Claim: Explosive underwater volcanoes were a major feature of 'Snowball Earth'

From the UNIVERSITY OF SOUTHAMPTON the “splode” department comes this interesting claim that tries to make CO2 the driver rather than volcanoes themselves. It looks like a big leap of speculation to me.


Around 720-640 million years ago, much of the Earth’s surface was covered in ice during a glaciation that lasted millions of years. Explosive underwater volcanoes were a major feature of this ‘Snowball Earth’, according to new research led by the University of Southampton.

Many aspects of this extreme glaciation remain uncertain, but it is widely thought that the breakup of the supercontinent Rodinia resulted in increased river discharge into the ocean. This changed ocean chemistry and reduced atmospheric CO2 levels, which increased global ice coverage and propelled Earth into severe icehouse conditions.

Because the land surface was then largely covered in ice, continental weathering effectively ceased. This locked the planet into a ‘Snowball Earth’ state until carbon dioxide released from ongoing volcanic activity warmed the atmosphere sufficiently to rapidly melt the ice cover. This model does not, however, explain one of the most puzzling features of this rapid deglaciation; namely the global formation of hundreds of metres thick deposits known as ‘cap carbonates’, in warm waters after Snowball Earth events.

The Southampton-led research, published in Nature Geoscience, now offers an explanation for these major changes in ocean chemistry.

Lead author of the study Dr Tom Gernon, Lecturer in Earth Science at the University of Southampton, said: “When volcanic material is deposited in the oceans it undergoes very rapid and profound chemical alteration that impacts the biogeochemistry of the oceans. We find that many geological and geochemical phenomena associated with Snowball Earth are consistent with extensive submarine volcanism along shallow mid-ocean ridges.”

During the breakup of Rodinia, tens of thousands of kilometres of mid-ocean ridge were formed over tens of millions of years. The lava erupted explosively in shallow waters producing large volumes of a glassy pyroclastic rock called hyaloclastite. As these deposits piled up on the sea floor, rapid chemical changes released massive amounts of calcium, magnesium and phosphorus into the ocean.


Extensive underwater volcanism during ridge spreading led to rapid alteration of volcanic deposits and major changes in ocean chemistry. CREDIT Gary Hincks

Dr Gernon explained: “We calculated that, over the course of a Snowball glaciation, this chemical build-up is sufficient to explain the thick cap carbonates formed at the end of the Snowball event.

“This process also helps explain the unusually high oceanic phosphorus levels, thought to be the catalyst for the origin of animal life on Earth.”


166 thoughts on “Claim: Explosive underwater volcanoes were a major feature of 'Snowball Earth'

    • I’m not seeing “CO2 causes volcanoes” anywhere in there.
      All they’re saying is that during the time of snowball earth, the mid-oceanic rifts were explosive volcanoes whose lava build-up is sufficient to explain an existing minor scientific puzzle.
      Interesting, sure. Hardly controversial.

      • Actually, quite controversial, if you read geological literature. If you look at modern Mars as an analog of the earth at that time, the principle difference is that we had a great, planetary ocean and an active plate [tectonic] system. [Mars] had comparatively shallow seas. Presently, the Martian south pole contains the vast majority of the water and CO2 on Mars. There may also be ice sheets under dust toward the equator, but the current condition of the planet is largely due to the orographic effects of the southern highlands. The ice built up there, initially selectively pulling water vapor out of the atmosphere, chilling the planet from the southern pole northward. As the planet cooled, CO2 also began to freeze out primarily at the south pole, further limiting the atmosphere’s heat retention and thinning he atmosphere, ultimately producing the planet we see today. The big difference is that Mars does not have an active plate tectonic system. The planet is too small and too cold internally, with too thick a crust.
        The break up of Rodinia on earth coincides with the end of the snow ball earth ad the inception of the Phanerozoic. Geography and plate tectonics are all we need to explain both the inception and end of “snow ball” earth. Other effects might have contributed but they are contributors rather than causal agents.

      • Sheesh – “tectonic” not “tectonci” and “Mars” not Mar’s”. Fingers living lives of their own.

  1. This is what a former professor of mine would call a “SWAG”. That is a “scientific wild assed guess”. But in this case it is a bad, bad guess because CO2 does not have the magical powers those fools think it does. This is just horrible heifer dust “science”.

