The post-industrial impacts that humans have had on the Earth and its atmosphere may pinpoint the mid-20th century as the start of a new geological epoch.
January 18, 2016 — GEOLOGISTS ARE CONVINCED that humans have left a mark upon the planet that will detectable millions of years from now.
Long after human civilization has perished, there could be a stratum of fossilized rock and a geological time zone that says: “We were here.” So there is a case for calling the present epoch “the Anthropocene” — probably dating from about 65 years ago.
The term Anthropocene derives from the ancient Greek for humankind. And for more than a decade, scientists have been arguing about whether what is officially known as the Holocene epoch of the Quaternary period of the Cenozoic era should be renamed to indicate human impact. There have been arguments aplenty.
Humans have appropriated most of the world’s available fresh water for their own use; as miners, road-makers and city builders, they have become a greater earth-moving force even than wind, water and ice; and they have altered the composition of the atmosphere.
They have also dramatically altered the natural land cover and have pushed into the shadow of extinction an alarming proportion of the other 10 million or so species that share the planet and its resources.
— Bryce Stewart (@BD_Stew) January 8, 2016
Aluminium is plentiful in the Earth’s crust in compound mineral form, but refined aluminium is a marker of 20th-century human presence. So is concrete. The ancient Romans may have pioneered the use of this crushed and baked version of limestone, but as a universal and ubiquitous building material, it began to appear only in the last 100 years.
The combustion of fossil fuels has distributed soot, heavy metals and aerosols in mixtures and concentrations that had never existed before commercial power stations, factories, railways and motor cars. And the atmospheric tests in the 1950s and 1960s of atomic and thermonuclear weapons left a series of “spikes” of signature isotopes.
— Canadian Geographers (@CanGeographers) January 8, 2016
Soil nitrogen and phosphorus levels have doubled in the last century because of agricultural use, and even in places where agriculture does not happen the nitrate levels in the lakes of Greenland are higher than at any time in the last 10,000 years.
And if the signature of altered ratios of “natural” materials was not enough, humankind will have left its mark in exotic plastic fabrics gathering in the planet’s oceans at an estimated rate in 2015 of 9 million tonnes a year.
The precise nomenclature of geological time zones is a convenience largely for professional geologists and paleontologists. But the researchers do not see their argument as a purely academic one. Names tell us something.
‘Quite unlike other subdivisions of geological time, the implications of formalizing the Anthropocene reach well beyond the geological community,’ they conclude.
by Malcolm Turnbull, Nick Ross | Independent Australia