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Scientists Pinpoint Exact Date When Humans Began to Dominate Earth

Mar 12, 2015 12:57 PM EDT

(Photo : Pixabay)

It has long been suggested that our impact on the planet is so substantial that it grants its own new geological epoch - known as the Anthropocene. While the beginning of this new era has been heatedly debated, one group of scientists believes it has finally pinpointed the exact date of when humans began to dominate the Earth.

The year was 1610, when the effects of the collision between the New and Old Worlds, which occurred a century earlier, were first felt around the globe. That is, there was an unusual drop in atmospheric carbon dioxide (CO2) as well as an irreversible exchange of species during this time.

Previous research has argued for other ideas as to when the Anthropocene, or age of humans, actually began, ranging from the start of agriculture thousands of years ago to the Industrial Revolution - or possibly its beginning hasn't even arrived yet, with the greatest human-made changes yet to come. Another strong contender was July 16, 1945 - the dawn of the nuclear era.

However, researchers from the University College London (UCL) suggest that 1610 is the rightful start of the Anthropocene.

But how do we know that humans are actually a strong enough force to push the Earth into a new epoch - one that will supposedly last for millions of years? Previous epochs began and ended due to drastic phenomena such as meteorite strikes, sustained volcanic eruptions and the shifting of the continents. But the collision of the New and Old Worlds was just as cataclysmic, according to the researchers.

When Europeans arrived in the Americas in 1492, subsequent global trade moved species to new continents and oceans, resulting in a global re-ordering of life on Earth. For example, maize, a Latin American species, first showed up in Europe in 1600 and became more abundant there in later centuries. Such long-term changes satisfy one criterion of what makes a new epoch.

In addition, the team found a "golden spike" that can be dated to the same time - that is, a natural marker of when a global environmental change occurred. That marker is a pronounced dip in atmospheric CO2 in 1610, as evidenced by Antarctic ice-core records, and is a direct result of the arrival of Europeans in the Americas. (Scroll to read on...)

(Photo : Flickr: Ian MacKenzie)

"In a hundred thousand years scientists will look at the environmental record and know something remarkable happened in the second half of the second millennium. They will be in no doubt that these global changes to Earth were caused by their own species. Today we can say when those changes began and why. The Anthropocene probably began when species jumped continents, starting when the Old World met the New. We humans are now a geological power in our own right - as Earth-changing as a meteorite strike," lead author, Dr. Simon Lewis said in a statement.

So what specifically caused this Earth-altering dip in CO2? According to Lewis and his colleagues, when Europeans colonized the New World, they killed about 50 million indigenous people by spreading disease such as smallpox. This meant that just within a few decades - an extremely short period of time - farming across the continent stopped and forests were able to re-grow, removing enough CO2 from the air to produce a dramatic drop.

But regardless of when it began and when it will end, there is no doubt that humans are leaving our mark, drastically changing our planet.

"A more wide-spread recognition that human actions are driving far-reaching changes to the life-supporting infrastructure of Earth will have implications for our philosophical, social, economic and political views of our environment," said study co-author Professor Mark Maslin, a geologist at UCL. "But we should not despair, because the power that humans wield is unlike any other force of nature, it is reflexive and therefore can be used, withdrawn or modified. The first stage of solving our damaging relationship with our environment is recognizing it."

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