Leaving Our Mark: The Age of Humans

Humanity is literally changing the face of the Earth with actions like global warming, pollution and deforestation, so much so that scientists are considering naming the time we live in "the Anthropocene"- the age of humans.

The past 12,000 years are referred to as the Holocene - Greek for "entirely recent" - but experts think that the time period should be coined Anthropocene, given the way humans are altering the planet, especially in terms of climate.

"Never in its 4.6 billion-year-old history has the Earth been so affected by one species as it is being affected now by humans," W. John Kress, acting undersecretary of science for the Smithsonian, told The Associated Press (AP).

The new word, a combination of the scientific and cultural, seems to only give humans a bad rep. It considers not just climate change, but ozone loss, ocean acidification, deforestation, and a host of other factors as well.

For example, "Probably in the late part of the last century, humans became responsible for moving more soil or rock than natural agencies," geographer Tony Brown told the Smithsonian. "We've increased erosion rates in most parts of the world, but we've also trapped a lot of sediments, because we've dammed most of world's really big rivers."

The International Union of Geological Sciences' Commission on Stratigraphy - the ruling body that decides where a geologic age begins - is considering making the Anthropocene name official. Although changes will likely not come into place for a while - the last effort to name an era, the Ediacaran period some 600 million years ago, took about 15 years.

At the heart of the debate is when this human age actually began. Some say at the start of agriculture, while others suggest the Industrial Revolution or the use of the atomic bomb, according to the AP. Other issues are that the suffix "cene" usually signals an epoch spanning tens of millions of years, or an age - like the Holocene - that's millions of years long. Some believe a different, smaller unit would be more appropriate.

Regardless of its boundaries, it's obvious that humans, who arrived only recently on the geologic time scale, are drastically changing our planet - so much so that it's even unmistakable from space.

"We're changing the Earth. There is no question about that, I've seen it from space," astronaut John Grunsfeld told the AP.

"Humans are profoundly affecting the environment, probably as much as natural events have in the past," added Hap McSween, president of the Geological Society of America. "And when effects become profound enough, we draw a new boundary and make it a period. ... It's a good way to point out the environmental havoc that humans are causing."