Holocene extinction event
Encyclopedia
The Holocene extinction refers to the extinction
Extinction event
An extinction event is a sharp decrease in the diversity and abundance of macroscopic life. They occur when the rate of extinction increases with respect to the rate of speciation...

 of species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 during the present Holocene
Holocene
The Holocene is a geological epoch which began at the end of the Pleistocene and continues to the present. The Holocene is part of the Quaternary period. Its name comes from the Greek words and , meaning "entirely recent"...

 epoch
Epoch (geology)
An epoch is a subdivision of the geologic timescale based on rock layering. In order, the higher subdivisions are periods, eras and eons. We are currently living in the Holocene epoch...

 (since around 10,000 BC). The large number of extinctions span numerous families of plant
Plant
Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The group is also called green plants or...

s and animal
Animal
Animals are a major group of multicellular, eukaryotic organisms of the kingdom Animalia or Metazoa. Their body plan eventually becomes fixed as they develop, although some undergo a process of metamorphosis later on in their life. Most animals are motile, meaning they can move spontaneously and...

s including mammal
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...

s, bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...

s, amphibian
Amphibian
Amphibians , are a class of vertebrate animals including animals such as toads, frogs, caecilians, and salamanders. They are characterized as non-amniote ectothermic tetrapods...

s, reptile
Reptile
Reptiles are members of a class of air-breathing, ectothermic vertebrates which are characterized by laying shelled eggs , and having skin covered in scales and/or scutes. They are tetrapods, either having four limbs or being descended from four-limbed ancestors...

s and arthropod
Arthropod
An arthropod is an invertebrate animal having an exoskeleton , a segmented body, and jointed appendages. Arthropods are members of the phylum Arthropoda , and include the insects, arachnids, crustaceans, and others...

s; a sizeable fraction of these extinctions are occurring in the rainforest
Rainforest
Rainforests are forests characterized by high rainfall, with definitions based on a minimum normal annual rainfall of 1750-2000 mm...

s. 875 extinctions occurring between 1500 and 2009 have been documented by the International Union for Conservation of Nature and Natural Resources. However, most extinctions go undocumented. According to the species-area theory
Species-area curve
In ecology, a species-area curve is a relationship between the area of a habitat, or of part of a habitat, and the number of species found within that area. Larger areas tend to contain larger numbers of species, and empirically, the relative numbers seem to follow systematic mathematical...

 and based on upper-bound estimating, up to 140,000 species per year may be the present rate of extinction.

In broad usage, Holocene extinction includes the disappearance of large mammal
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...

s, known as megafauna
Megafauna
In terrestrial zoology, megafauna are "giant", "very large" or "large" animals. The most common thresholds used are or...

, starting roughly 11,500 years ago (especially in North America in which a comet is theorized to have struck the continent) due to abrupt climate change at the end of the last Ice Age. Such disappearances have normally been considered as either a result of climate change
Climate change
Climate change is a significant and lasting change in the statistical distribution of weather patterns over periods ranging from decades to millions of years. It may be a change in average weather conditions or the distribution of events around that average...

, a result of the proliferation
Overpopulation
Overpopulation is a condition where an organism's numbers exceed the carrying capacity of its habitat. The term often refers to the relationship between the human population and its environment, the Earth...

 of modern humans, or both; however in 2007 a cometary impact hypothesis was presented, but has not been broadly accepted. These extinctions, occurring near the Pleistocene
Pleistocene
The Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....

–Holocene boundary, are sometimes referred to as the Quaternary extinction event
Quaternary extinction event
The Quaternary period saw the extinctions of numerous predominantly larger, especially megafaunal, species, many of which occurred during the transition from the Pleistocene to the Holocene epoch. However, the extinction wave did not stop at the end of the Pleistocene, but continued especially on...

 or Ice Age extinction. However, the Holocene extinction may be regarded as continuing into the 21st century.

There is no general agreement on whether to consider more recent extinctions as a distinct event, merely part of the Quaternary extinction event
Quaternary extinction event
The Quaternary period saw the extinctions of numerous predominantly larger, especially megafaunal, species, many of which occurred during the transition from the Pleistocene to the Holocene epoch. However, the extinction wave did not stop at the end of the Pleistocene, but continued especially on...

