The Ancient Global Snowball: When CO2 Saved Life on Earth

August 26, 2015

The story of ‘snowball earth” has been distorted and used as confusion fodder by climate denial luminaries like His Celestial Magnanimity, the looney “Lord” Monckton, – see above.(starts about 1:50)

In contrast to today, when warming from our industrial injection of carbon dioxide into the atmosphere threatens life on the planet, in the deep past, CO2 pulled planet earth from a permanent, deathly world-wide deep freeze, maybe more than once.  In both cases, it’s those same heat-trapping properties that made the difference.

It’s all more evidence of how co2 has acted as the planet’s “biggest control knob” for temperature over 4 billion years.

Ian Fairchild, PhD, in The Conversation:

The idea of a deep-frozen world, “snowball Earth”, has captured the imagination since first proposed in the 1990s. On several occasions in history, long before animals evolved, apparently synchronous ice sheets existed on all the continents. However, much like falling into a crevasse on a glacier, it’s easy enough to enter such an ice age, but very difficult to escape.

The snowball Earth theory came from climate modellers who found that low carbon dioxide levels could trigger the growth of ice sheets. The whole planet would become glaciated and its mean temperature drop to as low as -45°C. As ice is much more reflective than the sea, or bare land, the Earth at that point would have been bouncing nearly all of the sun’s radiation back into space. So how could the planet ever emerge from such an ice age?

Volcanoes had to be the answer. Only they could emit enough carbon dioxide into the atmosphere to overcome the effects of Earth’s cool reflective surface. But climate models still found it difficult to plausibly describe how the Earth could have shed its glaciers.

We now have the first full explanation for how the best-known snowball event, the Marinoan, finished 635 million years ago with a several hundred metre rise in sea level. The study is the result of work by an international team of scientists, including myself. Our results are published in the journal Nature Geoscience.

We found slight wobbles of the Earth’s spin axis caused differences in the heat received at different places on the planet’s surface. These changes were small, but enough over thousands of years to cause a change in the places where snow accumulated or melted, leading the glaciers to advance and retreat.

The Earth was left looking just like the McMurdo Dry Valleys in Antarctica – arid, with lots of bare ground, but also containing glaciers up to 3km thick. Such an Earth would have been darker than previously envisaged, absorbing more of the sun’s radiation; it was easier to see how the escape from the snowball happened.

dryvalleysToday, to find exposed rocks that can tell us about the carbon dioxide content of the atmosphere in the Marinoan, you have to go to the Norwegian Arctic island of Svalbard. In 2009 snowball theory was vindicated after we found the telltale signal of high carbon dioxide levels in Svalbard limestone that formed during the ice age.

Immediately underneath the Marinoan deposits are some beds of rocks deposited at very regular intervals – so regular that they must have formed over thousands of years, influenced by wobbles in the Earth’s orbit. Since Svalbard was near the Equator at the time, the most likely type of wobble is caused by the Earth slowly shifting (“precessing”) its axis on cycles of approximately 20,000 years.

Researchers also found evidence of the same process in the Snowball deposits themselves. Fluctuations in ice in relation to the Earth’s orbit are a feature of our modern ice ages over the past million years, but had not been found in such an old glaciation.

Lead researcher Doug Benn (University of Svalbard) stood alongside rocks from the same region created during the late stages of the snowball, as glaciers came and went. Ian Fairchild, Author provided

For a long time the Earth was too cold for glaciers to erode and deposit sediment – the main snowball period. The sediments then show several advances and retreats of the ice. When the glaciers retreated, they left behind a patchwork of environments: shallow and deep lakes, river channels, and floodplains that appeared as arid as anything known in Earth’s history.

Carbon dioxide appears to have remained at the same high level throughout the deposition of these sediments. Since it takes millions of years for CO2 to build up in the atmosphere, this implies the sediment layers must have formed quickly – on the order of 100,000 years. All this fits with the idea of 20,000 year precession cycles.

A group of climate modellers from Paris tested the theory. The rocks and the models agreed: wobbles in the Earth’s axis had caused the planet to escape its snowball phase.

