A recent report in the journal Nature is proposing the year 1610 as the beginning of what has become known as the Anthropocene – literally, the Age of Man – a new epoch in the Earth's geological history in which the dominant agent of change is humanity.
That was when Europeans started coming in large numbers to the Americas, not just for exploration but for exploitation. It was the start of a trade movement that triggered the beginning of a global change that is as dramatic as the major shifts in the Earth's environment that have happened in the geological past.
The Anthropocene epoch is so dramatic, it will be visible millions of years from now as a layer in the Earth's crust.
The idea of a new epoch remains controversial, and is embraced by environmental scientists but largely rejected by geologists.
The term Anthropocene was coined in 1922 by Russian geologist Alexei Pavlov, who described the present time as an Anthropogenic System, referring to the human influence on the Earth's ecosystem. It was intended to be the latest in a long list of geologic time frames that have marked great changes in the Earth's history, such as the Cambrian, Jurassic or Pleistocene.
Scientists define these time periods by different layers of sedimentary rock, ice cores, tree rings or mud from the bottom of lakes. This geological calendar chronicles periods throughout the Earth's history when conditions on the planet were very different than what we experience today. They tell us how continents have moved, when animals on land and in the seas evolved, then became extinct.
Many of these shifts in the environment were from meteor impacts, volcanic eruptions and variations in solar activity that were so dramatic, they were literally felt around the world.
We know that today, another major extinction event is taking place, as species are disappearing at a rate that is greater than the one that eliminated the dinosaurs. At the same time, the climate is changing, vegetation is shifting around the globe – in fact, the very face of the planet is transforming – all because of human activity.
In other words, we are causing a global change on the same scale as the profound geological changes in the past, so our presence will remain in the Earth's geological record.
The question is, when did the Anthropocene actually begin?
Some have argued it should be at the emergence of agriculture, roughly 10,000 years ago, which began the transformation of the land. Others say it should be the beginning of the Industrial Revolution in the 1700s, when fossil fuels came into favour and began heating up the atmosphere.
The Pleistocene era lasted more than two million years, ending after the last Ice Age, 11,700 years ago, and coinciding with the extinction of many gigantic mammals, such as woolly mammoths in North America.
While these changes did eventually become global in their effect, they started in only certain parts of the planet.
That's why the year 1610 was chosen, because many different global changes happened at the same time. The arrival of Europeans in the Americas marked the beginning of global trade, where plants and animals were transported and transplanted between continents.
Disease brought by those Europeans killed roughly 50 million native Americans, who were mostly farmers. Their abandoned farmland was taken over by forest and jungle in such a growth spurt, it sucked carbon dioxide out of the atmosphere, a dip that can be seen today in ice cores. So, it was global trade that marks the beginning of the Anthropocene Epoch.
We are now in the Holocene era, but the last epoch before this – the Pleistocene – lasted more than two million years, ending after the last Ice Age, 11,700 years ago. It coincided with the extinction of many gigantic mammals, such as woolly mammoths in North America.
But there is one big difference this time. The Anthropocene was brought about by humans, not by an Ice Age, or a random rock falling from the sky. Which raises an interesting question: How will the Anthropocene end?
Will the extinction rate of species be so great that it will eventually include the human race, or will we be able to change the course of history towards a more sustainable existence?
If it is the former, then future scientists, who may be alien visitors, will discover the Anthropocene layer poking out of the side of a hill, along with bits of plastic, glass and artifacts of a once-great civilization. They may wonder how such a global catastrophe happened, when it was entirely preventable.
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