Sixth Mass Extinction
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The Holocene extinction, or Anthropocene extinction, is the ongoing
extinction event An extinction event (also known as a mass extinction or biotic crisis) is a widespread and rapid decrease in the biodiversity on Earth. Such an event is identified by a sharp change in the diversity and abundance of multicellular organisms. I ...
during the
Holocene The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togeth ...
epoch. The
extinction Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the Endling, last individual of the species, although the Functional ext ...
s span numerous families of
bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were am ...
,
fungi A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately fr ...
,
plant Plants are predominantly photosynthetic eukaryotes of the kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all current definitions of Plantae excl ...
s, and
animal Animals are multicellular, eukaryotic organisms in the biological kingdom Animalia. With few exceptions, animals consume organic material, breathe oxygen, are able to move, can reproduce sexually, and go through an ontogenetic stage ...
s, including
mammal Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur ...
s,
bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...
s,
reptile Reptiles, as most commonly defined are the animals in the class Reptilia ( ), a paraphyletic grouping comprising all sauropsids except birds. Living reptiles comprise turtles, crocodilians, squamates ( lizards and snakes) and rhynchocephalia ...
s,
amphibian Amphibians are four-limbed and ectothermic vertebrates of the class Amphibia. All living amphibians belong to the group Lissamphibia. They inhabit a wide variety of habitats, with most species living within terrestrial, fossorial, arbo ...
s,
fish Fish are Aquatic animal, aquatic, craniate, gill-bearing animals that lack Limb (anatomy), limbs with Digit (anatomy), digits. Included in this definition are the living hagfish, lampreys, and Chondrichthyes, cartilaginous and bony fish as we ...
,
invertebrate Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chorda ...
s, and affecting not just terrestrial species but also large sectors of
marine life Marine life, sea life, or ocean life is the plants, animals and other organisms that live in the salt water of seas or oceans, or the brackish water of coastal estuaries. At a fundamental level, marine life affects the nature of the planet. ...
. With widespread degradation of
biodiversity hotspot A biodiversity hotspot is a biogeographic region with significant levels of biodiversity that is threatened by human habitation. Norman Myers wrote about the concept in two articles in ''The Environmentalist'' in 1988 and 1990, after which the c ...
s, such as
coral reef A coral reef is an underwater ecosystem characterized by reef-building corals. Reefs are formed of Colony (biology), colonies of coral polyp (zoology), polyps held together by calcium carbonate. Most coral reefs are built from stony corals, wh ...
s and
rainforest Rainforests are characterized by a closed and continuous tree canopy, moisture-dependent vegetation, the presence of epiphytes and lianas and the absence of wildfire. Rainforest can be classified as tropical rainforest or temperate rainfores ...
s, as well as other areas, the vast majority of these extinctions are thought to be undocumented, as the species are undiscovered at the time of their extinction, which goes unrecorded. The current rate of extinction of species is estimated at 100 to 1,000 times higher than natural
background extinction rate Background extinction rate, also known as the normal extinction rate, refers to the standard rate of extinction in Earth's geological and biological history before humans became a primary contributor to extinctions. This is primarily the pre-huma ...
s, and is increasing. During the past 100–200 years, biodiversity loss and species extinction have accelerated, to the point that most
conservation biologists Conservation biology is the study of the conservation of nature and of Earth's biodiversity with the aim of protecting species, their habitats, and ecosystems from excessive rates of extinction and the erosion of biotic interactions. It is an in ...
now believe that
humankind Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, culture, ...
has either entered a period of mass extinction, or is on the cusp of doing so. As such, the event has also been referred to as the sixth mass extinction or sixth extinction. The Holocene extinction includes the disappearance of large land animals known as
megafauna In terrestrial zoology, the megafauna (from Greek μέγας ''megas'' "large" and New Latin ''fauna'' "animal life") comprises the large or giant animals of an area, habitat, or geological period, extinct and/or extant. The most common thresho ...
, starting at the end of the last glacial period. Megafauna outside of the African mainland, which did not evolve alongside humans, proved highly sensitive to the introduction of human
predation Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill ...
, and many died out shortly after early humans began spreading and hunting across the Earth. Many African species have also gone extinct in the Holocene, along with species in North America, South America, and Australia, but – with some exceptions – the megafauna of the Eurasian mainland was largely unaffected until a few hundred years ago. These extinctions, occurring near the
Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...
Holocene The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togeth ...
boundary, are sometimes referred to as the
Quaternary extinction event The Quaternary period (from 2.588 ± 0.005 million years ago to the present) has seen the extinctions of numerous predominantly megafaunal species, which have resulted in a collapse in faunal density and diversity and the extinction of key ecolog ...
. The most popular theory is that human
overhunting Overexploitation, also called overharvesting, refers to harvesting a renewable resource to the point of diminishing returns. Continued overexploitation can lead to the destruction of the resource, as it will be unable to replenish. The term ap ...
of species added to existing stress conditions as the Holocene extinction coincides with human colonization of many new areas around the world. Although there is debate regarding how much human
predation Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill ...
and
habitat loss Habitat destruction (also termed habitat loss and habitat reduction) is the process by which a natural habitat becomes incapable of supporting its native species. The organisms that previously inhabited the site are displaced or dead, thereby ...
affected their decline, certain population declines have been directly correlated with the onset of human activity, such as the extinction events of
New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island coun ...
and
Hawaii Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only stat ...
. Aside from humans,
climate change In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to ...
may have been a driving factor in the megafaunal extinctions, especially at the end of the
Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...
. In the
twentieth century The 20th (twentieth) century began on January 1, 1901 (1901, MCMI), and ended on December 31, 2000 (2000, MM). The 20th century was dominated by significant events that defined the modern era: Spanish flu, Spanish flu pandemic, World War I and ...
, human numbers quadrupled, and the size of the global economy increased twenty-five-fold. This Great Acceleration or
Anthropocene The Anthropocene ( ) is a proposed geological epoch dating from the commencement of significant human impact on Earth's geology and ecosystems, including, but not limited to, anthropogenic climate change. , neither the International Commissio ...
Epoch has also accelerated species extinction.
Ecologically Ecology () is the study of the relationships between living organisms, including humans, and their biophysical environment, physical environment. Ecology considers organisms at the individual, population, community (ecology), community, ecosy ...
, humanity is now an unprecedented "global superpredator", which consistently preys on the adults of other
apex predator An apex predator, also known as a top predator, is a predator at the top of a food chain, without natural predators of its own. Apex predators are usually defined in terms of trophic dynamics, meaning that they occupy the highest trophic lev ...
s, takes over other species' essential habitats and displaces them, and has worldwide effects on
food web A food web is the natural interconnection of food chains and a graphical representation of what-eats-what in an ecological community. Another name for food web is consumer-resource system. Ecologists can broadly lump all life forms into one o ...
s. There have been extinctions of species on every
land mass A landmass, or land mass, is a large region or area of land. The term is often used to refer to lands surrounded by an ocean or sea, such as a continent or a large island. In the field of geology, a landmass is a defined section of continent ...
and in every
ocean The ocean (also the sea or the world ocean) is the body of salt water that covers approximately 70.8% of the surface of Earth and contains 97% of Earth's water. An ocean can also refer to any of the large bodies of water into which the wor ...
: there are many famous examples within Africa,
Asia Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an are ...
,
Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...
,
Australia Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. With an area of , Australia is the largest country by ...
,
North North is one of the four compass points or cardinal directions. It is the opposite of south and is perpendicular to east and west. ''North'' is a noun, adjective, or adverb indicating direction or geography. Etymology The word ''north ...
and
South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the sou ...
, and on smaller islands. Overall, the Holocene extinction can be linked to the
human impact on the environment Human impact on the environment (or anthropogenic impact) refers to changes to biophysical environments and to ecosystems, biodiversity, and natural resources caused directly or indirectly by humans. Modifying the environment to fit the need ...
. The Holocene extinction continues into the
21st century The 21st (twenty-first) century is the current century in the ''Anno Domini'' era or Common Era, under the Gregorian calendar. It began on 1 January 2001 ( MMI) and will end on 31 December 2100 ( MMC). Marking the beginning of the 21st centur ...
, with
human population growth Population growth is the increase in the number of people in a population or dispersed group. Actual global human population growth amounts to around 83 million annually, or 1.1% per year. The global population has grown from 1 billion in 1800 to ...
, increasing per capita consumption, and meat production, among others, being the primary drivers of mass extinction.
Deforestation Deforestation or forest clearance is the removal of a forest or stand of trees from land that is then converted to non-forest use. Deforestation can involve conversion of forest land to farms, ranches, or urban use. The most concentrated ...
,
overfishing Overfishing is the removal of a species of fish (i.e. fishing) from a body of water at a rate greater than that the species can replenish its population naturally (i.e. the overexploitation of the fishery's existing fish stock), resulting in t ...
,
ocean acidification Ocean acidification is the reduction in the pH value of the Earth’s ocean. Between 1751 and 2021, the average pH value of the ocean surface has decreased from approximately 8.25 to 8.14. The root cause of ocean acidification is carbon dioxid ...
, the destruction of
wetlands A wetland is a distinct ecosystem that is flooded or saturated by water, either permanently (for years or decades) or seasonally (for weeks or months). Flooding results in oxygen-free (anoxic) processes prevailing, especially in the soils. The p ...
, and the
decline in amphibian populations Since the 1980s, decreases in amphibian populations, including population decline and localized mass extinctions, have been observed in locations all over the world. These declines are known as one of the most critical threats to global biodiversi ...
, among others, are a few broader examples of global
biodiversity loss Biodiversity loss includes the worldwide extinction of different species, as well as the local reduction or loss of species in a certain habitat, resulting in a loss of biological diversity. The latter phenomenon can be temporary or permanent, de ...
.


Background

Mass extinctions An extinction event (also known as a mass extinction or biotic crisis) is a widespread and rapid decrease in the biodiversity on Earth. Such an event is identified by a sharp change in the diversity and abundance of multicellular organisms. It ...
are characterized by the loss of at least 75% of
species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriat ...
within a geologically short period of time. The Holocene extinction is also known as the "sixth extinction", as it is possibly the sixth mass extinction event, after the
Ordovician–Silurian extinction events The Late Ordovician mass extinction (LOME), sometimes known as the end-Ordovician mass extinction or the Ordovician-Silurian extinction, is the first of the "big five" major mass extinction events in Earth's history, occurring roughly 443 Mya. It ...
, the
Late Devonian extinction The Late Devonian extinction consisted of several extinction events in the Late Devonian Epoch, which collectively represent one of the five largest mass extinction events in the history of life on Earth. The term primarily refers to a major ex ...
, the
Permian–Triassic extinction event The Permian–Triassic (P–T, P–Tr) extinction event, also known as the Latest Permian extinction event, the End-Permian Extinction and colloquially as the Great Dying, formed the boundary between the Permian and Triassic geologic periods, ...
, the
Triassic–Jurassic extinction event The Triassic–Jurassic (Tr-J) extinction event, often called the end-Triassic extinction, marks the boundary between the Triassic and Jurassic periods, , and is one of the top five major extinction events of the Phanerozoic eon, profoundly affect ...
, and the
Cretaceous–Paleogene extinction event The Cretaceous–Paleogene (K–Pg) extinction event (also known as the Cretaceous–Tertiary extinction) was a sudden mass extinction of three-quarters of the plant and animal species on Earth, approximately 66 million years ago. With the ...
. The
Holocene The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togeth ...
is the current geological
epoch In chronology and periodization, an epoch or reference epoch is an instant in time chosen as the origin of a particular calendar era. The "epoch" serves as a reference point from which time is measured. The moment of epoch is usually decided ...
.


Overview

There is no general agreement on where the
Holocene The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togeth ...
, or
anthropogenic Anthropogenic ("human" + "generating") is an adjective that may refer to: * Anthropogeny, the study of the origins of humanity Counterintuitively, anthropogenic may also refer to things that have been generated by humans, as follows: * Human i ...
, extinction begins, and the
Quaternary extinction event The Quaternary period (from 2.588 ± 0.005 million years ago to the present) has seen the extinctions of numerous predominantly megafaunal species, which have resulted in a collapse in faunal density and diversity and the extinction of key ecolog ...
, which includes climate change resulting in the end of the last ice age, ends, or if they should be considered separate events at all. The Holocene extinction is mainly caused by human activities. Some have suggested that anthropogenic extinctions may have begun as early as when the first modern humans spread out of Africa between 200,000 and 100,000 years ago; this is supported by rapid megafaunal extinction following recent human colonisation in
Australia Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. With an area of , Australia is the largest country by ...
,
New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island coun ...
and
Madagascar Madagascar (; mg, Madagasikara, ), officially the Republic of Madagascar ( mg, Repoblikan'i Madagasikara, links=no, ; french: République de Madagascar), is an island country in the Indian Ocean, approximately off the coast of East Afric ...
. In many cases, it is suggested that even minimal hunting pressure was enough to wipe out large fauna, particularly on geographically isolated islands. Only during the most recent parts of the extinction have plants also suffered large losses.