So after several million years of being frozen, this icy Earth with a hot atmosphere rich in carbon dioxide had reached a Goldilocks zone – too warm to stay completely frozen, too cold to lose its ice. This transitional period lasted around 100,000 years before the glaciers fully melted and present-day Svalbard was flooded by the sea.


17 Responses to “The Ancient Global Snowball: When CO2 Saved Life on Earth”

  1. Andy Lee Robinson Says:

    I get this for Peter Hadfield’s Monckton video:
    “This video contains content from BBC Worldwide, who has blocked it in your country on copyright grounds.”

    Youtube can be a mystery sometimes, how it decides what is allowed or not.

  2. Bob Doublin Says:

    This post has been blocked from sharing on Facebook because of what they claim is content that has been reported as abusive. Are you being targeted Peter? All you did was speak the truth about Monckton.

  3. Bob Doublin Says:

    I just shared it fine. Looks like they acquitted you of the charges,you naughty boy. Maybe his lordship showed mercy to the rabble like a true member of the peerage.

  4. I still get blocked result.

  5. Please, someone, anyone, I’m puzzled.

    It seems to me that until 50 years ago Earth’s climate was temperature driven. Well, for the last 2.5m years or so, in the current tectonic configuration.

    Every 100 000 yrs or so, the Milankovitch cycles lined up. So temperature rose. So C02 was released by the oceans. After the “Milankovitch peak” the water got colder again and so it absorbed more CO2.

    The total amount of CO2 in the system was CONSTANT. What varied was the PROPORTION in the oceans and in the atmosphere. Atmospheric CO2 was at most 300 ppm. The difference between an “ice-age” and an… (I don’t know – in French it’s called an “inter-glaciaire”) was 100 ppm.

    Then we came along. We started injecting vast quantities of NEW CO2 into the atmosphere. Atmospheric CO2 is now at 400 ppm!!

    Temperature is now – and will henceforth be – CO2 driven. This is change on a geological scale.

    Please, someone, anyone, tell me I’m wrong!

    • petermogensen Says:

      I’m not sure what you suspect you’re wrong about. Your summary seems “good enogh” for a 1st approximation to me.

      Yes, we’ve effectively removed the possibility of another glacial period.

      Click to access archer.2005.trigger.pdf

      Some would probably argue that that’s a good thing … And in theory it is. At some point the ability to do that could have come in handy.
      However… there was really no “ice age” in sight the next many thousands of years (16.000-50.000), so it seems a little premature to release CO2 to prevent it.
      The current interglacial we destined to be remarkable stable (look at the insolation curves for the milankovitch cycles. … so we had plenty of time to evolve technology to prevent an ice age.

      What we’ve done now, is to cancel an “ice age problem” which wouldn’t happen the first 16.000 years anyway, by introducing a catastropic warming problem within the next 200 years.

      Einstein was probably right… there’s only two things which are infite…

      • “Interglacial”… yes, obviously. Thank you.

        What I might be wrong about? Well, I panicked a bit because the article might be read as suggesting that atmospheric CO2 caused temperature rise. And I was pissed as a rat at the time after a good night in the local bistro!

        In fact, it was a chicken-and-egg thing: it got warmer, so atmospheric CO2 rose, so it got warmer…

        The basic, stable state of planet Earth is a “snowball”. All of “human history” has happened since the end of the last ice-age.

        Incidentally, I see no point in taking too much account of stuff that happened hundreds of millions of years ago, because to all all intents and purposes it wasn’t the same planet. At most, we can look back about 40m years to when the Australian plate separated from Antarctica and the Humboldt Current started up.

        That’s why I mentioned the “current tectonic configuration”.

        Thank you for taking the time to comment.

        I blog on climate change (here: but most of my stuff in French because there’s a terrible dearth of reliable climate-change information in the “infosphere”.

        Do have a look. And, please, tell me if you spot anything that’s… well, wrong.


        • greenman3610 Says:

          for more on this

          • Thank you. This (Hansen) reinforces my understanding. But it’s far too complicated for the general public.

            I’ll get back to you later on this. I need to summarise lots of stuff I’ve written in French.

