Accelerated modern human-induced species losses: Entering the sixth mass extinction.
Accelerated modern human-induced species losses: Entering the sixth mass extinction.
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DOI：
10.1126/sciadv.1400253
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发表时间：
2015-06
期刊：
影响因子：
13.6
通讯作者：
Palmer TM
中科院分区：
文献类型：
--
作者：
Ceballos G;Ehrlich PR;Barnosky AD;García A;Pringle RM;Palmer TM
人类正在导致6500万年来没有先例的大规模动物灭绝。经常重复的说法是，地球生物群正在进入第六次“大灭绝”，这取决于清楚地表明，目前的灭绝率远远高于前五次大灭绝之间的“背景”率。早期对灭绝率的估计因使用可能高估灭绝危机严重性的假设而受到批评。我们使用非常保守的假设来评估人类活动是否导致了大规模灭绝。首先，我们使用最近的估计，每100年每10,000个物种2个哺乳动物灭绝的背景率（即2 E/MSY），这是以前广泛使用的估计的两倍。然后我们将这一速度与当前哺乳动物和脊椎动物的灭绝速度进行比较。后者是保守的低，因为将一个物种列为灭绝物种需要满足严格的标准。即使在我们的假设下，这将倾向于减少早期大规模灭绝的证据，在过去的世纪，脊椎动物物种损失的平均速度高达100倍以上的背景速度。在2 E/MSY的背景速率下，根据脊椎动物分类单元的不同，上个世纪灭绝的物种数量需要800到10，000年才能消失。这些估计显示，在过去几个世纪里，生物多样性的丧失异常迅速，这表明第六次大规模灭绝已经开始。通过加强保护工作，仍然有可能避免生物多样性急剧衰减以及随之而来的生态系统服务丧失，但这一机会之窗正在迅速关闭。
Humans are causing a massive animal extinction without precedent in 65 million years. 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. Earlier estimates of extinction rates have been criticized for using assumptions that might overestimate the severity of the extinction crisis. We assess, using extremely conservative assumptions, whether human activities are causing a mass extinction. 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. We then compare this rate with the current rate of mammal and vertebrate extinctions. The latter is conservatively low because listing a species as extinct requires meeting stringent criteria. 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. 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. These estimates reveal an exceptionally rapid loss of biodiversity over the last few centuries, indicating that a sixth mass extinction is already under way. 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.