whole,” Earth system science proposes to scale up the same array of concepts to the Earth system that ecologists had been unable to make operational or even intelligible in relation to ecological communities or systems.

Environmentalists, by contrast, have seen results when they apply cause-and-effect thinking to find technical fixes to environmental problems. Because certain aerosols deplete the protective ozone layer, for example, substitutes for them were found. Because the combustion of fossil fuel creates a “greenhouse effect” that raises global temperatures and, with them, sea levels, scientists worked to improve non-fossil fuels — for example, nuclear energy, as well as energy storage technology that can make intermittent sources of energy, such as wind and solar power, more relevant. Because nitrogen runoff from farms causes eutrophication, scientists have found ways for farmers to use less fertilizer and create buffers. This kind of cause-and-effect, case-by-case, often linear and mechanistic thinking has resulted in impressive gains in air and water quality in the United States and elsewhere.

Advocates of the advent of the Anthropocene sometimes disparage this kind of problem-solving. It is not holistic enough. “The Anthropocene concerns human impacts on the Earth System, not on the environment,” writes one prominent theorist of the Anthropocene.43 But what the Anthropocene offers is simply a theoretical fix — the Earth system — to energy, nitrification, acidification, and other problems that could yield to technological fixes instead.

5.

Environmental historian Donald Worster has written that “every generation . . . writes its own description of the natural order, which generally reveals as much about human society and its changing concerns as it does about nature.”44 For the neo-Malthusian pessimists of the second part of the 20th century, the natural order was a lifeboat. What mattered was its carrying capacity, which ecological economist Herman Daly analogized to its Plimsoll line, or how much weight it could displace without sinking.45 Scientists warned that consumption already vastly exceeded what nature could supply and would only increase further as populations grew and standards of living improved. Thus, The Population Bomb, a best seller Paul Ehrlich published in 1968, began, “The battle to feed all of humanity is over. In the 1970s the world will undergo famines — hundreds of millions of people are going to starve to death in spite of any crash programs embarked upon now. At this late date nothing can prevent a substantial increase in the world death rate.” 

The collapse of civilization in the 1970s was not only imminent and inevitable, but also necessary and essential.46 It followed as a logical consequence of the scientific description of the natural order. If one assumes that the natural resources of the world and its capacity to absorb wastes are fixed and finite, it follows that if people consume those stocks and fill those sinks at an increasing rate, civilization must eventually hit a ceiling and rapidly collapse to a low level. Several computer models demonstrated this at the time because it is a conceptual truth.

The predictions of the neo-Malthusians of the 20th century proved spectacularly wrong, which may explain why they are rarely repeated by today’s Earth system scientists. These scientists bring to the world the good news that nature “contains within it the possibility of mutually harmonious human–Earth enhancement.”47 According to Earth system scientist Clive Hamilton, the power to choose is ours. He argues that “on the side of responsibility are gathered the armies of scientific insight into Earth’s physical limits.” Against these are “mobilized the armies of avarice intrinsic to an economic structure driven by the profit motive.”48

The good news is that there is a safe operating space for humanity. There is a harbor toward which science can steer Lifeboat Earth. According to four prominent Earth scientists, their teaching is “explicitly based on returning the Earth system to the Holocene domain, the environmental envelope within which contemporary civilization has developed and thrived.”49

The environmental science of the late 20th century was Old Testament science; the environmental science of the early 21st century is New Testament science. The Old and New Testaments concur in their creation myth and account of the Fall of Man. Old Testament and New Testament science agree that creation was completed with the Holocene, the warm period that began about 11 millennia ago. To his credit, James Ussher got it almost right. 

This halcyon Holocene provided practically a Garden of Eden for humanity until it tasted of the fruit of technology, which it ate at the beginning of the Industrial Revolution and gorged on after the Second World War. This led to the Great Acceleration that cursed the Earth and produced the Sixth Mass Extinction and other global catastrophes, including famine, drought, plagues, floods, and the war of each against all. Everyone who was not a science denialist agreed about this.

Old Testament and New Testament environmental science part ways on what happens next. They differ fundamentally in their eschatology. According to Old Testament science, after the Great Tribulation of the 1970s, the Earth entered its final days; humanity was destroyed, and the world went on without us.50 According to New Testament science, the Man of System arose from sullen earth to bring humanity within planetary limits. Buckminster Fuller wrote that the Earth did not come with an instruction book. Earth system scientists discovered that the power was theirs to write one.

