Official recognition for the Anthropocene would focus minds on the challenges to come.
Geologists are used to dealing with heavy subjects, so who better to decide on one of the more profound debates of the time: does human impact on the planet deserve to be officially recognized? Are we living in a new geological epoch — the Anthropocene?
This is no idle conundrum. Although the term has long been used informally to refer to the current, human-dominated phase of Earth's history, a working group of the International Commission on Stratigraphy, the body that defines the divisions of geological time, is studying the case for making it official (see Nature 473, 133; 2011).
The Anthropocene would be a peculiar addition to the geological timescale. So far, it is more a prediction than a fact of Earth's history, because many of its defining features are only starting to register in the rock record. And the driving force behind the geological transition it labels is not a continental rearrangement, massive volcanism or an extraterrestrial impact — forces that have reshaped the planet in the past. Yet the Anthropocene does deserve proper recognition. It reflects a grim reality on the ground, and it provides a powerful framework for considering global change and how to manage it.
Human activity is set to leave an indelible mark on the geological record. Deforestation, mining and road building have unleashed tides of sediment down rivers and onto the ocean floor. Fossil-fuel use and land clearance have already emitted perhaps a quarter as much carbon into the atmosphere as was released during one of the greatest planetary crises of the past, the Palaeocene–Eocene Thermal Maximum 55 million years ago. Now, as then, corals and other organisms are recording a global carbon-isotope shift. The increasing acidification of the oceans as they absorb carbon dioxide will dissolve carbonate from deep sediments, and what is likely to be the sixth great mass extinction in Earth's history will gather speed, adding vivid new markers to the record.
But is it too soon to declare an end to the Holocene, the stable, largely benign epoch that has lasted just 11,700 years — a heartbeat in geological time? What impact will an official change in the geological timescale have on the funding and status of Holocene studies? And is it wise for stratigraphers to endorse a term that comes gift-wrapped as a weapon for those on both sides of the political battle over the fate of the planet?
The scale of the changes already under way and the real value of a unified approach to studying human influences on the planet should surely quash these concerns. The Anthropocene is defined not just by climate change or extinctions, but by a linked set of effects on Earth and its biosphere, from perturbations in the nitrogen cycle to the dispersal of species around the globe. Official recognition of the concept would invite cross-disciplinary science. And it would encourage a mindset that will be important not only to fully understand the transformation now occurring but to take action to control it.
Humans may yet ensure that these early years of the Anthropocene are a geological glitch and not just a prelude to a far more severe disruption. But the first step is to recognize, as the term Anthropocene invites us to do, that we are in the driver's seat.