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Earth

Scientists Stunned To Discover Plants Beneath Mile-Deep Greenland Ice (sciencedaily.com) 157

KindMind shares a report from ScienceDaily: In 1966, US Army scientists drilled down through nearly a mile of ice in northwestern Greenland -- and pulled up a fifteen-foot-long tube of dirt from the bottom. Then this frozen sediment was lost in a freezer for decades. It was accidentally rediscovered in 2017. In 2019, University of Vermont scientist Andrew Christ looked at it through his microscope -- and couldn't believe what he was seeing: twigs and leaves instead of just sand and rock. That suggested that the ice was gone in the recent geologic past -- and that a vegetated landscape, perhaps a boreal forest, stood where a mile-deep ice sheet as big as Alaska stands today.

Over the last year, Christ and an international team of scientists -- led by Paul Bierman at UVM, Joerg Schaefer at Columbia University and Dorthe Dahl-Jensen at the University of Copenhagen -- have studied these one-of-a-kind fossil plants and sediment from the bottom of Greenland. Their results show that most, or all, of Greenland must have been ice-free within the last million years, perhaps even the last few hundred-thousand years. "Ice sheets typically pulverize and destroy everything in their path," says Christ, "but what we discovered was delicate plant structures -- perfectly preserved. They're fossils, but they look like they died yesterday. It's a time capsule of what used to live on Greenland that we wouldn't be able to find anywhere else."
The findings appear in the journal Proceedings of the National Academy of Science.
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Scientists Stunned To Discover Plants Beneath Mile-Deep Greenland Ice

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  • "Life, uh... finds a way." - Dr. Ian Malcolm

    • Over the last year, Christ and an international team of scientists

      Nice to see the church adopting scientific methods at last, although having to bring in their founder just to get them adopted still implies there's a fair bit of resistance in there.

    • TFS doesn't claim that the specimens found are still alive.

      As for :

      "Ice sheets typically pulverize and destroy everything in their path," says Christ,

      That may be an idea that people have in the first year or two of their geological training - it is hard for me to think back that far - but it shouldn't last long. A question aimed at disabusing students of that notion was in one of my high-school mock exams (for which the marking schemes are released to teachers, for discussion with the pupils some months b

  • US Army drilling into ice back in 1966? Before commencing dig, did they all stand around marking the circumference of a dark circular object visible beneath the ice? Any certainty this 'sample' wasn't thrown free of the circular object upon impact? I've seen this documentary a few times and it doesn't end well for the researchers. I really hope they keep it frozen.
    • Ummm, a film reference? Care to put a name to it?

      A comedy, masquerading as a horror? Care to put a name to it - it sounds hilarious.

  • some context (Score:4, Interesting)

    by Jodka ( 520060 ) on Tuesday March 16, 2021 @10:00PM (#61166914)

    Rud Istvan provides some context [wattsupwiththat.com]; Conditions have changed over the previous million years to make a repeat less likely

    First, Greenland used to) sit over a very active tectonic zone, still forming Iceland. 1 mya Greenland was further south, not north oriented, and considered a separate tectonic plate. (It is now mostly snuggled up to the North American plate, with a lot of tectonic earthquakes along the border.) It has uplifted as it approached North America, drifted further north, and tilted more North/ South in the past million years. So its present climatology is not its climatology 1 mya. It remains (maybe until recently) a separate tectonic plate because Greenland also contains some of the oldest known exposed crustal rocks, dated to 3.7-3.8 mya. (Only also isolated Australia competes in the age of oldest rocks, zircon dated.)

    Second, about 1 mya in the mid Pleistocene (which itself started maybe about 2.7 mya, arguably with the tectonic closure of the Panama Isthmus), the glaciation/deglaciation (two chaotic strange attractors?) system provably shifted from about a symmetric 40 kya ice age/40kya non-ice interval to an asymmetric about 100 kya ice age/about 20 kya non-ice interval. Nobody knows why, but it geologically provably did. So, a 40/40 cycle 1 mya would have meant much less icecap on Greenland, much more melting, and thus plants during at least part of the non-ice intervals. NOT NOW, with the new asymmetric 100/20 ice cap cycle.

