Earth’s Sixth Mass Extinction Event Already Under Way, Scientists Warn

Researchers talk of “biological annihilation” as study reveals billions of populations of animals have been lost in recent decades.

Photo Credit: Maggy Meyer/Shutterstock

A “biological annihilation” of wildlife in recent decades means a sixth mass extinction in Earth’s history is under way and is more severe than previously feared, according to research.

Scientists analyzed both common and rare species and found billions of regional or local populations have been lost. They blame human overpopulation and overconsumption for the crisis and warn that it threatens the survival of human civilization, with just a short window of time in which to act.

The study, published in the peer-reviewed journal Proceedings of the National Academy of Sciences, eschews the normally sober tone of scientific papers and calls the massive loss of wildlife a “biological annihilation” that represents a “frightening assault on the foundations of human civilization”.

Prof Gerardo Ceballos, at the Universidad Nacional Autónoma de México, who led the work, said: “The situation has become so bad it would not be ethical not to use strong language.”

Previous studies have shown species are becoming extinct at a significantly faster rate than for millions of years before, but even so extinctions remain relatively rare giving the impression of a gradual loss of biodiversity. The new work instead takes a broader view, assessing many common species which are losing populations all over the world as their ranges shrink, but remain present elsewhere.

The scientists found that a third of the thousands of species losing populations are not currently considered endangered and that up to 50 percent of all individual animals have been lost in recent decades. Detailed data is available for land mammals, and almost half of these have lost 80 percent of their range in the last century. The scientists found billions of populations of mammals, birds, reptiles and amphibians have been lost all over the planet, leading them to say a sixth mass extinction has already progressed further than was thought.

Nearly half of the 177 mammal species surveyed lost more than 80% of their distribution between 1900 and 2015

Percent of species which have lost more than 80 percent of their range

Billions of animals have been lost as their habitats have become smaller with each passing year. (Guardian graphic | source: PNAS)

The scientists conclude: “The resulting biological annihilation obviously will have serious ecological, economic and social consequences. Humanity will eventually pay a very high price for the decimation of the only assemblage of life that we know of in the universe.”

They say, while action to halt the decline remains possible, the prospects do not look good: “All signs point to ever more powerful assaults on biodiversity in the next two decades, painting a dismal picture of the future of life, including human life.”

Wildlife is dying out due to habitat destruction, overhunting, toxic pollution, invasion by alien species and climate change. But the ultimate cause of all of these factors is “human overpopulation and continued population growth, and overconsumption, especially by the rich”, say the scientists, who include Prof Paul Ehrlich, at Stanford University in the U.S., whose 1968 book The Population Bomb is a seminal, if controversial, work.

“The serious warning in our paper needs to be heeded because civilization depends utterly on the plants, animals, and microorganisms of Earth that supply it with essential ecosystem services ranging from crop pollination and protection to supplying food from the sea and maintaining a livable climate,” Ehrlich told the Guardian. Other ecosystem services include clean air and water.

“The time to act is very short,” he said. “It will, sadly, take a long time to humanely begin the population shrinkage required if civilization is to long survive, but much could be done on the consumption front and with ‘band aids’—wildlife reserves, diversity protection laws—in the meantime.” Ceballos said an international institution was needed to fund global wildlife conservation.

The research analyzed data on 27,500 species of land vertebrates from the IUCN and found the ranges of a third have shrunk in recent decades. Many of these are common species and Ceballos gave an example from close to home: “We used to have swallows nesting every year in my home near Mexico city—but for the last 10 years there are none.”

The researchers also point to the “emblematic” case of the lion: “The lion was historically distributed over most of Africa, southern Europe, and the Middle East, all the way to northwestern India. [Now] the vast majority of lion populations are gone.”

Current and historic distribution of lions

Historically lions lived across Africa, southern Europe, the Middle East, all the way up to Northwestern India. Today their habitat has been reduced to a few tiny pockets of the original area. (Guardian graphic | source: PNAS)

Prof. Stuart Pimm, at Duke University in the US and not involved in the new work, said the overall conclusion is correct, but he disagrees that a sixth mass extinction is already under way: “It is something that hasn’t happened yet—we are on the edge of it.”