Extinction rate

The contemporary rate of extinction of species is estimated at 100 to 1,000 times higher than the
background extinction rate Background extinction rate, also known as the normal extinction rate, refers to the standard rate of extinction in Earth's geological and biological history before humans became a primary contributor to extinctions. This is primarily the pre-huma ...
, the historically typical rate of extinction (in terms of the natural evolution of the planet); also, the current rate of extinction is 10 to 100 times higher than in any of the previous
mass extinction An extinction event (also known as a mass extinction or biotic crisis) is a widespread and rapid decrease in the biodiversity on Earth. Such an event is identified by a sharp change in the diversity and abundance of multicellular organisms. I ...
s in the history of Earth. One scientist estimates the current extinction rate may be 10,000 times the
background extinction rate Background extinction rate, also known as the normal extinction rate, refers to the standard rate of extinction in Earth's geological and biological history before humans became a primary contributor to extinctions. This is primarily the pre-huma ...
, although most scientists predict a much lower extinction rate than this outlying estimate.
Theoretical ecologist Theoretical ecology is the scientific discipline devoted to the study of ecological systems using theoretical methods such as simple conceptual models, mathematical models, computational simulations, and advanced data analysis. Effective models im ...
Stuart Pimm Stuart Leonard Pimm (born 27 February 1949) is an American-British biologist and theoretical ecologist specializing in scientific research of biodiversity and conservation biology. Education Pimm was born in Derbyshire, United Kingdom. He was e ...
stated that the extinction rate for plants is 100 times higher than normal. Some contend that contemporary extinction has yet to reach the level of the previous five mass extinctions, and that this comparison downplays how severe the first five mass extinctions were. John Briggs argues that there is inadequate data to determine the real rate of extinctions, and shows that estimates of current species extinctions varies enormously, ranging from 1.5 species to 40,000 species going extinct due to human activities each year. Both papers from Barnosky et al. (2011) and Hull et al. (2015) point out that the real rate of extinction during previous mass extinctions is unknown, both as only some organisms leave fossil remains, and as the temporal resolution of the fossil layer is larger than the time frame of the extinction events. However, all these authors agree that there is a modern
biodiversity crisis Biodiversity loss includes the worldwide extinction of different species, as well as the local reduction or loss of species in a certain habitat, resulting in a loss of biological diversity. The latter phenomenon can be temporary or permanent, de ...
with population declines affecting numerous species, and that a future anthropogenic mass extinction event is a big risk. The 2011 study by Barnosky et al. confirms that "current extinction rates are higher than would be expected from the fossil record" and adds that anthropogenic ecological stressors, including climate change, habitat fragmentation, pollution, overfishing, overhunting, invasive species and expanding human
biomass Biomass is plant-based material used as a fuel for heat or electricity production. It can be in the form of wood, wood residues, energy crops, agricultural residues, and waste from industry, farms, and households. Some people use the terms bio ...
will intensify and accelerate extinction rates in the future without significant mitigation efforts. In ''The Future of Life'' (2002),
Edward Osborne Wilson Edward Osborne Wilson (June 10, 1929 – December 26, 2021) was an American biologist, naturalist, entomologist and writer. According to David Attenborough, Wilson was the world's leading expert in his specialty of myrmecology, the study of an ...
of Harvard calculated that, if the current rate of human disruption of the
biosphere The biosphere (from Greek βίος ''bíos'' "life" and σφαῖρα ''sphaira'' "sphere"), also known as the ecosphere (from Greek οἶκος ''oîkos'' "environment" and σφαῖρα), is the worldwide sum of all ecosystems. It can also ...
continues, one-half of Earth's higher lifeforms will be extinct by 2100. A 1998 poll conducted by the
American Museum of Natural History The American Museum of Natural History (abbreviated as AMNH) is a natural history museum on the Upper West Side of Manhattan in New York City. In Theodore Roosevelt Park, across the street from Central Park, the museum complex comprises 26 int ...
found that 70% of biologists acknowledge an ongoing anthropogenic extinction event. In a pair of studies published in 2015, extrapolation from observed extinction of Hawaiian snails led to the conclusion that 7% of all species on Earth may have been lost already. A 2021 study published in the journal ''Frontiers in Forests and Global Change'' found that only around 3% of the planet's terrestrial surface is ecologically and
fauna Fauna is all of the animal life present in a particular region or time. The corresponding term for plants is '' flora'', and for fungi, it is '' funga''. Flora, fauna, funga and other forms of life are collectively referred to as '' biota''. ...
lly intact, meaning areas with healthy populations of native animal species and little to no human footprint. The 2019 ''
Global Assessment Report on Biodiversity and Ecosystem Services Global means of or referring to a globe and may also refer to: Entertainment * ''Global'' (Paul van Dyk album), 2003 * ''Global'' (Bunji Garlin album), 2007 * ''Global'' (Humanoid album), 1989 * ''Global'' (Todd Rundgren album), 2015 * Bruno ...
'', published by the
United Nations The United Nations (UN) is an intergovernmental organization whose stated purposes are to maintain international peace and security, develop friendly relations among nations, achieve international cooperation, and be a centre for harmoni ...
'
Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services The Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) is an intergovernmental organization established to improve the interface between science and policy on issues of biodiversity and ecosystem services. It ...
(IPBES), posits that roughly one million species of plants and animals face extinction within decades as the result of human actions. Organized human existence is jeopardized by increasingly rapid destruction of the systems that support life on Earth, according to the report, the result of one of the most comprehensive studies of the health of the planet ever conducted. Moreover, the 2021 ''Economics of Biodiversity'' review, published by the UK government, asserts that "biodiversity is declining faster than at any time in human history." According to a 2022 study published in '' Frontiers in Ecology and the Environment'', a survey of more than 3,000 experts says that the extent of the mass extinction might be greater than previously thought, and estimates that roughly 30% of species "have been globally threatened or driven extinct since the year 1500." In a 2022 report, IPBES listed unsustainable fishing,
hunting Hunting is the human activity, human practice of seeking, pursuing, capturing, or killing wildlife or feral animals. The most common reasons for humans to hunt are to harvest food (i.e. meat) and useful animal products (fur/hide (skin), hide, ...
and
logging Logging is the process of cutting, processing, and moving trees to a location for transport. It may include skidding, on-site processing, and loading of trees or logs onto trucks or skeleton cars. Logging is the beginning of a supply cha ...
as being some of the primary drivers of the global extinction crisis.


Attribution

There is widespread consensus among scientists that human activity is accelerating the extinction of many animal species through the destruction of habitats, the consumption of animals as resources, and the elimination of species that humans view as threats or competitors. That humans have become the primary driver of modern extinctions is undeniable, rising extinction trends impacting numerous animal groups including mammals, birds, reptiles, and amphibians have prompted scientists to declare a biodiversity crisis. Text and images are available under
Creative Commons Attribution 4.0 International License


Scientific debate

Characterisation of recent extinction as a mass extinction has been debated among scientists.
Stuart Pimm Stuart Leonard Pimm (born 27 February 1949) is an American-British biologist and theoretical ecologist specializing in scientific research of biodiversity and conservation biology. Education Pimm was born in Derbyshire, United Kingdom. He was e ...
, for example, asserts that the sixth mass extinction "is something that hasn't happened yet – we are on the edge of it." Several studies posit that the earth has entered a sixth mass extinction event, including a 2015 paper by Barnosky et al. and a November 2017 statement titled " World Scientists’ Warning to Humanity: A Second Notice", led by eight authors and signed by 15,364 scientists from 184 countries which asserted that, among other things, "we have unleashed a mass extinction event, the sixth in roughly 540 million years, wherein many current life forms could be extirpated or at least committed to extinction by the end of this century." The
World Wide Fund for Nature The World Wide Fund for Nature Inc. (WWF) is an international non-governmental organization founded in 1961 that works in the field of wilderness preservation and the reduction of human impact on the environment. It was formerly named the W ...
's 2020 ''
Living Planet Report The ''Living Planet Report'' is published every two years by the World Wide Fund for Nature since 1998. It is based on the Living Planet Index and ecological footprint calculations. The ''Living Planet Report'' is the world's leading, science- ...
'' says that
wildlife Wildlife refers to undomesticated animal species, but has come to include all organisms that grow or live wild in an area without being introduced by humans. Wildlife was also synonymous to game: those birds and mammals that were hunted ...
populations have declined by 68% since 1970 as a result of
overconsumption Overconsumption describes a situation where a consumer overuses their available goods and services to where they can't, or don't want to, replenish or reuse them. In microeconomics, this may be described as the point where the marginal cost of ...
,
population growth Population growth is the increase in the number of people in a population or dispersed group. Actual global human population growth amounts to around 83 million annually, or 1.1% per year. The global population has grown from 1 billion in 1800 to ...
and
intensive farming Intensive agriculture, also known as intensive farming (as opposed to extensive farming), conventional, or industrial agriculture, is a type of agriculture, both of crop plants and of animals, with higher levels of input and output per unit of ...
, which is further evidence that humans have unleashed a sixth mass extinction event; however, this finding has been disputed by one 2020 study, which posits that this major decline was primarily driven by a few extreme outlier populations, and that when these outliers are removed, the trend shifts to that of a decline between the 1980s and 2000s, but a roughly positive trend after 2000. A 2021 report in ''Frontiers in Conservation Science'' which cites both of the aforementioned studies, says "population sizes of vertebrate species that have been monitored across years have declined by an average of 68% over the last five decades, with certain population clusters in extreme decline, thus presaging the imminent extinction of their species," and asserts "that we are already on the path of a sixth major extinction is now scientifically undeniable." A January 2022
review article A review article is an article that summarizes the current state of understanding on a topic within a certain discipline. A review article is generally considered a secondary source since it may analyze and discuss the method and conclusions i ...
published in ''Biological Reviews'' builds upon previous studies documenting biodiversity decline to assert that a sixth mass extinction event caused by anthropogenic activity is currently underway. A December 2022 study published in ''
Science Advances ''Science Advances'' is a peer-reviewed multidisciplinary open-access scientific journal established in early 2015 and published by the American Association for the Advancement of Science. The journal's scope includes all areas of science, inclu ...
'' states that "the planet has entered the sixth mass extinction" and warns that current anthropogenic trends, particularly regarding climate and land-use changes, could result in the loss of more than a tenth of plant and animal species by the end of the century. According to the
UNDP The United Nations Development Programme (UNDP)french: Programme des Nations unies pour le développement, PNUD is a United Nations agency tasked with helping countries eliminate poverty and achieve sustainable economic growth and human dev ...
's 2020
Human Development Report The Human Development Report (HDR) is an annual Human Development Index report published by the Human Development Report Office of the United Nations Development Programme (UNDP). The first HDR was launched in 1990 by the Pakistani economist ...
, ''The Next Frontier: Human Development and the Anthropocene'': The 2022 ''Living Planet Report'' found that vertebrate wildlife populations have plummeted by an average of almost 70% since 1970, with
agriculture Agriculture or farming is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled people ...
and
fishing Fishing is the activity of trying to catch fish. Fish are often caught as wildlife from the natural environment, but may also be caught from fish stocking, stocked bodies of water such as fish pond, ponds, canals, park wetlands and reservoirs. ...
being the primary drivers of this decline. Some scientists, including
Rodolfo Dirzo Rodolfo Dirzo is a professor, conservationist, and tropical ecologist. He is a Bing Professor in environmental science at Stanford and a senior fellow at the Stanford Woods Institute for the Environment. His research interests mainly focus on plant ...
and
Paul R. Ehrlich Paul Ralph Ehrlich (born May 29, 1932) is an American biologist known for his warnings about the consequences of population growth and limited resources. He is the Bing Professor Emeritus of Population Studies of the Department of Biology of St ...
, contend that the sixth mass extinction is largely unknown to most people globally, and is also misunderstood by many in the scientific community. They say it is not the disappearance of species, which gets the most attention, that is at the heart of the crisis, but "the existential threat of myriad population extinctions."


Anthropocene

The abundance of species extinctions considered
anthropogenic Anthropogenic ("human" + "generating") is an adjective that may refer to: * Anthropogeny, the study of the origins of humanity Counterintuitively, anthropogenic may also refer to things that have been generated by humans, as follows: * Human i ...
, or due to human activity, has sometimes (especially when referring to hypothesized future events) been collectively called the "Anthropocene extinction". ''Anthropocene'' is a term introduced in 2000. Some now postulate that a new geological epoch has begun, with the most abrupt and widespread extinction of species since the
Cretaceous–Paleogene extinction event The Cretaceous–Paleogene (K–Pg) extinction event (also known as the Cretaceous–Tertiary extinction) was a sudden mass extinction of three-quarters of the plant and animal species on Earth, approximately 66 million years ago. With the ...
66 million years ago. The term "anthropocene" is being used more frequently by scientists, and some commentators may refer to the current and projected future extinctions as part of a longer Holocene extinction. The Holocene–Anthropocene boundary is contested, with some commentators asserting significant human influence on climate for much of what is normally regarded as the
Holocene The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togeth ...
Epoch In chronology and periodization, an epoch or reference epoch is an instant in time chosen as the origin of a particular calendar era. The "epoch" serves as a reference point from which time is measured. The moment of epoch is usually decided ...
. Other commentators place the Holocene–Anthropocene boundary at the
industrial revolution The Industrial Revolution was the transition to new manufacturing processes in Great Britain, continental Europe, and the United States, that occurred during the period from around 1760 to about 1820–1840. This transition included going f ...
and also say that " rmal adoption of this term in the near future will largely depend on its utility, particularly to earth scientists working on late Holocene successions." It has been suggested that human activity has made the period starting from the mid-20th century different enough from the rest of the Holocene to consider it a new geological epoch, known as the
Anthropocene The Anthropocene ( ) is a proposed geological epoch dating from the commencement of significant human impact on Earth's geology and ecosystems, including, but not limited to, anthropogenic climate change. , neither the International Commissio ...
, a term which was considered for inclusion in the timeline of Earth's history by the
International Commission on Stratigraphy The International Commission on Stratigraphy (ICS), sometimes referred to unofficially as the "International Stratigraphic Commission", is a daughter or major subcommittee grade scientific daughter organization that concerns itself with stratigr ...
in 2016. In order to constitute the
Holocene The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togeth ...
as an
extinction event An extinction event (also known as a mass extinction or biotic crisis) is a widespread and rapid decrease in the biodiversity on Earth. Such an event is identified by a sharp change in the diversity and abundance of multicellular organisms. I ...
, scientists must determine exactly when anthropogenic
greenhouse gas emissions Greenhouse gas emissions from human activities strengthen the greenhouse effect, contributing to climate change. Most is carbon dioxide from burning fossil fuels: coal, oil, and natural gas. The largest emitters include coal in China and ...
began to measurably alter natural atmospheric levels on a global scale, and when these alterations caused changes to global climate. Using chemical proxies from Antarctic ice cores, researchers have estimated the fluctuations of
carbon dioxide Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is t ...
(CO2) and
methane Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane ...
(CH4) gases in the Earth's atmosphere during the
late Pleistocene The Late Pleistocene is an unofficial age in the international geologic timescale in chronostratigraphy, also known as Upper Pleistocene from a stratigraphic perspective. It is intended to be the fourth division of the Pleistocene Epoch withi ...
and Holocene epochs. Estimates of the fluctuations of these two gases in the atmosphere, using chemical proxies from Antarctic ice cores, generally indicate that the peak of the Anthropocene occurred within the previous two centuries: typically beginning with the
Industrial Revolution The Industrial Revolution was the transition to new manufacturing processes in Great Britain, continental Europe, and the United States, that occurred during the period from around 1760 to about 1820–1840. This transition included going f ...
, when the highest greenhouse gas levels were recorded.