When the ICS recognizes the Anthropocene as a chronostratigraphic/geochronological epoch (preferably during Advent or perhaps Easter), it should also sort the geologic time scale into three eras: creation, fall, and redemption. This kind of revision is the logical or conceptual consequence of the annunciation of the Anthropocene. Earth system science shall redeem future generations from the sins of their ancestors. 

Since the time of Hutton, geology has struggled to study the Earth as a scientific object separate from the religious, ideological, and political persuasions of the day. With the Anthropocene, that struggle, such as it was, is over. By enshrining the Anthropocene, geologists are asked to name an epoch ad hoc and ex ante, in prospect rather than in retrospect, in view of the future not of the past, in order to take sides in what Hamilton calls “this titanic struggle over how to use our agency.” The point of the naming act originates in the Manichean conflict between “the armies of insight” and “the forces of avarice.” In the Anthropocene, the agenda and the science are, once more, the same thing.

MARK SAGOFF


Mark Sagoff is a senior fellow at George Mason University's Institute for Philosophy and Public Policy and author of The Economy of the Earth.


[1] “In 2001, IGBP and the other international global-change programmes held a major conference in Amsterdam. The conference produced the historic Amsterdam Declaration on Earth System Science.” See “2001 Amsterdam Declaration on Earth System Science,” International Geosphere–Biosphere Programme (July 13, 2001).
[2] Paul J. Crutzen, “Geology of Mankind,” Nature 415, no. 23 (2002).
[3] “The human epoch,” editorial, Nature 473 (2011): 254.
[4] David Archer, The Long Thaw: How Humans Are Changing the Next 100,000 Years of Earth’s Climate (Princeton, NJ: Princeton University Press, 2009).
[5] Erle Ellis, et al., “Involve Social Scientists in Defining the Anthropocene,” comment, Nature 540, no. 7632 (2016): 192.
[6] For discussion, see Bruno Latour, “Agency at the Time of the Anthropocene,” New Literary History 45, no. 1 (2014): 1–18.
[7] For commentary, see Gordon Y. Craig, “James Hutton’s Geological Vocabulary,” in Bernd Naumann, Frans Plank, and Gottfried Hofbauer, eds., Language and Earth: Elective Affinities between the Emerging Sciences of Linguistics and Geology, Studies in the History of the Language Sciences 66 (Amsterdam: John Benjamins Publishing, 1992), 401.
[8] Jan Zalasiewicz, et al., “When Did the Anthropocene Begin? A Mid-twentieth Century Boundary Level Is Stratigraphically Optimal,” Quaternary International 383 (2015): 196–203.
[9] Jan Zalasiewicz, et al., “Scale and Diversity of the Physical Technosphere: A Geological Perspective,” The Anthropocene Review 4, no. 1 (2016): 9–22.
[10] Jan Zalasiewicz, et al., “The Working Group on the Anthropocene: Summary of Evidence and Interim Recommendations,” Anthropocene 19 (2017): 55–60.
[11] Charles Darwin, “General Summary and Conclusion,” The Descent of Man (1871): ch. XXI.
[12] Gerardo Ceballos, Paul R. Ehrlich, Anthony D. Barnosky, et al., “Accelerated Modern Human-induced Species Losses: Entering the Sixth Mass Extinction,” Science Advances 1, no. 5 (2015): e1400253. An article published in Science magazine in 2016 affirmed that the dire predictions of the 1990s were correct, but that “there may be a long extinction lag time. The species-area curve is driven by equilibrium phenomena, and ecosystems may take a long time to equilibrate.” See Quentin Cronk, “Plant Extinctions Take Time,” Science 353, no. 6298 (2016): 446. Articles in the current literature find ways to reconcile the empirical evidence with the predictions of the 1990s. For an effort along these lines, see Benjamin Gilbert and Jonathan M. Levine, “Plant Invasions and Extinction Debts,” Proceedings of the National Academy of Sciences 110, no. 5 (2013): 1744–1749.
[13] Norman Myers, The Sinking Ark: A New Look at the Problem of Disappearing Species (Pergamon Press, 1979). Myers said in 1997 that by 2007, “we may have lost 1 million of Earth’s putative 10 million species, counting all extinctions since the start of the biotic crisis a half-century ago.” See Norman Myers, “The Meaning of Biodiversity Loss,” in Peter H. Raven and Tania Williams, eds., Nature and Human Society: The Quest for a Sustainable World, Proceedings of the 1997 Forum on Biodiversity (Washington, DC: National Academy Press, 2000), 63.