Pimm also said there were important caveats that result from the broad-brush approach used. “Should we be concerned about the loss of species across large areas—absolutely—but this is a fairly crude way of showing that,” he said. “There are parts of the world where there are massive losses, but equally there are parts of the world where there is remarkable progress. It is pretty harsh on countries like South Africa which is doing a good job of protecting lions.”

Robin Freeman, at the Zoological Society of London, U.K., said: “While looking at things on aggregate is interesting, the real interesting nitty gritty comes in the details. What are the drivers that cause the declines in particular areas?”

Freeman was part of the team that produced a 2014 analysis of 3000 species that indicated that 50 percent of individual animals have been lost since 1970, which tallies with the new work but was based on different IUCN data. He agreed strong language is needed: “We need people to be aware of the catastrophic declines we are seeing. I do think there is a place for that within the [new] paper, although it’s a fine line to draw.”

Citing human overpopulation as the root cause of environmental problems has long been controversial, and Ehrlich’s 1968 statement that hundreds of millions of people would die of starvation in the 1970s did not come to pass, partly due to new high-yielding crops that Ehrlich himself had noted as possible.

Ehrlich has acknowledged “flaws” in The Population Bomb but said it had been successful in its central aim—alerting people to global environmental issues and the the role of human population in them. His message remains blunt today: “Show me a scientist who claims there is no population problem and I’ll show you an idiot.”

Earth’s five previous mass extinctions

End-Ordovician, 443 million years ago

A severe ice age led to sea level falling by 100m, wiping out 60-70 percent of all species which were prominently ocean dwellers at the time. Then soon after the ice melted leaving the oceans starved of oxygen.

Late Devonian, c 360 million years ago

A messy prolonged climate change event, again hitting life in shallow seas very hard, killing 70 percent of species including almost all corals.

Permian-Triassic, c 250 million years ago

The big one—more than 95 percent of species perished, including trilobites and giant insects—strongly linked to massive volcanic eruptions in Siberia that caused a savage episode of global warming.

Triassic-Jurassic, c 200 million years ago

Three-quarters of species were lost, again most likely due to another huge outburst of volcanism. It left the Earth clear for dinosaurs to flourish.

Cretaceous-Tertiary, 65 million years ago

An giant asteroid impact on Mexico, just after large volcanic eruptions in what is now India, saw the end of the dinosaurs and ammonites. Mammals, and eventually humans, took advantage.


Vertebrate species populations in dramatic decline


By Philip Guelpa
1 November 2016

An alarming new study, the Living Planet Report 2016, prepared by researchers from the World Wildlife Fund and the Zoological Society of London, projects that by the year 2020, little more than three years from now, the population abundance of vertebrate species around the world will have dropped by two-thirds from what it was in 1970.

This dramatic decline encompasses species of fish, amphibians, reptiles, birds, and mammals. Invertebrates and plants are, undoubtedly suffering similar effects, as demonstrated by the recently reported death of a large portion of the Great Barrier Reef in Australia, a 2,300-kilometer-long system of coral reefs, which is a UNESCO World Heritage Site, and has existed for 25 million years.

The rate of decline shows no sign of slowing. Between 1970 and 2012, a span of 42 years, the overall vertebrate population abundance (the total numbers of animals for each species) dropped by 58 percent, according to the study. By 2020, only another eight years, that figure is expected to reach a 67 percent decrease. If this pace were to continue, total extinction (a decrease of 100 percent) would be reached by the middle of the 21st century. These figures are based on a large data set, the Living Planet Index (LPI), derived from the monitoring of 14,000 animal populations that encompass 3,700 species. While some level of uncertainty is to be expected when attempting to assess such a large and complex phenomenon, the general trend is clear.