          • greenman3610 Says:

            right, it’s complex, but communicators like yourself and others must understand the big picture and work hard to communicate more widely.

        • petermogensen Says:

          Yes… The mechanism of getting from a glacial period to an interglacial is that orbital changes provides more insolation at the high latitutes, so it gets warmer and ice starts to melt (lowering albedo and making it even warmer), which in turn releases CO2 from the ocean, starting a feedback loop great enough to make the temperature difference.

          But no… it’s inaccurate to say that the “stable state of planet Earth is a snowball”.

          We are currently in the quartenary ice age (since 2.55 mill. year ago), but you could hardly call it a “snowball”. Ice seldom extended below the Alpes.

          Earth have had several prior “ice ages”, some of which actually resulted in a “snowball” with ice extending to the equator. But those ice ages happenedes several 100 million years ago and are *not* the same as the glacial periodes we normaly call “ice ages” (the last ending ca. 12-18.000 years ago).
          Yes, all of human history happened since the last glacial period.

          I admit it’s rather confusing… and most in the denier-camp can’t figure it out either.
          There’s the big “ice ages” in geological terms, which there’s been 5 ot 6 of. We are currently in such an “ice age” – the quatenary ice age.
          There’s the “glacial periods”, which is what we normally call an “ice age”, which is recurring glaciations of the northern hemisphere with “interglacials” roughly every 100.000 years (due to orbital cycles). We are currently in such an interglacial (called the “Holocene”, – the last one being “The Eemian”). – providing relatively warm climate (which is why we don’t think of it as an “ice age”). The Holocene would have lasted at least 16.000 years without human intervention.
          … and then there’s the infamous “Little ice age”, which is not an ice age at all, but a temporary cool period in our current interglacial. … There’s some discussion whether it qualifies as a “stadial”.

          People often get the 3 things confused.

  6. There is such a huge gulf between the understanding people have and the understanding people need…

    For example, I sent this earlier to a guy who’s been reading my blog:

    Oh dear, oh dear, oh dear…

    Michael, my friend, if you don’t know what the IPCC is, you are way, way behind the 8-ball. I’m sorry, but there’s no way to say that tactfully.

    Please, please, read this for a start (Wikepedia):

    “The Intergovernmental Panel on Climate Change (IPCC) is a scientific intergovernmental body under the auspices of the United Nations,[1][2] set up at the request of member governments.[3] It was first established in 1988 …” (etc, etc. – cf. Wikipedia)

    The IPCC is THE scientific reference in all things climate change. It’s been publishing reports for the last thousand years or so but no one reads ’em! You can find the “Executive Summary” of the last report (n°5) here: It’s only 26 pages long and it’s surprisingly readable. This has to be your starting point.

    Then I would suggest you read:

    – Cliive Hamilton: Requiem for A Species
    – Naomi Oreskes & Eric Conway: The Merchants of Doubt
    – Naomi Klein: This Changes Everything

    On another site (here: someone was kind enough to qualify my summary as “good enough for a first approximation”, which – I must confess – I found slightly condescending. I’ve spent years pouring over this stuff – not just the headlines and the occasional article in the Guardian, but the science itself. I’ve given myself a solid grounding in the whole fucking kit an’ caboodle.

    I don’t want to give you the impression I’m yelling at you. That would be insulting – and anyway, yelling is seldom productive!

    I’m just surprised. The tone and direction of your previous comments left me with the impression you knew what you were talking about. Maybe you do. Maybe I’ve got you all wrong. Maybe you just expressed yourself clumsily – hey, shit happens!

    Please get back to me on this, if only to tell me I owe you an apology…


    You see how many words it takes to say – even approximately – what you think? And what use is it? Do you think that guy will get back to me? Do you think he will actually read anything? Learn anything? Or will he just sit there on his well-intentioned but under-informed “opinions”?

    I care. And I think beyond the present. Millions of people will die tomorrow. Hundreds of thousands of them avoidably. And yes, you’re right, that stinks. But I can’t do anything about it. And in any case those hundreds of thousands pale into utter insignificance beside the millions of generations who ought to be humanity’s future and who will never see the light of day if we don’t get global warming sorted now.