    • rapid chemical changes released massive amounts of calcium,….
      …..the global formation of hundreds of metres thick deposits known as ‘cap carbonates’
      We call it liming……common way to reduce calcium in city water

  2. > “Because the land surface was then largely covered in ice, continental weathering effectively ceased. ”
    How much time has the author spent several miles under an ice sheet to determine this?

    • I live around the Boston area. I have lots of nice little round rocks in my back yard complements of the glaciers.

    • From wiki: “Weathering occurs in situ, roughly translated to: “with no movement” , and thus should not be confused with erosion, which involves the movement of rocks and minerals by agents such as water, ice, snow, wind, waves and gravity and then being transported and deposited in other location.”
      Glaciers cause erosion but hinder weathering.

      • And weathering occurs because dust is blown across the face of the rocks, or rain water runs down the surface, dissolving chemicals. Weathering is, thus, “in situ” erosion, but it happens because “something” moves against its surface, be it dust, rain, or a glacier. If it didn’t have an agent working against the surface, it wouldn’t “weather.” Granted, in general, we wouldn’t consider a glacier “weather.”

  3. Pardon me for raising the hand of skepticism here, but it should be noted that (1) Animal Life is well documented in the Precambrian Era, long before the time of Rodinia’s breakup; (2) One can’t have shallow marine volcanic deposits along Mid-Ocean Ridges as the ridge eruptions are by definition, the deepest ocean areas along a Mid-Ocean Ridge; (3) Dr. Gernon is a Populist Lecturer and by no means an acknowledged expert on Rodinia, Mid-Ocean Ridge Eruptions, or Subsea Volcanic Chemistry! His claims to fame involve Kimberlite Deposits, which are about as far from Mid-Ocean Ridge Eruptions as one can get. His ideas of subsea chemistry belie the facts that hyaloclastite deposits, which are by nature tufflike Glassy breccias, do not spontaneously convert to carbonates – at least so far anywhere else in the world where they form! Frankly, his claims amount to so much balderdash, that any competent volcanologist would have dismissed Dr. Gernon’s ridiculous notions as seemingly coming from some seriously deranged individual – which pretty much sums up those publishing from the University(?) of Southampton.

    • Read the abstract and SI; paper is paywalled. It is all computer simulations. MonteCarlo’s, no less!
      And there is an apparent logic flaw. The simulations assume all this happens under thick ocean ice, which would prevent biosynthesis of the calcium carbonate caps he seeks to explain. No alternative abiological synthesis route is provided.
      Nor does any of this explain why snowball earth melted thanks to enhanced volcanic CO2 (the abstract’s posited mechanism) since calcium carbonate sequesters CO2 until released by heating in subduction zones. A SWAG at best.

    • The first possible fossil evidence of animals (or Metazoa, ie motile multicellular eukaryotes) is indeed from the Cryogenian Period, apparently sponge-like organisms dating either late in the Sturtian glaciation or between it and the Marinoan (c. 665 Ma). However, some have interpreted trace fossils from the Tonian Period (c. 1000-720 Ma) as having been made by metazoans. Others point out that large single-celled organisms can make similar burrows.
      The hypothesis that “unusually high oceanic phosphorus levels” account for the origin of animals has been around since at least 2010:
      The idea is that “phosphorus would wash into the ocean, where it would fertilize algal blooms that could drive a surge in the production of organic matter and oxygen”. And further, that “the added organic matter that settled into the mud on the ocean bottom would leave additional oxygen behind, eventually boosting atmospheric and oceanic oxygen”. The apparent history of stromatolites suggests that this claim is at least plausible.
      Finding fossils of soft-bodied metazoa will remain chancy, but maybe with time we’ll get a better handle on the timing of the evolution of mobile multicellular heterotrophs.
      IMO however there are better explanations for the end of Snowball Earth episodes than the currently fashionable CO2 hypothesis.

