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posted by mrpg on Thursday April 19 2018, @07:37PM   Printer-friendly
from the Wakanda dept.

Can We Be Sure We're the First Industrial Civilization on Earth?

In a new paper, Gavin Schmidt of the NASA Goddard Institute for Space Studies and Adam Frank from the University of Rochester ask a provocative question [open, DOI: 10.1017/S1473550418000095] [DX]: Could there have been an industrial civilization on Earth millions of years ago? And if so, what evidence of it would we be able to find today?

The authors first considered what signs of industrial civilization would be expected to survive in the geological record. In our own time, these include plastics, synthetic pollutants, increased metal concentrations, and evidence of large-scale energy use, such as carbon-based fossil fuels. Taken together, they mark what some scientists call the Anthropocene era, in which humans are having a significant and measurable impact on our planet.

The authors conclude, however, that it would be very difficult after tens of millions of years to distinguish these industrial byproducts from the natural background. Even plastic, which was previously thought to be quite resistant, can be degraded by enzymes relatively quickly. Only radiation from nuclear power plants—or from a nuclear war—would be discernible in the geological rock record after such a long time.

Anonymous Coward says "I told you so!" and starts babbling about megaliths.

Related: Homo Sapiens Began Advanced Toolmaking, Pigment Use, and Trade Earlier Than Previously Thought


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  • (Score: 2) by TheRaven on Friday April 20 2018, @10:12AM (2 children)

    by TheRaven (270) on Friday April 20 2018, @10:12AM (#669581) Journal

    Things like stainless steel

    Corrodes in acid. After periods of volcanic activity, stainless steel will be damaged. It's also subject to stress from weather and can be damaged by lightning strikes. Over a period of a few million years, don't expect it to be very obvious. It also takes a long time for a new civilisation to understand it. If there had been a giant stainless steel structure sitting anywhere where humans evolved, it would likely have been completely stripped by the iron age.

    concrete with re-rod

    Concrete degrades noticeably after a hundred years and is unlikely to be visible at all after a couple of thousand. Re-bar steel is cheap crap that rusts very quickly when exposed to water (which will happen after the concrete is weathered away). Expect it to be completely undetectable after a million years.

    glass

    Glass is fragile and smashes. Weather the pieces enough and you're left with sand.

    aluminum

    You might be onto something there. It takes a lot of energy to refine aluminium, but once you have done it's pretty resistant to corrosion. That said, it does end up coated in a fine layer of aluminium oxide, which may be stripped by abrasion over a sufficiently long timescale and allow the next layer to be exposed.

    Mining rich metal deposits, mapping magnetic anomalies, oil exploration using explosive charges to generate earth penetrating waves, and Space Shuttle radar have all demonstrated the ability to find buried relics.

    Most of these are under a thousand years old.

    Buried stuff often ceases to degrade in low-groundwater areas.

    Assuming a tectonically stable area, of course.

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  • (Score: 2) by Phoenix666 on Friday April 20 2018, @02:22PM (1 child)

    by Phoenix666 (552) on Friday April 20 2018, @02:22PM (#669652) Journal

    I was going to say the same thing. The premise is that over millions of years crust gets subducted and recycled, so it's tough to think of tells that would last that long. It's pretty darn recent that we found enough evidence to support the theory of plate tectonics (in the 1950's and 60's), and it's not that many sites that supplied it. Gros Morne National Park [emporia.edu] in Newfoundland was designated a geologic UNESCO World Heritage site because its strata helped clinch it (really cool place, BTW--highly recommend it).

    So it doesn't seem that hard to accept the possibility that we could have missed evidence of earlier civilizations, even if they had left fissile products, if we were looking in the wrong places. Heck, it's only just now that archeologists are searching below the waves for evidence of human habitation in Doggerland [thevintagenews.com], in recognition that sea levels and shorelines (where early peoples tended to settle) changed dramatically after the last ice age.

    When I read the article I thought perhaps someplace off the Earth like the Moon would be a better place to preserve evidence of previous terrestrial industrialized civilizations, but that would further assume that that civilization also made it to the Moon and that the evidence was not covered up by ejecta from impacts occurring over that long time span.

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    • (Score: 2) by TheRaven on Saturday April 21 2018, @12:07PM

      by TheRaven (270) on Saturday April 21 2018, @12:07PM (#670028) Journal

      When I read the article I thought perhaps someplace off the Earth like the Moon would be a better place to preserve evidence of previous terrestrial industrialized civilizations

      The moon is a pretty harsh environment. Two weeks of direct (unfiltered by atmosphere) followed by two weeks of no sunlight gives a temperature variation of a couple of hundred degrees, which weakens most materials. Radiation and vacuum both weaken things more. Lack of atmosphere also means impacts from micrometeors (tiny ones will burn up in our atmosphere, but will abrade the surface of the moon). Anything buried would have a much better chance of surviving (no tectonics, no temperature changes once you're deep enough, but we'd also be unlikely to find anything buried deep enough to be safe.

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