人类世开始的标志

One way to view the history of science is as a repeated puncturing of humanity’s claims to be special.

看待科学史的一种方式是把它看作是对人类声称自我特殊性的一再戳穿。

In scientific terms Homo sapiens is an oddly hairless species of ape that has existed for 200,000 years—an eyeblink in Earth’s 4.5bn-year history.

用科学术语来说,智人是一种奇怪的无毛猿类,已经存在了20万年——不过在地球45亿年的历史中只是一眨眼的功夫。

For the past couple of decades, though, some scientists have been arguing that perhaps humans do deserve a bit of special recognition after all.

然而,在过去的几十年里,一些科学家一直在争论,也许人类的确应该得到一些特殊的认可。


In 2000 Paul Crutzen, a Dutch meteorologist and chemist, suggested that human influence over Earth was sufficiently profound that its effects would remain visible in the geological record for millions of years.

2000年,荷兰气象学家和化学家保罗·克鲁岑提出,人类对地球的影响非常深远,其影响将在数百万年的地质记录中保持可见。

For that reason, he argued, it was time to bring down the curtain on the Holocene—the current geological epoch, which has lasted for the past 12,000 years or so—and ring in a new one: the Anthropocene.

基于这个原因,他认为,是时候为持续了大约12000年的全新世——目前的地质时代划上句号,并且开启一个新的时代:人类世。

The idea quickly caught on.

这个想法很快就流行起来。

In 2016 the Anthropocene Working Group (awg), an appendage of the International Union of Geological Sciences (iugs), voted in favour of adopting it in principle.

2016年,国际地质科学联合会的附属机构,人类世工作组投票赞成在原则上采用这一标准。

And on July 11th it suggested a precise geological feature, dating back to the 1950s, that could mark the Anthropocene’s beginning.

7月11日,它提出了一个精确的地质特征,可以追溯到20世纪50年代,这可能标志着人类世的开始。

The committee recommended bestowing the honour upon sediments laid down at the bottom of Crawford Lake, a flooded sinkhole about 20 miles from Toronto.

委员会建议将这一荣誉授予克劳福德湖底的沉积物,克劳福德湖底是一个被洪水淹没的天坑,距离多伦多约20英里。

The beginning of the Holocene was marked by a natural warming of the climate and the retreat of the world’s ice sheets.

全新世开始的标志是气候的自然变暖和世界冰盖的缩减。

The idea behind the Anthropocene is that human activity has disturbed the planet on a similarly grand scale.

人类世背后的观点是,人类活动对地球造成了类宏大规模的干扰。

Humans have boosted the concentration of carbon dioxide in the atmosphere by about half in the past 250 years, to its highest level in around 3m years.

在过去的250年里,人类使大气中的二氧化碳浓度增加了大约一半,达到了300万年来的最高水平。

That spike will be clearly visible to geologists 100,000 years from now, assuming any exist, and may have delayed the start of the next ice age by tens of thousands of years.

假设它在10万年后仍然存在的话,那时的地质学家将清晰地发现这个尖峰,它可能将下一个冰河时代的开始推迟数万年。


There are markers besides climate change, too.

除了气候变化之外,还有其他标志。

Microplastics in oceans and rivers are laying down sedimentary layers of chemicals never seen before in nature.

海洋和河流中的微塑料正在沉积为化学物质层,这在自然界中从未被发现过。

Nitrogen fertilisers have altered the balance of chemical isotopes in peat bogs.

氮肥改变了泥炭沼泽中化学同位素的平衡。

The world is in the midst of a mass extinction.

世界正处于大灭绝之中。

At the same time shipping and air travel have scattered much of the remaining flora and fauna far from where they evolved.

与此同时,航运和航空旅行使许多现存的动植物远离了它们进化的地方。

Both the extinction and the redistribution will be visible when what is alive today joins the fossil record of the past.

当今天活着的生物与过去的化石记录结合在一起时,灭绝和重新分布都将同时可见。

The iugs’s rules say that geological transitions must be marked not just by a particular event, but by a specific alteration in a specific geological feature.

国际地质勘探局的规则指出,地质变迁不仅要以某一特定事件为标志,还要以某一特定地质特征的特定变化为标志。

(For instance, the start of the Edicarian period, 635m years ago, is defined by a visible change in a band of exposed rocks in southern Australia.)

(例如,6.35亿年前伊迪卡利亚时期的开始,是由澳大利亚南部裸露岩石带的明显变化确定的。)

The awg’s announcement marked the end of a years-long search for a suitable marker for the Anthropocene.

人类世工作组的宣布标志着长达数年的寻找人类世合适标志工作的结束。

Scientists examined sites from the estuaries of San Francisco to the sediment beneath Vienna’s main square, before settling on Crawford Lake.

科学家们考察了从旧金山河口到维也纳主要广场下的沉积物,最后选定了克劳福德湖。

The lake has several advantages.

这个湖有几个优点。

Every summer, as the surface waters warm, flakes of calcium carbonate precipitate out and drift to the bottom.

每年夏天,随着表层海水变暖,碳酸钙薄片沉淀出来,沉向海底。

There they form regular white bands amid the sediments, much like age rings in trees.

它们在沉积物中形成规则的白色带,很像树木的年轮。

The sediments themselves lie deep enough that they remain undisturbed by the wind and waves above.

沉积物本身埋藏得足够深,不受上面风浪的干扰。

They therefore contain records, in date order, of everything from CO2 concentrations to particles of plutonium from the explosions of nuclear weapons, the first of which happened in 1945.

因此,它们按日期顺序包含了从二氧化碳浓度到核武器爆炸产生的钚颗粒的所有记录,第一次核武器爆炸发生在1945年。

Indeed, the awg has proposed that the subsequent spike in plutonium—an element which was vanishingly rare before the atomic age—should serve as the “primary marker” for the beginning of the Anthropocene.

事实上,人类世工作组已经提出,钚(一种在原子时代之前非常罕见的元素)随后的峰值应该作为人类世开始的“主要标志”。

Not everyone is convinced, for plutonium is unstable.

并不是所有人都相信这一点,因为钚是不稳定的。

The isotopes that the awg have in mind have half-lives of 6,500 and 24,000 years, meaning almost all the plutonium will be gone within 200,000 years.

人类世工作组所考虑的同位素的半衰期分别为6500年和24000年,这意味着几乎所有的钚都将在20万年内消失。

Dissidents suggest that fly ash from fossil-fuel combustion would make a better alternative.

唱反调者认为化石燃料燃烧产生的粉煤灰是更好的替代品。

Like plutonium, it is not something that the planet has seen before.

就像钚一样,这是地球上以前从未见过的东西。

And unlike plutonium, it will, if left undisturbed, hang around in the rocks for many millions of years to come.

与钚不同的是,如果不受干扰,它将在未来数百万年里在岩石中徘徊。

来源:经济学人

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