      • Stromatolite history in the deserts of Australia date to between 1.1 and 1.2 Billion Years ago, nearly half a millennium before the breakup of Rodinia. Other stromatolite formations have been dated as old as 2.3 Billion years. The typical explanation for the formation of these massive deposits is very shallow marine algal mats forming for millions if not billions of years in relatively undisturbed marine environments. Periodic inundation by ocean storms sink the mats with sediments, the algal filaments rise back to the near surface and the cycle continues. The current environmental regime normally used to illustrate such an environment is shallow coastal areas similar to the mangrove swamps of Florida. As such, these formations could not have occurred during a Snowball Earth and therefore must have either pre-dated such a time, the Snowball Earth concept with 2-3 km global oceanic ice is not valid, or any such ice age was not global. Assuming that the somehow derived amounts of phosphorous created an algal bloom, one has to ponder the Dr. Gernon’s Chicken and Egg dilemma – If a Snowball Earth is required to form the Carbonites necessary for Pre-Existing Stromatolite Formation, and that the Environment required for Stromatolite growth is shallow warm marine seas, then all I see from Dr. Gernon’s proposal is a lot of “Egg on the Face”!

      • The point about stromatolites is that they flourish when there are no or fewer animals to consume the photosynthesizing cyanobacteria and other prokaryotes of which they are composed. Their incidence fell from about a billion years ago, which has suggested to some that the earliest animals “grazed” upon them. There might however well be other reasons for the apparent drop in their numbers during the Tonian. Stromatolites made comebacks after the Ordovician and Permian mass extinctions as well. So a lower number of the formations during the hiatus in Cryogenian glaciations has been attributed to the emergence of animals.

      • Gloateus Maximus – January 18, 2016 at 12:10 pm said:

        IMO however there are better explanations for the end of Snowball Earth episodes than the currently fashionable CO2 hypothesis.

        The currently fashionable CO2 hypothesis is simply “junk science”.
        Quoting article:

        This locked the planet into a ‘Snowball Earth’ state until carbon dioxide released from ongoing volcanic activity warmed the atmosphere sufficiently to rapidly melt the ice cover.

        DUH, …. in a Snowball Earth condition it matters not a twit how much CO2 is in the atmosphere simply because there is little to none IR radiation from the earth’s surface to per se “warm” said atmospheric CO2.
        Ice and snow will reflect solar irradiance but they do not emit IR radiation.
        CO2 is only a small fractional component of the total emissions from volcanic activity.
        Dust particulate is the primary component of the total emissions from volcanic activity and when said particulate settles on top of the ice and snow they will absorb the solar irradiance and their increase in temperature results in the per se “rapid melting” of the ice.

    • sz239 – I think by “Animal life” they probably mean modern multicellular animals. Yes there were lots of single celled entities — some capable of photosynthesis, some not — back to perhaps 3.8 billion years BP, but the first multicellular creatures seem to have appeared about 600,000,000 years ago soon after the snowball earth ended. It’s not clear whether those entities were animals in the modern sense or maybe something else entirely. There were lots of them, but they were soft bodied and generally don’t preserve very well. They aren’t well understood at all. Undoubted modern animals — mollusks, echinoderms, arthropods, brachiopods, vertebrates — appeared about 50 million years later. Modern animals may or may not be related to the older Ediacarians.
      I think perhaps the key point is the cap carbonates. Those formations are real. You can visit one if you really want to — e.g. the Nonnday Dolomite in Death Valley. Nothing similar forms during modern deglaciations, so they do need an explanation. I have no idea if they are somehow explained by vulcanism. (IANAG-I am not a Geologist)

      • Don, they discovered that volcanoes produce calcium hydroxide…and that causes calcium carbonate to precipitate out of solution forming those deposits…at least that’s what they are blaming it on they just don’t know it
        It’s called lime softening….common cheap way to soften city water

      • Dr Gernon’s SWAG Hypothesis requires a Geochemical mechanism to turn Glass Breccia into carbonates. Will some Geochemist on this blog please explain if such a mechanism exists or if Dr. Gernon is just another University(?) of Southampton Imbecile? My research indicates that Mid-Ocean Ridge Basalts, in particular, are very low in Alkalies, such as the required CaO and MgO which would make any conversion to Cap Carbonates rather mote under any circumstances. Even a SWAG requires some modicum of intelligent rational, but Dr. Gernon seems to be oblivious to Reality, much less Mid Ocean Ridges, Geochemistry, Volcanology, and maybe Basic Science!

