Should the Geological Time Scale be changed?
Thu Feb 25 2016 13:00:00 GMT+1300 (New Zealand Daylight Time)
Should the Geological Time Scale be changed?
25 February 2016
Professor John R McNeill
Millions of tonnes of concrete laid since the 1950s and radioactivity from nuclear weapons testing, among other things, are being studied by historians and geologists to decide whether there should be a change to the Geological Time Scale to add the Anthropocene era.
The Anthropocene is a proposed epoch that begins when human activities started to have a significant global impact on Earth's geology and ecosystems.
Professor John McNeill of Georgetown University in Washington DC will speak at the University of Auckland next month on the potential to make the 'Anthropocene' a geological epoch at the same hierarchical level as the Pleistocene and Holocene epochs, revising the Geological Time Scale in a major way for the first time in over 100 years.
Professor McNeill is one of only two historians among a group of 30 geologists on the Anthropocene Working Group (AWG) tasked with making a recommendation to the International Commission on Stratigraphy in late 2016.
The Commission’s primary objective is to precisely define global units of the International Chronostratigraphic Chart that, in turn, are the basis for the units (periods, epochs, eras, and ages) of the International Geologic Time Scale; thus setting global standards for the fundamental scale for expressing the history of the Earth.
Professor McNeill was invited to join the Anthropocene Working Group by British geologist Jan Zalasiewicz. The group first met in Berlin late last year and will meet again in Oslo in April. They take various forms of evidence for the Anthropocene into account before making their recommendation including archaeology, soil science and climate science.
But he says for most members of the AWG the crucial evidence is the "golden spike", formally known as a Global Stratigraphic Section and Point (GSSP).
“For stratigraphers, the intervals of time in earth history are marked off from one another by golden spikes, or at least that is the ideal, not yet always met. So the Anthropocene needs its own golden spike, something in the sediments that will be durable over geological time,” Professor McNeill says.
“Suggestions include the millions of tons of concrete laid down since 1950, or radioactivity from nuclear weapons testing, or the millions of oil and gas wells dug since 1900.”
Professor McNeill says there are pros and cons if the recommendation is not taken, but he would like to see it go ahead.
“If it were up to me, I would formalize the Anthropocene in the Geological Time Scale. I think the evidence is already here that human action has affected fundamental earth systems sufficiently to put them outside the Holocene range of variability.”
“From the point of view of many scientists and scholars, ignoring the scale and scope of ongoing global environmental change would be morally corrupt, politically imprudent, and intellectually dishonest. So when the evidence (as they see it) piles up so convincingly, the question becomes clear.”
But from the point of view of some geologists, the pros of not elevating the Anthropocene to the status of an epoch or era in the Geological Time Scale include the possibility that it’s too soon to tell if the human impact is a blip or a durable interval of time. Plus, some scholars feel, there are unwelcome political implications to the possible move.
“Also, no intervals are named for any single species; it would be hubristic to name one after ourselves.”
“The term also unfairly lumps all humans together, so even if the concept is OK, the term is not. Only some people are responsible, not all people, for the environmental changes that signal the Anthropocene.”
Professor McNeill’s talk, “The Anthropocene Debates”, in on Wednesday 9 March, 6.30-7.30pm in Room 439, Engineering Building (Building 410), The University of Auckland, City Campus.
Contact
Anna Kellett, Media Relations Adviser
Email: anna.kellett@auckland.ac.nz