Human ecology

A 2015 article in ''Science'' suggested that humans are unique in ecology as an unprecedented "global superpredator", regularly preying on large numbers of fully grown terrestrial and marine
apex predators An apex predator, also known as a top predator, is a predator at the top of a food chain, without natural predators of its own. Apex predators are usually defined in terms of trophic dynamics, meaning that they occupy the highest trophic lev ...
, and with a great deal of influence over food webs and climatic systems worldwide. Although significant debate exists as to how much human predation and indirect effects contributed to prehistoric extinctions, certain population crashes have been directly correlated with human arrival. Human activity has been the main cause of mammalian extinctions since the
Late Pleistocene The Late Pleistocene is an unofficial age in the international geologic timescale in chronostratigraphy, also known as Upper Pleistocene from a stratigraphic perspective. It is intended to be the fourth division of the Pleistocene Epoch withi ...
. A 2018 study published in ''
PNAS ''Proceedings of the National Academy of Sciences of the United States of America'' (often abbreviated ''PNAS'' or ''PNAS USA'') is a peer-reviewed multidisciplinary scientific journal. It is the official journal of the National Academy of Scie ...
'' found that since the dawn of human civilization, the
biomass Biomass is plant-based material used as a fuel for heat or electricity production. It can be in the form of wood, wood residues, energy crops, agricultural residues, and waste from industry, farms, and households. Some people use the terms bio ...
of wild mammals has decreased by 83%. The biomass decrease is 80% for marine mammals, 50% for plants and 15% for fish. Currently, livestock make up 60% of the biomass of all mammals on earth, followed by humans (36%) and wild mammals (4%). As for birds, 70% are domesticated, such as poultry, whereas only 30% are wild.


Historic extinction


Human activity


Activities contributing to extinctions

Extinction of animals, plants, and other organisms caused by human actions may go as far back as the late
Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...
, over 12,000 years ago. There is a correlation between megafaunal extinction and the arrival of humans. Over the past 125,000 years, the average body size of wildlife has fallen by 14% as human actions eradicated
megafauna In terrestrial zoology, the megafauna (from Greek μέγας ''megas'' "large" and New Latin ''fauna'' "animal life") comprises the large or giant animals of an area, habitat, or geological period, extinct and/or extant. The most common thresho ...
on all continents with the exception of Africa.
Human civilization A civilization (or civilisation) is any complex society characterized by the development of a state, social stratification, urbanization, and symbolic systems of communication beyond natural spoken language (namely, a writing system). Civi ...
was founded on and grew from
agriculture Agriculture or farming is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled people ...
. The more land used for farming, the greater the population a civilization could sustain, and subsequent popularization of farming led to habitat conversion. Habitat destruction by humans, thus replacing the original local ecosystems, is a major driver of extinction. The sustained conversion of biodiversity rich forests and wetlands into poorer fields and pastures (of lesser carrying capacity for wild species), over the last 10,000 years, has considerably reduced the Earth's carrying capacity for wild birds, among other organisms, in both population size and species count. Other, related human causes of the extinction event include
deforestation Deforestation or forest clearance is the removal of a forest or stand of trees from land that is then converted to non-forest use. Deforestation can involve conversion of forest land to farms, ranches, or urban use. The most concentrated ...
,
hunting Hunting is the human activity, human practice of seeking, pursuing, capturing, or killing wildlife or feral animals. The most common reasons for humans to hunt are to harvest food (i.e. meat) and useful animal products (fur/hide (skin), hide, ...
,
pollution Pollution is the introduction of contaminants into the natural environment that cause adverse change. Pollution can take the form of any substance (solid, liquid, or gas) or energy (such as radioactivity, heat, sound, or light). Pollutants, th ...
, the introduction in various regions of
non-native species An introduced species, alien species, exotic species, adventive species, immigrant species, foreign species, non-indigenous species, or non-native species is a species living outside its native distributional range, but which has arrived there ...
, and the widespread
transmission Transmission may refer to: Medicine, science and technology * Power transmission ** Electric power transmission ** Propulsion transmission, technology allowing controlled application of power *** Automatic transmission *** Manual transmission ** ...
of
infectious disease An infection is the invasion of tissues by pathogens, their multiplication, and the reaction of host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmissible disease or communicable di ...
s spread through livestock and crops.


Agriculture and climate change

Recent investigations into the practice of landscape burning during the
Neolithic Revolution The Neolithic Revolution, or the (First) Agricultural Revolution, was the wide-scale transition of many human cultures during the Neolithic period from a lifestyle of hunting and gathering to one of agriculture and settlement, making an inc ...
has a major implication for the current debate about the timing of the Anthropocene and the role that humans may have played in the production of greenhouse gases prior to the
Industrial Revolution The Industrial Revolution was the transition to new manufacturing processes in Great Britain, continental Europe, and the United States, that occurred during the period from around 1760 to about 1820–1840. This transition included going f ...
. Studies of early hunter-gatherers raise questions about the current use of population size or density as a
proxy Proxy may refer to: * Proxy or agent (law), a substitute authorized to act for another entity or a document which authorizes the agent so to act * Proxy (climate), a measured variable used to infer the value of a variable of interest in climate re ...
for the amount of land clearance and anthropogenic burning that took place in pre-industrial times. Scientists have questioned the correlation between population size and early territorial alterations. Ruddiman and Ellis' research paper in 2009 makes the case that early farmers involved in systems of agriculture used more land per capita than growers later in the Holocene, who intensified their labor to produce more food per unit of area (thus, per laborer); arguing that agricultural involvement in rice production implemented thousands of years ago by relatively small populations have created significant environmental impacts through large-scale means of deforestation. While a number of human-derived factors are recognized as contributing to rising atmospheric concentrations of CH4 (methane) and CO2 (carbon dioxide), deforestation and territorial clearance practices associated with agricultural development may be contributing most to these concentrations globally. Scientists that are employing a variance of
archaeological Archaeology or archeology is the scientific study of human activity through the recovery and analysis of material culture. The archaeological record consists of artifacts, architecture, biofacts or ecofacts, sites, and cultural landscap ...
and paleoecological data argue that the processes contributing to substantial human modification of the environment spanned many thousands of years on a global scale and thus, not originating as late as the
Industrial Revolution The Industrial Revolution was the transition to new manufacturing processes in Great Britain, continental Europe, and the United States, that occurred during the period from around 1760 to about 1820–1840. This transition included going f ...
. Gaining popularity on his uncommon hypothesis, palaeoclimatologist
William Ruddiman William F. Ruddiman is a palaeoclimatologist and Professor Emeritus at the University of Virginia. Ruddiman earned an undergraduate degree in geology in 1964 at Williams College, and a Ph.D. in marine geology from Columbia University in 1969. Ru ...
in 2003, has argued that in the early Holocene 11,000 years ago, atmospheric carbon dioxide and methane levels fluctuated in a pattern which was different from the
Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...
epoch before it. He argued that the patterns of the significant decline of CO2 levels during the last ice age of the Pleistocene inversely correlates to the Holocene where there have been dramatic increases of CO2 around 8000 years ago and CH4 levels 3000 years after that. The correlation between the decrease of CO2 in the
Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...
and the increase of it during the
Holocene The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togeth ...
implies that the causation of this spark of greenhouse gases into the atmosphere was the growth of human agriculture during the Holocene such as the anthropogenic expansion of (human) land use and
irrigation Irrigation (also referred to as watering) is the practice of applying controlled amounts of water to land to help grow crops, landscape plants, and lawns. Irrigation has been a key aspect of agriculture for over 5,000 years and has been devel ...
.


Climate change

One of the main theories for the extinction's cause is historic climate change. The climate change theory has suggested that a change in climate near the end of the late Pleistocene stressed the megafauna to the point of extinction. Some scientists favor abrupt climate change as the catalyst for the extinction of the mega-fauna at the end of the Pleistocene, but there are many who believe increased hunting from early modern humans also played a part, with others even suggesting that the two interacted. However, the annual mean temperature of the current
interglacial period An interglacial period (or alternatively interglacial, interglaciation) is a geological interval of warmer global average temperature lasting thousands of years that separates consecutive glacial periods within an ice age. The current Holocene in ...
for the last 10,000 years is no higher than that of previous interglacial periods, yet some of the same megafauna survived similar temperature increases. In the Americas, a controversial explanation for the shift in climate is presented under the Younger Dryas impact hypothesis, which states that the impact of comets cooled global temperatures. A 2020 study published in ''
Science Advances ''Science Advances'' is a peer-reviewed multidisciplinary open-access scientific journal established in early 2015 and published by the American Association for the Advancement of Science. The journal's scope includes all areas of science, inclu ...
'' found that human population size and/or specific human activities, not climate change, caused rapidly rising global mammal extinction rates during the past 126,000 years. Around 96% of all mammalian extinctions over this time period are attributable to human impacts. According to Tobias Andermann, lead author of the study, "these extinctions did not happen continuously and at constant pace. Instead, bursts of extinctions are detected across different continents at times when humans first reached them. More recently, the magnitude of human driven extinctions has picked up the pace again, this time on a global scale."


Megafaunal extinction

Megafauna play a significant role in the lateral transport of mineral nutrients in an ecosystem, tending to translocate them from areas of high to those of lower abundance. They do so by their movement between the time they consume the nutrient and the time they release it through elimination (or, to a much lesser extent, through decomposition after death). In South America's
Amazon Basin The Amazon basin is the part of South America drained by the Amazon River and its tributaries. The Amazon drainage basin covers an area of about , or about 35.5 percent of the South American continent. It is located in the countries of Boli ...
, it is estimated that such lateral diffusion was reduced over 98% following the megafaunal extinctions that occurred roughly 12,500 years ago. Given that
phosphorus Phosphorus is a chemical element with the symbol P and atomic number 15. Elemental phosphorus exists in two major forms, white phosphorus and red phosphorus, but because it is highly reactive, phosphorus is never found as a free element on Ea ...
availability is thought to limit productivity in much of the region, the decrease in its transport from the western part of the basin and from floodplains (both of which derive their supply from the uplift of the
Andes The Andes, Andes Mountains or Andean Mountains (; ) are the longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range is long, wide (widest between 18°S – 20°S ...
) to other areas is thought to have significantly impacted the region's ecology, and the effects may not yet have reached their limits. The extinction of the
mammoth A mammoth is any species of the extinct elephantid genus ''Mammuthus'', one of the many genera that make up the order of trunked mammals called proboscideans. The various species of mammoth were commonly equipped with long, curved tusks an ...
s allowed
grasslands A grassland is an area where the vegetation is dominated by grasses ( Poaceae). However, sedge (Cyperaceae) and rush ( Juncaceae) can also be found along with variable proportions of legumes, like clover, and other herbs. Grasslands occur nat ...
they had maintained through grazing habits to become birch forests. The new forest and the resulting forest fires may have induced
climate change In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to ...
. Such disappearances might be the result of the proliferation of
modern human Early modern human (EMH) or anatomically modern human (AMH) are terms used to distinguish ''Homo sapiens'' (the only extant Hominina species) that are anatomically consistent with the range of phenotypes seen in contemporary humans from extin ...
s; some recent studies favor this theory. Large populations of megaherbivores have the potential to contribute greatly to the atmospheric concentration of
methane Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane ...
, which is an important
greenhouse gas A greenhouse gas (GHG or GhG) is a gas that absorbs and emits radiant energy within the thermal infrared range, causing the greenhouse effect. The primary greenhouse gases in Earth's atmosphere are water vapor (), carbon dioxide (), methane ...
. Modern
ruminant Ruminants (suborder Ruminantia) are hoofed herbivorous grazing or browsing mammals that are able to acquire nutrients from plant-based food by fermenting it in a specialized stomach prior to digestion, principally through microbial actions. The ...
herbivores A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpart ...
produce methane as a byproduct of
foregut fermentation Foregut fermentation is a form of digestion that occurs in the foregut of some animals. It has evolved independently in several groups of mammals, and also in the hoatzin bird. Foregut fermentation is employed by ruminants and pseudoruminants, so ...
in digestion, and release it through belching or flatulence. Today, around 20% of annual
methane emissions Increasing methane emissions are a major contributor to the rising concentration of greenhouse gases in Earth's atmosphere, and are responsible for up to one-third of near-term global heating. During 2019, about 60% (360 million tons) of methane r ...
come from livestock methane release. In the
Mesozoic The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretace ...
, it has been estimated that
sauropod Sauropoda (), whose members are known as sauropods (; from '' sauro-'' + '' -pod'', ' lizard-footed'), is a clade of saurischian ('lizard-hipped') dinosaurs. Sauropods had very long necks, long tails, small heads (relative to the rest of their ...
s could have emitted 520 million tons of methane to the atmosphere annually, contributing to the warmer climate of the time (up to 10 °C warmer than at present). This large emission follows from the enormous estimated biomass of sauropods, and because methane production of individual herbivores is believed to be almost proportional to their mass. Recent studies have indicated that the extinction of megafaunal herbivores may have caused a reduction in
atmospheric methane Atmospheric methane is the methane present in Earth's atmosphere. Atmospheric methane concentrations are of interest because it is one of the most potent greenhouse gases in Earth's atmosphere. Atmospheric methane is rising. The 20-year globa ...
. This hypothesis is relatively new. One study examined the methane emissions from the
bison Bison are large bovines in the genus ''Bison'' (Greek: "wild ox" (bison)) within the tribe Bovini. Two extant and numerous extinct species are recognised. Of the two surviving species, the American bison, ''B. bison'', found only in North A ...
that occupied the
Great Plains The Great Plains (french: Grandes Plaines), sometimes simply "the Plains", is a broad expanse of flatland in North America. It is located west of the Mississippi River and east of the Rocky Mountains, much of it covered in prairie, steppe, a ...
of North America before contact with European settlers. The study estimated that the removal of the bison caused a decrease of as much as 2.2 million tons per year. Another study examined the change in the methane concentration in the atmosphere at the end of the
Pleistocene epoch The Pleistocene ( , often referred to as the '' Ice age'') is the geological epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was finally confirmed i ...
after the extinction of megafauna in the Americas. After early humans migrated to the Americas about 13,000 BP, their hunting and other associated ecological impacts led to the extinction of many megafaunal species there. Calculations suggest that this extinction decreased methane production by about 9.6 million tons per year. This suggests that the absence of megafaunal methane emissions may have contributed to the abrupt climatic cooling at the onset of the
Younger Dryas The Younger Dryas (c. 12,900 to 11,700 years BP) was a return to glacial conditions which temporarily reversed the gradual climatic warming after the Last Glacial Maximum (LGM, c. 27,000 to 20,000 years BP). The Younger Dryas was the last stag ...
. The decrease in atmospheric methane that occurred at that time, as recorded in
ice core An ice core is a core sample that is typically removed from an ice sheet or a high mountain glacier. Since the ice forms from the incremental buildup of annual layers of snow, lower layers are older than upper ones, and an ice core contains ...
s, was 2–4 times more rapid than any other decrease in the last half million years, suggesting that an unusual mechanism was at work.


