by Fazale RanaJuly 14, 2021
It is hard to imagine that anything good could have come from the COVID-19 pandemic.
But something has. Thanks to the 2020 “lockdowns,” there was a 17% decrease in global carbon emissions and a 20% drop in nitrous oxide levels. Many of the world’s waterways also became cleaner.
Sadly, these environmental gains will only be temporary, as life returns to normal and harmful emissions increase once again.
In addition to these temporary environmental benefits, the COVID-19 pandemic has also had a damaging impact on Earth’s ecosystems, one that will be long-lasting. As a result of travel restrictions, the ecotourism industry collapsed. The income generated from ecotourism funds much of the world’s conservation efforts. In a short period of time, this lack of funding has made it harder to prevent poaching and habitat loss, threatening some of the world’s most fragile ecosystems, home to species already on the brink of extinction.
This alarming trend isn’t a recent phenomenon. Since our species’ inception, we have caused harm to ecosystems around the world. Humans instigated the extinction of a large number of animals when they began their migration out of Africa and around the world around 60,000 to 70,000 years ago.1 As early modern humans made their way from Africa and into Asia, Australia, Europe, and eventually the Americas, they precipitated the wide-scale extinction of large animals. (This loss is called the Quaternary Global Megafauna Extinctions.)
Many environmentalists have expressed concern that the damage humans are causing to the world’s ecosystems has accelerated in recent years. In fact, many of these scientists think that we are on the verge of the sixth great mass extinction. Unlike Earth’s previous extinctions caused by some type of cataclysmic event—such as an asteroid impact or massive volcanic eruption—this mass extinction appears to be triggered by human environmental abuse.
Yet others question the human contribution to the sixth mass extinction. In fact, there are even some who question if a mass extinction is underway at all.2 So:
• Are we on the verge of the sixth mass extinction?
• Are humans responsible for ecosystem collapse around the world?
• What should we do about it, if anything at all?
• What should our response be as Christians to environmental crises?
Are We Really Entering the Sixth Mass Extinction?
Species have been lost to extinction throughout Earth’s history. Ecologists refer to the average rate of species loss between mass extinctions as the background rate. It goes without saying: mass extinctions are defined as the periods in Earth’s history when the extinction rate dramatically exceeds the background rate of species loss.
If we truly are on the brink of the sixth mass extinction, then the recent rate of species loss should significantly outpace the background rate.
Determining the rate of species loss is no easy feat. The fossil record is key for determining the background rate of species loss. Those who express skepticism about whether we are entering into the sixth mass extinction question the background rate estimates used by many ecologists of between 0.1 and 1 species extinction per 1 million species per year. The basis for their skepticism, in part, rests on the fact that this estimate is heavily weighted by the marine invertebrate fossil record. These animals are thought to have a much greater species longevity than vertebrates, making the background rate artificially low and the severity of species loss today greater than it may be.
In 2015, an international research team, which included the famed ecologist Paul Ehrlich, sought to put this question to rest.3 They used mammal extinctions to establish the background extinction rate. Based on the fossil record, mammal species disappear at a rate of 2 species extinctions per 1 million species per year. This background rate is between 2 to 20 times greater than the background extinction rate usually used by environmental scientists as a reference point relative to current extinction rates.
Using data produced by the International Union for Conservation of Nature, these researchers discovered that, since 1500, 338 vertebrate extinctions have been recorded. Another 279 species are considered as extinct or possibly extinct. Using these numbers, the extinction rate over the last 500 years is 8 to 100 times higher than the background extinction rate (of 2 species extinctions per 1 million species per year). Included in this list are 69 mammal species, 80 bird species, 24 reptile species, 146 amphibian species, and 158 fish species.
A more recent study published in 2021 by an international team of environmental scientists adds further support for the onset of the sixth mass extinction.4 These researchers generated a mathematical map that showed the spectrum of biological traits and behavioral features displayed by 75,000 species of vascular plants (39,260 species), mammals (4,653 species), birds (9,802 species), reptiles (6,567 species), amphibians (6,776 species) and freshwater fish (10,705 species). These traits and features reflect the contribution these species make to the world’s ecosystems. The researchers then mapped the extinction risk for each of these organisms onto the spectra of traits and behaviors.
They discovered that extinction risks weren’t randomly distributed among the sample. Instead, the species that are most vulnerable are larger in size, have a slower pace of life, and lower fecundity. They also discovered that some of the smallest animal species are also extremely vulnerable to extinction because they lack the ability to disperse. This inability keeps them confined to their immediate surroundings, making them vulnerable when their local habitat disappears or becomes damaged from pollution.
