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Research Supports "Snowball Earth" Hypothesis 243

Posted by kdawson
from the big-chill dept.
u2boy_nl writes, "A new U.S. study finds evidence for 'Snowball Earth,' the hypothesis that the entire Earth was ice-covered for long periods on several occasions, most recently 600-700 million years ago. The icy conditions (Earth's oceans frozen completely with ice more than a kilometer thick) ended violently under extreme greenhouse conditions — snowballearth.org suggests the meltdown could have occurred in as little as 2,000 years. Snowball Earth challenges long-held assumptions regarding the limits of global change. Wikipedia has more on the hypothesis."
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Research Supports "Snowball Earth" Hypothesis

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  • Frost post! (Score:5, Funny)

    by Harmonious Botch (921977) * on Sunday November 05, 2006 @11:01PM (#16731205) Homepage Journal
    Sorry.. couldn't resist it.

    Seriously, I wonder if there could be evidence of organisms tolerant of saltier conditions if all that ice left the remaining water saltier.
    • Re: (Score:2, Funny)

      by modecx (130548)
      Seriously, I wonder if there could be evidence of organisms tolerant of saltier conditions if all that ice left the remaining water saltier.

      Well, there's Paris Hilton...
  • Hmm... (Score:3, Funny)

    by locokamil (850008) on Sunday November 05, 2006 @11:03PM (#16731219) Homepage
    I always did want to live on Hoth. The big question, however, is whether or not we'll have tontons when the next snowball era rolls around.
    • Wontons (Score:2, Funny)

      by tygt (792974)
      Let's combine that hypothetical event with a hypothetical future cultural takeover and we get..... Tauntaun Wontons!

      Just bring a package of wonton skins along with you on your next perimeter patrol - if things go too badly, gut your tauntaun with your light saber, carve it up a bit, wrap some in a wonton skin, and then use the light saber to boil some water.

      Scrumptious!

    • Based on that obvious eventuality, I've been hard at work attempting to create Tom-Toms.
      I've developed a two-step plan towards this end:

      1) Breed goats to produce giant goats; breed chickens to produce giant chickens. As a test, also procede to step #2 with regular chickens and goats.
      2) Crossbreed chickens and goats.

      I know it seems simple, since there's only two steps...unfortunately, I keep running into technical problems - especially with step #2. Fortunately, though, I've got some goat costumes for c
  • The Bush administration will probably love this! This will just confirm their assertions that the Earth's climate can swign wildly on its own, therefore we have no influence on it, yeah right.

    In all seriousness though, how can the Earth being an axial dipole (2 magnetic poles along a single axis) hundreds of millions of years ago suggest an Earth that was covered by up to a kilometer of ice? The Earth is currently in the same magnetic configuration, and there's certainly no indication of an impending s
    • by greenguy (162630)
      I, for one, feel greatly assured knowing that having the entire Earth, including the oceans, covered by a kilometer of ice is a completely natural phenomenon.

      As an aside, with the entire planet covered by a kilometer of ice, how much water does that leave to constitute the oceans?
      • by Salvance (1014001) *
        Assuming there wasn't also a kilometer of water over the surfaces, an average depth of 2km of water would be underneath the ice given that the average depth of our oceans is approximately 3km today (source: Oceans Alive [mos.org])
        • by greenguy (162630)
          Thanks.

          Follow-up question: Since life evolved long before 300 million years ago, we are left to assume that it somehow survived in the oceans... on the sunlight that made it through a kilometer of ice. Or have I missed something?
          • by uncadonna (85026)
            No, you are right on target. That is one of the very big questions about the snowball. Some people have suggested a slushball alternative, with some open water on the equator, but that hasn't panned out in model studies. That configuration appears to be unstable. So, yeah, how life survived is a question. Probably some very local geothermal effect saved a few tiny critters.
          • by init100 (915886)

            Since life evolved long before 300 million years ago, we are left to assume that it somehow survived in the oceans... on the sunlight that made it through a kilometer of ice. Or have I missed something?

