Earth Entering New Geologic Epoch?
Human effects on the planet have reached the point where many scientists think we have entered a new geologic epoch.
Instead of the Holocene Epoch, defined as about 11,500 years ago to present, we may be already a couple of hundred years into the Anthropocene Epoch, as human effects begin to dominate the planet. Those influences will leave a profound mark in the geologic record.
The case for officially designating 1800 A.D. onward as the Anthropocene is now being made by members of the Geological Society of London.
Their case is outlined in an article in the February issue of GSA Today. The scientific body that decides such matters is theInternational Commission on Stratigrophy.
"What we've done is examine it in geological terms," said geologist Jan Zalasiewicz of the University of Leicester. Put another way, they have asked whether the present-day activities of humans will be reflected as a globally significant force in the kinds of sediments that are collected today and will be preserved in Earth's geologic record.
Previous studies have already pinned some pretty global effects on humans. There is, for instance, the fact that humans are now the largest earth-moving force on the planet. There are the rising sea levels linked to global warming and the wave of extinctions being seen around the world. There is even a carbon isotope difference in today's sediments, caused by humans burning fossil fuels.
All will leave lasting marks on the geologic record.
Some researchers argue that the change came when coal arrived on the scene, around 1800, followed by steam engines that dramatically increased the power of humans to reshape the surface of the Earth. It's the difference between a plow pulled by a horse and a bulldozer, Zalasiewicz told Discovery News.
"Humans can basically do a whole lot more," said Zalasiewicz. There were also a lot more humans around -- about a billion by 1800, he said.
"If this suggestion is going to be taken seriously by mainstream geologists, then we have to discuss when the (human-caused) changes became dominant," said Zalasiewicz.
Some researchers are in favor of establishing the Anthropocene, but consider the geologists' criteria too conservative.
"They are Earth scientists trying to look at it a traditional way," said civil and environmental engineer Braden Allenby of Arizona State University. In other words, geologists are trying to anticipate how the present epoch will appear in the geological record to geologists tens of thousands of years from now. But it's clear today that there are big changes underway all over the planet.
"In terms of biology," said Allenby, "there's probably not a place on Earth that's not affected by humans."
Which raises another question: Are we truly in a new epoch, or just serving the same role as an asteroid impact, i.e., ending one epoch and making room for the next? Two centuries may be a lot in terms of human history, but it's insignificant in terms of geological time.
"We don't know just yet," Allenby told Discovery News. "We're just beginning the story here. It may be that we're just a flash in the pan."
Scientists: We've Entered a New Epoch, the Anthropocene
Researchers Believe an Era of Overwhelming Human-Caused Change in Earth Needs New Name
By Lee Dye, ABCnews.com, Jan. 3, 2007
We humans are having such a dramatic impact on our planet that some leading scientists think the current era needs a new name. We're no longer in the Holocene epoch, they say. We're now well into what they are calling the Anthropocene.
This planet is being changed by human activities in ways that will continue to alter Earth for millions of years. The most obvious example is global climate change precipitated by the release of greenhouse gases from fossil fuels, but there are many more, some so obvious it's hard to think of them as insidious threats to our environment.
But they are indeed, according to the leader of the Anthropocene movement, Nobel laureate Paul J. Crutzen, who is said to have coined the word during a science meeting in 2000. Crutzen, former chief of atmospheric chemistry at the Max-Planck-Institute in
The paper, published by the
"Global warming and many other human-driven changes to the environment are raising concerns about the future of Earth's environment and it's ability to provide the services required to maintain viable human civilizations. The consequences of this unintended experiment of humankind on its own life support system are hotly debated, but worst-case scenarios paint a gloomy picture for the future of contemporary societies."
Pretty scary stuff, but Crutzen and his co-authors have done their homework. In fact, they argue that about the only thing that might head off a global human catastrophe is some other catastrophe, like "a meteorite impact, a world war or a pandemic." Here are just a few of their points, in their own words:
· Earth is rapidly moving into a less biologically diverse, less forested, much warmer and probably wetter and stormier state.
· Between 1800 and 2000 population grew more than sixfold, the global economy about 50-fold, and energy use about 40-fold. (Population is expected to reach 10 billion in this century.)
· Energy use grew 16-fold just during the 20th century, causing 160 million tons of atmospheric sulphur dioxide emissions per year. The number of motor vehicles increased dramatically from about 40 million at the end of World War II to nearly 700 million by 1996. (And according to other studies, all those vehicles are owned by just 15 percent of the world's population.)
· About 30 percent to 50 percent of the planet's land surface is exploited by humans. Tropical rain forests are disappearing at a fast pace, releasing carbon dioxide and strongly increasing species extinction.
· So far, these effects have largely been caused by only 25 percent of the world population.
A sticking point on labeling this a new epoch is disagreement over when the Anthropocene actually began. Some argue it began when our ancestors abandoned hunting and gathering and took up farming. Huge swaths of land were cleared and the trees burned, launching the rise in greenhouse gases.
A forester once told me that many years ago it would have been possible to walk from the
Crutzen and his colleagues Will Steffen of the Australian National University, Canberra, and John R. McNeill of Georgetown University concede that those early folks had a significant impact, but they argue that the real turning point began in the late 18th century with the industrial revolution, and it reached a new level at the end of the Second World War. They call the modern period the Great Acceleration of the Anthropocene, when humans began to overwhelm their planet.
In their own words:
"The Great Acceleration is reaching criticality. Enormous, immediate challenges confront humanity over the next few decades as it attempts to pass through a bottleneck of continued population growth, excessive resources use, and environmental deterioration. In most parts of the world the demand for fossil fuels overwhelms the desire to significantly reduce greenhouse gas emissions.
About 60 percent of ecosystem services are already degraded and will continue to degrade further unless significant social changes in values and management occur. There is also evidence for radically different directions built around innovative, knowledge-based solutions. Whatever unfolds, the next few decades will surely be a tipping point in the evolution of the Anthropocene."