On the surface, this result is disconcerting because ecologists have discovered that large animals wield a disproportionate influence on ecosystems. Consequently, the vulnerability of large organisms risks the stability of entire ecosystems.
Along these lines, the researchers discovered that—despite functional and behavioral redundancy in ecosystems (in which two or more organisms perform the same services for the ecosystem)—the loss of vulnerable organisms reduces the functional and behavioral diversity and richness of the world’s ecosystems. Through modeling studies, they learned that these losses will also force ecosystems to reorganize. Both effects exacerbate future extinction risks for remaining organisms, particularly for mammals and amphibians.
In other words, as dire as it may be to think that one-quarter of the world’s plant and animal species (which numbers around one million species) are on the brink of extinction, as these species disappear their loss will become amplified because of the loss of diversity within ecosystems and their ensuing reorganization. In other words, a vicious circle exists in which extinctions lead to more extinctions.
Are Humans Really Causing the Sixth Mass Extinction?
Five mass extinctions have occurred over the last 450 million years of life’s history, each one destroying between 70 to 95% of plant, animal, and microbial species. On this basis, it could be argued that mass extinctions are an inevitable part of life’s history. They are part of the natural order of things.
All five mass extinctions appear to have been triggered by cataclysmic events. For example:
• The Late Devonian Extinction—resulting in the loss of 75% of Earth’s species—appears to have been triggered by a dramatic reduction in the oxygen levels in Earth’s oceans due to either an algae bloom or volcanic eruptions.
• The Permian-Triassic Extinction—resulting in the loss of 96% of marine species and 70% of terrestrial species—appears to have been caused by rampant volcanic activity.
• The K-Pg Extinction—resulting in the loss of 75% of Earth’s species—appears to have been instigated by a massive asteroid impact.
Clearly, a sixth possible mass extinction won’t be attributed to a sudden cataclysm. Instead, it appears to be due to changes in the world’s ecosystems caused by human activity. While humans did indeed trigger mass extinctions when they began migrating around the world millennia ago, the damage they have caused to the environment has exponentially increased since the Neolithic revolution (about 12,000 years ago), which ushered in wide-scale agricultural practices and led to the onset of human civilization. Part of this damage relates to the dramatic increase in the human population size. At the time of the Neolithic revolution, estimates place the human population at about 1 million people. Today the human population is around 7.7 billion and growing. As the human population has ballooned it has led to habitat loss and a polluted environment, which in turn has produced an accelerating rate of extinctions.
The work by Paul Ehrlich and his collaborators (published in 2015) provides empirical support for the relatively recent accelerating rate of extinctions.5 Excluding birds and mammals, the extinction rates for most vertebrates were just above the background extinction rate as recently as the 1500s. While a marked increase in the extinction rate took place in the 1700s (most likely because of the industrial revolution), the last 200 years have been catastrophic for vertebrate populations. Over this period, extinction rates have skyrocketed. The researchers illustrate this point using amphibian extinctions. There are about 7,300 known amphibian species. Between 1500 and 1980, life scientists have documented the loss of 34 species. Since 1980, over 100 species have disappeared.
Using a background rate of 2 species extinctions per 1 million species per year, the team also demonstrated that the extinctions that occurred between 1500 and 1900 should have taken about 10,000 years to transpire, not a few hundred years.
In 2020, another international team of collaborators (which also involved Ehrlich) bolstered the case for accelerating mass extinctions driven by human activity.6 Instead of attempting to assess the number of vertebrate species that have become extinct, they assessed the extinction risk for nearly 30,000 terrestrial vertebrate species. To do this, they estimated the population sizes of these species. Complicating their analysis is the recognition that many of these species have incomplete or inadequate population data. Of those that do, one-quarter of them have fewer than 1,000 species—in some instances, the numbers are well below 1,000 individuals. They classified these species as on the brink of extinction. Of the 515 species on the brink of extinction, most are birds, followed by amphibians, mammals, and reptiles. Geographically, most of the at-risk mammalian species live in Asia and Oceania and most of the vulnerable bird species locate to Oceania and South America.
The research team also developed another category: species on the road to the brink of extinction. They define this category (which consists of 388 species) as those species that number under 5,000 individuals. Around 85% of species in this category are found in the same locales as species on the brink of extinction.