Disease

The hyperdisease hypothesis, proposed by Ross MacPhee in 1997, states that the megafaunal die-off was due to an indirect transmission of diseases by newly arriving humans. According to MacPhee, aboriginals or animals travelling with them, such as
domestic dog The dog (''Canis familiaris'' or ''Canis lupus familiaris'') is a domesticated descendant of the wolf. Also called the domestic dog, it is Domestication of the dog, derived from the extinct Pleistocene wolf, and the modern wolf is the dog's n ...
s or livestock, introduced one or more highly virulent diseases into new environments whose native population had no immunity to them, eventually leading to their extinction.
K-selection In ecology, ''r''/''K'' selection theory relates to the selection of combinations of traits in an organism that trade off between quantity and quality of offspring. The focus on either an increased quantity of offspring at the expense of individ ...
animals, such as the now-extinct megafauna, are especially vulnerable to diseases, as opposed to
r-selection In ecology, ''r''/''K'' selection theory relates to the selection of combinations of traits in an organism that trade off between quantity and quality of offspring. The focus on either an increased quantity of offspring at the expense of individ ...
animals who have a shorter
gestation period In mammals, pregnancy is the period of reproduction during which a female carries one or more live offspring from implantation in the uterus through gestation. It begins when a fertilized zygote implants in the female's uterus, and ends once ...
and a higher population size. Humans are thought to be the sole cause as other earlier migrations of animals into North America from Eurasia did not cause extinctions. There are many problems with this theory, as this disease would have to meet several criteria: it has to be able to sustain itself in an environment with no
hosts A host is a person responsible for guests at an event or for providing hospitality during it. Host may also refer to: Places * Host, Pennsylvania, a village in Berks County People *Jim Host (born 1937), American businessman *Michel Host ...
; it has to have a high infection rate; and be extremely lethal, with a
mortality rate Mortality rate, or death rate, is a measure of the number of deaths (in general, or due to a specific cause) in a particular population, scaled to the size of that population, per unit of time. Mortality rate is typically expressed in units of d ...
of 50–75%. Disease has to be very virulent to kill off all the individuals in a
species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriat ...
, and even such a virulent disease as
West Nile fever West Nile fever is an infection by the West Nile virus, which is typically spread by mosquitoes. In about 80% of infections people have few or no symptoms. About 20% of people develop a fever, headache, vomiting, or a rash. In less than 1% of ...
is unlikely to have caused extinction. However, diseases have been the cause for some extinctions. The introduction of
avian malaria Avian malaria is a parasitic disease of birds, caused by parasite species belonging to the genera '' Plasmodium'' and '' Hemoproteus'' (phylum Apicomplexa, class Haemosporidia, family Plasmoiidae). The disease is transmitted by a dipteran vecto ...
and
avipoxvirus ''Avipoxvirus'' (avian pox) is a genus of viruses within the family ''Poxviridae''. ''Poxviridae'' is the family of viruses which cause the afflicted organism to have poxes as a symptom. Poxviruses have generally large genomes, and other such ex ...
, for example, have had a negative impact on the
endemic birds of Hawaii There are 71 known taxa of birds endemic to the Hawaiian Islands, of which 30 are extinct, 6 possibly extinct and 30 of the remaining 48 species and subspecies are listed as endangered or threatened by the United States Fish and Wildlife Service. ...
.


Contemporary extinction


History

Contemporary
human overpopulation Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, cultu ...
and continued
population growth Population growth is the increase in the number of people in a population or dispersed group. Actual global human population growth amounts to around 83 million annually, or 1.1% per year. The global population has grown from 1 billion in 1800 to ...
, along with per-capita
consumption Consumption may refer to: *Resource consumption *Tuberculosis, an infectious disease, historically * Consumption (ecology), receipt of energy by consuming other organisms * Consumption (economics), the purchasing of newly produced goods for curren ...
growth, prominently in the past two centuries, are regarded as the underlying causes of extinction. The loss of animal species from ecological communities,
defaunation Defaunation is the global, local or functional extinction of animal populations or species from ecological communities. The growth of the human population, combined with advances in harvesting technologies, has led to more intense and efficient ...
, is primarily driven by human activity. This has resulted in
empty forest Empty forest is a term coined by Kent H. Redford's article "The Empty Forest" (1992), which was published in ''BioScience''. An "empty forest" refers to an ecosystem that is void of large mammals. Empty forests are characterized by an otherwise e ...
s, ecological communities depleted of large vertebrates. This is not to be confused with extinction, as it includes both the disappearance of species and declines in abundance. Defaunation effects were first implied at the Symposium of Plant-Animal Interactions at the University of Campinas, Brazil in 1988 in the context of Neotropical forests. Since then, the term has gained broader usage in conservation biology as a global phenomenon. Some scholars assert that the emergence of
capitalism Capitalism is an economic system based on the private ownership of the means of production and their operation for profit. Central characteristics of capitalism include capital accumulation, competitive markets, price system, private ...
as the dominant economic system has accelerated ecological exploitation and destruction, and has also exacerbated mass species extinction.
CUNY The City University of New York ( CUNY; , ) is the public university system of New York City. It is the largest urban university system in the United States, comprising 25 campuses: eleven senior colleges, seven community colleges and seven prof ...
professor
David Harvey David W. Harvey (born 31 October 1935) is a British-born Marxist economic geographer, podcaster and Distinguished Professor of anthropology and geography at the Graduate Center of the City University of New York (CUNY). He received his P ...
, for example, posits that the
neoliberal Neoliberalism (also neo-liberalism) is a term used to signify the late 20th century political reappearance of 19th-century ideas associated with free-market capitalism after it fell into decline following the Second World War. A prominent f ...
era "happens to be the era of the fastest mass extinction of species in the Earth's recent history". Major lobbying organizations representing corporations in the agriculture, fisheries, forestry and paper, mining, and oil and gas industries, including the
United States Chamber of Commerce The United States Chamber of Commerce (USCC) is the largest lobbying group in the United States, representing over three million businesses and organizations. The group was founded in April 1912 out of local chambers of commerce at the urgin ...
, have been pushing back against legislation that could address the extinction crisis. A 2022 report by the climate think tank InfluenceMap stated that "although industry associations, especially in the US, appear reluctant to discuss the biodiversity crisis, they are clearly engaged on a wide range of policies with significant impacts on biodiversity loss."
Big cat The term "big cat" is typically used to refer to any of the five living members of the genus ''Panthera'', namely the tiger, lion, jaguar, leopard, and snow leopard. Despite enormous differences in size, various cat species are quite similar ...
populations have severely declined over the last half-century and could face extinction in the following decades. According to 2011
IUCN The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...
estimates:
lions The lion (''Panthera leo'') is a large cat of the genus '' Panthera'' native to Africa and India. It has a muscular, broad-chested body; short, rounded head; round ears; and a hairy tuft at the end of its tail. It is sexually dimorphic; ad ...
are down to 25,000, from 450,000;
leopards The leopard (''Panthera pardus'') is one of the five extant species in the genus ''Panthera'', a member of the cat family, Felidae. It occurs in a wide range in sub-Saharan Africa, in some parts of Western and Central Asia, Southern Russia, a ...
are down to 50,000, from 750,000;
cheetahs The cheetah (''Acinonyx jubatus'') is a large cat native to Africa and central Iran. It is the fastest land animal, estimated to be capable of running at with the fastest reliably recorded speeds being , and as such has evolved specialized ...
are down to 12,000, from 45,000;
tigers The tiger (''Panthera tigris'') is the largest living cat species and a member of the genus ''Panthera''. It is most recognisable for its dark vertical stripes on orange fur with a white underside. An apex predator, it primarily preys on un ...
are down to 3,000 in the wild, from 50,000. A December 2016 study by the Zoological Society of London,
Panthera Corporation Panthera Corporation, or Panthera, is a charitable organization devoted to preserving wild cats and their ecosystems around the globe. Founded in 2006, Panthera is devoted to the conservation of the world’s 40 species of wild cats and the vast ec ...
and
Wildlife Conservation Society The Wildlife Conservation Society (WCS) is a non-governmental organization headquartered at the Bronx Zoo in New York City, that aims to conserve the world's largest wild places in 14 priority regions. Founded in 1895 as the New York Zoological ...
showed that cheetahs are far closer to extinction than previously thought, with only 7,100 remaining in the wild, existing within only 9% of their historic range. Human pressures are to blame for the cheetah population crash, including prey loss due to overhunting by people, retaliatory killing from farmers, habitat loss and the illegal wildlife trade. The term
pollinator decline Pollinator decline is the reduction in abundance of insect and other animal pollinators in many ecosystems worldwide that began being recorded at the end of the 20th century. Multiple lines of evidence exist for the reduction of wild pollinato ...
refers to the reduction in abundance of insect and other animal pollinators in many ecosystems worldwide beginning at the end of the twentieth century, and continuing into the present day. Pollinators, which are necessary for 75% of food crops, are declining globally in both abundance and diversity. A 2017 study led by Radboud University's Hans de Kroon indicated that the biomass of insect life in Germany had declined by three-quarters in the previous 25 years. Participating researcher Dave Goulson of
Sussex University , mottoeng = Be Still and Know , established = , type = Public research university , endowment = £14.4 million (2020) , budget = £319.6 million (2019–20) , chancellor = Sanjeev Bhaskar , vice_chancellor = Sasha Roseneil , ...
stated that their study suggested that humans are making large parts of the planet uninhabitable for wildlife. Goulson characterized the situation as an approaching "ecological Armageddon", adding that "if we lose the insects then everything is going to collapse." A 2019 study found that over 40% of insect species are threatened with extinction. The most significant drivers in the decline of insect populations are associated with
intensive farming Intensive agriculture, also known as intensive farming (as opposed to extensive farming), conventional, or industrial agriculture, is a type of agriculture, both of crop plants and of animals, with higher levels of input and output per unit of ...
practices, along with pesticide use and climate change. The world's insect population decreases by around 1 to 2 per cent per year. Various species are predicted to become extinct in the near future, among them the
rhinoceros A rhinoceros (; ; ), commonly abbreviated to rhino, is a member of any of the five extant species (or numerous extinct species) of odd-toed ungulates in the family Rhinocerotidae. (It can also refer to a member of any of the extinct specie ...
, nonhuman
primates Primates are a diverse order of mammals. They are divided into the strepsirrhines, which include the lemurs, galagos, and lorisids, and the haplorhines, which include the tarsiers and the simians ( monkeys and apes, the latter including ...
,
pangolins Pangolins, sometimes known as scaly anteaters, are mammals of the order Pholidota (, from Ancient Greek ϕολιδωτός – "clad in scales"). The one extant family, the Manidae, has three genera: ''Manis'', ''Phataginus'', and ''Smutsia'' ...
, and
giraffes The giraffe is a large African hoofed mammal belonging to the genus ''Giraffa''. It is the tallest living terrestrial animal and the largest ruminant on Earth. Traditionally, giraffes were thought to be one species, '' Giraffa camelopardal ...
.
Hunting Hunting is the human activity, human practice of seeking, pursuing, capturing, or killing wildlife or feral animals. The most common reasons for humans to hunt are to harvest food (i.e. meat) and useful animal products (fur/hide (skin), hide, ...
alone threatens bird and mammalian populations around the world. The direct killing of
megafauna In terrestrial zoology, the megafauna (from Greek μέγας ''megas'' "large" and New Latin ''fauna'' "animal life") comprises the large or giant animals of an area, habitat, or geological period, extinct and/or extant. The most common thresho ...
for meat and body parts is the primary driver of their destruction, with 70% of the 362 megafauna species in decline as of 2019. Mammals in particular have suffered such severe losses as the result of human activity that it could take several million years for them to recover. Contemporary assessments have discovered that roughly 41% of amphibians, 25% of mammals, 21% of reptiles and 14% of birds are threatened with extinction, which could disrupt ecosystems on a global scale and eliminate billions of years of
phylogenetic diversity Phylogenetic diversity is a measure of biodiversity which incorporates phylogenetic difference between species. It is defined and calculated as "the sum of the lengths of all those branches that are members of the corresponding minimum spanning pa ...
. 189 countries, which are signatory to the
Convention on Biological Diversity The Convention on Biological Diversity (CBD), known informally as the Biodiversity Convention, is a multilateral treaty. The Convention has three main goals: the conservation of biological diversity (or biodiversity); the sustainable use of its ...
(Rio Accord), have committed to preparing a Biodiversity Action Plan, a first step at identifying specific
endangered species An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and inv ...
and habitats, country by country.