, or just a result of natural evolution on a non-geologic scale of time. Only during these most recent parts of the extinction have plant
Plant
Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The group is also called green plants or...

s also suffered large losses. Overall, the Holocene extinction can be characterized by climate change and humanity's presence.

The prehistoric extinction events

There was a limited debate as to the extent to which the disappearance of megafauna
Megafauna
In terrestrial zoology, megafauna are "giant", "very large" or "large" animals. The most common thresholds used are or...

 at the end of the last glacial period
Glacial period
A glacial period is an interval of time within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate within an ice age...

 can also be attributed to human activities, directly, by hunting, or indirectly, by decimation of prey populations. While climate change
Climate change
Climate change is a significant and lasting change in the statistical distribution of weather patterns over periods ranging from decades to millions of years. It may be a change in average weather conditions or the distribution of events around that average...

 is still cited as another important factor, anthropogenic
Anthropogenic
Human impact on the environment or anthropogenic impact on the environment includes impacts on biophysical environments, biodiversity and other resources. The term anthropogenic designates an effect or object resulting from human activity. The term was first used in the technical sense by Russian...

 explanations have become predominant.

The ongoing extinction seems more outstanding in light of separating recent extinctions (approximately since the industrial revolution
Industrial Revolution
The Industrial Revolution was a period from the 18th to the 19th century where major changes in agriculture, manufacturing, mining, transportation, and technology had a profound effect on the social, economic and cultural conditions of the times...

) from the Pleistocene extinction near the end of the last glacial period
Glacial period
A glacial period is an interval of time within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate within an ice age...

. The latter is exemplified by the extinction of large herbivores such as the woolly mammoth
Woolly mammoth
The woolly mammoth , also called the tundra mammoth, is a species of mammoth. This animal is known from bones and frozen carcasses from northern North America and northern Eurasia with the best preserved carcasses in Siberia...

 and the carnivores that preyed on them.

However, modern climatology
Climatology
Climatology is the study of climate, scientifically defined as weather conditions averaged over a period of time, and is a branch of the atmospheric sciences...

 suggests the current Holocene epoch is no more than the latest in a series of interglacial
Interglacial
An Interglacial period is a geological interval of warmer global average temperature lasting thousands of years that separates consecutive glacial periods within an ice age...

 intervals. Furthermore, there is a continuum of extinctions since 11,000 BCE. If only considering human impact, the vulnerability and extinction rate of species simply rises with the increase in human population, so there would be no need to separate the Pleistocene extinction from the recent one. Nevertheless, the Pleistocene extinction event is large enough and has not been resolved completely.

New Zealand

c. 1500, several species became extinct after Polynesia
Polynesia
Polynesia is a subregion of Oceania, made up of over 1,000 islands scattered over the central and southern Pacific Ocean. The indigenous people who inhabit the islands of Polynesia are termed Polynesians and they share many similar traits including language, culture and beliefs...

n settlers arrived, including:
  • Ten species of Moa
    Moa
    The moa were eleven species of flightless birds endemic to New Zealand. The two largest species, Dinornis robustus and Dinornis novaezelandiae, reached about in height with neck outstretched, and weighed about ....

    , giant flightless ratite
    Ratite
    A ratite is any of a diverse group of large, flightless birds of Gondwanan origin, most of them now extinct. Unlike other flightless birds, the ratites have no keel on their sternum—hence the name from the Latin ratis...

     birds.
  • The giant Haast's Eagle, Harpagornis
  • The flightless predatory Adzebill
    Adzebill
    The adzebills, genus Aptornis, were two closely related bird species, the North Island Adzebill, Aptornis otidiformis, and the South Island Adzebill, Aptornis defossor, of the extinct family Aptornithidae. The family was endemic to New Zealand.They have been placed in the Gruiformes but this is not...

    s.

Pacific, including Hawaii

Recent research, based on archaeological and paleontological
Paleontology
Paleontology "old, ancient", ὄν, ὀντ- "being, creature", and λόγος "speech, thought") is the study of prehistoric life. It includes the study of fossils to determine organisms' evolution and interactions with each other and their environments...

 digs on 70 different islands, has shown that numerous species went extinct as people moved across the Pacific, starting 30,000 years ago in the Bismarck Archipelago
Bismarck Archipelago
The Bismarck Archipelago is a group of islands off the northeastern coast of New Guinea in the western Pacific Ocean and is part of the Islands Region of Papua New Guinea.-History:...

 and Solomon Islands
Solomon Islands
Solomon Islands is a sovereign state in Oceania, east of Papua New Guinea, consisting of nearly one thousand islands. It covers a land mass of . The capital, Honiara, is located on the island of Guadalcanal...