      • The evidence for advanced Multi-cellular organisms lies in the fact that shortly after the beginning of the Cambrian Period, an entire ecosystem of marine life suddenly appears. The idea that simply because of a chance fossilization of soft bodied organisms, especially the bizarre forms of the Burgess Shale that these forms did NOT evolve much earlier flies in the face of modern evolutionary thought. Entire Ecosystems do NOT suddenly appear without pre-existing developments. This is the same type of Hubris that led to the claim that the Ozone Hole dates solely from the time when a satellite was first launched that could measure Ozone in the upper atmosphere, as opposed to it being a Natural Phenomenon that has existed for thousands of years.

      • Don K,
        Interesting link (even though I tend to agree with Willis re: snowball earth).
        Prof. Lindzen wrote that temperatures at the equator have not changed by 1ºC over the past billion years, so there’s no way that a true ‘snowball earth’ has happened in that time.

      • “sz939: The evidence for advanced Multi-cellular organisms lies in the fact that shortly after the beginning of the Cambrian Period, an entire ecosystem of marine life suddenly appears.”
        It’s not THAT sudden. Sometime around 550 million years ago (give or take a bit) ichnofossils of feeding traces of (probably) modern animals start to appear. They increase in number and complexity over time. Then body fossils start to turn up here and there. Some of those body fossils are recognizably related to later forms. Often they have features like shells, antennae, mouths, teeth, eyes, legs that can be related to (more) modern animals without too much hemming and hawing. At the same time fossilized algal mats start to become less common — presumably because some of the animals were grazing on them. No real conflict with evolutionary theory there although there are some LARGE gaps including the pretty much complete absence of fossils of a key group called bilaterans that were conceptually the ancestors of modern animals except sponges and cnidaria (corals and jellyfish). There are also some older, hard shelled forms that are very likely primitive animals.
        A bit earlier, another, (unrelated?) diverse eco-system showed up. These things appear to be sessile. Some are frond like. Others are flat with radiating or parallel tubes (like an air matress). They don’t have antennae, mouths, teeth, eyes, legs or much of anything else that looks like an animal. A few MIGHT, if you stretch really hard be primitive ancestors to modern animals … or not. On the whole likely not. There are well developed communities of these things exposed in volcanic ash beds at Mistaken Point, Newfoundland that are radiometrically dated to 585 million years BP and some similar fossils have been found nearby in even older rocks. These Ediacarian faunas have been found pretty much worldwide — Newfoundland, England, Russia, Australia, Namibia, Northwest Canada, the Sonoran desert, North Carolina. The ediacarians faded out in the Cambrian and probably disappeared completely sometime in the Ordovician.
        I used to know a lot more about this than I do now. There are abundant resources on the internet for anyone who is curious.

      • @ Don K – January 18, 2016 at 7:50 pm

        “sz939: The evidence for advanced Multi-cellular organisms lies in the fact that shortly after the beginning of the Cambrian Period, an entire ecosystem of marine life suddenly appears.”
        It’s not THAT sudden.

        Well now, it t’was geologically “sudden” enough to be called the Cambrian Explosion. And t’was the time when all the major animal phyla evolved, …. which I am convinced said “explosion” had to be the result of Horizontal Gene Transfers during the time that the DNA was a much simpler form (un-cluttered with tens of thousands of mutations such as it is today).

      • Samuel,
        It was called the Cambrian Explosion because few if any Pre-Cambrian fossils had been found at the time the term was coined. It still looks sudden because of the proliferation of larger animals with much more easily fossilized hard body parts. The ancestors of the animal phyla which appear in the Cambrian lived in the Ediacaran and Cryogenic Periods or the Pre-Cambrian.
        The DNA of Cambrian creatures would scarcely have been less complicated than that of present-day animals.

      • The DNA of Cambrian creatures would scarcely have been less complicated than that of present-day animals.