Recent extinction

Recent extinctions are more directly attributable to human influences, whereas prehistoric extinctions can be attributed to other factors, such as global climate change. The
International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...
(IUCN) characterises 'recent' extinction as those that have occurred past the cut-off point of 1500, and at least 875 plant and animal species have gone extinct since that time and 2009. Some species, such as the
Père David's deer The Père David's deer (''Elaphurus davidianus''), also known as the ''milu'' () or elaphure, is a species of deer native to the subtropical river valleys of China. It grazes mainly on grass and aquatic plants. It is the only extant member of ...
and the
Hawaiian crow The Hawaiian crow or alalā (''Corvus hawaiiensis'') is a species of bird in the crow family, Corvidae, that is currently extinct in the wild, though reintroduction programs are underway. It is about the size of the carrion crow at in length, bu ...
, are extinct in the wild, and survive solely in captive populations. Other populations are only
locally extinct Local extinction, also known as extirpation, refers to a species (or other taxon) of plant or animal that ceases to exist in a chosen geographic area of study, though it still exists elsewhere. Local extinctions are contrasted with global extinct ...
(extirpated), still existent elsewhere, but reduced in distribution, as with the extinction of
gray whale The gray whale (''Eschrichtius robustus''), also known as the grey whale,Britannica Micro.: v. IV, p. 693. gray back whale, Pacific gray whale, Korean gray whale, or California gray whale, is a baleen whale that migrates between feeding and bre ...
s in the
Atlantic The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe ...
, and of the
leatherback sea turtle The leatherback sea turtle (''Dermochelys coriacea''), sometimes called the lute turtle or leathery turtle or simply the luth, is the largest of all living turtles and the heaviest non-crocodilian reptile, reaching lengths of up to and weight ...
in Malaysia. Humans are rapidly driving the largest vertebrate animals towards extinction, and in the process interrupting a 66-million-year-old feature of ecosystems, the relationship between diet and body mass, which researchers suggest could have unpredictable consequences. A 2019 study published in ''
Nature Communications ''Nature Communications'' is a peer-reviewed, open access, scientific journal published by Nature Portfolio since 2010. It is a multidisciplinary journal and it covers the natural sciences, including physics, chemistry, earth sciences, medic ...
'' found that rapid biodiversity loss is impacting larger mammals and birds to a much greater extent than smaller ones, with the body mass of such animals expected to shrink by 25% over the next century. Another 2019 study published in ''
Biology Letters ''Biology Letters'' is a peer-reviewed, biological, scientific journal published by the Royal Society. It focuses on the rapid publication of short high quality research articles, reviews and opinion pieces across the biological sciences. ''Biolog ...
'' found that extinction rates are perhaps much higher than previously estimated, in particular for bird species. The 2019 ''
Global Assessment Report on Biodiversity and Ecosystem Services Global means of or referring to a globe and may also refer to: Entertainment * ''Global'' (Paul van Dyk album), 2003 * ''Global'' (Bunji Garlin album), 2007 * ''Global'' (Humanoid album), 1989 * ''Global'' (Todd Rundgren album), 2015 * Bruno ...
'' lists the primary causes of contemporary extinctions in descending order: (1) changes in land and sea use (primarily agriculture and overfishing respectively); (2) direct exploitation of organisms such as hunting; (3) anthropogenic climate change; (4) pollution and (5) invasive alien species spread by human trade. This report, along with the 2020 ''
Living Planet Report The ''Living Planet Report'' is published every two years by the World Wide Fund for Nature since 1998. It is based on the Living Planet Index and ecological footprint calculations. The ''Living Planet Report'' is the world's leading, science- ...
'' by the WWF, both project that climate change will be the leading cause in the next several decades. A June 2020 study published in ''
PNAS ''Proceedings of the National Academy of Sciences of the United States of America'' (often abbreviated ''PNAS'' or ''PNAS USA'') is a peer-reviewed multidisciplinary scientific journal. It is the official journal of the National Academy of Scie ...
'' posits that the contemporary extinction crisis "may be the most serious environmental threat to the persistence of civilization, because it is irreversible" and that its acceleration "is certain because of the still fast growth in human numbers and consumption rates." The study found that more than 500
vertebrate Vertebrates () comprise all animal taxa within the subphylum Vertebrata () ( chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, with ...
species are poised to be lost in the next two decades.


Habitat destruction

Humans both create and destroy crop cultivar and
domesticated animal This page gives a list of domesticated animals, also including a list of domestication of animals, animals which are or may be currently undergoing the process of domestication and animals that have an extensive relationship with humans beyond simp ...
varieties. Advances in transportation and
industrial farming Industrial agriculture is a form of modern farming that refers to the industrialized production of crops and animals and animal products like eggs or milk. The methods of industrial agriculture include innovation in agricultural machinery and far ...
has led to
monoculture In agriculture, monoculture is the practice of growing one crop species in a field at a time. Monoculture is widely used in intensive farming and in organic farming: both a 1,000-hectare/acre cornfield and a 10-ha/acre field of organic kale are ...
and the extinction of many cultivars. The use of certain plants and animals for food has also resulted in their extinction, including
silphium Silphium (also known as ''silphion'', ''laserwort'', or ''laser'') is an unidentified plant that was used in classical antiquity as a seasoning, perfume, aphrodisiac, and medicine. It also was used as a contraceptive by ancient Greeks and Romans ...
and the
passenger pigeon The passenger pigeon or wild pigeon (''Ectopistes migratorius'') is an extinct species of pigeon that was endemic to North America. Its common name is derived from the French word ''passager'', meaning "passing by", due to the migratory habits ...
. It was estimated in 2012 that 13 percent of Earth's ice-free land surface is used as row-crop agricultural sites, 26 percent used as pastures, and 4 percent urban-industrial areas. In March 2019, ''
Nature Climate Change ''Nature Climate Change'' is a monthly peer-reviewed scientific journal published by Nature Publishing Group covering all aspects of research on global warming, the current climate change, especially its effects. It was established in 2011 as the ...
'' published a study by ecologists from
Yale University Yale University is a private research university in New Haven, Connecticut. Established in 1701 as the Collegiate School, it is the third-oldest institution of higher education in the United States and among the most prestigious in the w ...
, who found that over the next half century, human land use will reduce the habitats of 1,700 species by up to 50%, pushing them closer to extinction. That same month ''
PLOS Biology ''PLOS Biology'' is a monthly peer-reviewed scientific journal covering all aspects of biology. Publication began on October 13, 2003. It is the first journal published by the Public Library of Science. The editor-in-chief is Nonia Pariente. In a ...
'' published a similar study drawing on work at the
University of Queensland , mottoeng = By means of knowledge and hard work , established = , endowment = A$224.3 million , budget = A$2.1 billion , type = Public research university , chancellor = Peter Varghese , vice_chancellor = Deborah Terry , city = B ...
, which found that "more than 1,200 species globally face threats to their survival in more than 90% of their habitat and will almost certainly face extinction without conservation intervention". Since 1970, the populations of migratory freshwater fish have declined by 76%, according to research published by the
Zoological Society of London The Zoological Society of London (ZSL) is a charity devoted to the worldwide conservation of animals and their habitats. It was founded in 1826. Since 1828, it has maintained the London Zoo, and since 1931 Whipsnade Park. History On 29 ...
in July 2020. Overall, around one in three freshwater fish species are threatened with extinction due to human-driven habitat degradation and overfishing. Some scientists and academics assert that
industrial agriculture Industrial agriculture is a form of modern farming that refers to the industrialized production of crops and animals and animal products like eggs or milk. The methods of industrial agriculture include innovation in agricultural machinery and fa ...
and the growing demand for
meat Meat is animal flesh that is eaten as food. Humans have hunted, farmed, and scavenged animals for meat since prehistoric times. The establishment of settlements in the Neolithic Revolution allowed the domestication of animals such as chic ...
is contributing to significant global
biodiversity loss Biodiversity loss includes the worldwide extinction of different species, as well as the local reduction or loss of species in a certain habitat, resulting in a loss of biological diversity. The latter phenomenon can be temporary or permanent, de ...
as this is a significant driver of
deforestation Deforestation or forest clearance is the removal of a forest or stand of trees from land that is then converted to non-forest use. Deforestation can involve conversion of forest land to farms, ranches, or urban use. The most concentrated ...
and habitat destruction; species-rich habitats, such as the
Amazon region The Amazon basin is the part of South America drained by the Amazon River and its tributaries. The Amazon drainage basin covers an area of about , or about 35.5 percent of the South American continent. It is located in the countries of Bolivi ...
and
Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Gui ...
being converted to agriculture. A 2017 study by the
World Wildlife Fund The World Wide Fund for Nature Inc. (WWF) is an international non-governmental organization founded in 1961 that works in the field of wilderness preservation and the reduction of human impact on the environment. It was formerly named the W ...
(WWF) found that 60% of biodiversity loss can be attributed to the vast scale of feed crop cultivation required to rear tens of billions of farm animals. Moreover, a 2006 report by the
Food and Agriculture Organization The Food and Agriculture Organization of the United Nations (FAO)french: link=no, Organisation des Nations unies pour l'alimentation et l'agriculture; it, Organizzazione delle Nazioni Unite per l'Alimentazione e l'Agricoltura is an intern ...
(FAO) of the
United Nations The United Nations (UN) is an intergovernmental organization whose stated purposes are to maintain international peace and security, develop friendly relations among nations, achieve international cooperation, and be a centre for harmoni ...
, ''
Livestock's Long Shadow ''Livestock's Long Shadow: Environmental Issues and Options'' is a United Nations report, released by the Food and Agriculture Organization (FAO) of the United Nations on 29 November 2006, that "aims to assess the full impact of the livestock s ...
'', also found that the livestock sector is a "leading player" in biodiversity loss. More recently, in 2019, the
IPBES The Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) is an intergovernmental organization established to improve the interface between science and policy on issues of biodiversity and ecosystem services. It ...
''
Global Assessment Report on Biodiversity and Ecosystem Services Global means of or referring to a globe and may also refer to: Entertainment * ''Global'' (Paul van Dyk album), 2003 * ''Global'' (Bunji Garlin album), 2007 * ''Global'' (Humanoid album), 1989 * ''Global'' (Todd Rundgren album), 2015 * Bruno ...
'' attributed much of this ecological destruction to agriculture and fishing, with the meat and dairy industries having a very significant impact. Since the 1970s food production has soared in order to feed a growing human population and bolster
economic growth Economic growth can be defined as the increase or improvement in the inflation-adjusted market value of the goods and services produced by an economy in a financial year. Statisticians conventionally measure such growth as the percent rate o ...
, but at a huge price to the environment and other species. The report says some 25% of the earth's ice-free land is used for cattle grazing. A 2020 study published in ''
Nature Communications ''Nature Communications'' is a peer-reviewed, open access, scientific journal published by Nature Portfolio since 2010. It is a multidisciplinary journal and it covers the natural sciences, including physics, chemistry, earth sciences, medic ...
'' warned that human impacts from housing, industrial agriculture and in particular meat consumption are wiping out a combined 50 billion years of earth's evolutionary history (defined as phylogenetic diversity) and driving to extinction some of the "most unique animals on the planet," among them the
Aye-aye The aye-aye (''Daubentonia madagascariensis'') is a long-fingered lemur, a strepsirrhine primate native to Madagascar with rodent-like teeth that perpetually grow and a special thin middle finger. It is the world's largest nocturnal primate. ...
lemur, the
Chinese crocodile lizard The Chinese crocodile lizard (''Shinisaurus crocodilurus'') is a semiaquatic anguimorph lizard found only in cool forests in southeast China and northeast Vietnam. The Chinese crocodile lizard spends much of its time in shallow water or in over ...
and the
pangolin Pangolins, sometimes known as scaly anteaters, are mammals of the order Pholidota (, from Ancient Greek ϕολιδωτός – "clad in scales"). The one extant family, the Manidae, has three genera: '' Manis'', ''Phataginus'', and '' Smuts ...
. Said lead author Rikki Gumbs:


Climate change

Climate change In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to ...
is expected to be a major driver of extinctions from the 21st century. Rising levels of carbon dioxide are resulting in influx of this gas into the ocean, increasing its acidity. Marine organisms which possess calcium carbonate shells or
exoskeleton An exoskeleton (from Greek ''éxō'' "outer" and ''skeletós'' "skeleton") is an external skeleton that supports and protects an animal's body, in contrast to an internal skeleton ( endoskeleton) in for example, a human. In usage, some of the ...
s experience physiological pressure as the carbonate reacts with acid. For example, this is already resulting in
coral bleaching Coral bleaching is the process when corals become white due to various stressors, such as changes in temperature, light, or nutrients. Bleaching occurs when coral polyps expel the zooxanthellae ( dinoflagellates that are commonly referred to as ...
on various
coral reef A coral reef is an underwater ecosystem characterized by reef-building corals. Reefs are formed of Colony (biology), colonies of coral polyp (zoology), polyps held together by calcium carbonate. Most coral reefs are built from stony corals, wh ...
s worldwide, which provide valuable habitat and maintain a high biodiversity. Marine
gastropod The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, from freshwater, and from land. T ...
s,
bivalve Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class (biology), class of marine and freshwater Mollusca, molluscs that have laterally compressed bodies enclosed by a shell consisting of two hing ...
s and other invertebrates are also affected, as are the organisms that feed on them. Some studies have suggested that it is not climate change that is driving the current extinction crisis, but the demands of contemporary human civilization on nature.


