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Geologists are a staid, frequently bourgeois agglomeration, not known for making political waves. These are the people for whom the idea of plate tectonics was so heretical that information technology took decades to accomplish scientific consensus within the field, because continental drift threatened the idea that the Earth was static and and unchanging in structure. Now another controversy has erupted amidst geologists.  It concerns the so-chosen Anthropocene, the idea  that humans accept contradistinct World in such a way equally to crusade human activity to appear globally in the geological record, which constitutes a purlieus between epochs in the history of our planet. This thought was presented by a working grouping delegated past the International Geological Congress, after seven years of deliberation.  But opinions in the field remain sharply divided. So let'south accept this apart, shall nosotros?

Here's the statement presented by the IGC working grouping:

Geological time moves slowly, and in big increments of sidereal time: a geological age takes millions of years to pass, an epoch tens of millions. Sometimes in the history of our planet, Something Big has happened that leaves a global mark, like the design of growth rings in a tree: differing layers in the strata prove a articulate, unambiguous signal that in that location has been a change in the pattern. That's what nosotros employ to divide upward the history of our planet into manageable temporal chunks like epochs and ages. Like the K-T impact event that left a fine dusting of meteorite iridium in the global stratigraphic tape, the advent of the nuclear age left a fine dusting of manmade radioisotopes in the sedimentary layers around the world, and in the polar ice caps too. Since sedimentary rock is made from silt and sand and other such sediment, the activities of man sometimes represent a literal, actual line in the sand. And since information technology's humans who drew the radioisotopic line, the working group recommended naming the ensuing fourth dimension after humans, in the manner that we named the Cambrian era after the Cambrian explosion visible in the fossil strata. Enter the Anthropocene Epoch: the "new age of man." To put a effectively indicate on it, the working group proposed a formal start engagement of 16 July 1945 – the day of the beginning diminutive bomb blast.

nature-anthropocene-1203-a

But there's withal dissent in the ranks. A rebuttal published by the Geological Order of America dismisses the thought that humans have changed the planet equally "pop culture" – claiming that no such trace on the planet's record exists, and that people who like the idea of an Anthropocene era tin have it, but should keep their noses out of geology entirely. Other commenters misfile the Anthropocene epoch with the idea of anthropogenic climate change. Accusations of political bias have been lobbed at the working group. One fellow member of the working group really went on tape maxim that we should stop thinking well-nigh this problem for a 1000 years considering to practise otherwise would be "premature."

That's the contrary of science.

Let me exist articulate: nobody is accusing dissenting scientists of malice or bad faith. Just whatsoever whatsoever private's politics might be, the definition of a geological epoch is a thing of ascertainment. The International Stratigraphic Commission says it looks for a "golden spike": an outcome that's sudden and sharply divers, a boundary after which the whole world was dissimilar. And "nosotros're spoiled for option," explains Jan Zalasiewicz, head of the working group. Nature points out that through mining activities lone, humans move more sediment than all the world's rivers combined. Starting nigh the middle of the twentieth century, we started using things like plastics, fertilizers, coal power plants, concrete and leaded gasoline, all of which left an imprint in the sedimentary record.

The rebuttal letter from the GSA reminds us that "Fourth dimension stratigraphic units represent layers of rock containing lithologic, fossil, mineral, chemic, or geophysical signatures that let for the recognition and measurement of geologic time." But at that place'southward show of all these things, up to and including the bones left past the "global proliferation of the domestic chicken." On the deep seafloor, the layer of sediment representing the past 70 years would be less than a millimeter thick, but that millimeter could contain heavy elements like manmade radioisotopes or lead from airline fuel. Nobody volition know until we get down there and dig upwardly some silt and cheque.

In any event, a lot more than questions have to be answered earlier the Quaternary commission will accept the proposed Anthropocene epoch. Does the "golden spike" have to exist a single signal, present everywhere? In that location'south supposed to be a defined place in the rocks that marks the physical get-go of the new epoch. The pastiche of human chemic changes to the sedimentary record is present everywhere we become, but it's not one single thing: it's patches of radiocontamination, heavy metals, plastics, and the like. If we haven't leaded the sea floor all the same, it'south only because nobody has done mass commercial submarine trips. What of the smashing dams we've built? What of the mountaintops nosotros've leveled, the mines we've dug, and the roads we've carved out through solid stone? Everything humans touch, nosotros change. Our presence on this planet is written in rock, and nosotros should recognize it.

The first of the Anthropocene isn't a political statement. It's just a thing that happened. Humans accept made an impact on the Earth that's visible in the planetary geological record. Apart entirely from anyone'south views on popular culture, nosotros're talking about rocks here. Everyone agrees that in terms of geological time, if you tin can't find it in the rocks, it doesn't count. Invoking the climate alter nontroversy is nothing merely a straw man.