 (Steadman & Martin 2003). It is currently estimated that among the bird species of the Pacific some 2000 species have gone extinct since the arrival of humans (Steadman 1995). Among the extinctions were:
  • The Moa-nalo
    Moa-nalo
    The moa-nalo are a group of extinct aberrant, goose-like ducks that lived on the larger Hawaiian Islands, except Hawaii itself, in the Pacific...

    s, grazing ducks from Hawaii
    Hawaii
    Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...

    .
  • The Nēnē-nui
    Nene-nui
    The Nēnē-nui or Woodwalking Goose is an extinct species of goose that once inhabited Maui and possibly Kauai, Oahu and perhaps Molokai in the Hawaiian Islands...

    , or Woodwalking Goose, an extinct species of goose that once inhabited Maui.
  • A giant megapode from New Caledonia
    New Caledonia
    New Caledonia is a special collectivity of France located in the southwest Pacific Ocean, east of Australia and about from Metropolitan France. The archipelago, part of the Melanesia subregion, includes the main island of Grande Terre, the Loyalty Islands, the Belep archipelago, the Isle of...

    .
  • Mekosuchine crocodiles from New Caledonia, Fiji
    Fiji
    Fiji , officially the Republic of Fiji , is an island nation in Melanesia in the South Pacific Ocean about northeast of New Zealand's North Island...

     and Samoa
    Samoa
    Samoa , officially the Independent State of Samoa, formerly known as Western Samoa is a country encompassing the western part of the Samoan Islands in the South Pacific Ocean. It became independent from New Zealand in 1962. The two main islands of Samoa are Upolu and one of the biggest islands in...

    .


Ten species or subspecies of birds have disappeared from the Hawaiian islands since the 1980s. These include the Kaua'i O'o, Nukupu'u, 'Akialoa, Kama'o, Po'ouli, and others.

Madagascar

Starting with the arrival of humans around 2000 years ago, nearly all of the island's megafauna became extinct, including:
  • Eight or more species of elephant birds
    Elephant bird
    Elephant birds are an extinct family of flightless birds found only on the island of Madagascar and comprising the genera Aepyornis and Mullerornis.-Description:...

    , giant flightless ratite
    Ratite
    A ratite is any of a diverse group of large, flightless birds of Gondwanan origin, most of them now extinct. Unlike other flightless birds, the ratites have no keel on their sternum—hence the name from the Latin ratis...

    s in the genera Aepyornis and Mullerornis.
  • 17 species of lemur, known as giant, subfossil lemur
    Subfossil lemur
    Subfossil lemurs are lemurs from Madagascar that are represented by recent remains dating from nearly 26,000 years ago to approximately 560 years ago. They include both living and extinct species, although the term more frequently refers to the extinct giant lemurs...

    s, including:
    • Giant Aye-aye
      Giant Aye-aye
      The giant aye-aye is an extinct relative of the aye-aye, the only other species in the genus Daubentonia. It lived in Madagascar, appears to have disappeared less than 1,000 years ago, is entirely unknown in life, and is only known from subfossil remains.As of 2004, giant aye-aye remains consisted...

       (Daubentonia robusta)
    • Sloth lemurs, including chimpanzee-sized Palaeopropithecus and gorilla-sized Archaeoindris
      Archaeoindris
      Archaeoindris fontoynonti is an extinct species of Malagasy lemur that was the largest primate to evolve on Madagascar. It weighed about and measured around 1.5m in height, more than a silverback gorilla. Archaeoindris is one of eight known members of the Palaeopropithecinae subfamily...