Overexploitation

Overhunting can reduce the local population of game animals by more than half, as well as reducing population density, and may lead to extinction for some species. Populations located nearer to villages are significantly more at risk of depletion. Several conservationist organizations, among them
IFAW Ifo is a town in south-western Nigeria near Lagos. Transport It is served by a junction station on the national railway network. See also * Railway stations in Nigeria Railway stations in Nigeria include: Maps UN MapUNHCR A ...
and
HSUS The Humane Society of the United States (HSUS) is an American nonprofit organization that focuses on animal welfare and opposes animal-related cruelties of national scope. It uses strategies that are beyond the abilities of local organizations. ...
, assert that trophy hunters, particularly from the United States, are playing a significant role in the decline of giraffes, which they refer to as a "silent extinction". The surge in the mass killings by
poachers Poaching has been defined as the illegal hunting or capturing of wild animals, usually associated with land use rights. Poaching was once performed by impoverished peasants for subsistence purposes and to supplement meager diets. It was set a ...
involved in the illegal ivory trade along with habitat loss is threatening African elephant populations. In 1979, their populations stood at 1.7 million; at present there are fewer than 400,000 remaining. Prior to European colonization, scientists believe Africa was home to roughly 20 million elephants. According to the Great Elephant Census, 30% of African elephants (or 144,000 individuals) disappeared over a seven-year period, 2007 to 2014. African elephants could become extinct by 2035 if poaching rates continue. Fishing has had a devastating effect on marine organism populations for several centuries even before the explosion of destructive and highly effective fishing practices like
trawling Trawling is a method of fishing that involves pulling a fishing net through the water behind one or more boats. The net used for trawling is called a trawl. This principle requires netting bags which are towed through water to catch different spec ...
. Humans are unique among predators in that they regularly prey on other adult
apex predator An apex predator, also known as a top predator, is a predator at the top of a food chain, without natural predators of its own. Apex predators are usually defined in terms of trophic dynamics, meaning that they occupy the highest trophic lev ...
s, particularly in marine environments;
bluefin tuna Bluefin tuna is a common name used to refer to several species of tuna A tuna is a saltwater fish that belongs to the tribe Thunnini, a subgrouping of the Scombridae (mackerel) family. The Thunnini comprise 15 species across five genera, th ...
,
blue whales The blue whale (''Balaenoptera musculus'') is a marine mammal and a baleen whale. Reaching a maximum confirmed length of and weighing up to , it is the largest animal known to have ever existed. The blue whale's long and slender body can b ...
,
North Atlantic right whale The North Atlantic right whale (''Eubalaena glacialis'') is a baleen whale, one of three right whale species belonging to the genus '' Eubalaena'', all of which were formerly classified as a single species. Because of their docile nature, their s ...
s and over fifty species of
shark Sharks are a group of elasmobranch fish characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified within the clade Selachi ...
s and
ray Ray may refer to: Fish * Ray (fish), any cartilaginous fish of the superorder Batoidea * Ray (fish fin anatomy), a bony or horny spine on a fin Science and mathematics * Ray (geometry), half of a line proceeding from an initial point * Ray (gr ...
s are vulnerable to predation pressure from human fishing, in particular commercial fishing. A 2016 study published in ''Science'' concludes that humans tend to hunt larger species, and this could disrupt ocean ecosystems for millions of years. A 2020 study published in ''
Science Advances ''Science Advances'' is a peer-reviewed multidisciplinary open-access scientific journal established in early 2015 and published by the American Association for the Advancement of Science. The journal's scope includes all areas of science, inclu ...
'' found that around 18% of marine megafauna, including iconic species such as the
Great white shark The great white shark (''Carcharodon carcharias''), also known as the white shark, white pointer, or simply great white, is a species of large mackerel shark which can be found in the coastal surface waters of all the major oceans. It is nota ...
, are at risk of extinction from human pressures over the next century. In a worst-case scenario, 40% could go extinct over the same time period. According to a 2021 study published in ''Nature'', 71% of oceanic shark and ray populations have been destroyed by
overfishing Overfishing is the removal of a species of fish (i.e. fishing) from a body of water at a rate greater than that the species can replenish its population naturally (i.e. the overexploitation of the fishery's existing fish stock), resulting in t ...
(the primary driver of ocean
defaunation Defaunation is the global, local or functional extinction of animal populations or species from ecological communities. The growth of the human population, combined with advances in harvesting technologies, has led to more intense and efficient ...
) from 1970 to 2018, and are nearing the "point of no return" as 24 of the 31 species are now threatened with extinction, with several being classified as critically endangered.


Disease

The decline of amphibian populations has also been identified as an indicator of environmental degradation. As well as habitat loss, introduced predators and pollution,
Chytridiomycosis Chytridiomycosis ( ) is an infectious disease in amphibians, caused by the chytrid fungi '' Batrachochytrium dendrobatidis'' and '' Batrachochytrium salamandrivorans''. Chytridiomycosis has been linked to dramatic population declines or extinc ...
, a fungal infection accidentally spread by human travel, globalization and the wildlife trade, has caused severe population drops of over 500 amphibian species, and perhaps 90 extinctions, including (among many others) the extinction of the
golden toad The golden toad (''Incilius periglenes'') is an extinct species of true toad that was once abundant in a small, high-altitude region of about in an area north of the city of Monteverde, Costa Rica. It was endemic to elfin cloud forest. Also ca ...
in Costa Rica, the
Gastric-brooding frog The gastric-brooding frogs or platypus frogs (''Rheobatrachus'') is a genus of extinct ground-dwelling frogs native to Queensland in eastern Australia. The genus consisted of only two species, both of which became extinct in the mid-1980s. The ...
in Australia, the Rabb's fringe-limbed treefrog and the extinction of the
Panamanian golden frog The Panamanian golden frog (''Atelopus zeteki''), also known as Cerro Campana stubfoot toad and other names, is a species of toad endemic to Panama. Panamanian golden frogs inhabit the streams along the mountainous slopes of the Cordilleran cloud ...
in the wild. Chytrid fungus has spread across Australia, New Zealand, Central America and Africa, including countries with high amphibian diversity such as
cloud forest A cloud forest, also called a water forest, primas forest, or tropical montane cloud forest (TMCF), is a generally tropical or subtropical, evergreen, montane, moist forest characterized by a persistent, frequent or seasonal low-level cloud ...
s in
Honduras Honduras, officially the Republic of Honduras, is a country in Central America. The republic of Honduras is bordered to the west by Guatemala, to the southwest by El Salvador, to the southeast by Nicaragua, to the south by the Pacific Oce ...
and
Madagascar Madagascar (; mg, Madagasikara, ), officially the Republic of Madagascar ( mg, Repoblikan'i Madagasikara, links=no, ; french: République de Madagascar), is an island country in the Indian Ocean, approximately off the coast of East Afric ...
. ''
Batrachochytrium salamandrivorans ''Batrachochytrium salamandrivorans'' (''Bsal'') is a pathogenic chytrid fungus that infects amphibian species. Although salamanders and newts seem to be the most susceptible, some anuran species are also affected. ''Bsal'' has emerged recen ...
'' is a similar infection currently threatening
salamander Salamanders are a group of amphibians typically characterized by their lizard-like appearance, with slender bodies, blunt snouts, short limbs projecting at right angles to the body, and the presence of a tail in both larvae and adults. All t ...
s. Amphibians are now the most endangered vertebrate group, having existed for more than 300 million years through three other
mass extinction An extinction event (also known as a mass extinction or biotic crisis) is a widespread and rapid decrease in the biodiversity on Earth. Such an event is identified by a sharp change in the diversity and abundance of multicellular organisms. I ...
s. Millions of bats in the US have been dying off since 2012 due to a fungal infection known as
white-nose syndrome White-nose syndrome (WNS) is a fungal disease in North American bats which has resulted in the dramatic decrease of the bat population in the United States and Canada, reportedly killing millions as of 2018. The condition is named for a distincti ...
that spread from European bats, who appear to be immune. Population drops have been as great as 90% within five years, and extinction of at least one bat species is predicted. There is currently no form of treatment, and such declines have been described as "unprecedented" in bat evolutionary history by Alan Hicks of the
New York State Department of Environmental Conservation The New York State Department of Environmental Conservation (informally referred to as NYSDEC, DEC, EnCon or NYSENCON) is a department of New York state government. The department guides and regulates the conservation, improvement, and protection ...
. Between 2007 and 2013, over ten million beehives were abandoned due to
colony collapse disorder Colony collapse disorder (CCD) is an abnormal phenomenon that occurs when the majority of worker bees in a honey bee colony disappear, leaving behind a queen, plenty of food, and a few nurse bees to care for the remaining immature bees. While s ...
, which causes
worker bee A worker bee is any female (eusocial) bee that lacks the full reproductive capacity of the colony's queen bee; under most circumstances, this is correlated to an increase in certain non-reproductive activities relative to a queen. While worker be ...
s to abandon the
queen Queen or QUEEN may refer to: Monarchy * Queen regnant, a female monarch of a Kingdom ** List of queens regnant * Queen consort, the wife of a reigning king * Queen dowager, the widow of a king * Queen mother, a queen dowager who is the mother ...
. Though no single cause has gained widespread acceptance by the scientific community, proposals include infections with ''
Varroa ''Varroa'' is a genus of parasitic mesostigmatan mites associated with honey bees, placed in its own family, Varroidae. The genus was named for Marcus Terentius Varro, a Roman scholar and beekeeper. The condition of a honeybee colony being infe ...
'' and ''Acarapis''
mite Mites are small arachnids (eight-legged arthropods). Mites span two large orders of arachnids, the Acariformes and the Parasitiformes, which were historically grouped together in the subclass Acari, but genetic analysis does not show clear e ...
s;
malnutrition Malnutrition occurs when an organism gets too few or too many nutrients, resulting in health problems. Specifically, it is "a deficiency, excess, or imbalance of energy, protein and other nutrients" which adversely affects the body's tissues ...
; various
pathogen In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a g ...
s; genetic factors;
immunodeficiencies Immunodeficiency, also known as immunocompromisation, is a state in which the immune system's ability to fight infectious diseases and cancer is compromised or entirely absent. Most cases are acquired ("secondary") due to extrinsic factors that a ...
;
loss of habitat Habitat destruction (also termed habitat loss and habitat reduction) is the process by which a natural habitat becomes incapable of supporting its native species. The organisms that previously inhabited the site are displaced or dead, thereby ...
; changing
beekeeping Beekeeping (or apiculture) is the maintenance of bee colonies, commonly in man-made beehives. Honey bees in the genus ''Apis (insect), Apis'' are the most-commonly-kept species but other honey-producing bees such as ''Melipona'' stingless bees ar ...
practices; or a combination of factors.


By region

Megafauna In terrestrial zoology, the megafauna (from Greek μέγας ''megas'' "large" and New Latin ''fauna'' "animal life") comprises the large or giant animals of an area, habitat, or geological period, extinct and/or extant. The most common thresho ...
were once found on every continent of the world, but are now almost exclusively found on the continent of
Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...
. In some regions, megafauna experienced population crashes and
trophic cascade Trophic cascades are powerful indirect interactions that can control entire ecosystems, occurring when a trophic level in a food web is suppressed. For example, a top-down cascade will occur if predators are effective enough in predation to reduce t ...
s shortly after the earliest human settlers. Worldwide, 178 species of the world's largest mammals died out between 52,000 and 9,000 BC; it has been suggested that a higher proportion of African megafauna survived because they evolved alongside humans. The timing of South American megafaunal extinction appears to precede human arrival, although the possibility that human activity at the time impacted the global climate enough to cause such an extinction has been suggested.


