A new study worked to define the Earth's epochs and pinpoint when exactly the human reign over the planet began.
The human-dominated epoch, dubbed the Anthropocene, is believed to have started around the year 1610 and was characterized by a drop in atmospheric carbon dioxide, University College London reported. The start and finish of most previous epochs were believed to have been prompted by events such as meteorite strikes and volcanic eruptions, and many worry human actions may be driving the planet into a new epoch.
The defining of an epoch requires two major criteria: documentation of long-lasting changes to our planet, and changes in the global environment evident in natural material such as rock. To make their findings the researchers compared human impacts on the environment over the past 50,000 years with these two main requirements. The only two dates that proved to meet this criteria were 1610 ( the collisions the New and Old worlds), and 1964 (the fallout from nuclear weapons tests); the researchers believed 1610 is the stronger candidate.
The research team argued that the joining of the northern and southern hemispheres re-ordered life on Earth in a way that has never been seen before, setting the Earth on a new path. The team noted a drop in atmospheric carbon that they believe is a direct result of the arrival of Europeans in the Americas. Colonization of the news world killed about 50 million indigenous people as a result of the spread of smallpox. This led to an abrupt and dramatic decrease in farming across Latin America. The first pollen maize was also seen in the region in the 1600s, marking a permanent change in species population.
"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," said lead author Simon Lewis of the University of Leeds.
The beginning of the Industrial Revolution, which started in the 18th century, has been suggested to be the start of the Anthropocene. This period was characterized by a steep rise in atmospheric carbon dioxide as a result of coal burning, leading to long-term environmental changes. The researchers do not believe this was the start of the epoch because the effects were too localized, and the global rise in CO2 has been too "smooth" to be precisely dated.
"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. 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," said co-author, geologist Professor Mark Maslin of UCL Geography.
The findings were published in a recent edition of the journal Nature.
