We assess, using extremely conservative assumptions, whether human activities are causing a mass extinction. Earlier estimates of extinction rates have been criticized for using assumptions that might overestimate the severity of the extinction crisis. The oft-repeated claim that Earth’s biota is entering a sixth “ mass extinction†depends on clearly demonstrating that current extinction rates are far above the “background†rates prevailing between the five previous mass extinctions. Averting a dramatic decay of biodiversity and the subsequent loss of ecosystem services is still possible through intensified conservation efforts, but that window of opportunity is rapidly closing.Īccelerated modern human–induced species losses: Entering the sixth mass extinctionĬeballos, Gerardo Ehrlich, Paul R. ![]() These estimates reveal an exceptionally rapid loss of biodiversity over the last few centuries, indicating that a sixth mass extinction is already under way. Under the 2 E/MSY background rate, the number of species that have gone extinct in the last century would have taken, depending on the vertebrate taxon, between 800 and 10,000 years to disappear. Even under our assumptions, which would tend to minimize evidence of an incipient mass extinction, the average rate of vertebrate species loss over the last century is up to 100 times higher than the background rate. The latter is conservatively low because listing a species as extinct requires meeting stringent criteria. ![]() We then compare this rate with the current rate of mammal and vertebrate extinctions. First, we use a recent estimate of a background rate of 2 mammal extinctions per 10,000 species per 100 years (that is, 2 E/MSY), which is twice as high as widely used previous estimates. ![]() The oft-repeated claim that Earth's biota is entering a sixth " mass extinction" depends on clearly demonstrating that current extinction rates are far above the "background" rates prevailing between the five previous mass extinctions. Our results confirm that current extinction rates are higher than would be expected from the fossil record, highlighting the need for effective conservation measures.Īccelerated modern human-induced species losses: Entering the sixth mass extinction.Ĭeballos, Gerardo Ehrlich, Paul R Barnosky, Anthony D GarcÃa, Andrés Pringle, Robert M Palmer, Todd M Here we review how differences between fossil and modern data and the addition of recently available palaeontological information influence our understanding of the current extinction crisis. Biologists now suggest that a sixth mass extinction may be under way, given the known species losses over the past few centuries and millennia. Palaeontologists characterize mass extinctions as times when the Earth loses more than three-quarters of its species in a geologically short interval, as has happened only five times in the past 540 million years or so. Has the Earth's sixth mass extinction already arrived?īarnosky, Anthony D Matzke, Nicholas Tomiya, Susumu Wogan, Guinevere O U Swartz, Brian Quental, Tiago B Marshall, Charles McGuire, Jenny L Lindsey, Emily L Maguire, Kaitlin C Mersey, Ben Ferrer, Elizabeth A ![]() The oft-repeated claim that Earth?s biota is entering a sixth ? mass extinction? depends on clearly demonstrating that current extinction rates are far above the ?background? rates prevailing between the five previous mass extinctions. 2004 …Īccelerated modern human?induced species losses: Entering the sixth mass extinctionĬeballos, Gerardo Ehrlich, Paul R. 2008 Steffen, Crutzen, and McNeill 2007 Thomas et al. Humanity is currently in the midst of a sixth, human-induced great mass extinction of plant and animal life (e.g., Alroy 2008 Jackson 2008 Lewis 2006 McDaniel and Borton 2002 Rockstrom et al. Five past great mass extinctions have occurred during Earth's history.
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