[14] Colin Norman, “The Threat to One Million Species,” Science 214, no. 4525 (1981): 1105–1107.
[15] Niles Eldredge, “The Sixth Extinction,” ActionBioscience, June 2001. Wilson estimated in 1988 that extinctions exceeded 17,500 per year. See Edward O. Wilson, “The Current State of Biodiversity,” in E. O. Wilson and Frances M. Peter, eds., Biodiversity (Washington, DC: National Academy Press, 1988), 3–18. That would be more than a half million by now.
[16] Richard Leakey and Roger Lewin, The Sixth Extinction: Patterns of Life and the Future of Humankind (Doubleday, 1995). See also Daan P. van Uhm, “The Sixth Mass Extinction,” The Illegal Wildlife Trade: Inside the World of Poachers, Smugglers and Traders (Springer, 2016), 17–32.
[17] Peter H. Raven, “The Politics of Preserving Biodiversity,” BioScience 40, no. 10 (1990): 769–774.
[18] Anthony D. Barnosky, et al., “Has the Earth’s Sixth Mass Extinction Already Arrived?” Nature 471 (2011): 51–57. Google Scholar as of June 15, 2018, lists 1,830 citations. See also Ann Gibbons, “Are We in the Middle of a Sixth Mass Extinction?” Science, March 2, 2011.
[19] Gerardo Ceballos, Paul R. Ehrlich, and Rodolfo Dirzo, “Biological Annihilation via the Ongoing Sixth Mass Extinction Signaled by Vertebrate Population Losses and Declines,” Proceedings of the National Academy of Sciences 114, no. 30 (2017): E6089–E6096.
[20] According to ecologist Nigel Stork, “If some of these higher estimates were true, then we should have already witnessed the extinction of up to 50 percent of all species on Earth in the last 30 years.” See “Re-assessing Current Extinction Rates,” Biodiversity and Conservation 19, no. 2 (2010): 357–371. Many influential biologists suggested an extinction rate of 5 percent to 30 percent of all species on Earth per decade. Stork cites several examples, e.g., Tom Lovejoy, who wrote in 1980, “An estimate prepared for the Global 2000 Study suggests that between half a million and 2 million species — 15 to 20 percent of all species on earth — could be extinguished by 2000, mainly because of loss of wild habitat but also in part because of pollution.” See T. E. Lovejoy, “A Projection of Species Extinctions,” in Council on Environmental Quality (CEQ), The Global 2000 Report to the President (Washington, DC, 1980). Stork provides a table of similarly authoritative scientific predictions and projections that would require, if true, that a mass extinction have occurred by now.
[21] In the 1990s, predictions of mass extinction accompanied neo-Malthusian predictions, going back to the 1960s and 1970s, which foresaw imminent resource depletion especially of petroleum, the inability of the world to feed its growing population, and global collapse because of the increasing size of the “human footprint,” which had even by then vastly exceeded the carrying capacity of the Earth. In spite of growing world prosperity, many scientists stand by and even double down on these predictions, arguing that the collapse, which is inevitable, will only be more terrible when it comes. See, for example, A. Y. Hoekstra and T. O. Wiedmann, “Humanity’s Unsustainable Environmental Footprint,” Science 344, no. 6188 (2014): 1114–1117. See also Paul R. Ehrlich and Anne H. Ehrlich, “Can a Collapse of Global Civilization Be Avoided?” Proceedings of the Royal Society B 280, no. 1754 (2013). For discussion, see Ciara Raudsepp-Hearne, et al., “Untangling the Environmentalist’s Paradox: Why Is Human Well-being Increasing as Ecosystem Services Degrade?” BioScience 60, no. 8 (2010): 576–589. For a more general analysis, see Leon Festinger, When Prophecy Fails: A Social and Psychological Study of a Modern Group that Predicted the Destruction of the World (University of Minnesota Press, 1956).