Afroeurasia

Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...
experienced the smallest decline in megafauna compared to the other continents. This is presumably due to the idea that Afroeurasian megafauna evolved alongside humans, and thus developed a healthy fear of them, unlike the comparatively tame animals of other continents. Unlike other continents, the megafauna of Eurasia went extinct over a relatively long period of time, possibly due to climate fluctuations fragmenting and decreasing populations, leaving them vulnerable to over-exploitation, as with the steppe bison (''Bison priscus''). The warming of the arctic region caused the rapid decline of grasslands, which had a negative effect on the grazing megafauna of Eurasia. Most of what once was
mammoth steppe During the Last Glacial Maximum, the mammoth steppe, also known as steppe-tundra, was the Earth's most extensive biome. It spanned from Spain eastward across Eurasia to Canada and from the List of islands in the Arctic Ocean, arctic islands sout ...
was converted to
mire A mire, peatland, or quagmire is a wetland area dominated by living peat-forming plants. Mires arise because of incomplete decomposition of organic matter, usually litter from vegetation, due to water-logging and subsequent anoxia. All types ...
, rendering the environment incapable of supporting them, notably the
woolly mammoth The woolly mammoth (''Mammuthus primigenius'') is an extinct species of mammoth that lived during the Pleistocene until its extinction in the Holocene epoch. It was one of the last in a line of mammoth species, beginning with '' Mammuthus s ...
.


Americas

There has been a debate as to the extent to which the disappearance of
megafauna In terrestrial zoology, the megafauna (from Greek μέγας ''megas'' "large" and New Latin ''fauna'' "animal life") comprises the large or giant animals of an area, habitat, or geological period, extinct and/or extant. The most common thresho ...
at the end of the last
glacial period A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate betwe ...
can be attributed to human activities by hunting, or even by slaughter of prey populations. Discoveries at Monte Verde in South America and at
Meadowcroft Rock Shelter Meadowcroft Rockshelter is an archaeological site located near Avella, Pennsylvania, Avella in Jefferson Township, Washington County, Pennsylvania, Jefferson Township, Pennsylvania. The site is a rock shelter in a bluff overlooking Cross Creek (a ...
in Pennsylvania have caused a controversyThe Early Settlement of North America. The Clovis Era. Gary Haynes 2002 . 18–19. regarding the
Clovis culture The Clovis culture is a prehistoric Paleoamerican culture, named for distinct stone and bone tools found in close association with Pleistocene fauna, particularly two mammoths, at Blackwater Locality No. 1 near Clovis, New Mexico, in 1936 ...
. There likely would have been human settlements prior to the Clovis culture, and the history of humans in the Americas may extend back many thousands of years before the Clovis culture. The amount of correlation between human arrival and megafauna extinction is still being debated: for example, in
Wrangel Island Wrangel Island ( rus, О́стров Вра́нгеля, r=Ostrov Vrangelya, p=ˈostrəf ˈvrangʲɪlʲə; ckt, Умӄиԓир, translit=Umqiḷir) is an island of the Chukotka Autonomous Okrug, Russia. It is the 91st largest island in the w ...
in Siberia the extinction of dwarf
woolly mammoth The woolly mammoth (''Mammuthus primigenius'') is an extinct species of mammoth that lived during the Pleistocene until its extinction in the Holocene epoch. It was one of the last in a line of mammoth species, beginning with '' Mammuthus s ...
s (approximately 2000 BCE) did not coincide with the arrival of humans, nor did megafaunal mass extinction on the South American continent, although it has been suggested climate changes induced by anthropogenic effects elsewhere in the world may have contributed. Comparisons are sometimes made between recent extinctions (approximately since the
industrial revolution The Industrial Revolution was the transition to new manufacturing processes in Great Britain, continental Europe, and the United States, that occurred during the period from around 1760 to about 1820–1840. This transition included going f ...
) and the Pleistocene extinction near the end of the last
glacial period A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate betwe ...
. The latter is exemplified by the extinction of large herbivores such as the
woolly mammoth The woolly mammoth (''Mammuthus primigenius'') is an extinct species of mammoth that lived during the Pleistocene until its extinction in the Holocene epoch. It was one of the last in a line of mammoth species, beginning with '' Mammuthus s ...
and the carnivores that preyed on them. Humans of this era actively hunted the
mammoth A mammoth is any species of the extinct elephantid genus ''Mammuthus'', one of the many genera that make up the order of trunked mammals called proboscideans. The various species of mammoth were commonly equipped with long, curved tusks an ...
and the
mastodon A mastodon ( 'breast' + 'tooth') is any proboscidean belonging to the extinct genus ''Mammut'' (family Mammutidae). Mastodons inhabited North and Central America during the late Miocene or late Pliocene up to their extinction at the end of th ...
, but it is not known if this hunting was the cause of the subsequent massive ecological changes, widespread extinctions and climate changes. The ecosystems encountered by the first Americans had not been exposed to human interaction, and may have been far less resilient to human made changes than the ecosystems encountered by industrial era humans. Therefore, the actions of the Clovis people, despite seeming insignificant by today's standards could indeed have had a profound effect on the ecosystems and wild life which was entirely unused to human influence.


Australia

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...
was once home to a large assemblage of megafauna, with many parallels to those found on the African continent today. Australia's fauna is characterised by primarily
marsupial Marsupials are any members of the mammalian infraclass Marsupialia. All extant marsupials are endemic to Australasia, Wallacea and the Americas. A distinctive characteristic common to most of these species is that the young are carried in a po ...
mammals, and many reptiles and birds, all existing as giant forms until recently.
Humans Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, culture, ...
arrived on the continent very early, about 50,000 years ago. The extent human arrival contributed is controversial; climatic drying of Australia 40,000–60,000 years ago was an unlikely cause, as it was less severe in speed or magnitude than previous regional climate change which failed to kill off megafauna. Extinctions in Australia continued from original settlement until today in both
plants Plants are predominantly Photosynthesis, photosynthetic eukaryotes of the Kingdom (biology), kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all curr ...
and
animals Animals are multicellular, eukaryotic organisms in the biological kingdom Animalia. With few exceptions, animals consume organic material, breathe oxygen, are able to move, can reproduce sexually, and go through an ontogenetic stage in ...
, whilst many more animals and
plants Plants are predominantly Photosynthesis, photosynthetic eukaryotes of the Kingdom (biology), kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all curr ...
have declined or are endangered. Due to the older timeframe and the soil chemistry on the continent, very little subfossil preservation evidence exists relative to elsewhere. However, continent-wide extinction of all genera weighing over 100 kilograms, and six of seven genera weighing between 45 and 100 kilograms occurred around 46,400 years ago (4,000 years after human arrival) and the fact that megafauna survived until a later date on the island of
Tasmania ) , nickname = , image_map = Tasmania in Australia.svg , map_caption = Location of Tasmania in AustraliaCoordinates: , subdivision_type = Country , subdi ...
following the establishment of a land bridge suggest direct hunting or anthropogenic ecosystem disruption such as fire-stick farming as likely causes. The first evidence of direct human predation leading to extinction in Australia was published in 2016. A 2021 study found that the rate of extinction of Australia's megafauna is rather unusual, with some generalistic species having gone extinct earlier while highly specialised ones having become extinct later or even still surviving today. A mosaic cause of extinction with different anthropogenic and environmental pressures has been proposed.


Caribbean

Human arrival in the
Caribbean The Caribbean (, ) ( es, El Caribe; french: la Caraïbe; ht, Karayib; nl, De Caraïben) is a region of the Americas that consists of the Caribbean Sea, its islands (some surrounded by the Caribbean Sea and some bordering both the Caribbean Se ...
around 6,000 years ago is correlated with the extinction of many species. These include many different genera of ground and arboreal sloths across all islands. These sloths were generally smaller than those found on the South American continent. ''
Megalocnus ''Megalocnus'' ("great sloth" in Greek) is a genus of extinct large ground sloths that were native to Cuba during the Pleistocene and Holocene epochs. They were among the largest of the Caribbean sloths (Megalocnidae), with individuals estimate ...
'' were the largest genus at up to , ''
Acratocnus ''Acratocnus'' is an extinct genus of ground sloths that were found on Cuba, Hispaniola (today the Dominican Republic and Haiti), and Puerto Rico. Classification Like all of the Antillean sloths, ''Acratocnus'' was formerly thought on the bas ...
'' were medium-sized relatives of modern
two-toed sloth ''Choloepus'' is a genus of xenarthran mammals of Central and South America within the monotypic family Choloepodidae, consisting of two-toed sloths, sometimes also called two-fingered sloths. The two species of ''Choloepus'' (which means "la ...
s endemic to
Cuba Cuba ( , ), officially the Republic of Cuba ( es, República de Cuba, links=no ), is an island country comprising the island of Cuba, as well as Isla de la Juventud and several minor archipelagos. Cuba is located where the northern Caribbea ...
, '' Imagocnus'' also of Cuba, ''
Neocnus ''Neocnus'' is an extinct genus of ground sloth, whose species ranged across Cuba and Hispaniola (today split between Haiti and the Dominican Republic). ''Neocnus'' would have resembled a typical ground sloth, though much smaller, with a lon ...
'' and many others.


Macaronesia

The arrival of the first human settlers in the
Azores ) , motto =( en, "Rather die free than subjected in peace") , anthem= ( en, "Anthem of the Azores") , image_map=Locator_map_of_Azores_in_EU.svg , map_alt=Location of the Azores within the European Union , map_caption=Location of the Azores wi ...
saw the introduction of invasive plants and livestock to the archipelago, resulting in the extinction of at least two plant species on
Pico Island Pico Island (''Ilha do Pico,'' ) is an island in the Central Group of the Portuguese Azores. The landscape features an eponymous volcano, Ponta do Pico, which is the highest mountain in Portugal, the Azores, and the highest elevation of the Mid- ...
. Lacustrine ecosystems were ravaged by human colonisation, as evidenced by hydrogen isotopes from C30 fatty acids recording hypoxic bottom waters caused by eutrophication in Lake Funda on Flores Island beginning between 1500 and 1600 AD. In the
Canary Islands The Canary Islands (; es, Canarias, ), also known informally as the Canaries, are a Spanish autonomous community and archipelago in the Atlantic Ocean, in Macaronesia. At their closest point to the African mainland, they are west of Morocc ...
, native thermophilous woodlands were decimated and two tree taxa were driven extinct following the arrival of its first humans, primarily as a result of increased fire clearance and soil erosion and the introduction of invasive pigs, goats, and rats. Invasive species introductions accelerated during the
Age of Discovery The Age of Discovery (or the Age of Exploration), also known as the early modern period, was a period largely overlapping with the Age of Sail, approximately from the 15th century to the 17th century in European history, during which seafarin ...
when Europeans first settled the
Macaronesia Macaronesia (Portuguese: ''Macaronésia,'' Spanish: ''Macaronesia'') is a collection of four volcanic archipelagos in the North Atlantic, off the coasts of Africa and Europe. Each archipelago is made up of a number of Atlantic oceanic islands ...
n archipelago. The archipelago's laurel forests, though still negatively impacted, fared better due to being less suitable for human economic use.
Cabo Verde , national_anthem = () , official_languages = Portuguese , national_languages = Cape Verdean Creole , capital = Praia , coordinates = , largest_city = capital , demonym ...
, like the Canary Islands, witnessed precipitous deforestation upon the arrival of European settlers and various invasive species brought by them in the archipelago, with the archipelago's thermophilous woodlands suffering the greatest destruction. Introduced species, overgrazing, increased fire incidence, and soil degradation have been attributed as the chief causes of Cabo Verde's ecological devastation.


Pacific

Archaeological and paleontological digs on 70 different Pacific islands suggested that numerous species became extinct as people moved across the Pacific, starting 30,000 years ago in the Bismarck Archipelago and
Solomon Islands Solomon Islands is an island country consisting of six major islands and over 900 smaller islands in Oceania, to the east of Papua New Guinea and north-west of Vanuatu. It has a land area of , and a population of approx. 700,000. Its capita ...
. It is currently estimated that among the bird species of the Pacific, some 2000 species have gone extinct since the arrival of humans, representing a 20% drop in the biodiversity of birds worldwide. The first human settlers of the
Hawaiian islands The Hawaiian Islands ( haw, Nā Mokupuni o Hawai‘i) are an archipelago of eight major islands, several atolls, and numerous smaller islets in the North Pacific Ocean, extending some from the island of Hawaii in the south to northernmost Kur ...
are thought to have arrived between 300 and 800 CE, with European arrival in the 16th century. Hawaii is notable for its
endemism Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...
of plants,
birds Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweigh ...
, insects, mollusks and
fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of li ...
; 30% of its organisms are endemic. Many of its species are endangered or have gone extinct, primarily due to accidentally introduced species and livestock grazing. Over 40% of its bird species have gone extinct, and it is the location of 75% of extinctions in the United States. Extinction has increased in Hawaii over the last 200 years and is relatively well documented, with extinctions among native snails used as estimates for global extinction rates.