            The answer might be hydrothermal vents [wikipedia.org]. From the article:

            Relative to the majority of the deep sea, the areas around hydrothermal vents are biologically productive, often hosting complex communities fueled by the chemicals dissolved in the vent fluids. Chemosynthetic archaea form the base of the food ch

          • by Ironsides (739422)
            Anarobic bacteria. They can survive without light or oxygen. Not all food chains are based on photosynthesis.
          • by jc42 (318812)
            Since life evolved long before 300 million years ago, we are left to assume that it somehow survived in the oceans...

            But note that, until about 600 million years ago, life on Earth was entirely single cells, mostly bacteria. The last "snowball" period seems to have ended roughly 600 million years ago, and that's about the date of the first multi-cellular fossils. All the living things you can see around you (without a microscope) have evolved since that last great glaciation.

            So the actual question is "How
          • by CastrTroy (595695)
            Well, they've recently found life 3 KM down in the ROCK [www.cbc.ca], where no light can reach it. There's no sunlight, no thermal vents, but it is pretty warm, due to being so deep. So we don't necessarily need sunlight for life. I suggest you listen to the audio files linked to in the page above. It's pretty interesting stuff.
    • Re: (Score:3, Interesting)

      by jd (1658)
      It's interesting to note which country the researchers came from... Being an axial dipole means exactly nothing, unless you encounter a horseshoe-shaped planet. The magnetic axis wobbles all over the place and even reverses, but I've never heard even the remotest suggestion that it has ever been anything other than a very simple axis. The Earth's core generates a magnetic field as a result of (a) being molten, and (b) rotating, so is probably produced by circulatory currents within that core. The only possi
      • >The magnetic axis wobbles all over the place and even reverses, but I've never heard even the remotest suggestion that it has ever been anything other than a very simple axis. The Earth's core generates a magnetic field as a result of (a) being molten, and (b) rotating, so is probably produced by circulatory currents within that core.

        This gets interesting.

        There is a quadrupole moment, and it can exceed the dipole moment just before a pole reversal.

        The assumption all along was that the magnetic field was
      • by uncadonna (85026)
        It's dreadful journalism, but it's describing real science. The study breathlessly referred to by the confused journalist only confirms one step in the chain of evidence behind the snowball hypothesis.

        The snowball itself pretty much a done deal in the geophysics community. A slightly exagerrated but entertaining and accessible popularization of the story is available and I highly recommend it: Snowball Earth: The Story of a Maverick Scientist and His Theory of the Global Catastrophe That Spawned Life A [amazon.com]

      • by Salvance (1014001) *

        600 million years is not a long time, geologically speaking - or even evolutionarily-speaking - and I'm not convinced that every necessary process to get from Iceworld to habitable planet could occur in such a short space of time. I could be wrong, but I would need some VERY hard evidence.

        600 Million years isn't a long time? The earth is believed to be under 5 Billion years old, so geologically speaking they are referring to over 10% of all geological history. The oldest multi-cellular creatures are b

      • by arivanov (12034)
        One minor problem with your argument: 600 million years is a lot of time. It took less then 200 million years to erode the Pennines from a 8km high Himalaya like mountain to the gentle rolling hills of nowdays England. A glacier valley deep as the Grand Canyon will be unrecognisable in less then 50 million years. Same for lava beds. The only evidence from that far back is from chemical composition and crystallisation of rocks. Here the situation is even worse. Obsidian which the best marker for extreme cool
    • Re: (Score:2, Interesting)

      by btgreat (895041)
      "In all seriousness though, how can the Earth being an axial dipole (2 magnetic poles along a single axis) hundreds of millions of years ago suggest an Earth that was covered by up to a kilometer of ice? The Earth is currently in the same magnetic configuration, and there's certainly no indication of an impending super ice age.

      Using the same logic, would Geologists in 600 Million years look back on today and say the Earth was covered by ice now?"