        It appears to me that your above statement is in reference to the post-proliferation of the larger animal phyla ….. whereas my claim of “less complicated DNA” was is in reference to the pre-proliferation of the larger animal phyla.
        Horizontal Gene Transfers, which create more complex DNA, is the only logical reason that can explain the diversity of the Cambrian Explosion.
        And the more complicated the DNA becomes, the less likely that additional cross-species Gene Transfers will or can occur. (except in present day GMO bio-labs)
        The physical attributes of the Platypus cannot be explained by claiming it was the result of gene mutations within a single(specific) pre-Cambrian animal species that occurred over tens of thousands of years.
        Gloateus, have you ever considered the possibility that our pre-human ancestors evolved “sweat glands” in the total epidermal surface area of their body for the sole purpose of ridding the body of excess salt that was consumed as a result of their feeding habits?
        Too little or too much “salt” ……. will kill a human lickety split.

      • Samuel,
        Horizontal gene transfer occurs in only the simplest unicellular organisms, not in eukaryotes, let alone multicellular organisms. Bacterial genomes do get incorporated into those of eukaryotes, but that’s not the same as HGT.
        You might as well claim that HGT happens between shrimp and scorpions as between Anomalocaris species or trilobites.

      • Gloateus Maximus January 24, 2016 at 3:09 pm Edit

        Horizontal gene transfer occurs in only the simplest unicellular organisms, not in eukaryotes, let alone multicellular organisms. Bacterial genomes do get incorporated into those of eukaryotes, but that’s not the same as HGT.
        You might as well claim that HGT happens between shrimp and scorpions as between Anomalocaris species or trilobites.

        Ummm … well … no. Emphasis mine:

        Horizontal Gene Transfer a Hallmark of Animal Genomes?
        Foreign genes in animal genomes may be of bacterial or fungal origin, according to a new analysis.
        By Jyoti Madhusoodanan | March 12, 2015
        Many animal genomes include bacterial and fungal genes acquired by horizontal gene transfer (HGT) during evolution, according to a study published today (March 12) in Genome Biology. Scanning the genomes of fruit flies, nematodes, primates, and humans, among other animals, researchers found evidence to suggest that some of these horizontally acquired genes may even be functional.

        Nature often finds ways to do things that humans think are impossible …

      • Willis,
        No one doubts that animal genomes include genes acquired via HGT while the ancestors of animals were single-celled organisms. And, as I said, bacterial and other genomes now get incorporated into those of animals, but the process isn’t by the same mechanism as HGT in single-celled organisms.
        The point is that the genomes of large Cambrian were about as complex as of those today. Their DNA wasn’t simpler. Anomalocaris, as noted, would have had a genome comparable to that of a lobster.

    • Iceland is an above-surface portion of the mid-Atlantic ridge. The valley of Thingvellir is spreading right in time with the ocean, and there is no shortage of volcanoes erupting. I’m not sure what the definition involved may be, but Iceland certainly isn’t the deepest part of any ocean.

      • Yes, Ellen, but Dr. Gernon’s own drawing indicates that the Mid-Ocean Ridge Eruptions were obviously in deep water. Also, you will not find the Hyaloclastic Deposits Dr. Gernon requires on surface eruptions in Iceland. And like most such Mid-Ocean Ridge Basalts, the ones in Iceland are also very low in the required Alkalies necessary to form (somehow) Dr. Gernon’s Cap Carbonates.

      • sz939 — You said “(2) One can’t have shallow marine volcanic deposits along Mid-Ocean Ridges as the ridge eruptions are by definition, the deepest ocean areas along a Mid-Ocean Ridge…” I was simply taking issue with”…by definition, the deepest…”. It’s a poor definition when “deepest” rises above sea level.

      • Iceland is an unique case. It’s the only place with a major landmass on a mid-ocean ridge and it is due to the very rare coincidence that a major hotspot happens to lie right on the ridge (or perhaps slightly east of it).

    • I stand corrected. I was wrong to say “Hardly controversial.” Thanks for your contribution, sz939, I’m much better informed.
      I’m still not seeing “CO2 causes volcanoes”, though.

    • I seem to recall plenty of eruptions in shallow seas around Iceland today. The Surtsey eruption occurred in relatively shallow (130 m) before finally broaching the surface. There are also chains of Volcanic islands in the Pacific above hotspots producing formations such as the Nazca Ridge and its associated volcanic Islands. I see no reason to assume similar events could not have happened in the geological past.
      That said I see no justification for drawing any connection between the en of snowball earth and the formation of carbonates which would seem to reduce atmospheric CO2 levels by sequestration rather than increasing them. It would seem more likely that they formed AFTER the event as CO2 levels rose due to the Volcanic action that split up Rodinia. We know that other large scale eruptions such as the Siberian Traps event can release massive amounts of CO2

    • When a super continent begins to break up, the lines of break up that will in the future become mid-ocean ridges are at first at continental surface, then in shallow seas and then after enough time has passed, mid-ocean.