[22] “Four insect groups (butterflies, tiger beetles, dragonflies, damselflies) have been of special interest to amateur and professional entomologists. Each group is well known, it has a worldwide distribution and its species extinction during the past 500 years is documented. Among these four groups, 25,260 species have been evaluated, and only three were found to have become extinct.” See John C. Briggs, “Emergence of a Sixth Mass Extinction?” Biological Journal of the Linnean Society 122, no. 2 (2017): 243–248. See also J. C. Briggs, “Global Biodiversity Loss: Exaggerated versus Realistic Estimates,” Environmental Skeptics and Critics 5, no. 2 (2016): 20–27.
[23] According to Gonzalez et al., “Since 1600, an estimated 906 known species have gone extinct globally. While this represents a small fraction of the world’s eight or more million species of eukaryotes, the rate of extinction (>900 species in ca. 400 years) is 100–1,000 times the historical rate in the fossil record.” See Andrew Gonzalez, et al., “Estimating Local Biodiversity Change: A Critique of Papers Claiming No Net Loss of Local Diversity,” Ecology 97, no. 8 (2016): 1949. It is not clear what sample size these authors have in mind, but the “small fraction” to which they apparently refer — 906 species from 8 million species over 400 years — amounts to a loss of about 2 species per 8 million each year or one-quarter of one species per million species per year. This fraction is so small that it is negligible and of no concern no matter how many times greater than “background” or “normal” extinction rates it may be. Of course, the 906 extinctions have to be understood in terms of some sample size, probably not 8 million, but it is not obvious what it is.
[24] Peter Kareiva and Michelle Marvier, “Uncomfortable Questions and Inconvenient Data in Conservation Science,” in Peter Kareiva, Michelle Marvier, and Brian Silliman, eds., Effective Conservation Science: Data Not Dogma (Oxford University Press, 2017), 4. See also Keith Kloor, “The Science Police,” Issues in Science and Technology 33, no. 4 (2017).
[25] Robert H. MacArthur and Edward O. Wilson, The Theory of Island Biogeography (Princeton, NJ: Princeton University Press, 1967).
[26] “Exotic plant addition to islands is highly nonrandom, with an almost perfect 1 to 1 match between the number of naturalized and native plant species on oceanic islands.” See Dov F. Sax and Steven D. Gaines, “Species Invasions and Extinction: The Future of Native Biodiversity on Islands,” Proceedings of the National Academy of Sciences 105, supplement 1 (2008): 11490–11497. For a more recent review, see Mark Vellend, et al., “Plant Biodiversity Change across Scales during the Anthropocene,” Annual Review of Plant Biology 68 (2017): 563–586. “Nonnative species introductions have greatly increased plant species richness in many regions of the world at the same time that they have led to the creation of new hybrid polyploid species by bringing previously isolated congeners into close contact” (563).
[27] As philosopher of science Andrew Inkpen has explained, MacArthur and Wilson “reasoned that since rates of immigration depend on distance from the mainland (i.e., an increase in distance ‘lowers’ the immigration curve), and since rates of extinction depend on the size of an island (i.e., an increase in size ‘lowers’ the extinction curve),” the species richness of an island will reach an equilibrium where these curves intersect, i.e., at a number of species that reflects both the size of an island and its distance from the mainland. See S. A. Inkpen, “Like Hercules and the Hydra: Trade-offs and Strategies in Ecological Model-Building and Experimental Design,” Studies in History and Philosophy of Biological and Biomedical Sciences 57 (2016): 34–43.
[28] Luke J. Harmon and Susan Harrison, “Species Diversity Is Dynamic and Unbounded at Local and Continental Scales,” The American Naturalist 185, no. 5 (2015): 584–593. See also Thomas J. Stohlgren, et al., “The Rich Get Richer: Patterns of Plant Invasions in the United States,” Frontiers in Ecology and the Environment 1, no. 1(2003): 11–14. For a recent discussion, see Rubén G. Mateo, et al., “Biodiversity Models: What If Unsaturation Is the Rule?” Trends in Ecology & Evolution 32, no. 8 (2017): 556–566.
