The results are in. After extensive research and debate a team of scientists has concluded that Earth has moved into a new geological epoch, the Anthropocene, and they've backdated its arrival to 1950.
This is the first geological epoch triggered by a lifeform and it turns out that was just one of countless thousands of species. It was us, you and me and the folks who came before us. That's why it's called the Anthropocene, because it's man-made.
The previous geological Epoch, the Holocene, lasted a mere 12,000 years. Before that, epochs lasted from 1.5 to 20 million years at a stretch. The Holocene, which I like to think of as the 'Heaven on Earth' epoch featured a relatively gentle climate perfectly suited to things such as the development of human civilization which, not surprisingly, it did. Then, not content with a good thing, we went ahead and rubbished it.
To define a new geological epoch, a signal must be found that occurs globally and will be incorporated into deposits in the future geological record. For example, the extinction of the dinosaurs 66m years ago at the end of the Cretaceous epoch is defined by a “golden spike” in sediments around the world of the metal iridium, which was dispersed from the meteorite that collided with Earth to end the dinosaur age.
For the Anthropocene, the best candidate for such a golden spike are radioactive elements from nuclear bomb tests, which were blown into the stratosphere before settling down to Earth. “The radionuclides are probably the sharpest – they really come on with a bang,” said [professor Jan Zalasiewicz, chair of the Working Group on the Anthropocene]. “But we are spoiled for choice. There are so many signals.”
Other spikes being considered as evidence of the onset of the Anthropocene include the tough, unburned carbon spheres emitted by power stations. “The Earth has been smoked, with signals very clearly around the world in the mid-20th century,” said Zalasiewicz.
Other candidates include plastic pollution, aluminium and concrete particles, and high levels of nitrogen and phosphate in soils, derived from artificial fertilisers. Although the world is currently seeing only the sixth mass extinction of species in the 700m-year history of complex life on Earth, this is unlikely to provide a useful golden spike as the animals are by definition very rare and rarely dispersed worldwide.
In contrast, some species have with human help spread rapidly across the world. The domestic chicken is a serious contender to be a fossil that defines the Anthropocene for future geologists. “Since the mid-20th century, it has become the world’s most common bird. It has been fossilised in thousands of landfill sites and on street corners around the world,” said Zalasiewicz. “It is is also a much bigger bird with a different skeleton than its prewar ancestor.”
...Prof Chris Rapley, a climate scientist at University College London and former director of the Science Museum in London said: “The Anthropocene marks a new period in which our collective activities dominate the planetary machinery.
“Since the planet is our life support system – we are essentially the crew of a largish spaceship – interference with its functioning at this level and on this scale is highly significant. If you or I were crew on a smaller spacecraft, it would be unthinkable to interfere with the systems that provide us with air, water, fodder and climate control. But the shift into the Anthropocene tells us that we are playing with fire, a potentially reckless mode of behaviour which we are likely to come to regret unless we get a grip on the situation.”