Scientists recently determined that when humans began testing nuclear weapons on Earth's surface, a new geological age began, the Anthropocene age.
Scientists now believe that hundreds and thousands of years from now, future generations of scientists will look at sediment on Earth and be able to pinpoint the beginning of that age somewhere between the 1940s and 1960s because the use of nuclear weapons during that time left its mark on the planet's surface.
Researchers note that this time period also coincides with a "great acceleration" of human population, economic development and industrialization. Cities became bigger than ever, meaning that we used more minerals to make more concrete. Already, sediment deposits all over the world see less of these minerals, and as a result of that, and other human interference, we've also seen more species face extinction.
Combine all that with the testing of nuclear weapons during the mid-twentieth century, and these scientists believe that this time period marks the beginning of a new geological age on Earth, an ongoing age where humans continue to make alterations to the planet.
The most important question for researchers, though, is when did this start? This group of researchers believes that the dawn of the nuclear weapon is a good answer because the fallout from that testing resulted in changes in Earth's sediment that will be evident to scientists hundreds of thousands of years in the future.
Beginning with the first detonation of a nuclear weapon in New Mexico in 1945, fallout from nuclear testing resulted in an abundance of plutonium-239, an isotope not often found in nature. However, it remains in sediments up to 100,000 years, long enough for generations of future scientists to see it as a defining moment in Earth's geological history.
"It is sobering to think that the actions of humanity over a few short years in the mid-20th century created such large amounts of artificial radionuclides that scattered across the Earth as fallout, producing a signal in modern strata that, in the case of plutonium, will be a detectable for about 100,000 years into the future," says Dr. Colin Waters of the British Geological Survey.
Fortunately, the Partial Nuclear Test-Ban Treaty banned above ground testing in 1962, but 20 years of such testing left its mark on the planet.
Scientists hope that they can take this potential marking of the beginning of the Anthropocene age and have it formalized, perhaps making its way into future textbooks for students of Earth's geological history.
"The Anthropocene has struck a chord in the wider world that none of the other geological time units have done - not even the dinosaur-haunted Jurassic," says Professor Jan Zalasiewicz of the University of Leicester. "Human beings don't merely inhabit the world. They alter it, on an increasingly epic scale."
[Photo Credit: Ed Uthman | Flickr]