Welcome to the Anthropocene

There’s nothing like looking at a timeline of Earth’s history to remind oneself that, relatively speaking, humans haven’t been around for very long. But while humans have only roamed the planet for a miniscule fraction of the planet’s 4.5 billion year history, geologists and paleontologists have learned an awful lot about different times in the ancient past. They’ve segmented time on Earth according to major events or changes that took place, such as mass extinctions or beginnings of ice ages. These events created periods of time so distinct that the effects can still be seen in layers of rock today. For example, the past 12,000 years of Earth's history are described as the Holocene epoch.

Scientists say that modern human influence is sending the planet into a new geological epoch — the “Anthropocene.” Credit: YiFan Photography/iStock

Now, many scientists insist that recent human activity, beginning about 250 years ago, is having such a significant environmental impact on the Earth’s climate, geography, and biological composition that we have actually entered into a new period of geologic time. That means this change to the “age of man” — or the “Anthropocene” epoch — could be distinctly recognizable when future geologists sift through tiered cakes of rock thousands of years from now.

Nobel prize-winning chemist Paul Crutzen brought the idea of the Anthropocene into the scientific spotlight in 2002 (Crutzen is famous for having studied atmospheric chemistry relating to the hole in the ozone layer), but it is not yet an accepted term in geology vernacular. However, in the March 2011 issue of the Philosophical Transactions of the Royal Society A, a group of researchers are attempting to make the case that the profound human-driven impacts on the planet in recent years fit the criteria for a new geological distinction.

In this month’s issue of National Geographic magazine, journalist Elizabeth Kolbert writes about the Anthropocene, and she points out that it is surprising which kinds of human behavior are expected to have the longest-lasting impacts (from a geologic perspective, at least). The skyscrapers, the highways, and the suburban sprawl?

None of these are likely to leave as indelible a mark as the increasing concentration of carbon dioxide in the atmosphere, which is causing global climate change, sea level rise, and ocean acidification. And though deforestation is rapidly transforming vast swaths of the planet’s landscape today, Kolbert points out that the most serious and noticeable consequence of this in the future could be a mass extinction event caused by the clear-cut. It may be thousands of years before our particular era can be truly verified as a new epoch, but scientists say the measurable transformations that are happening now are so rapid and distinct they make this time a good candidate for a name change. And if nothing else, some say that adopting the Anthropocene name will raise awareness of the fact that humans are having enduring affect on the planet.

If you can’t fathom parsing through the 13 peer-reviewed journal articles in Philosophical Transcations A, Kolbert’s take on the Anthropocene is certainly a worthwhile read.