Madagascar

Within 500 years of the arrival of
humans Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, culture, ...
between 2,500 and 2,000 years ago, nearly all of Madagascar's distinct,
endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...
and geographically isolated megafauna became extinct. The largest animals, of more than , were extinct very shortly after the first human arrival, with large and medium-sized species dying out after prolonged hunting pressure from an expanding human population moving into more remote regions of the island around 1000 years ago. The eight or more species of
elephant bird Elephant birds are members of the extinct ratite family Aepyornithidae, made up of flightless birds that once lived on the island of Madagascar. They are thought to have become extinct around 1000-1200 CE, probably as a result of human activity. ...
s, giant flightless ratites in the genera ''
Aepyornis ''Aepyornis'' is a genus of aepyornithid, one of three genera of ratite birds endemic to Madagascar until their extinction sometime around 1000 CE. The species ''A. maximus'' weighed up to , and until recently was regarded as the largest known ...
'', ''
Vorombe ''Vorombe'' is one of three genera of elephant birds, an extinct family of large ratite birds endemic to Madagascar. Originally considered to be large '' Aepyornis'' specimens, it is now thought ''Vorombe'' are the largest and heaviest birds kno ...
'', and ''
Mullerornis ''Mullerornis'' is a genus of extinct elephant birds (Aepyornithidae) of Madagascar. Description ''Mullerornis'' is smaller than the more well-known '' Aepyornis''. A bone possibly belonging to ''Mullerornis'' has been radiocarbon dated to abo ...
'', are extinct from over-hunting, as well as 17 species of lemur, known as giant, subfossil lemurs. Some of these lemurs typically weighed over , and their fossils have provided evidence of human butchery on many species. Smaller fauna experienced initial increases due to decreased competition, and then subsequent declines over the last 500 years. All fauna weighing over died out. The primary reasons for the decline of Madagascar's biota, which at the time was already stressed by natural
aridification Aridification is the process of a region becoming increasingly arid, or dry. It refers to long term change, rather than seasonal variation. It is often measured as the reduction of average soil moisture content. It can be caused by reduced precip ...
, were human hunting, herding, farming, and forest clearing, all of which persist and threaten Madagascar's remaining taxa today. The natural ecosystems of Madagascar as a whole were further impacted by the much greater incidence of fire as a result of anthropogenic fire production; evidence from Lake Amparihibe on the island of
Nosy Be Nosy Be (formerly Nossi-bé and Nosse Be) is an island off the northwest coast of Madagascar. Nosy Be is Madagascar's largest and busiest tourist resort. It has an area of , and its population was 109,465 according to the provisional results of ...
indicates a shift in local vegetation from intact rainforest to a fire-disturbed patchwork of grassland and woodland between 1300 and 1000 BP.


New Zealand

New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...
is characterised by its
geographic isolation Allopatric speciation () – also referred to as geographic speciation, vicariant speciation, or its earlier name the dumbbell model – is a mode of speciation that occurs when biological populations become geographically isolated from ...
and
island biogeography Insular biogeography or island biogeography is a field within biogeography that examines the factors that affect the species richness and diversification of isolated natural communities. The theory was originally developed to explain the pattern of ...
, and had been isolated from mainland Australia for 80 million years. It was the last large land mass to be colonised by humans. The arrival of
Polynesia Polynesia () "many" and νῆσος () "island"), to, Polinisia; mi, Porinihia; haw, Polenekia; fj, Polinisia; sm, Polenisia; rar, Porinetia; ty, Pōrīnetia; tvl, Polenisia; tkl, Polenihia (, ) is a subregion of Oceania, made up of ...
n settlers circa 12th century resulted in the extinction of all of the islands' megafaunal birds within several hundred years. The
moa Moa are extinct giant flightless birds native to New Zealand. The term has also come to be used for chicken in many Polynesian cultures and is found in the names of many chicken recipes, such as Kale moa and Moa Samoa. Moa or MOA may also refe ...
, large flightless ratites, became extinct within 200 years of the arrival of human settlers. The Polynesians also introduced the
Polynesian rat The Polynesian rat, Pacific rat or little rat (''Rattus exulans''), known to the Māori as ''kiore'', is the third most widespread species of rat in the world behind the brown rat and black rat. The Polynesian rat originated in Southeast Asia, ...
. This may have put some pressure on other birds but at the time of early European contact (18th century) and colonisation (19th century) the bird life was prolific. With them, the Europeans brought various invasive species including ship rats, possums, cats and mustelids which devastated native bird life, some of which had adapted flightlessness and ground nesting habits, and had no defensive behavior as a result of having no native mammalian predators. The kakapo, the world's biggest parrot, which is flightless, now only exists in managed breeding sanctuaries. New Zealand's national emblem, the
kiwi Kiwi most commonly refers to: * Kiwi (bird), a flightless bird native to New Zealand * Kiwi (nickname), a nickname for New Zealanders * Kiwifruit, an edible berry * Kiwi dollar or New Zealand dollar, a unit of currency Kiwi or KIWI may also ref ...
, is on the endangered bird list.


Mitigation

Stabilizing
human populations Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, culture, an ...
, reining in
capitalism Capitalism is an economic system based on the private ownership of the means of production and their operation for profit. Central characteristics of capitalism include capital accumulation, competitive markets, price system, private ...
and decreasing economic demands, transitioning to plant-based diets, and increasing the number and size of terrestrial and marine protected areas are the keys to avoiding or limiting
biodiversity loss Biodiversity loss includes the worldwide extinction of different species, as well as the local reduction or loss of species in a certain habitat, resulting in a loss of biological diversity. The latter phenomenon can be temporary or permanent, de ...
and a possible sixth mass extinction.
Rodolfo Dirzo Rodolfo Dirzo is a professor, conservationist, and tropical ecologist. He is a Bing Professor in environmental science at Stanford and a senior fellow at the Stanford Woods Institute for the Environment. His research interests mainly focus on plant ...
and
Paul R. Ehrlich Paul Ralph Ehrlich (born May 29, 1932) is an American biologist known for his warnings about the consequences of population growth and limited resources. He is the Bing Professor Emeritus of Population Studies of the Department of Biology of St ...
suggest that "the one fundamental, necessary, 'simple' cure, ... is reducing the scale of the human enterprise." A 2018 article in ''
Science Science is a systematic endeavor that builds and organizes knowledge in the form of testable explanations and predictions about the universe. Science may be as old as the human species, and some of the earliest archeological evidence for ...
'' advocated for the global community to designate 30 percent of the planet by 2030, and 50 percent by 2050, as
protected area Protected areas or conservation areas are locations which receive protection because of their recognized natural, ecological or cultural values. There are several kinds of protected areas, which vary by level of protection depending on the ena ...
s in order to mitigate the contemporary extinction crisis. It highlighted that the human population is projected to grow to 10 billion by the middle of the century, and consumption of food and water resources is projected to double by this time. In November 2018, the UN's biodiversity chief Cristiana Pașca Palmer urged people around the world to put pressure on governments to implement significant protections for wildlife by 2020. She called biodiversity loss a "silent killer" as dangerous as
global warming In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to E ...
, but said it had received little attention by comparison. "It’s different from climate change, where people feel the impact in everyday life. With biodiversity, it is not so clear but by the time you feel what is happening, it may be too late." In January 2020, the UN
Convention on Biological Diversity The Convention on Biological Diversity (CBD), known informally as the Biodiversity Convention, is a multilateral treaty. The Convention has three main goals: the conservation of biological diversity (or biodiversity); the sustainable use of its ...
drafted a Paris-style plan to stop biodiversity and
ecosystem collapse An ecosystem is considered collapsed when its unique biotic (characteristic biota) or abiotic features are lost from all previous occurrences. Ecosystem collapse causes ecological collapse within a system; essentially altering its stability, re ...
by setting the deadline of 2030 to protect 30% of the earth's land and oceans and to reduce
pollution Pollution is the introduction of contaminants into the natural environment that cause adverse change. Pollution can take the form of any substance (solid, liquid, or gas) or energy (such as radioactivity, heat, sound, or light). Pollutants, th ...
by 50%, with the goal of allowing for the restoration of ecosystems by 2050. The world failed to meet the Aichi Biodiversity targets for 2020 set by the convention during a summit in Japan in 2010. Of the 20 biodiversity targets proposed, only six were "partially achieved" by the deadline. It was called a global failure by Inger Andersen, head of the
United Nations Environment Programme The United Nations Environment Programme (UNEP) is responsible for coordinating responses to environmental issues within the United Nations system. It was established by Maurice Strong, its first director, after the United Nations Conference on th ...
: Some scientists have proposed keeping extinctions below 20 per year for the next century as a global target to reduce species loss, which is the biodiversity equivalent of the 2 °C climate target, although it is still much higher than the normal background rate of two per year prior to anthropogenic impacts on the natural world. An October 2020 report on the "era of pandemics" from
IPBES The Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) is an intergovernmental organization established to improve the interface between science and policy on issues of biodiversity and ecosystem services. It ...
found that many of the same human activities that contribute to
biodiversity loss Biodiversity loss includes the worldwide extinction of different species, as well as the local reduction or loss of species in a certain habitat, resulting in a loss of biological diversity. The latter phenomenon can be temporary or permanent, de ...
and
climate change In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to E ...
, including
deforestation Deforestation or forest clearance is the removal of a forest or stand of trees from land that is then converted to non-forest use. Deforestation can involve conversion of forest land to farms, ranches, or urban use. The most concentrated ...
and the
wildlife trade Wildlife trade refers to the of products that are derived from non-domesticated animals or plants usually extracted from their natural environment or raised under controlled conditions. It can involve the trade of living or dead individuals, ti ...
, have also increased the risk of future
pandemics A pandemic () is an epidemic of an infectious disease that has spread across a large region, for instance multiple continents or worldwide, affecting a substantial number of individuals. A widespread endemic disease with a stable number of in ...
. The report offers several policy options to reduce such risk, such as taxing
meat Meat is animal flesh that is eaten as food. Humans have hunted, farmed, and scavenged animals for meat since prehistoric times. The establishment of settlements in the Neolithic Revolution allowed the domestication of animals such as chic ...
production and consumption, cracking down on the illegal wildlife trade, removing high disease-risk species from the legal wildlife trade, and eliminating subsidies to businesses which are harmful to the environment. According to marine zoologist John Spicer, "the
COVID-19 crisis The COVID-19 pandemic, also known as the coronavirus pandemic, is an ongoing global pandemic of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The novel virus was first identi ...
is not just another crisis alongside the biodiversity crisis and the climate change crisis. Make no mistake, this is one big crisis – the greatest that humans have ever faced." According to a 2021 paper published in '' Frontiers in Conservation Science'', humanity almost certainly faces a "ghastly future" of mass extinction, biodiversity collapse, climate change and their impacts unless major efforts to change human industry and activity are rapidly undertaken. A 2022 report published in ''Science'' warned that 44% of earth's terrestrial surface, or 24.7 million square miles, must to be conserved and made "ecologically sound" in order to prevent further biodiversity loss.


See also

*
Biodiversity loss Biodiversity loss includes the worldwide extinction of different species, as well as the local reduction or loss of species in a certain habitat, resulting in a loss of biological diversity. The latter phenomenon can be temporary or permanent, de ...
*
Extinction Rebellion Extinction Rebellion (abbreviated as XR) is a global environmental movement, with the stated aim of using nonviolent civil disobedience to compel government action to avoid tipping points in the climate system, biodiversity loss, and the risk o ...
*
Extinction risk from climate change The extinction risk of climate change is the risk of species becoming extinct due to the effects of climate change. Climate change is the long-term conversion of temperature and average weather patterns. Currently, 19% of species on the IUCN Red L ...
*
Extinction symbol The extinction symbol represents the threat of holocene extinction on Earth; a circle represents the planet and a stylised hourglass is a warning that time is running out for many species. The symbol dates to at least 2012 and has been attr ...
* ''Extinction: The Facts'' (2020 documentary) *
Human impact on the environment Human impact on the environment (or anthropogenic impact) refers to changes to biophysical environments and to ecosystems, biodiversity, and natural resources caused directly or indirectly by humans. Modifying the environment to fit the need ...
*
Lists of extinct species This page features lists of extinct species, organisms that have become extinct, either in the wild or completely disappeared from Earth. In actual theoretical practice, a species not definitely located in the wild in the last fifty years of cu ...
* Pleistocene rewilding *
Quaternary extinction The Quaternary period (from 2.588 ± 0.005 million years ago to the present) has seen the extinctions of numerous predominantly megafaunal species, which have resulted in a collapse in faunal density and diversity and the extinction of key ecol ...
* ''Racing Extinction'' (2015 documentary film) *
Timeline of extinctions in the Holocene This article is a list of biological species, subspecies, and evolutionary significant units that are known to have become extinct during the Holocene, the current geologic epoch, ordered by their known or approximate date of disappearance from ol ...
*
World Scientists' Warning to Humanity The "World Scientists' Warning to Humanity" was a document written in 1992 by Henry W. Kendall and signed by about 1,700 leading scientists. Twenty-five years later, in November 2017, 15,364 scientists signed "World Scientists' Warning to Humanity ...


Notes


References


Further reading

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External links


The Extinction Crisis
Center for Biological Diversity The Center for Biological Diversity is a nonprofit membership organization known for its work protecting endangered species through legal action, scientific petitions, creative media and grassroots activism. It was founded in 1989 by Kieran Suckl ...
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Vanishing: The extinction crisis is far worse than you think
CNN CNN (Cable News Network) is a multinational cable news channel headquartered in Atlanta, Georgia, U.S. Founded in 1980 by American media proprietor Ted Turner and Reese Schonfeld as a 24-hour cable news channel, and presently owned by ...
. December 2016.
Biologists say half of all species could be extinct by end of century
''The Guardian,'' 25 February 2017

''The Independent,'' 31 May 2017
Human activity pushing Earth towards 'sixth mass species extinction,' report warns
CBC. Mar 26, 2018
‘Terror being waged on wildlife', leaders warn
''The Guardian.'' October 4, 2018.
Earth Is on the Cusp of the Sixth Mass Extinction. Here’s What Paleontologists Want You to Know
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Discover Discover may refer to: Art, entertainment, and media * ''Discover'' (album), a Cactus Jack album * ''Discover'' (magazine), an American science magazine Businesses and brands * DISCover, the ''Digital Interactive Systems Corporation'' * D ...
''. December 3, 2020. {{DEFAULTSORT:Holocene Extinction
Species made extinct by human activities In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate sexe ...
Extinction
Extinction Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...
Extinction Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...
Environmental impact by effect Human ecology Human impact on the environment Anthropocene Extinction events hu:Pleisztocén-holocén becsapódási esemény