This dramatic decline is mainly attributed to a combination of climate change, environmental pollution, the human-facilitated spread of diseases, over-exploitation, and habitat destruction. Vertebrate populations are clearly under tremendous stress, as indicated by the substantial decreases in population sizes. The report identifies freshwater environments—rivers and lakes—as being the hardest hit, with an 81 percent decline in species abundance between 1970 and 2012. Terrestrial species abundance has fallen by 38 percent and marine species abundance by 36 percent.

Living Planet Report 2016 is but one of many studies in recent years that have identified a dramatic trend toward species decline and extinction.

The scale of the devastation documented in the 2016 LPR, occurring over a span of only 50 years, is on a trajectory to rival the five previous mass extinctions of life on earth. However, whereas the previous events were caused by a variety of natural processes, this impending sixth extinction is conclusively attributable to the anarchic development of the capitalist economy, which mindlessly pursues profit without regard to the consequences to society or nature.

In attempting to explain the forces driving these dramatic animal population declines, the Living Planet Report refers only to empirical trends such as human population growth, increases in carbon dioxide emissions and fertilizer consumption and the like, and offers only vague remedies such as the adoption of an “Earth system perspective.” No reference is made to the fact that decisions regarding industrial growth, resource exploitation, the development of more efficient technologies, and a whole range of other economic issues that affect the environment are made by the financial and corporate elites, a tiny minority of the world’s population, to protect their own interests.

The effects of unplanned development, undertaken with little or no scientific assessment of potential impacts to the environment, did not begin in 1970. Human activities have caused disruption of natural communities for thousands of years, beginning with the development of agriculture. However, these effects have accelerated dramatically in scope and scale over the last several centuries, with the development of capitalism and the industrial revolution. The rate of change has now reached a qualitative transition, reaching a pace never before seen. The consequences of this hyper-acceleration cannot be precisely predicted, but will undoubtedly cause substantial disruption of both natural ecosystems and human communities.

Biological communities exist as complex, dynamic systems of interaction between a whole range of organisms, from top vertebrate predators to microorganisms, as well as the components of the physical environment in which they exist. The rapid removal, both quantitatively and qualitatively (i.e., by extinction) of growing numbers of species from this dialectical relationship renders such systems increasingly unstable and prone to catastrophic collapse.

This fundamental shift is now being officially recognized by the scientific community. Based on research spanning over two centuries, scientists have developed a chronological framework to study the development of life on earth. Successive periods of evolutionary change are defined, at least in part, by the existence of more or less distinct groupings of organisms, reflecting significant changes in the earth’s fauna. The most recent major subdivision, the Cenozoic, termed the Age of Mammals, spans roughly the last 65 million years (i.e., since the extinction of the dinosaurs). It, in turn, is comprised of a series of smaller units (each spanning millions of years). The latest three are the Pliocene, Pleistocene, and Holocene, which encompass the evolution of human beings. The Pleistocene alone lasted roughly 2.5 million years.

The Holocene, characterized by the existence of the modern suite of mammals, began only 12,000 years ago, following the end of the last ice age. Therefore, compared to the length of previous periods, it has barely begun. Nevertheless, using the same procedure of defining geologic periods based on assemblages of species, some scientists have in recent years proposed that the Holocene has now ended and that a new period, the Anthropocene, has begun. The use of the prefix “anthro,” the Greek word for man, in the name, is intended to indicate that humans have now become a major factor in both biological evolution and the linked process of climate and environmental change.

Human science and technology have reached the point at which we now have an unprecedented capacity both to develop a much deeper understanding of the complexities of natural ecological systems and rationally plan an economy that takes this understanding into account in order to substantially reduce its impact on the natural world while, at the same time, meeting human needs.

However, unless capitalism is replaced by a planned socialist economy, and in relatively short order at that, the extreme negative effects of anarchic development make it highly likely that the natural systems which are fundamental to the maintenance of a livable planet will suffer drastic, and perhaps irreversible, degradation. Efforts by the rival capitalist nation states to address climate change and environmental degradation have been feeble and ineffective. The LPR 2016 report is a warning that the future of life on earth hangs in the balance.