Tweet This
Earth has arguably entered a new geological epoch, the Anthropocene (Credit:... [+]
An ongoing debate on whether Earth has entered into the Anthropocene, an epoch denoted by human influence, has reached a new consensus. A study led by the British Geological Survey recently published an article titled 'The Anthropocene is functionally and stratigraphically distinct from the Holocene' in Science. Here, scientists make the case that humanity's impact on Earth has become distinct enough to warrant a new geological epoch, the Anthropocene.
Although this may be the first you've heard of Anthropocene, the debate over human's influence on changing global geology and climate has been ongoing. Despite clear links to human's impact on our oceans, geology, climate, resources, and vegetation, there has been hesitation to recognize this as a new geologic time. In the aforementioned study, geologists viewed the Anthropocene from a stratigraphic record framework, identifying how human's influence has changed the sedimentary makeup of our earth. With this thorough framework, they argue that we have, in fact, entered into a new geologic epoch, the Anthropocene .
A geologic epoch is simply one way that geologists subdivide smaller chunks of geologic time. Often, geologic time is denoted by breaks or significant changes in global volcanism, mass extinctions, large scale climate variations, ocean circulation patterns, etc. Therefore, geologists can categorize Earth's history into periods of relative association and make sense of billions of years.
The Case for Anthropocene
Human rise on a global scale have brought with us global marketed changes in Earth's resources. Humans have redistributed metals, sediment, hydrocarbons, fossils, vegetation, ocean bodies, global ice distribution, and rocks throughout the world. We have also seen a marketed change in the carbon, nitrogen, and phosphorus cycles in the past several thousand years. Biotic changes include massive species invasions, accelerated rates of extinction, and genetically modified plants. These all combine to create signals that geologists interpret to denote a break in the Holocene, the previous epoch, and a demarcation of the Anthropocene.
However, what is the stratigraphic evidence laid forth to suggest we are in the Anthropocene? Geologists recognize new and novel materials present on Earth, which will one day be lithified and turned into sedimentary rock. These include concrete, plastics, aluminum, black carbon (soot), etc. These distinct and previously unseen materials make a marketed global increase in presence around 1950. For example, more than half of the concrete used in history was produced in the past 20 years. We also see increased sedimentary fluxes into our oceans as deforestation and road construction enhanced erosion. Therefore, the study suggests we've entered into the Anthropocene beginning circa 1945 to 1964.
In this sediment core from Greenland, there is a clear and abrupt demarcation from glacial... [+]
On the geochemical front, we have seen increases in chemical markers associated with pesticides, polyaromatic hydrocarbons, altered lead isotopic ratios from gasoline, increased nitrate levels from agriculture, ozone depleting chlorofluorocarbons, higher levels of CO2 and other greenhouse gases in the atmosphere, and unique isotopic signatures associated with nuclear and atomic weapons. Global thermonuclear weapons tests created a chemical release called the "bomb spike" where excess 14C, 239Pu, and artificial radionuclides were released globally from 1952 to 1980.
In many ways, the exact timing of the Anthropocene is difficult to pinpoint. Previous geologic times were seen as chemical, physical, or biological changes in the sedimentary record recorded in ancient rocks. However, this is often difficult to determine when looking at modern oceans and continents and describing what will in the future become Earth's sedimentary history.
The Anthropocene Ripple Effect
Since the beginning of the field, geologists have noted hundreds of geologic time periods both globally and locally. So why do we care now? What impact does it have whether we call this geologic epoch either Holocene or Anthropocene? Beyond nomenclature and classification, the potential influence and ripple effect extends far beyond the geological community.
The onset of the Anthropocene, if agreed upon by the geological community, represents a newfound recognition of human's role in Earth's continued history. It expresses the extent to which humans have altered the world around us and instills a sense of ownership in the future of Earth.
The Nature paper grimly suggests that “Current trends of habitat loss and overexploitation, if maintained, would push Earth into the sixth mass extinction event (with ~75% of species extinct) in the next few centuries, a process that is probably already underway."
For billions of years, conditions on Earth have dictated the rise and fall of species. It has been a one-way street, where global forcing has dictated every species outcome. However, we are now in a period where human influence partially drives global forcing and thus species outcome. We hold as much our own fate as that of the world around us. Ownership of fate has, for the first time, been partially handed to a species.