    • Koala lemurs (Megaladapis), a koala-like, orangutan-sized arboreal lemur
    • Monkey lemur
      Monkey lemur
      The Monkey lemurs or Baboon lemurs are an extinct type of lemurs that includes one family, Archaeolemuridae, two genera and three species. Despite their common names, members of Archaeolemuridae were not as closely related to monkeys as they were to other lemurs....

      s, most terrestrial of lemurs, often compared to baboon
      Baboon
      Baboons are African and Arabian Old World monkeys belonging to the genus Papio, part of the subfamily Cercopithecinae. There are five species, which are some of the largest non-hominoid members of the primate order; only the mandrill and the drill are larger...

      s or macaque
      Macaque
      The macaques constitute a genus of Old World monkeys of the subfamily Cercopithecinae. - Description :Aside from humans , the macaques are the most widespread primate genus, ranging from Japan to Afghanistan and, in the case of the barbary macaque, to North Africa...

      s.
    • Pachylemur
      Pachylemur
      Pachylemur is an extinct genus of lemur most closely related to the ruffed lemurs . Its two representative species, Pachylemur insignis and Pachylemur jullyi, are only known from subfossil remains found at sites in central and southwestern Madagascar...

      , a genus of giant ruffed lemur
      Ruffed lemur
      The ruffed lemurs of the genus Varecia are strepsirrhine primates and the largest extant lemurs within the family Lemuridae. Like all living lemurs, they are found only on the island of Madagascar...

      s
  • Giant Fossa
  • Plesiorycteropus
    Plesiorycteropus
    Plesiorycteropus, also known as the bibymalagasy or Malagasy aardvark, is a recently extinct eutherian mammalian genus from Madagascar. Upon its description in 1895, it was classified with the aardvark, but recent studies have found little evidence to link it to aardvarks or any other order of...

    , a genus containing two species of digging mammal unlike anything alive today
  • Two species of Malagasy Hippopotamus
    Malagasy Hippopotamus
    Several species of Malagasy Hippopotamus lived on the island of Madagascar but are now believed to be extinct. The animals were very similar to the extant Hippopotamus and Pygmy Hippopotamus...


Indian Ocean Islands

Starting c. 1500, a number of species became extinct upon human settlement of the islands, including:
  • several species of giant tortoise
    Giant tortoise
    Giant tortoises are characteristic reptiles of certain tropical islands. Often reaching enormous size—they can weigh as much as 300 kg and can grow to be 1.3 m long—they live, or lived , in the Seychelles, the Mascarenes and the Galapagos...

     on Seychelles
    Seychelles
    Seychelles , officially the Republic of Seychelles , is an island country spanning an archipelago of 115 islands in the Indian Ocean, some east of mainland Africa, northeast of the island of Madagascar....

     and Mascarene Islands
    Mascarene Islands
    The Mascarene Islands is a group of islands in the Indian Ocean east of Madagascar comprising Mauritius, Réunion, Rodrigues, Cargados Carajos shoals, plus the former islands of the Saya de Malha, Nazareth and Soudan banks...

  • 14 species of birds
    Extinct birds
    Since 1500, over 190 species of birds have become extinct, and this rate of extinction seems to be increasing. The situation is exemplified by Hawaii, where 30% of all known recently extinct bird taxa originally lived...

     on the Mascarene Islands, including the Dodo
    Dodo
    The dodo was a flightless bird endemic to the Indian Ocean island of Mauritius. Related to pigeons and doves, it stood about a meter tall, weighing about , living on fruit, and nesting on the ground....

    , the Rodrigues Solitaire
    Rodrigues Solitaire
    The Rodrigues Solitaire was a flightless member of the pigeon order endemic to Rodrigues, Mauritius. It was a close relative of the Dodo.-Discovery:...

    , and the unrelated Réunion Solitaire
    Réunion Sacred Ibis
    The Réunion Sacred Ibis, Threskiornis solitarius, is an extinct bird species that was native to the island of Réunion. It is probably the same bird discovered by Portuguese sailors there in 1613...

    .

Ongoing Holocene extinction

One scientist estimates the extinction may be 10,000 times the background extinction rate
Background extinction rate
Background extinction rate, also known as ‘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...

 (the average between mass extinction events). Nevertheless, in earlier studies, most scientists predicted a much lower extinction rate than this outlying estimate.