    • PS: I suspect that the people of Iceland will be surprised to find out that they live in the deepest part of the ocean.

  4. If CO2 always follows Temperature, then this theory could be wrong, or perhaps only misinterpreted. We know that CO2 is readily absorbed by cold seawater. In that case it has Zero atmospheric effect, but may promote Carbonate formation on seafloor sediments. The article does not specifically say that Oceanic CO2 outgassed and caused Atmospheric warming, nor does it define in terms of time and conditions what is meant by “the end of the snowball event”. It may not be so ridiculous. Oceans are shallower because a lot of water is locked up in the snowball.

    • Don’t think the last sentance is correct. Oceans comprise about 71% of Earths surface and average about 3.7 km depth. Land mass has always been about 29% even though plate tectonics changes its location and distribution over geologic time. So on snoball Rodinia, suppose the ice was as thick as EAIS, average 2.3 km. That lowers sealevel (2.3 * 0.29) about 0.67 km, leaving an average ocean depth of (3.7-0.67) ~3km. Not shallow. By Archimedes principle, snoball earth sea ice makes no difference; it is floating.

      • “The long-term eruption data, spread over more than 700,000 years, showed that during the coldest times, when sea levels are low, undersea volcanism surges, producing visible bands of hills. When things warm up and sea levels rise to levels similar to the present, lava erupts more slowly, creating bands of lower topography. Tolstoy attributes this not only to the varying sea level, but to closely related changes in earth’s orbit. When the orbit is more elliptical, Earth gets squeezed and unsqueezed by the sun’s gravitational pull at a rapidly varying rate as it spins daily–a process that she thinks tends to massage undersea magma upward, and help open the tectonic cracks that let it out. When the orbit is fairly (though not completely) circular, as it is now, the squeezing/unsqueezing effect is minimized, and there are fewer eruptions.”

    • “and reduced atmospheric CO2 levels, which increased global ice coverage and propelled Earth into severe icehouse conditions.”
      I think the statement above pretty much lands this squarely in the ridiculous category.

      • deebodk,
        It’s only ridiculous to rational folks who pay taxes. But it’s pretty much a textbook example of rent seeking, grant trolling language. No doubt they discussed that sentence quite a bit to get it just right in hopes of snagging a grant.

  5. It’s far more likely that volcanism arising from the breakup of Rodinia was responsible for the cooling that led to snowball Earth. At the time of the split, the subsurface volcanism would not have been very deep and would have released massive amounts of material into the atmosphere which would have certainly reduced the amount of sunlight reaching the surface. The warming that followed snowball Earth was the expected result as the volcanism ebbed and the dust had a chance to settle out of the atmosphere. A breakup like this would have had an even larger climate impact than the explosion of a super volcano and would likely persist for millions of years and is what makes sense to me as the null hypothesis. Conputer (sic) models alone are insufficient for overturning the null hypothesis, especially when models have so many knobs that they can be tuned to produce whatever result you’re looking for.

  6. The Achilles heel of a brilliant white glacial world is, almost by definition, albedo. Lower the albedo and **presto** the ice will all melt. Now what links volcanoes with a lower albedo on the surface of ice sheets?? Errr, ummm, ohhh, gosh that’s a really difficult one…..
    Modulation of ice sheets via albedo, not CO2:

    • Ralph, interesting concept 😉
      This issue may be related to the difference between “iceball Earth,” meaning that the whole thing is covered from pole to pole, land and sea, with a continuous layer of ice, and “slushball Earth,” in which it is mostly ice-covered, but some areas around the equator remain open.
      If there remains some open water, there will be evaporation and snowfall that can cover the dirt spewed by the volcanoes, and thus albedo can be restored. Moreover, CO2, also spewed by the volcanoes, can be dissolved in the oceans and chemically or photosynthetically scavenged. So, advancing ice smothers the oceans’ ability to maintain the atmospheric conditions that favour glaciation, and therefore Earth may get close to the iceball stage but never quite reach it.

