Well, this is not the Age of Aquarius. Last week, geologists met in Berlin to discuss renaming our current geological epoch – the Holocene. They say it began when the ice age ended, 11,700 years ago. The geologists in Berlin debated splitting the Holocene into two pieces. The most recent part would be renamed the Anthropocene – literally, the age of New (-cene) Man (anthropo-). There are some persuasive reasons to consider this change in nomenclature.
Old Man, as we might call our distant ancestors, lived for 200,000 years in rather close commune with nature. Fire was tamed, stone tools were fashioned, animal skins served for warmth and perhaps modesty. But for most of those thousands of generations, the human animal population fit into the ecology with little impact and we numbered only a few hundred thousand. Our “carbon footprint” wasn’t much larger than a size 7 slipper. Then, around 8,000 years ago, New Man emerged. Agriculture and trips to the Moon soon followed. Progress in itself is not enough to warrant naming a new geological epoch for ourselves. Geologists base geological ages on more concrete entities. Distinct soils and rocks. Extinct animals. Changes in landforms and ocean chemistry. These have all identified past epoch transitions. Some geologists are arguing that New Man has modified the soil, killed some species, flooded a few islands, and added enough acid and carbon dioxide to the seas that we deserve having our name affixed to this altered stage of the planet. Congratulations to us.
In the past, the great ages of the Earth were divided into eras, periods, and epochs based largely on extinctions. When geologist Charles Lyell, in the mid-nineteenth century, named the major rock divisions (Paleozoic, Mesozoic, and Cenozoic) he and his colleagues distinguished them by their fossils. Those early geologists had no way of knowing the actual age of the formations – they guessed millions of years – but on the basis of the simple idea that younger rocks were in layers above older rocks, they worked out the relative ages. Fossil assemblages helped. Rather consistently, fossils occurring in deeper (older) rocks were simpler than the complex fossils found in shallower rocks. It was an early clue of evolution and astute geologists realized this years before Darwin explained the mechanisms involved.
Extinctions certainly formed the demarcation line between the time periods. Long before an asteroid was blamed for the transition between Cretaceous and Tertiary, geologists easily distinguished between the two. Cretaceous rocks hosted gigantic dinosaur bones while all the dinosaurs had vanished by the Tertiary. Similar stunning disappearances mark at least 5 other major time-boundaries. If extinctions were the only criterion designating the end of one age and the beginning of the next, then surely relabeling the most recent part of the Holocene as the Anthropocene makes sense – there have been many thousands of extinctions since New Man arrived on the scene. These famously include the dodo, golden toad, Yangtze River dolphin, passenger pigeon, and west African black rhino. There is good evidence human activity also ended the North American camel and perhaps the mastodon. These are the big photogenic creatures. There were also lesser animals that are no more. In a 1995 paper in Science, researchers showed that the extinction rate due to New Man’s activity is roughly 1,000 times greater than during the days of Old Man. There is, indeed, an Anthropocene extinction severe enough to show itself in the fossil record.
But defining the Anthropocene entails more than tallying extinctions. In addition to disappearing species, previous geological eras and epochs stand out for their distinguishing rock types. New Man is busy creating some interesting geology. We might think that our most obvious monuments to ourselves – our steel and concrete cities – will speak grandly of our existence a million years hence. Probably not. Although in a few thousand years cities may crumble and leave tell-tale rust spots on the landscape, the besmirched soil will eventually erode. In most cases, signs of our cities will not last. Erosion sweeps away landscapes. Oceanscapes, however, are often preserved.
Therefore, the legacy of New Man’s Anthropocene may be most evident in places that seem obscure to us today. Although astute future geologist-creatures will find traces of radioactive dust as a sign of the mid-twentieth century (remnants of the fallout of atmospheric nuclear bomb tests) and future archaeologists may find landfills with non-degradable diapers and plastic hypodermic needles, it will be the seas that most clearly demonstrate the start of the Anthropocene.
New Man’s brilliant ability to manipulate molecules into new chemicals has led to more effective fertilizers and pesticides. I am not opposed to these discoveries – our billions of human cousins need their bodies protected from malaria and malnutrition. We want a clean environment; but we can’t let people starve. But this not need to be an unsolvable dichotomy, a win-and-lose scenario, although we have mostly pointed our world towards a dead-end direction. Until we learn to curb our appetites for shiny bling-bling, we will raze our forests and ply the resulting fields with manufactured fertilizers and poisons. Modern chemistry is reshaping the soil (perhaps future geologists will notice the trace elements) but far worse is the damage to the basins into which our chemicals wash. It is in those basins – the world’s lakes, seas, and oceans – that the effects of the Anthropocene will remain the longest and be seen the most clearly.
Chemical runoff from fields and factories will unite with industrial aerial pollution, adding heavy muck to our seas. By the end of this century, enough carbon dioxide from the air will become mild carbolic acid in the oceans that the world’s coral reefs will die. The reefs will disappear as they have in each of the previous 5 major extinctions. Of course they may come back, as they have 5 times already. But there will be a million-year reef-gap and it will be associated with the human animal’s impact on the Earth.
The billions of tonnes of coal and oil which New Man has converted to energy and carbon dioxide are melting polar ice, raising sea level and flooding shorelines. Neither pollution, climate change, nor the extinctions will mark an end to life on Earth. They might not even mark an end to man’s time on the planet. The Earth has been hotter and damper and colder and more violently altered in the past, yet life has endured – all of that roiling upheaval actually contributed to the rise of the human animal. But that does not excuse New Man’s messy creation of the Anthropocene.
Last week, geologists at the Berlin meeting pondered the formal use of this new name. The International Union of Geological Sciences’ Commission on Stratigraphy will decide in 2016 if Anthropocene will be approved as the officially designated appellation for the current epoch. If they approve, the Age of New Man will be noted for a mass extinction of species, changed climate, flooded continental shelves – plus dabs of radioactive dust and a thin layer of Styrofoam coffee cups. These will document our existence on this planet.