Earth's geologic ages—time periods defined by evidence in rock layers—typically last more than three million years. We're barely 11,500 years into the current age, the Holocene. But a new paper argues that we've already entered a new one—the Anthropocene, or “new man”, age.
The name isn't brand-new. Nobel Prize winner Paul Crutzen, a co-author of the paper, coined it in 2002 to reflect the changes since the industrial revolution. The paper, however, is part of new push to formalize the Anthropocene age.
Recent human impacts have been so great that they'll result in an obvious boundary (界限 ) in Earth's rock layer, the author's say. “We are so skilled at using energy and exploiting the environment that we are now a defining force in the geological process on the surface of the Earth,” said co-author Jan Zala, a geologist with the University of Leicester in the UK. Even so, it could take years or even decades for the International Union of Geological Science to formalize the new age.
If the concept of the Anthropocene age is to be formalized, scientists will first have to identify and define a boundary line ,or marker, that's set in stone. “The key thing is thinking about how—thousands of years in the future—geologist might come back and actually recognize in the deposit in the UK.” It's not as straightforward as you might think. The market has to be very precise, and it has to be recognized in many different parts of the world,” said Haywood, who wasn't involved in the new study.
One candidate for the market is the distinctive radioactive signature left by atom bomb tests, which began in 1945. “The fallout (沉降 ) is basically across the world,” Haywood said. In a similar way, scientists used traces of the element iridium (铱) left by shooting star strikes to help define the boundary between the Cretaceous and Tertiary periods—the time of the great dinosaur extinctions.
The push for a formal declaration of the Anthropocene age is about more than just scientific curiosity. The move the scientists write in the last issue of the journal Environmental Science & Technology, “might be used as encouragement to slow carbon emissions andbiodiversity(生物多样性)loss” or “ as evidence on protection measures” Just as Haywood said, by underlining how much we're changing the environment, the formalization would be "a very powerful statement”.
