Holocene extinction

The Holocene extinction, also referred to as the Anthropocene extinction^[3][4] or the sixth mass extinction,^[5][6] is an ongoing extinction event caused exclusively by human activities during the Holocene epoch.^[7][8] This extinction event spans numerous families of plants^[9][10][11] and animals, including mammals, birds, reptiles, amphibians, fish, and invertebrates, impacting both terrestrial and marine species.^[12] Widespread degradation of biodiversity hotspots such as coral reefs and rainforests has exacerbated the crisis. Many of these extinctions are undocumented, as the species are often undiscovered before their extinctions.

Current extinction rates are estimated at 100 to 1,000 times higher than natural background extinction rates^{[13][14][15][16][17]} and are accelerating.^[18] Over the past 100–200 years, biodiversity loss has reached such alarming levels^[14] that some conservation biologists now believe human activities have triggered a mass extinction,^[19][20] or are on the cusp of doing so.^[21][22] As such, after the "Big Five" mass extinctions, the Holocene extinction event has been referred to as the sixth mass extinction.^[23][24][25] However, given the recent recognition of the Capitanian mass extinction, the term seventh mass extinction has also been proposed.^[26][27]

The Holocene extinction was preceded by the Late Pleistocene megafauna extinctions (lasting from 50,000 to 10,000 years ago), in which many large mammals – including 81% of megaherbivores – went extinct, a decline attributed at least in part to human (anthropogenic) activities.^[28][29] There continue to be strong debates about the relative importance of anthropogenic factors and climate change, but a recent review concluded that there is little evidence for a major role of climate change and "strong" evidence for human activities as the principal driver.^[30] Examples from regions such as New Zealand, Madagascar, and Hawaii have shown how human colonization and habitat destruction have led to significant biodiversity losses.

In the 20th century, the human population quadrupled, and the global economy grew twenty-five-fold.^[31][32] This period, often called the Great Acceleration, has intensified species' extinction.^[33][34] Humanity has become an unprecedented "global superpredator",^[35] preying on adult apex predators, invading habitats of other species,^[36] and disrupting food webs.^[37] As a consequence, many scientists have endorsed Paul Crutzen's concept of the Anthropocene to describe humanity's domination of the Earth.

The Holocene extinction continues into the 21st century, driven by anthropogenic climate change, human population growth,^{[38][39][40][41]} and increasing consumption^[14][42]—particularly among affluent societies.^[43][44][45] Factors such as rising meat production,^{[46][47][48][49][50][51]} deforestation,^[46] and the destruction of critical habitats compound these issues. Other drivers include overexploitation of natural resources, pollution, and climate change-induced shifts in ecosystems.

Major extinction events during this period have been recorded across all continents, including Africa, Asia, Europe, Australia, North and South America, and various islands. The cumulative effects of deforestation, overfishing, ocean acidification, and wetland destruction^[52] have further destabilized ecosystems. Decline in amphibian populations,^[53] in particular, serves as an early indicator of broader ecological collapse.

Despite this grim outlook, there are efforts to mitigate biodiversity loss. Conservation initiatives, international treaties, and sustainable practices aim to address this crisis. However, these efforts do not counteract the fact that human activity still threatens to cause large amounts of damage to the biosphere, including potentially to the human species itself.