      The answers to your questions are in the link marked "S
    • by ctr2sprt (574731)

      In all seriousness though, how can the Earth being an axial dipole (2 magnetic poles along a single axis) hundreds of millions of years ago suggest an Earth that was covered by up to a kilometer of ice? The Earth is currently in the same magnetic configuration, and there's certainly no indication of an impending super ice age.

      Well, there may be a feedback loop of some kind. That is, Earth gets hotter, which triggers some reaction which makes it hotter still, and so on. At a certain point such a reaction

      • Re: (Score:2, Funny)

        by cheater512 (783349)
        The earth runs out of bits and overflows in to negative temperatures.
        Once the feedback loop spirals out of control the temperature will drop to -32,768.
    • by wkcole (644783)

      In all seriousness though, how can the Earth being an axial dipole (2 magnetic poles along a single axis) hundreds of millions of years ago suggest an Earth that was covered by up to a kilometer of ice?

      You missed the other parts.

      1. There is a pattern of evaporite and carbonate rocks that implies rather cold conditions.
      2. The magnetic alignments in the various trace minerals (i.e. ferrites etc.) in that rock imply that it was formed at the magnetic equator, i.e. the rotational and climatic equator IFF
    • The Bush administration will probably love this! This will just confirm their assertions that the Earth's climate can swign wildly on its own, therefore we have no influence on it, yeah right.

      Politics aside, when you're looking at multi-million-year time scale, the Earth's climate does swing wildly on its own; and when compared to temperature changes of almost 200 deg F, anything we can possibly do will be negligible.

    • by Dasher42 (514179)
      The Bush administration will probably love this! This will just confirm their assertions that the Earth's climate can swign wildly on its own, therefore we have no influence on it, yeah right.

      Well, there certainly are some looneys who'll say so, but really it's not a valid concern. This was 600 million years ago, prior to the rise of any multicellular life as we know it. The sun was weaker. Also, a rapid defrost would be, in biological terms, a golden opportunity for "evolutionary radiation" as many ecol
    • Another little nigle; if the earth were a snowball a mere 2000 years ago, don't you think the egyptians and the chinese would've at least mentioned it? Or at least worn warmer clothes?

      Snowball earth seems very shaky to me...not in the least due to the geological evidence, but also because I don't see how exactly the warming up process would happen.
  • Cavemen (Score:3, Funny)

    by flyingfsck (986395) on Sunday November 05, 2006 @11:13PM (#16731285)
    Those cavemen must have burned a hell of a lot of oil to cause sufficient greenhouse gas to get the earth to warm up again.
    • Re: (Score:3, Funny)

      by ozbird (127571)
      Those cavemen must have burned a hell of a lot of oil to cause sufficient greenhouse gas to get the earth to warm up again.

      That was the Golgafrinchams burning the forests to solve the inflation problem caused by making leaves legal tender.
    • Re: (Score:3, Informative)

      by killjoe (766577)
      Actually the ice prevented the oceans from absorbing the CO2 that was spit out by volcanoes. Eventually it built up enough to melt the ice. Once the ice broke it started a chain reaction and it stormed for thousands of years. For some period after the ice broke it literally rained hydrochloric acid. You can see evidence in melted rocks today.

      Amazing any life lived though that but some plankton made it through and eventually it turned into humans.

      The truth is stranger then fiction.
      • by argStyopa (232550)
        Amazing any life lived though that but some plankton made it through

        That's liable to be a touch misleading.

        We're talking 600-700 million years ago. That "some plankton made it through" is pretty predictable, since there was nothing BUT single-cell and very early multicellular organisms (such as choanoflagellates) at that time.
    • by Dunbal (464142)
      burned a hell of a lot of oil to cause sufficient greenhouse gas

            Naw, it was dinosaur farts that warmed up the earth again.
  • by Jerf (17166) on Sunday November 05, 2006 @11:27PM (#16731375) Journal
    The Wikipedia article has some interesting connections to the Fermi Paradox, though the article doesn't call them out.