Megafaunal extinctions continue into the 21st century. Modern extinctions are more directly attributable to human influences. Extinction rates are minimized in the popular imagination by the survival of captive populations of animals that are extinct in the wild (Père David's Deer
Père David's Deer
Père David's Deer, Elaphurus davidianus, also known as the Milu , is a species of deer known only in captivity. It prefers marshland, and is believed to be native to the subtropics of China. It grazes on a mixture of grass and water plants. It is the only extant member of the genus Elaphurus...

, etc.), by marginal survivals of highly-publicized megafauna that are ecologically extinct (the Giant Panda
Giant Panda
The giant panda, or panda is a bear native to central-western and south western China. It is easily recognized by its large, distinctive black patches around the eyes, over the ears, and across its round body. Though it belongs to the order Carnivora, the panda's diet is 99% bamboo...

, Sumatran Rhinoceros
Sumatran Rhinoceros
The Sumatran Rhinoceros is a member of the family Rhinocerotidae and one of five extant rhinoceroses. It is the only extant species of the genus Dicerorhinus. It is the smallest rhinoceros, although is still a large mammal. This rhino stands high at the shoulder, with a head-and-body length of ...

, North American Black-Footed Ferret
Black-footed Ferret
The Black-footed Ferret , also known as the American polecat or Prairie Dog Hunter, is a species of Mustelid native to central North America. It is listed as endangered by the IUCN, because of its very small and restricted populations...

, etc.) and by extinctions among arthropod
Arthropod
An arthropod is an invertebrate animal having an exoskeleton , a segmented body, and jointed appendages. Arthropods are members of the phylum Arthropoda , and include the insects, arachnids, crustaceans, and others...

s. Some examples of modern extinctions of "charismatic" mammal fauna include:
  • Aurochs
    Aurochs
    The aurochs , the ancestor of domestic cattle, were a type of large wild cattle which inhabited Europe, Asia and North Africa, but is now extinct; it survived in Europe until 1627....

    , Europe
  • Tarpan, Europe
  • Thylacine
    Thylacine
    The thylacine or ,also ;binomial name: Thylacinus cynocephalus, Greek for "dog-headed pouched one") was the largest known carnivorous marsupial of modern times. It is commonly known as the Tasmanian tiger or the Tasmanian wolf...

     or Tasmanian Tiger, Thylacinus cynocephalus, Tasmania [extinction disputed]
  • Quagga
    Quagga
    The quagga is an extinct subspecies of the plains zebra, which was once found in great numbers in South Africa's Cape Province and the southern part of the Orange Free State. It was distinguished from other zebras by having the usual vivid marks on the front part of the body only...

    , a zebra relative, Southeast Africa
  • Steller's Sea Cow
    Steller's Sea Cow
    Steller's sea cow was a large herbivorous marine mammal. In historical times, it was the largest member of the order Sirenia, which includes its closest living relative, the dugong , and the manatees...

  • Falkland Island Fox
    Falkland Island Fox
    The Falkland Islands Wolf , also known as the Warrah and occasionally as the Falkland Islands Dog, Falkland Islands Fox or Antarctic Wolf, was the only native land mammal of the Falkland Islands. This endemic canid became extinct in 1876 , the first known canid to have gone extinct in historical...

  • Atlas Bear
    Atlas Bear
    The Atlas Bear is an extinct subspecies of the Brown Bear, which is sometimes classified as a distinct species.-Range and description:...

  • Eastern Cougar
    Eastern Cougar
    The North American Cougar , is the cougar subspecies once commonly found in eastern North America and still prevalent in the western half of the continent...

  • Western Black Rhinoceros
    Western Black Rhinoceros
    The Western Black Rhinoceros or West African Black Rhinoceros is an extinct subspecies of the Black Rhino...



Many birds have become extinct as a result of human activity, especially birds endemic
Endemic (ecology)
Endemism is the ecological state of being unique to a defined geographic location, such as an island, nation or other defined zone, or habitat type; organisms that are indigenous to a place are not endemic to it if they are also found elsewhere. For example, all species of lemur are endemic to the...

 to islands, including many flightless birds (see a more complete list under extinct birds
Extinct birds
Since 1500, over 190 species of birds have become extinct, and this rate of extinction seems to be increasing. The situation is exemplified by Hawaii, where 30% of all known recently extinct bird taxa originally lived...