    “We”? OK – that’s unfair. My generation has fucked up. My parents’ too? No – to be fair, they couldn’t know. The knowledge – most of it – didn’t exist, and what little there was was inaccessible. There was no Internet. A few thousand people at most – of my generation – knew enough to understand what was happening. Most of them couldn’t connect the dots. Some could…

    I care because I’ve learnt enough to realise that we humans are unique. Our intelligence and our consciousness are precious beyond words. Sure, there might be other intelligent species capable of manipulating their environment out there somewhere, somewhen. But they were/are/will be millions of light-years apart in time and space. So they might as well not be there. We are miraculous and we are our only chance. Take us away and the cosmos is immeasurably impoverished.

    And we’re only just getting started! Aristotle, Bach, Picasso are just the beginning! In just ten millennia we’ve gone from gathering grass to (almost) quantum computing and we’re getting cleverer faster. What might we not be capable of?


    • dumboldguy Says:

      “….someone was kind enough to qualify my summary as “good enough for a first approximation”, which – I must confess – I found slightly condescending”? Really? And how would you characterize your message to the poor benighted Michael? Was it not condescending?

      The “someone” who was “kind enough” to point out that you had made a good “first approximation” was petermogenson, and he was right on, particularly with his criticism of your statement that “the stable state of planet Earth is a snowball”. He understands “ice ages” far better than you.

      I would add my objection to the statement “I see no point in taking too much account of stuff that happened hundreds of millions of years ago, because to all all intents and purposes it wasn’t the same planet”. It has been the “same” planet for ~4.5 billion years, will continue to be once man is extinct, and understanding Earth’s evolution over “hundreds of millions of years” IS important to dealing with AGW.

      As for: “Our intelligence and our consciousness are precious beyond words. We are miraculous…take us away and the cosmos is immeasurably impoverished…. we’re getting cleverer faster…What might we not be capable of?”

      We are apparently not capable of avoiding our own extinction and perhaps that of most of the life on the planet. “precious”, “miraculous”, “the cosmos would be immeasurably impoverished”? Lord love a duck, but the hyperbole and anthropocentrism there is mindboggling. The “cosmos” doesn’t give a rat’s ass if the Earth exists, never mind if man survives here or not.

      Since we’re passing out reading lists, I suggest the following for you:
      Deep Future: The next 100,000 Years of Life on Earth by Curt Stager
      The World in 2050: Four Forces Shaping Civilization’s Northern Future, by Laurence Smith

      • Apparently we’re not coming from the same place. I maintain that we humans have unimaginable potential for creating good and beauty. Whether or not we shall survive long enough to realise that potential is – as you rightly point out – a matter of considerable doubt. And that saddens me immensely.

        As for Michael, you were not privy to our previous exchanges. I hope he will get back to me and if I can convince him to start reading seriously I won’t have wasted my time.

        Thank you for the book references.

  7. ralfellis Says:

    Actually, the biggest control knob is dust-albedo, not CO2.

    Paper: Modulation of Ice Ages via Precession and Dust-Albedo Feedbacks

    We present here a simple and novel proposal for the modulation and rhythm of ice ages and interglacials during the late Pleistocene. While the standard Milankovitch-precession theory fails to explain the long intervals between interglacials, these can be accounted for by a novel forcing and feedback system involving CO2, dust and albedo. During the glacial period, the high albedo of the northern ice sheets drives down global temperatures and CO2 concentrations, despite subsequent precessional forcing maxima. Over the following millennia CO2 is sequestered in the oceans and atmospheric concentrations eventually reach a critical minima of about 200 ppm, which causes a die-back of temperate and boreal forests and grasslands, especially at high altitude. The ensuing soil erosion generates dust storms, resulting in increased dust deposition and lower albedo on the northern ice sheets. As northern hemisphere insolation increases during the next Milankovitch cycle, the dust-laden ice-sheets absorb considerably more insolation and undergo rapid melting, which forces the climate into an interglacial period. The proposed mechanism is simple, robust, and comprehensive in its scope, and its key elements are well supported by empirical evidence.

    Modulation of Ice Ages via Precession and Dust-Albedo Feedbacks


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