The researchers then compared the historic geographic ranges for 48 mammal species and 29 bird species that are on the brink of extinction. They discovered that, on average, these species have lost around 95% of their geographical range since 1900. This habitat loss explains the dramatic reduction in local populations of these species. The researchers estimate that around 3,600 populations of the 48 mammal species have disappeared and 2,930 populations of the 29 bird species.
The researchers project that the species on the brink will soon join the hundreds of vertebrate species that have disappeared since 1900, as human activity continues to apply pressure to ecosystems around the world.
What Should the Christian Response Be to Mass Extinctions?
Regardless of one’s worldview, the prospects of a sixth mass extinction should be of foremost concern. Each time a species is lost, its unique contribution to the earth’s ecosystems is lost. In some instances, this loss may be relatively inconsequential. But often, species loss causes irreversible change.
Human civilization depends on functioning ecosystems to provide a stable climate, fresh water, agricultural pest control, control of disease-causing animal vectors, crop pollination, and many other services. To put it another way, humanity depends on functioning ecosystems for our life support. A sixth mass extinction could rightly be viewed as the most serious environmental threat facing humanity.
But for Christians, such an ominous event also raises concerns of a theological nature. If indeed, human activity continues to propel us out of control toward the brink of wide-scale extinctions and reorganizations of ecosystems around the world, then it represents a failure on our part to fulfill the command God gave to the first humans (and by extension to us) to be stewards and caretakers of creation.
According to the Genesis 1 creation account, human beings were uniquely made to bear God’s image. While Scripture doesn’t clearly delineate precisely what the image of God is, it does make it clear that, as image-bearers, we were given certain responsibilities that included:
• Multiplying and filling the earth
• Subduing the earth, bringing it under our control
• Exercising dominion over the creation
• Serving as caretakers for the planet and ensuring the health of all life on Earth
It is clear from these commands that we were to transform the wild and unruly state of creation into the type of order and organization that God instituted when he planted and caused the Garden of Eden to grow. To fulfill this responsibility, we were granted dominion over creation. God made it available for our benefit. But we were not to exploit or ravish creation. Instead, we were to care for it so that all life on Earth would flourish.
Because of these mandates, Christians have an obligation to embrace a responsible form of environmentalism—one that balances care for the environment with care and concern for human life. If anything, the insights into the causes and consequences of the sixth mass extinction drive home the point that these two objectives aren’t mutually exclusive. When we care for the environment, we care for one another.
Our responsibility as the planet’s stewards should also propel us to aggressively pursue green technologies and advocate the use of science and technology to reverse the damage we have caused to the environment. These efforts should include remediating environmental pollution and supporting conservation efforts to prevent additional species loss that may even include the use of emerging biotechnologies such as cloning and gene editing.
The Explanatory Power of the Christian Worldview
Clearly, the destruction of ecosystems that appears to have instigated the sixth mass extinction has part of its etiology in the ballooning worldwide human population, coupled with the activities associated with advancing and sustaining economies throughout the world. Along these lines, it is tempting to think we could mitigate our destructive impact if we reduced our numbers, gave more consideration to managing limited resources, and perhaps even returned to simpler ways of life.
Yet, when we consider the impact that the first humans had as they migrated around the world, it becomes clear that the exponential growth in the human population cannot be the sole explanation for the damage we are causing to the environment. Genetic variability data indicate the first wave of human migrations consisted of relatively small groups. Yet based on the Quaternary Global Megafauna Extinctions caused by human activity, it seems that even in limited numbers, humans possess an innate capacity to wreak environmental havoc on a grand scale.
As a Christian, this observation leads me to suggest that a significant contributor to the destructive impact we have had—and will continue to have—on the world’s ecosystems arises out of something intrinsic to our nature; namely, our propensity to sin and the fractured relationship between humans and nature that resulted from our sinful behavior.
According to Scripture, when humanity rebelled against God, not only was our relationship with our Maker and other human beings marred, so was our relationship with creation itself. As a result, we can no longer effectively serve as caretakers of the planet.
Scripture goes as far as to state that the ground is “cursed” because of human sin. And it appears this has been the case from the days of prehistoric hunter-gatherers to the present.
