The human-dominated geological epoch known as the Anthropocene probably began around the year 1610, with an unusual drop in atmospheric carbon dioxide and the irreversible exchange of species between the New and Old Worlds, according to new research published in Nature.
Previous epochs began and ended due to factors including meteorite strikes, sustained volcanic eruptions and the shifting of the continents. Human actions are now changing the planet, but are we really a geological force of nature driving Earth into a new epoch that will last millions of years?
Scientists at UCL have concluded that humans have become a geological power and suggest that human actions have produced a new geological epoch.
Defining an epoch requires two main criteria to be met. Long-lasting changes to the Earth must be documented. Scientists must also pinpoint and date a global environmental change that has been captured in natural material, such as rocks, ancient ice or sediment from the ocean floor. Such a marker – like the chemical signature left by the meteorite strike that wiped out the dinosaurs – is called a golden spike.
The study authors systematically compared the major environmental impacts of human activity over the past 50,000 years against these two formal requirements. Just two dates met the criteria: 1610, when the collision of the New and Old Worlds a century earlier was first felt globally; and 1964, associated with the fallout from nuclear weapons tests. The researchers conclude that 1610 is the stronger candidate.
The scientists say the 1492 arrival of Europeans in the Americas, and subsequent global trade, moved species to new continents and oceans, resulting in a global re-ordering of life on Earth. This rapid, repeated, cross-ocean exchange of species is without precedent in Earth’s history.