    (If you don't know what the Fermi Paradox is, look, Wikipedia [wikipedia.org]!)

    One of the possible answers to the Fermi Paradox (which I note doesn't show up in the Wikipedia article) is that life is common in the universe, but the worlds are either hospitable towards the life, resulting in no selection pressure towards complexity, or so hostile that the life totally dies out too often to advance. The general image is of a universe full of oceans full of simple, utterly stable bacteria, which by most standards is still basically lifeless. (We're really interested in other intelligent life, not a universe of little germs.) It has been hypothesized that the best scenario for complex life is a recurring series of disasters that almost, but not quite, kills off life each time, resulting in a strong selection pressure for the requisite complexity to handle such environmental pressures.

    Connect that idea with [wikipedia.org]:

    The carbon dioxide levels necessary to unfreeze the Earth have been estimated as being 350 times what they are today, but would be able to accumulate due to the opposite of the effect mentioned earlier as a possible mechanism triggering the freeze in the first place; if the Earth was completely covered with ice, silicate rocks would not be exposed during erosion, and carbon dioxide would not then be removed from the atmosphere. Eventually enough CO2 would accumulate, perhaps after an era of increased volcanic activity (a prodigious producer of this greenhouse gas), that the oceans around the equator would finally melt, which would produce a band of open ice-free water, much darker than the highly reflective ice, which would absorb more energy from the sun. This would in turn heat the Earth more, melting more water to absorb more light, and so on. Concurrently, the abundance of CO2 would provide plenty of food to feed a cyanobacterial population explosion, resulting in a relatively rapid reoxygenation of the atmosphere to feed the following Cambrian Explosion with the new multicellular lifeforms. This positive feedback loop would melt the ice in geological short order, perhaps less than 1000 years; replenishment of atmospheric oxygen and depletion of the CO2 levels would take more thousands of years.

    However, the carbon dioxide levels would still be two orders of magnitude higher than usual. Rain would wash CO2 out of the atmosphere as a weak solution of carbonic acid, which would turn exposed silicate rock to carbonate rock, which would then erode easily, wash into the ocean, and form deep layers of carbonate sedimentary rock. Thick layers of exactly this abiotic carbonate sediment can be found on top of the glacial till that first suggested the Snowball Earth.

    Eventually the carbon dioxide level would get so low that the Earth would freeze over again. This cycle went on until Rodinia had dispersed so much that the Earth's land was no longer strung out along the equator and the primary cause of Snowball Earth would no longer operate.
    The next section of the Wikipedia article mentions the effect this could have had on evolution.

    (I find the Fermi Paradox interesting because I believe it is actually by far the biggest problem facing science as a whole; science says life should be plentiful and easy and populating the stars ought to be possible at significant fractions of the speed of light, so where is the life that is doing so? It's easy to become numbed to the problem because it seems somewhat abstract, but it's not. Something is fundamentally wrong with at least one of biology, astronomy, cosmology, sociology, and/or the intersections of those disciplines we don't have names for, and we don't know what.)
    • "...so where is the life that is doing so?"


      Maybe all complex life eventually develops their version of Myspace?
      • by corbettw (214229)
        Maybe all complex life eventually develops their version of Myspace?

        Have you seen Myspace? Doesn't seem all the complex to me.
    • by wrook (134116)

      I find the Fermi Paradox interesting because I believe it is actually by far the biggest problem facing science as a whole; science says life should be plentiful and easy and populating the stars ought to be possible at significant fractions of the speed of light, so where is the life that is doing so? It's easy to become numbed to the problem because it seems somewhat abstract, but it's not. Something is fundamentally wrong with at least one of biology, astronomy, cosmology, sociology, and/or the intersec

    • by LS (57954)
      Based on your explanation, the problem of the Fermi Paradox is that it is too narrow minded. Perhaps evolution towards complexity accelerates, and becomes unrecognizable to humans very quickly. Using radio waves for communication may only be present for an extremely short period of time during the evolution of an intelligent species. Also, perhaps what we perceive to be the universe is only a tiny slice. Other intelligent species could quickly move to populating other dimensions. We would (or could) ha
  • by dsanfte (443781) on Sunday November 05, 2006 @11:30PM (#16731393) Journal
    From the website:
    Deposition of glacial or glacial marine strata close to the paleo-equator during the Marinoan, Sturtian and Makganyene glaciations, indicated by a growing body of reliable paleomagnetic data from different regions.