[29] Fangliang He and Stephen P. Hubbell, “Species–area Relationships Always Overestimate Extinction Rates from Habitat Loss,” Nature 473, no. 7347 (2011): 368. A vast literature defends the view that a mass extinction is underway on the basis of the species–area relationship and the theory of island biogeography. To “save the phenomena” for the theory, ecologists invoke concepts of “extinction debt” and of “trajectories toward extinction.” In a comment in Ecology, three ecologists wrote that the species–area relationship is used to predict, first, the “number of species that are endemic to the habitat at risk based on its area. Second, these endemic species are assumed to become extinct should this habitat be lost.” The habitat of a species is considered “lost” when it changes as a result of human activity, as, for example, because of human-assisted colonization by nonnative species. Whether or not extinctions are observed is irrelevant because the theory predicts their disappearance. The path to extinction is “deterministic” because the more that human beings alter the natural environment, the more species must go extinct. It is only a matter of time. See J. B. Axelsen, et al., “Species–area Relationships Always Overestimate Extinction Rates from Habitat Loss: Comment,” Ecology 94, no. 3 (2013): 761–763. See also John M. Halley, et al., “Extinction Debt and the Species–area Relationship: A Neutral Perspective,” Global Ecology and Biogeography 23, no. 1 (2013): 113–123.
[30] Ruth Graham, “How Many Animals Are Really Going Extinct?” Boston Globe, October 5, 2014. According to the Globe, “Hubbell, who was surprised by the vehement reactions to his paper, said that some conservationists have effectively told him, ‘Damn the data, we have an agenda.’” 
[31] Quentin Cronk, “Plant Extinctions Take Time,” Science 353, no. 6298 (2016): 446–447. Cronk defends the 1990s predictions of mass extinction, treating them as necessarily true, and suggests ways to reconcile them with the phenomena. 
[32] In a letter published recently in Science, Gerardo Ceballos and Paul Ehrlich have observed that “the rate of species extinction is now as much as 100 times that of the ‘normal rate’ throughout geological time.” See Ceballos and Ehrlich, “The Misunderstood Sixth Mass Extinction,” Science 360, no. 6393 (2018): 1080–1081. According to Mark Vellend and co-authors, “Roughly 350,000 plant species on earth have been named, representing an estimated 80–90% of the global total.” These authors studied estimates of the “background” or “normal” extinction rate for plants between mass extinctions. They found that “the central tendencies of background plant extinction rates fall mostly in the range 0.05–0.15 species per million species per year.” Vellend, “Plant Biodiversity Change across Scales during the Anthropocene,” 563-586. Even if current extinction rates are two orders of magnitude greater than “background” rates, as Ceballos and Ehrlich suggest, they may still appear negligible in relation to the numbers needed for a mass extinction.
[33] Michael L. Rosenzweig, “The Four Questions: What Does the Introduction of Exotic Species Do to Diversity?” Evolutionary Ecology Research 3 (2001): 365. Ecologists have argued that as species arrive in new places, they may evolve into new species, thus adding to biodiversity globally. The rate of speciation — and whether it exceeds the rate of extinction — is debated. See, for example, Chris D. Thomas, “Rapid Acceleration of Plant Speciation during the Anthropocene,” Trends in Ecology & Evolution 30, no. 8 (2015): 448–455. See also J. W. Bull and M. Maron, “How Humans Drive Speciation as well as Extinction,” Proceedings of the Royal Society B 283, no. 1833 (2016).      
[34] C. D. Preston, D. A. Pearman, and T. D. Dines, eds., New Atlas of the British and Irish Flora (Oxford University Press, 2002). Ten years later, a study supported by the Ministry of the Environment (DEFRA) in the UK registered 1,377 nonnative plants that were naturalized on the British Isles; the increase is likely due to new introductions. See Helen E. Roy, et al., “Non-native Species in Great Britain: Establishment, Detection and Reporting to Inform Effective Decision making,” Report to DEFRA (NERC Centre for Ecology & Hydrology, 2012).
