Friday, January 15, 2016

Modern Human Record Reveals The Anthropocene Epoch

Earth’s Geology

Human Waste: This does not make a pretty picture, but it represents to a large degree the record for at least the last 70 years of human mass consumption. Tia Ghose for Live Science poses the following question: “Should the detritus of modern human society, such as plastic bottles and tin cans, be used as geologic markers for a new, human-shaped geological era?”
Photo Credit: Steshkin Yevgeniy 
SourceLive Science

An article, by David Biello, in Scientific American says that geologists are putting forth the rather convincing (yet controversial) argument that Earth has entered a new geologic era, the Anthropocene Epoch, which some scientists say began as early as 70 years ago with the testing of the first atomic bomb on July 16, 1945. This geologic epoch coincides with increased layers of radiation, soot and plastic, all part of human technological achievements.

In “Humans Leave a Telltale Residue on Earth” (January 7, 2016), Biello writes:
“This Anthropocene signal is global, it is sharp and all the signs are big,” argues geologist Jan Zalasiewicz of Leicester University, chair of the group tasked with making a formal recommendation on the potential for a human-made, future-looking epoch. Twenty-four members of that working group, including Zalasiewicz, have just published their compilation of the gathering evidence in the January 8 Science. “A real geological phenomenon is taking place, it is still going on. In many respects, it’s accelerating even as we speak.”
The present geologic epoch is known as the Holocene, or “entirely recent,” stretching back 11,700 years before 1950 to when the last ice age began to melt and raised sea levels by roughly 120 meters over a few millennia. During that transition, carbon dioxide levels in the atmosphere increased by roughly one part per million per century. More recently, however, CO2 levels have been increasing by two ppm per year, and rather than slowly returning to an ice age the world has become ever warmer, melting more ice. The rapid increase in excess CO2 comes from the fossil fuel burning and land use of one species that first appeared approximately 200,000 years ago: Homo sapiens.
In fact, rapid development of technology, swelling population and growing consumption of resources from crops to metals have expanded humanity's impacts, particularly after 1950 or so, an inflection point some have dubbed the “Great Acceleration.” People have created long-lasting new materials, ranging from copper alloys to plastics that will form long-lived, so-called “technofossils.” Enough concrete has been made by now to cover every square meter of the world in a kilogram of the building material. Sufficient plastic is currently manufactured each year to weigh as much as all seven billion–plus humans on the planet. People move nearly three times as much rock and dirt via mining than the amount that travels with water through all the world’s rivers. Modern chemistry has even liberated civilization from the natural nitrogen cycle that has prevailed for the last 2.5 billion years. And tiny soot particles left over after burning coal, oil and natural gas now can be found in sediments from tropical lakes to the middle of the Pacific Ocean, a permanent smudge on the geologic record.
Yet, not everyone is convinced, most notably stratigraphers, scientists who study rock layers. Essentially, this is a debate between climate scientists and geologists on what markers one requires to define an epoch and what evidence in the form of stratas or layers must be found as conclusive. Geologists typically look back in times in periods of at least 100,000 years, so 70 years or even 200 years at the beginning of the industrial revolution is too short a period for many geologists to confirm if we have recently left the Holocene Epoch, which began about 12,000 years ago with the prominence of humans.

For more, go to [ScientAmer]

For the original paper, go to [Science]