Has the Holocene ended? Thinking in geologic timescale, have we entered a new epoch – the Anthropocene? Dr. Colin Waters of the British Geologic Survey seems to think so.
Have we humans, as a species, brought sufficient change into the Earth system, thereby producing a stratigraphic signature in sediments? Will that signature appear in ice and will it be distinct from Holocene Epoch? The answer may very well be an affirmative. The changes happening are as big as the ones which happened at the end of the last ice age. Also, there’s the rise of carbon and methane in the atmosphere, which is then found in the oceans. The scale of the rise in the atmosphere of these elements is faster than in the Holocene.
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The deposits of the current age consists of the elements which we use every day and cannot imagine our world without it –
Recent anthropogenic deposits contain new minerals and rock types, reflecting rapid global dissemination of novel materials including elemental aluminum, concrete, and plastics that form abundant, rapidly evolving “technofossils.” Fossil fuel combustion has disseminated black carbon, inorganic ash spheres, and spherical carbonaceous particles worldwide, with a near-synchronous global increase around 1950. Anthropogenic sedimentary fluxes have intensified, including enhanced erosion caused by deforestation and road construction. Widespread sediment retention behind dams has amplified delta subsidence.
Concrete has become the prevalent mode of construction and more than half of it ever produced, has been in the last 20 years.
Three centuries ago, 50% of all ice free lands was considered wild. Now it’s just 25% and this has increased the rate of extinction.
However, the real human fingerprint, if you will, on the geologic time, is radioactive fallout found as isotopes left from nuclear weapons testing in the 1950’s – 1960’s:
“It’s probably a good candidate [for a single line of evidence to justify a new epoch] ... we can recognise it in glacial ice, so if an ice core was taken from Greenland, we could say that’s where it [the start of the anthropocene] was defined,” Waters said.
Since the last Great War, there has been accelerated technological growth and population has kept pace, as has consumption. That consumption has produced an effect related to farming, agribusiness and its effects on soil:
“We are becoming a major geological force, and that’s something that really has happened since we had that technological advance after the second world war. Before that it was horse and cart transporting stuff around the planet, it was low key, nothing was happening particularly dramatically,” said Waters.
Hence, yes, the Anthropocene has arrived. However, the International Commission on Stratigraphy is being called upon to decide. Therefore, until they say so, we are still in the Holocene. If you do party in celebration, don’t use too much plastic. Because the we will have to enter the Anthropocene (yet another LINK!!).
Picture explained:
Indicators of the Anthropocene in recent lake sediments differ markedly from Holocene signatures.
These include unprecedented combinations of plastics, fly ash, radionuclides, metals, pesticides, reactive nitrogen, and consequences of increasing greenhouse gas concentrations. In this sediment core from west Greenland (69˚03'N, 49˚54'W), glacier retreat due to climate warming has resulted in an abrupt stratigraphic transition from proglacial sediments to nonglacial organic matter, effectively demarcating the onset of the Anthropocene. [Photo credit: J. P. Briner]
If you were interested, you could download the power-point in the last link, for yourself.
I’m loading this in the queue on Thursday night. I'll be on the road and cannot respond. I hope you all have a good week! :-)