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Earth Space

How Earth's Biosignature Will Change As the Planet Dies 95

Posted by Soulskill
from the we'll-have-to-start-forging-another-planet's-biosignature dept.
KentuckyFC writes "As the Sun expands into a red giant, life on Earth will die away. Now astrobiologists have worked out how this will look to distant observers watching the biosignature in our atmosphere. They say the first major effect of warming, about 1 billion years from now, will be a dramatic drop in atmospheric carbon dioxide as the oceans absorb more of it. That's bad news for trees and plants, which need carbon dioxide for photosynthesis, so they begin to die off. Since plants produce oxygen, atmospheric levels of oxygen will also drop, killing off the animals. Roughly 2 billion years from now, the only living things on Earth will be microbes. However, methane levels will have risen dramatically, caused by decaying plant matter. And decaying animals will release a gas called methanethiol, which breaks down into ethane, which ought to be visible too. Finally, they calculate that about 3 billion years from now, the oceans will boil and Earth will be a barren planet with little if any biosignature at all. But all this is not just a subject of morbid fascination. With the next generation of space telescopes, astronomers should see similar biosignatures on Earth-like planets around other stars that are also beyond their sell-by dates. So we'll be able to watch them die off first."
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How Earth's Biosignature Will Change As the Planet Dies

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  • Should become nice and warm, I hope! ;)

    • by unixisc (2429386)

      Will we be moving from planet to planet as the sun expands? Earth to Mars, Mars to Jupiter (or its moons), there to Saturn & so on?

      Unlike w/ software, where people/organizations may sometimes skip a generation, that won't be an option here. People would have to move to the nearest habitable planet. One good thing - real estate should be a lot cheaper there, since each of these planets will be much larger. Of course, that may also depend on how much of it would be under water, or whatever its

      • by Saethan (2725367)
        Pfft, haven't you seen Dr. Who? We'll have force-field satellites that keep planets in living condition until they are no longer deemed useful. And the sole remaining human will be a sack of skin.

        I seem to recall reading that the sun should expand to about 1.3AU, Mars is 1.38 AU right now, though it should drift a little further as the sun's gravity field weakens. It might still be a little toasty, so slinging some asteroids together in the asteroid belt might be nice.
      • One good thing - real estate should be a lot cheaper there, since each of these planets will be much larger.

        Gravity. You can't stand it!

        • by ls671 (1122017)

          Exactly, not to mention Jupiter is classified as a gas giant primarily composed of hydrogen. So indeed, not that many planets are suitable even with life support like it would be required on a moon base.

          Even staying on a moon for a while might screw you up due to low gravity. Astronauts that come back from a reduced time International Space Station mission lose bone mass and it can take them up to 6 months to recover it when they come back to Earth.

          I guess life support would have to provide artificial gravi

          • by ultranova (717540)

            Or we could simply accept that bodies adapted to Earth are a liability anywhere else. We could fortify them to solve such problems. Or, if it turns out human mind is indeed a Turing machine, upload them. A far-future humanity could well live in spaceborn datacenters and central computers of robots and spaceships.

    • If we get enough know-how, we can just build our own habitable spaces in space itself...

      • by mcgrew (92797) *

        If we don't die off in a billion years. In a billion years I'm sure we'll have infected most of the solar system with life.

  • You mean we will watch how they died off millions of years ago, right?

    • The furthest planet that we have found yet is 21,500 ± 3,300 light years away according to Wikipedia. Unless they are going to get far better telescopes, I don't think it will be millions of years old.
    • by durrr (1316311)

      Some men just wants to see the world burn.
      Who cares about what world and when.

    • by fisted (2295862)
      No. Independent of how long it takes for that information to reach us, what we receive is the original information so we do watch them die off. Right now (i.e. then).
      • by osu-neko (2604)
        Yeah, time travel is hell on verb tenses, and looking out across vast distances of space is like a kind of time travel, as you're looking back in time. But despite that you're looking into the past, you're doing the looking right now. You even though it happened then, you're watching it happen now. It's true that you're watching what happen*ed*, but you're actually watching it happen. You're watching it happen now, even though it's not happening now, because by looking back in time, you're watching then
        • When will then be now? [youtube.com]

          But no really, I think it's only a matter of time before we overcome the conceit that the speed of light is inexorably tied to causality.
          • by sconeu (64226)

            Soon.

