There’s no argument that humans have had a big impact on the earth. While those who advocate for more environmentally conscious practices would say that we’ve had more of a negative impact than others would. But now scientists are arguing about when we began to change the Earth with our actions — was it 10,000 years ago or only 50?
What age are we in?
The exact beginning of the age of man, also known as the Anthropocene epoch, is what’s in question, according to a new report published in the journal Science. An epoch is one of the measurements of the planet’s history.
Right now, it’s accepted that we’re living in the Holocene epoch and have been for 11,700 years. That began after the last ice age ended. But scientists are saying that we’ve moved into a new epoch and are looking for a clear geological boundary between the Holocene epoch and the Anthropocene epoch.
William Ruddiman, lead author of the new report who has worked as a paleoclimatologist at the University of Virginia, said the “anthropocene” title is an informal suggestion that would “allow room to recognize the millennia-long, rich history of anthropogenic changes.”
What would mark the beginning of the age of man?
Scientists are looking for geological evidence of when humans began to actually change the planet we inhabit. Scientific American wrote that human actions including hunting and burning, planting corn and wheat everywhere, ranching and herding, and clearing forests have contributed to changing the environment. Other more recent developments, like the industrial revolution and coal-burning, are possible starting points. These actions and when they began happening should be considered as scientists review when the new epoch may have begun.
Ruddiman even suggested that the start of the Anthropocene could be 11,000 years ago, when humans first started to cultivate crops.
“How can you define the Anthropocene as beginning in 1945 when most of the forests had been cut and most of the prairies had been plowed and planted?” Ruddiman said. “It just seems senseless to define the era of major human effects on Earth as beginning when huge chunks of that history had already happened.”
50 years or 400 years
A paper published in Nature in March examined nine possible start dates for the Anthropocene. Vox notes these possible dates:
One possibility is that the Anthropocene began around 50,000 years ago, when early human migration to North America began wiping out huge megafauna such as hairless mammoths and saber-toothed cats. Or perhaps it started around 11,000 years ago, at the dawn of agriculture. Or in 1492, when Christopher Columbus and subsequent European explorers initiated a massive exchange of plants and animals and diseases between the Old and New Worlds. Or in 1945 when the first atomic bomb was tested.
While the Science paper led by Ruddiman suggested a much earlier start date, the Nature paper focused in on two more recent dates: 1610 and 1964. According to the paper, greenhouse gas concentrations in the atmosphere dipped by 7 to 10 parts per million in 1610. This was caused by the growth of the Columbian Exchange, which brought new species into continents and led to the spread European diseases like smallpox. There was a dip in carbon dioxide as agriculture wasn’t doing as well and forests were re-growing. Such a dip is a good scientific marker for a new geological epoch. This was a time that changes in industry were felt across the world.
Now in 1964, radiation traces leftover from nuclear testing reached a peak. According to Vox, 1964 is also a year that falls in line with what some scientists have call the “Great Acceleration”: the last 50 years during which “economic and population growth really took off and technological advances accelerated.” This somewhat sudden acceleration will undoubtedly have an effect that will be more visible when we look back on it in the future.