Human Technology Defines New Geologic Epoch: The Anthropocene

Remember hearing back in school the basic explanation of geologic periods and epochs and the creatures that inhabited the world during those times? Thanks to Jurassic Park and other science fiction narratives, the dinosaurs of the Mesozoic era come to mind immediately. Experts now tell us that with technology, humans may have progressed the earth’s geology into a farther stage. People came into the picture in the Holocene epoch of the Quaternary period, our current time period. Or so we thought.

On Friday, in a paper entitled “The Anthropocene is functionally and stratigraphically distinct from the Holocene,” the journal Science published results of a stratigraphic study by a 24-member international team led by Colin N. Waters of the British Geological Survey.

Sediment column showing abrupt transition to the Anthropocene (sciencemag.org/J.P.Briner)

Through sediments and ice cores, the scientists reviewed climatic, biological, and geochemical evidence of human activity and technological changes. In this sediment core from western Greenland (see photo), glacier retreat due to climate warming caused by human activities results in an abrupt stratigraphic transition from proglacial sediments to nonglacial organic matter as the Anthropocene began. They define the criteria for declaring a new geological epoch:

“Any formal recognition of an Anthropocene epoch in the geological time scale hinges on whether humans have changed the Earth system sufficiently to produce a stratigraphic signature in sediments and ice that is distinct from that of the Holocene epoch.”

According to their investigation, the stratigraphic evidence points to a new post-Holocene epoch beginning sometime in the mid–20th century. It includes atmospheric carbon emissions higher than those of the last 65 million years, similarly elevated methane levels, and sea levels higher than those of the past 115,000 years.

The Guardian quotes Waters:

“We could be looking here at a stepchange from one world to another that justifies being called an epoch. What this paper does is to say the changes are as big as those that happened at the end of the last ice age. This is a big deal.”

The importance of the study lies in its revelation of the scale of changes experienced in the recent past. Waters describes it as “a whole set of changes to not just the atmosphere, but the oceans, the ice–the glaciers that we’re using for this project, might not be here in 10,000 years.”

A year 2000 contribution under the International Geosphere–Biosphere Programme by Paul J. Crutzen and Eugene F. Stoermer first posited the existence of an Anthropocene epoch. In 2011, The Economist described in detail both the process and the paradigm shift involved in such a transition.

Here’s a short list of the changes technology has wrought:

• Extinction rates of flora and fauna far exceed the long-term average. 75% of current species will become extinct in the next few centuries if current trends continue.
• Fossil fuel-burning since the industrial revolution has increased the concentrations of CO2 in the atmosphere by about 120 parts per million.
• Nuclear weapon tests in the 1950s and 60s left detectable traces of the isotopes 14C (fairly common) and the naturally rare isotope, 293Pu.
• So much human-created plastic is in our waterways and oceans that microplastic particles are everywhere and will even leave fossil records of their own.
• Fertilizer use has doubled the nitrogen and phosphorous in the soils in what may be the largest impact on the nitrogen cycle in 2.5 billion years
• Airborne soot, largely including black carbon from fossil fuel-burning, has created a permanent marker in both sediment and glacial ice.

It will be interesting for future geologists to observe the effects of the cleantech era.