[35] Richard Lewontin and Richard Levins, Biology Under the Influence: Dialectical Essays on Ecology, Agriculture, and Health (New York: Monthly Review Press, 2007). This may be slightly misleading because between 1840 and 1990 two plant species endemic to Great Britain did go extinct. See P. A. Stroh, et al., A Vascular Plant Red List for England (Bristol, UK: Botanical Society of Britain and Ireland, 2014), 31.
[36] Chris D. Thomas, “The Anthropocene Speciation Hypothesis Remains Valid: Reply to Hulme et al.,” Trends in Ecology & Evolution 30, no. 11 (2015): 636–638.
[37] Dov F. Sax, et al., “Species Invasions Exceed Extinctions on Islands Worldwide: A Comparative Study of Plants and Birds,” The American Naturalist 160, no. 6 (2002): 766–783. See also James H. Brown and D. F. Sax, “An Essay on Some Topics Concerning Invasive Species,” Austral Ecology 29, no. 5(2004): 530–536; and D. F. Sax, et al., “Ecological and Evolutionary Insights from Species Invasions,” Trends in Ecology & Evolution 22, no. 9 (2007): 465–471.
[38] Mark van Kleunen, et al., “Global Exchange and Accumulation of Non-native Plants,” Nature 525, no. 7567 (2015): 100.
[39]  Powell et al. have written, “plant invaders rarely cause regional extirpations or global extinctions, causing some to suggest that invasive species’ influence on native biodiversity may not be so dire.” See K. I. Powell, et al., “A Synthesis of Plant Invasion Effects on Biodiversity across Spatial Scales,” American Journal of Botany 98, no. 3 (2011): 539–548. Stohlgren and Rejmánek have pointed out “the absence of empirical evidence of continuing plant invasions causing extinctions.” See T. J. Stohlgren and Marcel Rejmánek, “No Universal Scale-dependent Impacts of Invasive Species on Native Plant Species Richness,” Biology Letters 10, no. 1 (2014). Downey and Richardson have written, “Although there are no documented examples of either ‘in the wild’ … or global extinctions … of native plants that are attributable solely to plant invasions, there is evidence that native plants have crossed or breached other thresholds along the extinction trajectory due to the impacts associated with plant invasions.” See Paul O. Downey and David M. Richardson, “Alien Plant Invasions and Native Plant Extinctions: A Six-threshold Framework,” AoB PLANTS 8, no. 1 (2016).
[40] Andrew C. Revkin, “Another Round: Conservation on a Human-shaped Planet,” New York Times Blog, April 11, 2012.
[41] Hans Joachim Schellnhuber, “‘Earth System’ Analysis and the Second Copernican Revolution,” Nature 402, no. 6761 (1999).
[42] Mark Vellend, The Theory of Ecological Communities, (Princeton University Press, 2016).
[43] Clive Hamilton, “Getting the Anthropocene So Wrong,” The Anthropocene Review 2, no. 2 (2015): 102–107.
[44] Donald Worster, Nature’s Economy: A History of Ecological Ideas, 2nd ed., (Cambridge University Press, 1994), 292.
[45] Herman E. Daly, “Allocation, Distribution, and Scale: Towards an Economics that is Efficient, Just, and Sustainable,” Ecological Economics 6, no. 3 (1992): 185–193.
[46] For discussion, see Thomas Robertson, The Malthusian Moment: Global Population Growth and the Birth of American Environmentalism (Rutgers University Press, 2012). 
[47] Clive Hamilton, Defiant Earth: The Fate of Humans in the Anthropocene (John Wiley & Sons, 2017), 144.
[48] Ibid, 134.
[49] Will Steffen, et al., “The Anthropocene: Conceptual and Historical Perspectives,” Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 369, no. 1938 (2011): 842–867.
[50] For a recent collection of papers that argue that the discourse of collapse is essential to ecological and environmental science, see Alison E. Vogelaar, Brack W. Hale, and Alexandra Peat, eds., The Discourses of Environmental Collapse: Imagining the End (Routledge Studies in Environmental Communication and Media, 2018). The editors of this volume in their introduction (p. 4) observe that however thoroughly science has adopted the discourse of collapse, its arguments and evidence have not produced political results. “And yet the very fact that this evidence continues to reproduce without provoking sufficient change at the appropriate levels suggests that we may require alternative approaches, which may even entail moving beyond ‘collapse’ as a singular, overarching event and narrative.”

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