      • Indeed, I cannot imagine a completely snow-ball Earth, otherwise all land and most oceanic animals would have perished.
        But CO2 cannot be the savior of a snowball Earth. If the albedo is 0.95 then nearly all the insolation, and nearly all the reradiated CO2 insolation, is being reflected. So you have to reduce the CO2 forcing component by 95%. And that is simply not going to cut the ice.
        So the only solution, is to reduce the albedo by some means.

      • Ralf,
        There were not much in the way of land animals in the Cryogenic. Microbes however can and do live in ice sheets and glaciers.
        As I mention elsewhere, there is no reason to suppose that seas covered most of or even all the time with ice would have wiped out living things in the oceans.

  7. “Lead author of the study Dr Tom Gernon, Lecturer in Earth Science at the University of Southampton, said: “When volcanic material is deposited in the oceans it undergoes very rapid and profound chemical alteration that impacts the biogeochemistry of the oceans. We find that many geological and geochemical phenomena associated with Snowball Earth are consistent with extensive submarine volcanism along shallow mid-ocean ridges.”
    So then Dr. Gernon, you would surely agree that the CURRENT volcanic activity happening on the ocean floor would ALSO/STILL be causing profound chemical alteration (like acidification) that impacts the biogeochemistry of the oceans today. RIGHT???
    And that if the PAST volcanic activity was “blocked” from evaporating directly into the air by the ice cover of the “snowball Earth”-to build up beneath that ice…then the CURRENT CO2 and other gases etc from the current volcanic activity on the ocean floor-which is NOT being blocked from reaching the atmosphere because the ice is gone-are most likely entering the atmosphere much faster and on a daily basis…right?

  8. “phosphorus” = “the catalyst for the origin of animal life on Earth” ??
    I must have missed this class … unless someone can fix my ignorance

    • Phosphorus IS a critical chemical as a fertilizer (plants), bone-growth (animals), electrolyte (blood, sweat, drinks), etc.
      Is it the “most important”? Not really, but without it, .. You die slowly.

      • Thanks.
        I appreciate the micro-nutrient and fertilizer parts, but the drama here went over my head.
        And what happened to carbon based life forms ?? Or are we pollutants ??

    • “phosphorus” = “the catalyst for the origin of animal life on Earth” ??

      Absolutely it is! Without phosphorus, there can be no DNA, RNA, ATP etc – the essential basis of life!

      • There was phosphorus all along, of course, but its level in seawater was elevated at this time.
        The hypothesis, as mentioned above, is that higher P concentration permitted greater photosynthesizer blooms, releasing more O2 into the water and air. To the extent that growth of cyanobacteria, et al, was P-limited, the hypothesis is plausible.

  9. I wonder how they took into account how plate tectonics affected the ocean currents? Or how they took into account the location/organization of landmass plates. Could it be the same plate movement which might have caused the snowballing of earth led to the breakup of snowball earth?
    Maybe I should apply for a grant.

  10. I think it’s pretty well established that the in primordial ( “prebiotic” except that term appears to be co-opted by some health nuts ) atmosphere all the O2 was tied up in CO2 , that is , over 200,000 ppm . But , it’s absorption lines are so saturated even at our 3 – 400 ppm that the atmosphere is opaque in its lines within a couple of hundred meters and Beer’s law says rules out much effect beyond that .
    This whole paradigm is absurd . At some point people really have to seriously demand explanations in terms of quantitative fundamental physical equations rather than Markov maybes .

    • But it’s so much easier to hang a theory on a theory to fit the current theory. The computer models confirm actual observations are not needed.

      • Hey , Google says that Wikipedia says : Prebiotic (nutrition) – Wikipedia, the free encyclopedia .
        But I do see the next link is : What Is A Prebiotic vs Probiotic | Prebiotics and Probiotics .
        However , there is no other definition for “prebiotic” .

      • A “Prebiotic” is what you took before you need a “Probiotic”?
        (I guess a “Postbiotic” comes next?)

