Paul Crutzen won the Nobel prize in Chemistry in 1995 for his work on the chemical compounds that were causing the hole in the ozone layer.
In 2000 Paul Crutzen, the Dutch atmospheric chemist and Nobel prize-winner, and American ecologist Eugene F Stoermer, proposed using the term ‘anthropocene’ for the current geological epoch to emphasize the central role of mankind in geology and ecology.
Fifteen years on, several of the papers that were presented at the four-day World Economic Forum in Davos, Switzerland, last week referred to the advent of the Anthropocene era, though it is doubtful if many of the 2,500 attendees paid much attention.
Geological Epochs
So what is a geological epoch, when did the Anthropocene epoch start, and how is the Anthropocene relevant to us?
You will know about the Jurassic period when dinosaurs roamed the earth*. But do you know some of the other periods of geological time: the Cambrian, the Devonian, the Carboniferous, the Triassic, the Cretaceous? The Cambrian period started about 540 million years ago, and the Cretaceous period ended 66 million years ago. This enormous length of time is only 10% of the age of the Earth, which is 4.6 million years old.
(*The dinosaurs actually first appeared in the Triassic period, 231.4 million years ago, and were the dominant terrestrial vertebrates for 135 million years, from the beginning of the Jurassic period until the end of the Cretaceous, 66 million years ago.)
The last 66 million years is also made up of geologic periods: the Paleogene, the Neogene and the Quaternary, and to make it more complicated, the Quaternary period is made up of two epochs, the Pleistocene (2.6 million years ago to 11,700 years ago) and the Holocene (11,700 years ago to the present day). Even though human beings first appeared between 400,000 and 250,000 years ago, the Holocene, the start of which is marked by the end of the last major ice age, encompasses the rise of modern humans, all human written history, the development of major civilizations, and the relatively recent transition toward urban living. The word Holocene means ‘entirely recent’ and comes from the Greek holos, meaning ‘whole’ or ‘entire’, and –cene meaning ‘new’.
In this geological time chart, the time before the Cambrian period, the Pre-Cambrian, which extends for most of the top level, covers seven-eighths of the age of the earth, with the remaining one-eighth expanded into levels below.
The Anthropocene Epoch
But for some time, geologists, climate scientists and ecologists have been debating whether the profound effect that the human species is having on the Earth means that we are moving from the Holocene to a new epoch, the Anthropocene (pronounced an-thropo-scene). The first use of a similar term however goes back to 1873 when the Italian geologist Antonio Stoppani acknowledged the increasing power and effect of humanity on the Earth’s systems and referred to an ‘anthropozoic era’. Incidentally Eugene Stoermer originally coined the term in the 1980s, but never formalised it until Paul Crutzen, who had started using the term, contacted him. The name Anthropocene is a combination of the Greek roots anthropo- meaning ‘human’ and -cene meaning ‘new’.
Geologic epochs primarily refers to geologic time based on boundaries between different rock strata differentiated by fossils, which is the science of stratigraphy, and any decision on recognising the Anthropocene epoch, which is still an informal term, lies with the International Commission on Stratigraphy (ISC). The ISC set up an international Anthropocene Working Group of scientists which was ‘tasked with developing a proposal for the formal ratification of the Anthropocene as an official unit amending the Geological Time Scale’. The working group, which first met in Berlin last year, has given itself until 2016 to come up with the proposal to submit to the ISC, but this month they put forward their initial view.
The Beginning of the Athropocene
The working group has proposed that if there were to be a single date to mark its beginning of the Anthropocene epoch, it would be 16 July 1945, the date that the first atomic-bomb test took place at the US Army testing range at Alamogordo in New Mexico, as the subsequent nuclear tests left an indelible mark around the Earth due to the release of radioactive isotopes or ‘fallout’ which settled in the soil and land around the world. This event also coincided with a worldwide ‘great acceleration’ of other human activities that ushered in a new geological epoch.
However a significant minority of the working group supported alternative dates, and the group plans to bring forward a formal, evidence based, proposal in 2016. Scientists have argued for a number of different dates that mark the start of this new human epoch. One date is the start of the industrial revolution in England in the 18th century when coal became the main source of fuel, production by hand changed to production by machine, new processes to produce iron were introduced, and the use of steam power increased dramatically. Earlier dates include the invention of agriculture and the clearing of forests about 10,000 years ago, and even further back to 14,000 to 15,000 years ago based on lithospheric evidence, the exposed top layers of the earth. These latter dates would be closely synchronous with the current epoch, the Holocene.
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