经济学人下载:欢迎来到人类纪

The geology of the planet
地球的地质情况

Welcome to the Anthropocene
欢迎来到人类纪

Humans have changed the way the world works. Now they have to change the way they think about it, too
人类改变了世界运行方式，现在，人类不得不改变他们思考世界的方式

May 26th 2011 | from the print edition

THE Earth is a big thing; if you divided it up evenly among its 7 billion inhabitants, they would get almost 1 trillion tonnes each. To think that the workings of so vast an entity could be lastingly changed by a species that has been scampering across its surface for less than 1% of 1% of its history seems, on the face of it, absurd. But it is not. Humans have become a force of nature reshaping the planet on a geological scale—but at a far-faster-than-geological speed.

地球是个庞然大物。如果你把它均分给其间的70亿居民，每个人能分到近1万亿吨。表面看来，一个渺小的物种，生命不及地球的万分之一，在其表面跑跑跳跳竟能永久性地改变如此巨大实体的运行机制，想一想都是荒谬之事。不过确有其事。人类已经成为重塑地球地质年表的自然力量，其速度比地质构造自然演化的过程快得多。

A single engineering project, the Syncrude mine in the Athabasca tar sands, involves moving 30 billion tonnes of earth—twice the amount of sediment that flows down all the rivers in the world in a year. That sediment flow itself, meanwhile, is shrinking; almost 50,000 large dams have over the past half- century cut the flow by nearly a fifth. That is one reason why the Earth’s deltas, home to hundreds of millions of people, are eroding away faster than they can be replenished.

阿萨巴斯卡油砂的辛克鲁德矿是一个单一工程项目。该项目涉及移动300亿吨泥土——这一数字是地球上所有河流一年中流动的泥沙总量的两倍。与此同时，泥沙流本身也在逐渐消减。在过去半个世纪中，近50000个大型大坝截断近1/5的泥沙流。这也是为什么数以百万计人类的家园——三角洲地区泥沙补给速度不及侵蚀速度而呈现蚀退之势。