). Notable extinct birds include:
  • the Dodo
    Dodo
    The dodo was a flightless bird endemic to the Indian Ocean island of Mauritius. Related to pigeons and doves, it stood about a meter tall, weighing about , living on fruit, and nesting on the ground....

    , the giant flightless pigeon of Mauritius
    Mauritius
    Mauritius , officially the Republic of Mauritius is an island nation off the southeast coast of the African continent in the southwest Indian Ocean, about east of Madagascar...

    , Indian Ocean
    Indian Ocean
    The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...

  • the Great Auk
    Great Auk
    The Great Auk, Pinguinus impennis, formerly of the genus Alca, was a large, flightless alcid that became extinct in the mid-19th century. It was the only modern species in the genus Pinguinus, a group of birds that formerly included one other species of flightless giant auk from the Atlantic Ocean...

     of islands in the north Atlantic
  • the Passenger Pigeon
    Passenger Pigeon
    The Passenger Pigeon or Wild Pigeon was a bird, now extinct, that existed in North America and lived in enormous migratory flocks until the early 20th century...

     of North America
  • several species of Moa
    Moa
    The moa were eleven species of flightless birds endemic to New Zealand. The two largest species, Dinornis robustus and Dinornis novaezelandiae, reached about in height with neck outstretched, and weighed about ....

    , giant flightless birds from New Zealand
  • the Carolina Parakeet
    Carolina Parakeet
    The Carolina Parakeet was the only parrot species native to the eastern United States. It was found from the Ohio Valley to the Gulf of Mexico, and lived in old forests along rivers. It was the only species at the time classified in the genus Conuropsis...

     of the American southeast


A 1998 poll conducted by the American Museum of Natural History
American Museum of Natural History
The American Museum of Natural History , located on the Upper West Side of Manhattan in New York City, United States, is one of the largest and most celebrated museums in the world...

 found that seventy percent of biologists believe that we are in the midst of an anthropogenic extinction. Numerous scientific studies—such as a 2004 report published in Nature
Nature (journal)
Nature, first published on 4 November 1869, is ranked the world's most cited interdisciplinary scientific journal by the Science Edition of the 2010 Journal Citation Reports...

, and papers authored by the 10,000 scientists who contribute to the IUCN's annual Red List of threatened species—have since reinforced this conviction. In The Future of Life (2002), E.O. Wilson of Harvard calculated that, if the current rate of human disruption of the biosphere continues, one-half of Earth's higher lifeforms will be extinct by 2100.

Peter Raven, past President of the American Association for the Advancement of Science
American Association for the Advancement of Science
The American Association for the Advancement of Science is an international non-profit organization with the stated goals of promoting cooperation among scientists, defending scientific freedom, encouraging scientific responsibility, and supporting scientific education and science outreach for the...

, states in the foreword to their publication AAAS Atlas of Population and Environment: "We have driven the rate of biological extinction, the permanent loss of species, up several hundred times beyond its historical levels, and are threatened with the loss of a majority of all species by the end of the 21st century." Some of the human causes of the current extinctions include deforestation
Deforestation
Deforestation is the removal of a forest or stand of trees where the land is thereafter converted to a nonforest use. Examples of deforestation include conversion of forestland to farms, ranches, or urban use....

, hunting
Hunting
Hunting is the practice of pursuing any living thing, usually wildlife, for food, recreation, or trade. In present-day use, the term refers to lawful hunting, as distinguished from poaching, which is the killing, trapping or capture of the hunted species contrary to applicable law...

, pollution
Pollution
Pollution is the introduction of contaminants into a natural environment that causes instability, disorder, harm or discomfort to the ecosystem i.e. physical systems or living organisms. Pollution can take the form of chemical substances or energy, such as noise, heat or light...

, climate change
Climate change
Climate change is a significant and lasting change in the statistical distribution of weather patterns over periods ranging from decades to millions of years. It may be a change in average weather conditions or the distribution of events around that average...

, and the introduction of non-native species
Introduced species
An introduced species — or neozoon, alien, exotic, non-indigenous, or non-native species, or simply an introduction, is a species living outside its indigenous or native distributional range, and has arrived in an ecosystem or plant community by human activity, either deliberate or accidental...

.
189 countries which are signatory to the Convention on Biological Diversity
Convention on Biological Diversity
The Convention on Biological Diversity , known informally as the Biodiversity Convention, is an international legally binding treaty...