    This is a fancy way of saying that they have found deposits of submarine rock near the equator that should only be forming in an arctic climate, and which date to the period of 'snowball earth' in question. This sediment has magnetic signatures which signify it formed originally at the equator, in an equatorial magnetic field, and did not simply arrive at the equator after having been formed previously in the arctic.

    Please note that we are speaking here of a process of lava cooling, and 'trapping' a fingerprint of whatever magnetic field was present at the time it cooled. That's how these fingerprints are formed and it is a well-known and documented process, and a basis for the current models of magnetic field shift.

    Had the magnetic system been different in the past (not a two-pole magnetic field) it would have rendered these results useless, but this article itself explains that there is now evidence that the Earth's magnetic field has always been a dipole (two-pole) field and that these results are correct.

    At least, that is my understanding.
    • by Salvance (1014001) *
      The problem is that all evidence points to the magnetic poles shifting, flipping, and changing in other ways over the course of the Earth's history. Every year the poles move by up to 40km, moving between continents within our own lifetimes. Here's an interesting article from NASA [nasa.gov] to explain the historical shifting/changing of the magnetic fields ... to me, this would invalidate the 'Snowball Earth' theory to some degree.
      • by dsanfte (443781)
        Well that's just it! This evidence shows that, despite shifts, the magnetic field has always fallen into a more-or-less stable "dipole" arrangement that has remained the 'average' after a shift.

        Therefore the evidence is reliable. If the field had been changing during the shifts themselves then it would have been recorded in the rock.
        • Of course Earth's magnetic field has always had a dipole arrangement: that's the only kind of magnetic field there is! As far as anyone knows, magnetic monopoles aren't physically possibly, much less tripoles etc. As for the shifting of the field and reversing the poles, well, shift happens.
        • Well that's just it! This evidence shows that, despite shifts, the magnetic field has always fallen into a more-or-less stable "dipole" arrangement that has remained the 'average' after a shift.

          Yes, but for the field to flip, it has to go through a period of effectively no magnetic field, which while short, does persist for I think a couple thousand years each time. Considering that the field flips on average every few hundred thousand years, then on a rough average, somewhere around a percent of the vol

          • by dsanfte (443781)
            To be fair, we are talking here about strata that took millions of years to lay down. A thousand-year magnetic anomaly would be an eyeblink in a stratum of sufficient age and the 'average' value of a normal dipole would be very predominant.
      • by eric76 (679787)
        That is, of course, the magnetic poles, not the geographic poles around which the Earth spins.

        People often get those confused. Some people who have heard of the north and south magnetic poles flipping think that the Earth is going to somehow magically flip over at that time as well.
    • by nametaken (610866)

      Thank you for that.
  • I find it amazing that people who believe in something with basically no verifiable proof of existence (i.e. God) have such a tough time believing in something that is so demonstrably happening in front of them.

    If ever there was proof of the power of man to delude himself, denying that we have a large and thus-far detrimental effect on climate change would be it.
    • by c_forq (924234)
      I think part of that goes to the whole humility thing. The teachings of the insignificance of man makes it easy to think that man could not possibly have an effect on something as vast as a planet. No one argues teh localized effects of polluting factories, but can't imagine that it is effecting the entire globe. It's like that flap of a butterflies wings causing a hurricane thing - people expect dominoes to knock over similarly sized dominoes, not knock over doors and walls.
      • by QuantumG (50515)
        No, sorry. The reason why people have so much trouble accepting what is going on is that there is simply no workable solution to solve the problem. "Change the way we live" is not a workable solution. It's a heck of a lot easier to ignore the issue than it is to accept that.
    • Re: (Score:3, Insightful)

      by nametaken (610866)
      That was a little out of left field, no?