The Christian worldview also proposes a solution to what may be the most significant environmental threat facing humanity. The answer is found in the transforming power of the gospel. Through the sacrifice of Christ on the cross, we can be reconciled to our Maker. But the impact of the gospel extends beyond our relationship to God. It extends to our relationship with one another as human beings and, even creation itself. The fall of humanity resulted in alienation between humanity and God, humanity with itself, and between humanity and nature. And it is through the redeeming work of Christ that alienation becomes reconciliation. We can be reconciled to God, reconciled to each other, and even reconciled to nature. It is out of this redeemed relationship with creation that we will have the wherewithal to salvage the damage we have caused to the world’s ecosystems and stave off the most serious environmental threat facing humanity.
Mass Extinctions and the Case for Human Exceptionalism
I find it remarkable to think that a single species could wreak so much havoc on the earth’s ecosystems. No other species that lives today—or that has ever lived—has the capability to cause such wide-scale destruction to our planet. This difference in capacities points to something distinct and unique about human beings—something exceptional.
Some anthropologists recognize the exceptional nature of human beings and now work to advance the case for human exceptionalism. For these anthropologists, human exceptionalism largely stems from our capacity for symbolism. As human beings, we effortlessly represent the world with discrete symbols. We denote abstract concepts with symbols. And our ability to represent the world symbolically has interesting consequences when coupled with our abilities to combine and recombine those symbols in nearly infinite ways to create alternate possibilities.
Evolutionary psychologist Thomas Suddendorf describes the difference between humans and other primates this way:
“We reflect on and argue about our present situation, our history, and our destiny. We envision wonderful harmonious worlds as easily as we do dreadful tyrannies. Our powers are used for good as they are for bad, and we incessantly debate which is which. Our minds have spawned civilizations and technologies that have changed the face of the Earth, while our closest living animal relatives sit unobtrusively in their remaining forests. There appears to be a tremendous gap between human and animal minds.”7
Our capacity for symbolism manifests in the form of language, art, music, and even body ornamentation. And we desire to communicate the scenarios we construct in our minds with other human beings. For some Christians, symbolism and our open-ended capacity to generate alternative hypotheses are scientific descriptors of the image of God.
It is our capacity for symbolism that led to the development of technologies that made possible the expansion of human population, human civilization and, consequently, our activities that have caused harm to the world’s ecosystems. It is also our capacity for symbolism that makes possible the scientific enterprise, which provides the means for us to understand the structure and function of ecosystems and to recognize the damage we have caused to the environment. It is our symbolic capacity that allows us to catalog and project species loss around the world. And it is our capacity for symbolism that suggests ways we can mitigate species loss, including using emerging biotechnologies to clone endangered and even extinct species.
From a Christian worldview perspective, our exceptional nature makes human life inherently valuable. But it also imbues us with a responsibility to care for the planet’s ecosystems and to protect and care for vulnerable organisms on the verge of extinction.
“Did Humans Cause the Global Extinction of Mammals?” by Fazale Rana (article)
“Does Animal Planning Undermine the Image of God?” by Fazale Rana (article)
“Primate Thanatology and the Case for Human Exceptionalism” by Fazale Rana (article)
“Molecular Scale Robotics Build a Case for Design” by Fazale Rana (article)
1. Christopher Sandom et al., “Global Late Quaternary Megafauna Extinctions Linked to Humans, Not Climate Change” Proceedings of the Royal Society B 281 (July 22, 2014): doi:10.1098/rspb.2013.3254.
2. John C. Briggs, “Emergence of a Sixth Mass Extinction?” Biological Journal of the Linnean Society 122 (October 2017): 243–248, doi:10.1093/biolinnean/blx063.
3. Gerardo Ceballos et al., “Accelerated Modern Human-Induced Species Losses: Entering the Sixth Mass Extinction,” Science Advances 1 (June 19, 2015): e1400253, doi:10.1126/sciadv.1400253.
4. Carlos P. Carmona et al., “Erosion of Global Functional Diversity across the Tree of Life,” Science Advances 7 (March 26, 2021): eabf2675, doi:10.1126/sciadv.abf2675.
5. Ceballos et al., “Accelerated Modern Human-Induced Species Losses.”
6. Gerardo Ceballos, Paul R. Ehrlich and Peter H. Raven, Vertebrates on the Brink as Indicators of Biological Annihilation and the Sixth Mass Extinction, The Proceedings of the National Academy of Sciences 117 (June 16, 2020): 13596–602, doi:10.1073/pnas.1922686117.
7. Thomas Suddendorf, The Gap: The Science of What Separates Us from Other Animals (New York: Basic Books, 2013), 2.
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