 (Rio Accord) have committed to preparing a Biodiversity Action Plan
Biodiversity Action Plan
A Biodiversity Action Plan is an internationally recognized program addressing threatened species and habitats and is designed to protect and restore biological systems. The original impetus for these plans derives from the 1992 Convention on Biological Diversity...

, a first step at identifying specific endangered species
Endangered species
An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...

 and habitats, country by country.

Human influence on extinction

Extinction of animals and plants caused by human actions may go as far back as the late Pleistocene
Pleistocene
The Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....

, over 12,000 years BP, but there is no direct evidence for this theory and it is more likely abrupt climate change played a much higher role in the extinction of larger mammals. Extinctions that are due to human activity (anthropogenic), particularly hypothesized future events, have also been labelled the anthropocene extinction. The Anthropocene
Anthropocene
The Anthropocene is a recent and informal geologic chronological term that serves to mark the evidence and extent of human activities that have had a significant global impact on the Earth's ecosystems...

 is a term introduced in 2000.

Recent extinctions described are well-documented, but the nomenclature
Nomenclature
Nomenclature is a term that applies to either a list of names or terms, or to the system of principles, procedures and terms related to naming - which is the assigning of a word or phrase to a particular object or property...

 used varies. The term Anthropocene
Anthropocene
The Anthropocene is a recent and informal geologic chronological term that serves to mark the evidence and extent of human activities that have had a significant global impact on the Earth's ecosystems...

 is a term that is used by few 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
Holocene
The Holocene is a geological epoch which began at the end of the Pleistocene and continues to the present. The Holocene is part of the Quaternary period. Its name comes from the Greek words and , meaning "entirely recent"...

 Epoch
Epoch (geology)
An epoch is a subdivision of the geologic timescale based on rock layering. In order, the higher subdivisions are periods, eras and eons. We are currently living in the Holocene epoch...

. Other commentators place the Holocene-Anthropocene boundary at the industrial revolution
Industrial Revolution
The Industrial Revolution was a period from the 18th to the 19th century where major changes in agriculture, manufacturing, mining, transportation, and technology had a profound effect on the social, economic and cultural conditions of the times...

 while also saying that "Formal adoption of this term in the near future will largely depend on its utility, particularly to earth scientists working on late Holocene successions. "

Three hypotheses have been proposed to explain the extinction of megafauna
Megafauna
In terrestrial zoology, megafauna are "giant", "very large" or "large" animals. The most common thresholds used are or...

 in the late Pleistocene
Late Pleistocene
The Late Pleistocene is a stage of the Pleistocene Epoch. The beginning of the stage is defined by the base of the Eemian interglacial phase before the final glacial episode of the Pleistocene 126,000 ± 5,000 years ago. The end of the stage is defined exactly at 10,000 Carbon-14 years BP...

. Of these, only two have much scientific credibility. Although Ross McPhee proposed that a hyper-disease may have been the cause of the extinction, the study by Lyons et al., demonstrated conclusively that a hyperdisease was unlikely to have caused the extinction. The two main theories to the extinction are climate change and human hunting. 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. Most scientists favor abrupt climate 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.

See also

  • Ape extinction
    Ape extinction
    Ape extinction, particularly great ape extinction, is one of the most widely held biodiversity concerns.There are very few breeding populations of non-human great apes outside captivity, and all such populations are not only formally classified as endangered species, but in the direct path of human...

  • Biodiversity
    Biodiversity
    Biodiversity is the degree of variation of life forms within a given ecosystem, biome, or an entire planet. Biodiversity is a measure of the health of ecosystems. Biodiversity is in part a function of climate. In terrestrial habitats, tropical regions are typically rich whereas polar regions...

  • Effects of global warming
    Effects of global warming
    This article is about the effects of global warming and climate change. The effects, or impacts, of climate change may be physical, ecological, social or economic. Evidence of observed climate change includes the instrumental temperature record, rising sea levels, and decreased snow cover in the...

  • Holocene extinctions (category)
  • List of extinct animals
  • List of extinct plants
  • Timeline of extinctions
    Timeline of extinctions
    The timeline of extinctions is an historical account of species that have gone extinct during the time that modern humans have occupied the earth....



External links

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