      I know plenty of people who believe both. In fact, I think there's actually LESS of a rivalry between religion and science than people suggest.

      I think little things like this are important evidence for what I'm saying...

      "John Paul insisted faith and science could coexist. In 1996, in a message to the Pontifical Academy of Sciences, he said that Darwin's theories were sound as long as they took into account that creation was the work of God and that Darwin's theory of
      • I know plenty of people who believe both. In fact, I think there's actually LESS of a rivalry between religion and science than people suggest.

        Good point - a lot of the born agains that slam science don't believe in Jesus either execept as a convenient name . Their God hates poor people and does what he's told for the merchants in the temple - but what would I know as an infidel - Oral Roberts excommunicated my entire continent because customs officals pissed him off.

      • by mike449 (238450)
        Note that it's almost always the religious types that try to "coexist". Science, by its nature, doesn't need religion. Religion, on the other hand, needs all the support from the science it can get.
        It is much harder (while still possible) to find a scientist that supports "coexistence".
      • by sckeener (137243)
        I know plenty of people who believe both. In fact, I think there's actually LESS of a rivalry between religion and science than people suggest.

        Keep saying it and Kansas will still be just as backwater.....Texas is only slightly better. (I live in Texas)

        "John Paul insisted faith and science could coexist. In 1996, in a message to the Pontifical Academy of Sciences, he said that Darwin's theories were sound as long as they took into account that creation was the work of God and that Darwin's theory of evolut
  • Bush made the ice melt just like he killed polar bears!!
    • by Dunbal (464142)
      Bush made the ice melt

            Of course he did. Saddam could have been hiding WMD's under there...
  • by plopez (54068) on Sunday November 05, 2006 @11:44PM (#16731467) Journal
    I can't wait till they get a hold of this one. Regardless of all the other evidence they will use it as a way to slag on evironmentalists, the Kyoto treaty, liberals, democrats, gay marriage, stem cell research and find creative ways to link all of them to terrorism. And champion corrupt corporations as being the benign benefactors of all humanity. This should be fun.

    The climate is dynamic. The question is: "are humans having a serious negative impact on the global climate?" And there is a bunch of evidence stacking up saying "yes."
    • I can't wait till they get a hold of this one. Regardless of all the other evidence they will use it as a way to slag on those who believe global climate change might be natural. They will say we should trust environmentalists to know the truth, should have signed the Kyoto treaty, vote in liberals and allow gay marriage and surely stem cell research will save the world. It is all linked to terrorists, who cause global warming with their suicide bombs. Corporations and "profits" cause all human misery. Ther
      • by rlp (11898)
        Oh come now, surely the Snowball earth represents yet another failure of the Bush administration. I'm sure there will be an editorial in the New York Times to that effect tomorrow.
    • by Cadallin (863437)
      Its pretty much irrelevant whether humans are causing global warming at this point. It IS happening, we know that. We also are quite painfully aware of the negative impact this has on the environment, both from our perspective (weather becomes much more chaotic and violently unpredictable, formerly arable land becomes desert, water supplies shift and in general the total amount of potable water decreases) and from the perspective of other species inhabiting the planet (various fungal, algal, and protist s
      • Damn... Just... Damn...

        So in order to solve this mess [global warming] that we've gotten ourselves into you're fully willing to go in the opposite direction and change the Earth's albedo despite having inconclusive and incomplete data on the subject? Are you the same person who will advocate driving around an SUV in 50 years to prevent global cooling because you so arrogantly fucked with nature again?