          • by khallow (566160)

            But no really, I think it's only a matter of time before we overcome the conceit that the speed of light is inexorably tied to causality.

            It's not the conceit you need to worry about. It's the evidence.

        • by lgw (121541)

          Except in General Relativity, something that happened 1 million years ago and 1 million light years away is happening now in the real, but non-intuitive, sense of "now". Our intuitions about time and distance are Newtonian, and not all that helpful at other scales.

          • by Vaphell (1489021)

            yes, but it is a bit unintuitive but not that hard to grasp. It's one of the easiest parts of general relativity to understand.

            there is no universal time scale and the reason is the speed of light being the hard cap. To make observations about chronology in the universal sense you'd have to be theoretically able to travel instantly to any point in the universe to witness simultaneous events as they happen or the information about these events would have to be able to propagate instantly so you can perceive

            • by lgw (121541)

              Well, I don't know. Relativity doesn't require ideas such as a universal clock or some universally common frame of reference, but there is one nevertheless. When speaking of some event 1 million years ago and 1 million LY away, both concepts of time are meaningful.

        • by mcgrew (92797) *

          Look at your hand. That's not your hand now, that's your hand a tiny fraction of a second ago.

    • Misery loves company

  • More than likely, we'll WMD ourselves into microbes by then.

    • by mspohr (589790)

      More likely climate change will make the planet uninhabitable within the next few hundred years.

      • by khallow (566160)
        Nobody has indicated a scenario by which this could happen. At a long term temperature sensitivity of 3C per doubling and three doublings in half a millennium, you still are speaking of a mere 9C increase over today, most of which would occur in the colder parts of the world. It's not going to make the world uninhabitable.
        • by Yomers (863527)

          Nobody has indicated a scenario by which this could happen.

          Wrong - http://en.wikipedia.org/wiki/Runaway_climate_change#Current_risk [wikipedia.org]

          • by khallow (566160)
            Ok, where? I just see at that Wikipedia article a bit of discussion about James Hansen claiming that temperature sensitivity could suddenly jump a slight bit above the current range with his usual lack of justification for why that would happen. He routinely claims disaster scenarios with little to no justification.
        • by mspohr (589790)

          There is some good science supporting this... if you believe in science. If you're a denier then keep your head in the sand.
          From the "Proceedings of the National Academy of Sciences":
          "We found that a 21-degree warming would put half of the world's population in an uninhabitable environment,"says study co-author Matthew Huber of Purdue University. While the Intergovernmental Panel on Climate Change found that the result of business-as-usual warming would be 7 degrees by 2100, eventual warming over several c

          • by khallow (566160)
            Another example backing my statement. Note here that the IPCC doesn't even have justification for the 7 F (or 4C) increase by the end of 2100! That claim is based on models which are already overstating temperature increases.

            And a 21 F (12 C) degree warming in three centuries? Where's that coming from? We're not burning enough fossil fuels now to make the necessary number of doublings. That means we have to see enough of an increase in methane, CFCs, or other greenhouse gases to make it.

            Looks like mor
  • If the sun is turning into a red giant and toasting our planet to a cinder, the biosignature of earth is a tiny footnote to the real event. Who cares if the plants die of a lack of CO2 right before they are incinerated? The main event is the star.
    • The sun's death will be a very slow one. Also, it's important to remember the scale of things. By the time the sun 'engulfs' the inner planets, its atmosphere will still be extremely diffuse near the Earth's orbit. Much closer to a vacuum than what we think of as an atmosphere.
    • by khallow (566160)
      The researchers think differently and I agree with them here. There are a huge number of stars slowly going through the early stages of becoming a red giant right now. It's quite possible that none of those stars have ever had life.
    • by dryeo (100693)

      The Sun has been getting hotter since its birth, with a 25% increase in output so far. It'll continue getting hotter until the oceans boil and the Earth is uninhabitable. The numbers I've heard are closer to a billion years vs the 3 billion in the summary.
      The reason for the increased output is that as the Sun ages, it converts hydrogen into helium and gets denser, being denser it burns hotter therefore converting more hydrogen into helium. Eventually in about 5 billion years it'll run short of hydrogen, sta

