Scientists suggest new geological epoch: ours

Scientists suggest new geological epoch: ours
Jeremy Hance, mongabay.com
January 30, 2008

It would be called the Anthropocene. The word was coined by chemist and Nobel Prize winner Paul Crutzen at a conference in 2000. It denotes a new geological epoch, beginning about 200 years ago at the time of the Industrial Revolution, when our planet's systems were increasingly affected by our species. While the term Anthropocene has been used informally for years, a recent peer-reviewed British paper argues that it is now time to officially accept Anthropocene as a distinct era and to leave the Holocene to the pre-Industrial past.

The contents of each geological strata contain clues about the time that created it, and according to the paper since 1800 "the global environmental effects of increased human population and economic development" has changed geological strata considerably enough to warrant the distinction of a new epoch.

"From the beginning of the Industrial Revolution to the present day," the paper explains, "global human population has climbed rapidly from under a billion to its current 6.5 billion […]. The exploitation of coal, oil, and gas in particular has enabled planet-wide industrialization, construction, and mass transport, the ensuing changes encompassing a wide variety of phenomena."

The paper, published by the Geological Society of America, discusses four different areas in which these changes are evident. The first is changes in physical sedimentation, including erosion due to deforestation, agriculture, construction, and damming rivers.

This shows temperature anomalies for the 2007 calendar year relative to the 1951-1980 mean. Warmer areas in red, cooler areas in blue. Largest increases were in the northern hemisphere. Credit: GISS

The second change is in global temperature. The paper points out that carbon levels are at the highest they have been in nearly one million years, and that they are predicted to double (at least) by the end of this century. Due to this, "temperature is predicted to rise by 1.1 °C to 6.4 °C by the end of this century […] leading to global temperatures not encountered since the Tertiary". The third is changes in biodiversity. The growing population of humans has caused extinction rates to increase on land and spread to the seas. The paper notes that climate change will put considerably more pressure on species, possibly leading to a mass extinction on scale with that of the dinosaurs.

Finally, oceans are also undergoing significant changes. Sea levels have already risen due to melting ice and thermal expansion of the water, but it has yet to be seen how far they will go. "Changes may be as large as a 10–30 meter sea-level rise per 1 °C temperature rise" asserts the paper. In addition, surface sea water is experiencing a rise in acidity. Since pre-Industrial times, pH units have risen 0.1 due to increased carbon. The levels, as well, are expected to continue rising. With such drastic planetary shifts, scientists see the necessity of a new epoch.

They even speculate that our modern world may not only be in a transition from one epoch to the next, i.e. the Holocene to the Anthropocene, but may be viewed in the future as a shift from one period to the next (in geology a period can encompass several epochs). If long-lasting changes occur in temperature, ice-volume, sea levels, and biodiversity (i.e. mass extinction) as many scientist's now predict than it may be appropriate to recognize that the Quaternary period (which began nearly two million years ago) is also at an end. To put in perspective the length of the 200-year-long Anthropocene in geologic time, recall the old adage: if geologic time were a single 24-hour-day than human beings would only appear in the last 30 seconds to midnight. The Anthropocene, therefore, would be at the tail's end of the very last second to midnight, comprising the final 50 milliseconds: in other words, half the blink of an eye.

To make the Anthropocene official a date or a golden-spike (a stratigraphic section used as a boundary between epochs) needs to be established by the International Commission on Stratigraphy.

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