Is the Anthropocene real? That is, the vigorously debated concept of a new geological epoch driven by humans.

Our environmental impact is indeed profound – there is little debate about that – but is it significant on a geological timescale, measured over millions of years? And will humans leave a distinctive mark upon the layers of rocks that geologists of 100,000,000AD might use to investigate the present day?

Together with other members of the Anthropocene Working Group we’ve just published a study in Science that pulls much of the evidence together.

The case for the Anthropocene might be distilled into five strands:

1. Carbon in the atmosphere

Carbon is important, both due to its growing impact on global warming and because it leaves long-lived geological traces. The increased levels of carbon dioxide in the atmosphere – now higher than at any time in at least the past few million years – can be found as fossil bubbles in the geologically short-lived “rock” that is polar ice.

But there are wider and more long-lived traces too, in the form of changed patterns of carbon isotopes (absorbed by every living thing) and in tiny, […]