  • Error. (Score:5, Interesting)

    by Jane Q. Public (1010737) on Friday November 01, 2013 @05:10PM (#45305103)
    The original paper [arxiv.org] on the very first page of the introduction, says atmospheric CO2 drawdown will reduce CO2 concentration in the oceans, not increase absorption. The latter doesn't make sense anyway, because the solubility of CO2 goes down as temperature goes up.
    • by Bengie (1121981)
      I assume they mean indirectly absorb CO2, but good catch.
      • I thought that at high temperatures, what increases is the absorption of CO2 by Earth's crust, not its concentration in the seas? There's supposed to be a negative feedback loop (which is why historically, atmospheric CO2 has been steadily decreasing through the ages in line with the Sun steadily brightening).
        • by lgw (121541)

          That's more to do with the amount of exposed rock vs rock covered by ice. Rock weathering is the only carbon cycle that matters on geological scales.

          • by dryeo (100693)

            Actually the way the continent[s] are laid out really affects the rock weathering as the Earth doesn't usually have icy poles.
            Super continents have a dry interior, land mass mostly distributed north and south catch more rain, varying amounts of mountains, the depth of the oceans and so on all affect the climate over geological time.

    • by cusco (717999)

      Wonder what effect it will have on the underground biosphere.

    • by khayman80 (824400)

      Error. The original paper [arxiv.org] [arxiv.org] on the very first page of the introduction, says atmospheric CO2 drawdown will reduce CO2 concentration in the oceans, not increase absorption. The latter doesn't make sense anyway, because the solubility of CO2 goes down as temperature goes up. [Jane Q. Public] [slashdot.org]

      Presumably you're referring to these sentences:

      "Rising temperatures cause silicate weathering rates to increase, increasing CO2 draw-down, lowering CO2 levels in the atmosphere. This results in conditions t

      • by khayman80 (824400)

        Oh, I see. You were responding to the Slashdot summary [slashdot.org] which wrongly claims that "the first major effect of warming, about 1 billion years from now, will be a dramatic drop in atmospheric carbon dioxide as the oceans absorb more of it."

        You were right to point out this error. The summary should say land, not ocean. Sorry for the interruption.

  • This signature is set to change dramatically in future. As the Sun begins to heat the planet, one of the counterintuitive effects will be a dramatic drop in the levels of carbon dioxide in the atmosphere.

    This happens because more carbon dioxide dissolves in the oceans making them acidic and reacting with rocks to form clays. Essentially, the carbon becomes trapped in sediment on the ocean floors.

    So, why would the oceans absorb more CO2? Other sources tell me that warming oceans would absorb less CO2 [rtcc.org]. Why would this happen in reverse in the far future? That seems important since it sets up the rest of the process.

    • by suutar (1860506)
      The summary is misunderstanding/misquoting the paper. The paper says that increased heat will increase silicate weathering, which results in more carbonate deposits; part of that is pulling CO2 out of the air. The reduction in atmospheric CO2 will allow more CO2 to come out of the ocean, but that'll get fixed into carbonates too.
      • by erice (13380)

        Still needs more comparative analysis though. Venus is much hotter than Earth. Why hasn't the CO2 in Venus's atmosphere been sucked into carbonates?

        • by mcgrew (92797) *

          There are no oceans on Venus. Oceans of lead maybe, but not oceans of water.

    • by osu-neko (2604)
      Yeah, the summary is crap. The original paper notes the oceans become more alkaline, contradicting your quoted text regarding them becoming acidic.
  • by wisnoskij (1206448) on Friday November 01, 2013 @05:17PM (#45305229) Homepage

    I had no idea it was that close. I had never read anything about when the sun would be significantly effecting life, just that in 3-4 the planet would unlivable.

    1 Billion is pretty small in planetary time, we are in the twilight of earth's life supporting existence, you could say.

    • by mcgrew (92797) *

      Yep, life's been here 3.5 billion years, we're getting a little long in the tooth. But a billion years gives us time to expand; how long did it take life to completely colonize the planet? [wikipedia.org] Who knows, life from Earth could be riding on one of the Voyagers.

      • by BitZtream (692029)

        Great pains are taken to ensure that doesn't happen. Most space organizations are VERY concerned with the possibility of accidentally infecting some other world with our spew. Perhaps, in the grand scheme of things, it would be better if they didn't try so hard.

