The sixth mass extinction¹ of life on Earth is unfolding more quickly than feared, scientists have warned.

科学家们警告称，全球野生动物“第六次大灭绝”的速度比预期的还要快。

More than 30 percent of animals with a backbone² - fish, birds, amphibians³, reptiles⁴ and mammals - are declining in both range and population, according to the first comprehensive analysis of these trends.

对动物灭绝趋势的首个全面分析结果显示，超过30%的脊椎动物，例如鱼类、鸟类、两栖动物、爬行动物以及哺乳动物等，它们的种类和数量都在减少。

"This is the case of a biological annihilation occurring globally," said Stanford professor Rodolfo Dirzo, co-author of a study published last Monday in the peer-reviewed US journal, Proceedings⁵ of the National Academy of Sciences.

这一研究结果近日在同行评审期刊《美国国家科学院院刊》上发表，该报告的合著者斯坦福大学教授鲁道夫?狄尔佐说：“这就是全球性生物大灭绝的现状。”

Around a decade ago, experts feared that a new planetary wipeout of species was looming⁶.

专家们在大约十年前就预料到新一阶段的全球性生物大灭绝即将到来。

Today, most agree that it is underway - but the new study suggests that the die-out is already ratcheting up a gear.

现在多数专家都一致认为生物灭绝已经开始，但是新的研究表明，生物灭绝已经加快了速度。

It provides much-needed data about the threat to wildlife, mapping the dwindling⁷ ranges and populations of 27,600 species. For 177 mammals, researchers combed through data covering the period 1900 to 2015.

研究中提供了威胁野生物种的重要数据，绘制出了27600种生物种类和数量下降的分布图。其中，研究人员专门针对177种哺乳动梳理出了1900年至2015年间的数据。

The mammal species that were monitored have lost at least a third of their original habitat, the researchers found.

研究人员发现，他们所观测的这些哺乳动物已经失去了至少三分之一的原始栖息地。

Forty percent of them - including rhinos⁸, orangutans, gorillas⁹ and many big cats - are surviving on 20 percent or less of the land they once roamed.

包括犀牛、猩猩、大猩猩以及大型猫科动物等在内的40%的哺乳动物，现在的活动区域仅为它们原有栖息地的20%或者更小。

The loss of biodiversity has recently accelerated.

生物多样性的减少最近也加速了。

"Several species of mammals that were relatively¹⁰ safe one or two decades ago are now endangered," including cheetahs¹¹, lions and giraffes, the study showed.

研究显示，包括猎豹、狮子以及长颈鹿在内的数种哺乳动物“在一二十年前还相对安全，然而现在处于濒危状态。”

Globally, the mass die-off - deemed to be the sixth in the last half-billion years - is the worst since three-quarters of life on Earth, including the non-avian dinosaurs¹², were wiped out 66 million years ago by a giant meteor impact.

6600万年前，由于一颗巨大陨石撞击地球，包括非鸟翼类恐龙在内，地球上四分之三的生物都遭到灭绝。这次全球性生物灭绝被认为是五亿年以来第六次生物大灭绝，而且是自恐龙灭绝以来最严重的。

There is no mystery as to why: our own ever-expanding species - which has more than doubled in number since 1960 to 7.4 billion - is eating, crowding and polluting its planetary cohabitants out of existence.

引发生物大灭绝的原因显而易见：人类不断繁衍壮大，人口达到74亿，相比1960年不止翻了一番。人们以动物为食，并把动物们挤出家园，同时还污染环境，让动物们无法生存。

By comparison, there are as few as 20,000 lions left in the wild, less than 7,000 cheetahs, 500 to 1,000 giant pandas and about 250 Sumatran rhinoceros¹³.

相比之下，在野外生活的狮子只剩下20000只，猎豹只有不到7000只，大熊猫只剩下500到1000只，苏门答腊犀牛也只有250头左右。

The main drivers of wildlife decline are habitat loss, overconsumption, pollution, invasive species, disease, as well as poaching in the case of tigers, elephants, rhinos and other large animals prized for their body parts.

野生动物减少的主要原因有：失去栖息地、人类过度消耗、环境污染、物种入侵、感染疾病以及偷猎活动（因为老虎、大象、犀牛以及其他大型动物的一些身体部位价值连城）。

Climate change is poised¹⁴ to become a major threat in the coming decades, with some animals - most famously polar bears - already in decline due to rising temperatures and changing weather patterns.

气候变化在未来的几十年将成为生物灭绝的主要威胁因素。由于气温升高，天气模式变化，一些动物——比如最著名的北极熊——已经减少。

"The massive loss of populations and species reflects our lack of empathy to all the wild species that have been our companions since our origins," said lead author Gerardo Ceballos of the National Autonomous¹⁵ University of Mexico.

“野生动物自古是人类的朋友，从数量和物种的大幅下降可以看出，我们缺少对这些动物的怜悯之情，”墨西哥国立自治大学的首席作者热拉尔多?塞巴洛斯说。

Beyond any moral imperative¹⁶, there are practical reasons to rue¹⁷ the eclipse of animals, whether megafauna or smaller and less "charismatic" creatures, the researchers said.

研究人员们说，无论是巨型动物、小型动物还是那些不太“有魅力”的动物，我们对它们的灭绝懊悔不仅仅是出于道德责任，还有更实际的原因。

The vanishing of a top-level carnivore or herbivore can have a cascading¹⁸ effect down the food chain, disrupting entire ecosystems¹⁹.

顶级肉食动物和食草动物如果消失，那么就会对下层的食物链产生级联效应，进而摧毁整个生态系统。

Other species directly provide "services" to humans, such as honeybees that pollinate crops or birds that ensure pest control.

其他物种还直接“服务”于人类，比如蜜蜂给庄稼传授花粉，小鸟吃害虫。

Previous studies show that ecosystems under stress, while resilient, have a breaking point - rapid change can lead to collapse²⁰.

既有的研究表明，在压力下的生态系统，即使有自我恢复能力，它也是有极限的。物种急剧的变化能让生态系统彻底崩溃。