    • Lies from Rud Istvan. I double checked his article because I couldn't imagine Greenland moving that much in a million years. He is wrong. According to NASA, his whole thing is completely nonsense because it hinges on the incorrect statement (aka lie) of Greenland being super far south 1 mya (million years ago). It was further south 100 mya, not 1 mya.

      Check the NASA video explanation. A million years ago Greenland was in what looks like vritually the exact same spot as today. 40 mya it was only a tiny bit fu

      • Lies from Rud Istvan.

        We knew that from the link to wattsupwiththat.

        I was doing a counting-on-fingers exercise while reading the BS from wattsup, and getting a figure of about 60miles movement in a million years, and it's about 2 units E-W for each 1 unit N-S. For a commercial boat, that's 3-5 hours steaming in good sea conditions.

        Now, if you go back 55 million years to the Palaeocene-Eocene Thermal Maximum - which was probably triggered by the elevation of the chain of hotspots including Mull, Skye, Anton

  • ...you say?

    Almost like...that ice hasn't been there forever? That it was in fact quite temperate for a long while?

  • Surely radio-carbon dating has an accuracy better than ~1 million years?

    • by codguy ( 629138 ) on Wednesday March 17, 2021 @12:40AM (#61167142)
      C-14 has a half-life of about 5,730 years, and like most radioactive decay and half-life based dating methods, it's only good back about seven half-lives. So radiocarbon dating can only generally be used for organic-based things back to about 35,000 - 40,000 years old, i.e. about seven half-lives. It can be extended back a little further to maybe 50K-60K years, too, but with less accuracy. Regarding the accuracy of radiocarbon dating, depending on the quality of sample, you might have +/- accuracy of just a decade or two for a really good sample. But it also depends on the radiocarbon calibration curve; i.e. for a sample of a given quality, it may have different +/- accuracy results because of wiggles in the radiocarbon calibration curve. With poor samples and contamination, you could be looking at +/- accuracy of hundreds or even thousands of years. With multiple good samples, wiggle matching of the radiocarbon calibration curve, Bayesian techniques, etc., one could get down to +/- accuracy of just a few calendar years. Back to the press release at hand--the plant/organic material they attempted to age date with radiocarbon was radiocarbon dead, i.e. no more measurable radiocarbon remained. They used other dating methods, too, including cosmogenic Be-10 dating (a speciality of Bierman, one of the authors) and luminescence dating as well, but they just very lightly mentioned these in the press release (not using the specific terms I have used above).
      • by kbahey ( 102895 )

        Just wanted to say thanks for the additional info. Really informative.

      • Nice summary, including the cosmochemistry clocks for the intermediate timescale (megayear order).

        The presence of unoxidised organic matter suggests little flowing pore water, and so poor prospects for thorium-series dating. Their basic sample testing would have told them that - not a lot of authigenic carbonates.

  • ... it's how biology is done. It isn't a science it's just observation. Biology has no first principles on which to found theories of life, it's just rampant speculation where dominant 'theories' are more about the personality of the researcher than anything like science.

  • And chillingly nothing of the civilization and the people who brought about that climate change remains.
    I mean _clearly_ humans are responsible for climate change so _clearly_ humans must have been responsible BUT nothing remains of them.
    Yes, folks, that is our fate as we repeat the mistakes of the past. ... and if you believe that well then you have more to fear than climate change my friend.

    • by 1s44c ( 552956 )

      This planet has been evolving constantly. It has not been in a perfectly stable state for billions of years until humans turned up. Human activity is one reason for change, not the only reason.

  • They would've been really surprised if they found Jimmy Hoffa.
  • This core was drilled as part of the secret U.S. military project to investigate the feasibility of placing ICBMs in silos under the ice. The project had the really cool name "Project Iceworm".

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