        Your attitude makes me sick.
        • by Cadallin (863437)
          No, I'm trying to advocate a solution that will mitigate the mid- to long-term consequences of human activity for the past century. I'm trying to advocate a course of action that would save the lives of untold millions of people, and thousands of other species on the earth. The things you, and the people replying to the article " A Sunshade In Space To Combat Global Warming" don't seem to understand are numerous. An orbital solar diffuser is REVERSIBLE, should it be necessary, although given the current
          • "An orbital solar diffuser is REVERSIBLE"

            Yes, and the Hubble was supposed to FOCUS. Things of complexity break down. What if -- just consider -- what if, your spacecraft drop and refuse communication? How then will you remove said cloud?

            Want another suggestion? One that is Earth-bound and therefore far more likely to be controllable? CO2 scrubbers.

    • by slughead (592713)
      Alter Relationship on Sunday November 05, @11:44PM (#16731467)
      I can't wait till they get a hold of this one. Regardless of all the other evidence they will use it as a way to slag on evironmentalists, the Kyoto treaty, liberals, democrats, gay marriage, stem cell research and find creative ways to link all of them to terrorism. And champion corrupt corporations as being the benign benefactors of all humanity. This should be fun.


      This just goes to show how the global warming debate is less about science an
    • At the moment the question seems to be "Are humans having a serious negative impact on the global climate?"

      This is used to reinforce the status quo, right? It's not our fault, what we're doing isn't the problem, so why bother stopping what we're doing?

      It seems to me like the questions should be:

      "Is the climate changing?"
      "Is it changing in a way that will benefit humanity?"
      "If not, how do we manufacture the change we desire?"

      These questions should be framed with the idea that the climate is changing and will
  • No more including Wikipedia links in articles. I mean seriously, does anyone out there really need help searching the wikipedia? Please, if you want to give real information on a subject, give a real primary or secondary source. If that means you have to learn how to do some real research, well thats a skill you need to learn at some point anyways.
    • by Dun Malg (230075)
      I have a proposal-- No more including Wikipedia links in articles. I mean seriously, does anyone out there really need help searching the wikipedia? Please, if you want to give real information on a subject, give a real primary or secondary source.
      There's nothing wrong with linking wikipedia for a simple overview. Why do you object to people including a freakin' hyperlink in their summary, demanding that people go look it up themselves? Get over yourself.
  • ... that we live on.

    Suppose that a mechanism of repeating cycles (and perhaps cycles within cycles) between ice ages (major and minor) has been a requisite factor in the evolution of life on Earth, with the regular cycles of extinction following the alternation of ice ages and greenhouse eras.

    It would make for a grand Darwinian scythe.

    What does that do to the various elements of the Drake equation?

    While the universe is certainly large enough for intelligent life to evolve under a wide variety of conditions,
  • Again I am pointing out to the submitter: why not mentioning the original peer-reviewed article (OPRA)? At least the source of it: Nature. Insasmuch I despise this pileload of pseudoscience which Nature is, it has the highest impact factor among the general science journals with peer-reviewed articles.

    I am pretty sure tons of specialists that visit ./ regularly would appreciate that. All academics have free access to Nature and many industrial scientists do as well.

    Here is the OPRA link [nature.com].
  • ...God just shook it and the window on top said, "Cannot Predict Now".

    (he'll shake it again soon)

  • I just watched a show on this on the Science Channel. It was pretty good. If you're interested in it, you should check for a re-broadcast.
  • Earth was ice-covered for long periods on several occasions, most recently 600-700 million years ago.

    Jeez, has it really been that long? Man, I must be getting old.

    -Eric

  • If all of those dinosaurs had just driven hybrids, that never would have happened.
  • The climate models described by the article point to the radiation received from the sun and the heat radiated into space but they don't seem to consider the heat originating from within the earth itself. It is obvious that the earth produces an enormous amount of heat from within, probably from radioactive decay, that affects temperatures at the surface (i.e. our 'climate') and yet the climate models never seem to consider that heat as an input into the model. The frequent and wide variations in the eart

Statistics are no substitute for judgement. -- Henry Clay

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