Human activities, including urban development, have resulted in markedly increased levels of plastic waste, nitrogen and phosphorus runoff, and atmospheric carbon dioxide concentrations. This has led a group of scientists, known as the Anthropocene Working Group, to present formal evidence of the Anthropocene, a newly proposed epoch beginning in the 1950s. (Source: Wikimedia Commons)
While there is little doubt that human development – including deforestation and urban development – has changed the landscape of the Earth, scientists are still debating whether human activity has become significant enough to define a new epoch in the geological time scale. An international team of scientists, the Anthropocene Working Group, has published a review in Science with geochemical evidence supporting the definition of a new epoch named the “Anthropocene” (1).
The current epoch, known as the Holocene, describes the time when humans first settled into agricultural societies. Researchers propose that the Holocene epoch should end, and the Anthropocene begin, around the period of rapid population growth of the 1950s (2). The review argues that human activity over these past five decades has produced deposits in the Earth’s crust that differ significantly from those seen in layers from the previous epoch (2). These include new “technofossils,” artificial materials, such as concrete and plastics, that do not readily decay. Lead and inorganic ash concentrations from gasoline, as well as nitrogen and phosphorus from fertilizer use, have also formed new geochemical signatures (1). They are particularly common in Greenland, where researchers noted that levels surpass those of any estimations for the past 100,000 years (1).
The paper also discusses atmospheric changes, including residue from thermonuclear devices and fossil fuels. Data shows that radionuclides (unstable, radioactive particles), carbon dioxide, and methane concentrations all deviated from Holocene around 50 years ago. Additional evidence comes from the increased rates of species extinction, land erosion, sea level rise, and, in particular, the average global temperature increase since 1950. All of these findings are distinct from the characteristics of the Holocene, leading researchers to conclude that there is a need to define a new epoch (1).
The team hopes to continue gathering evidence to refine and formalize the definition for the new Anthropocene epoch. They also hope to extrapolate this information to determine humanity’s future impacts on the biosphere (1).
References:
- Waters, C. N., Zalasiewicz, J., Summerhayes, C., Barnosky, A. D., Poirier, C., Gałuszka, A., … Wolfe, A. P. (2016). The Anthropocene is functionally and stratigraphically distinct from the Holocene. Science, 351(6269).doi: 10.1126/science.aad2622
- University of Leicester. (2016, January 7). The Anthropocene: Hard evidence for a human-driven Earth. ScienceDaily. Retrieved January 10, 2016 from www.sciencedaily.com/releases/2016/01/160107151738.htm
Contact brenda.y.miao.19@dartmouth.edu with questions.