        Who's to say that some random bacteria won't evolve eventually into something more worth of the beautiful thing called life than we are.

        Before my son was born, I thought we should be masters of the universe.

        Now, I find it odd that I suddenly value

        • by mcgrew (92797) *

          Yes, they are indeed careful, infecting, say, Mars would certainly screw up the search for life.

          Or at least I think I understand. I really don't.

          Knowing you are ignorant is wisdom.

          I just hate the idea of death and ceasing to exist now more than ever.

          Well, not existing for 13 billion years didn't bother you, did it? And how do you know that death is the end, rather than a transformation?

  • by Anonymous Coward

    It took 4.5 billion years out of a 5.5 billion year window for intelligent life to evolve.

    That has to signficantly reduce the odds of finding other intelligent species.

    • by Urkki (668283)

      Sample size of one does not give any odds for intelligent life elsewhere, nor any timescale prediction. We know hardly anything about life on Earth for the first 3,5 billion years, we have very few data points, so we can't even estimate how long it "should" have taken to evolve here.

    • by mspohr (589790)

      Not so intelligent.
      At the rate we are going, the planet will be uninhabitable for human species in a few hundred years.

  • The bit about having all the CO2 absorbed by the oceans doesn't make a lot of sense. Water can dissolve more (soluble) solids as the temp increases, but the solubility of gasses goes DOWN with increasing temperature. Not that I would expect the reporter to know this or ask about it - it isn't Ars, after all.
  • This really is too bad. Not that the Earth is going to die, but that humanity does not possess the necessary skills in cooperation and teamwork to move our collective asses somewhere else before it happens.

    • by Urkki (668283)

      This really is too bad. Not that the Earth is going to die, but that humanity does not possess the necessary skills in cooperation and teamwork to move our collective asses somewhere else before it happens.

      Time scale check. Life on Earth has enough time left to be wiped down to cockroaches and re-evolve to intelligence. Also, humanity will not do something like that as a whole. All it takes is a few hyper-rich to get their kicks out of becoming the pioneer visionaries, written down to history like Aristotle or Confucius or Buddha. A few centuries at most for self-sufficient space colonies (if we survive that long).

      • by BitZtream (692029)

        Time scale check. Life on Earth has enough time left to be wiped down to cockroaches and re-evolve to intelligence.

        Thousands of times.

  • Party like its 1000002013!

  • by Anonymous Coward

    Even without heating, the concentration of CO2 has been steadily dropping over geological history. This is due to organic sediments that are pulled away from the surface by the tectonic activity. Occassionaly these rise to the surface but only as stones (calcium-carbonate mountains). CO2 is replenished by vulcanism which was probably much violent in the past.
    Once oceans boil, tectonic activity will stop (yes, oceans are responsible for plate tectonics) and earth will become more like venus (geologically) -

  • Look, it didn't take a research project to figure it out either!

  • When I first read this I sat straight up in my chair because thought it said one million years, then realized it said one billion years.

    • On the other hand, if we're not able to do something to survive these sorts of things by a million years from now, I doubt another 999 million will help.

  • That's when the temperature will have risen enough due to the sun increasing in luminosity to preclude liquid water on Earths surface.
  • Niven's World out of Time story had a plausible method for boosting the Earth to a higher orbit. Drag it behind a gas giant. Moving the gas giant itself was a bit more of a problem, but he had this magical planetary sized fusion rocket motor that used the gas of the gas giant as its fuel. His Known Space and Ringworld stories have the Puppeteer civlization's planets on an interstellar trip powered by some magical motor provided by extremely advanced aliens.

    Don't know if the energy required to move the

    • by Agripa (139780)

      Niven's World out of Time story had a plausible method for boosting the Earth to a higher orbit. Drag it behind a gas giant. Moving the gas giant itself was a bit more of a problem, but he had this magical planetary sized fusion rocket motor that used the gas of the gas giant as its fuel.

      And then the Girls screwed it up and parked Earth in the wrong orbit. Even in the future there is a place for women drivers.

  • "The world will be wonderful after all the people are dead" Tuesday night @9pm after "Fat Stupid Rednecks Digging Random Shit Out Of the Ground"

  • As the sun becomes bigger in mass. All those invested solar panels will pay off.

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