  11. So, according to modern climate theory, all other factors mean nothing, not sun, not axial tilt, not volcanic activity. All climate change is because of the increase or decrease in carbon dioxide. It’s pretty amazing that, finally, an apparently complex and chaotic system is so fully understood to be neither, and that it all breaks down to one, simple, trace gas, which can be controlled easily by increasing taxes and regulating individual freedom.

      • “Elegant summary.” Although completely wrong.
        A cursory glance at any climate science will reveal lots of factors. Here is one from a WUWT article 2 days ago:
        Lots of factors in there apart from CO2. I don’t know if you think climatologists have just forgotten all this stuff since 1974, or why you would consider for a moment that climatologists think CO2 is the only factor.

      • seaice, I don’t think Richard is unaware of the spider web of connections between CO2 and other factors that influence the climate. His concern is the focus on CO2 as the only primary factor (or “forcing”) that is assumed to significantly change, whereas changes in solar and volcanic activity are neglected.

      • “whereas changes in solar and volcanic activity are neglected.” Why do you think these are neglected? The diagram shows that climatologists were very much aware of these things in 1974, as presumably Richard is today. Yet from his comments Richard seems to think that the climatologists have forgotten what they knew in 1974, and now think that only CO2 is significant. This is absurd. Richard’s summary is totally wrong.

        • “whereas changes in solar and volcanic activity are neglected.” Why do you think these are neglected?
          Because they DO NOT INCORPORATE “changes” of either one into the models. They make assumptions based on “averages” or “static” principles, not fluctuating changes that occur all the time. Not only that, but scientists today still have NO IDEA how much volcanic activity is happening in the oceans in any measurable way. You can’t put volcanic changes into the models if you don’t know HOW or WHAT or HOW MUCH results from those changes.Climate Scientists, and others, will tell you that the affect of volcanism on our climate is minimal, tiny, insignificant etc, but there is pathetic little research out there that actually even measures the exact amounts of chemicals, heat, particulates etc coming out of the LAND volcanoes…much less the underwater ones.

      • I am pretty sure the models include input from solar radiation. Any changes in solar are therefore included in the model if solar radiation is part of the model. This means they do not consider CO2 as the only factor. I believe the models are quite able to model cooling if solar radiation reduces, for example.
        I think what you mean to say is that you disagree with the conclusion that AFTER considering all these other factors, CO2 is the major forcing. That is a totally different thing from not considering the other factors.

  12. Do they think that CO2 causes volcanoes now, as well as everything else?
    “Because the land surface was then largely covered in ice, continental weathering effectively ceased. ” Just like under a glacier, I suppose.
    It all has to be caused by CO2 and nothing else.
    “and reduced atmospheric CO2 levels, which increased global ice coverage and propelled Earth into severe icehouse conditions.” The level of insanity reaches a crescendo.
    This must be one of the silliest propositions ever to come out of the University of Southampton and the World of CAGW Defence.

    • “Just like under a glacier, I suppose.” Yes exactly. Glaciers hinder weathering, which is different from erosion. Weathering occurs “without movement”, erosion is movement of material from one place to another.

      • Yes and no. Finely ground rock flour from glaciers can contain considerable amounts of biologically accessible minerals, though it varies a lot depending on the subglacial geology. That is why the waters in front of calving glaciers are the biologically richest areas in the Arctic oceans. Compare the waters around Greenland or Svalbard (=lots of glaciers) with the waters north of Siberia (=no glaciers).
        And that is why nutrient-demanding plants flourish on newly deglaciated areas at the beginning of interglacial, while subsequently the vegetations gets more and more dominated by plants that can tolerate nutrient-poor soils as the interglacial progresses. This pattern was first described by the Danish geologist Iverswen back in 1958.

  13. Carbon is the latest demonic fashion It is used nowadays to terrify the general public and to demand sacrifices It is the modern day continuation of the inca-madness. Computer models are used as a smoke-screen obscuring reality from too inquisive minds .Good luck with this superstition . Obama does not make a mistake calling.climate change the most urgent problem nowadays except that he is using a false narrative . .

  14. explosive above water volcanoes emittes vast amounts of dark ash, considering that there was no evaporation on snowball earth, and hence no snowfall, the acuumulating volcanic ash turns a white earth into black in the timeframe of several millenia. See this example of the small ash layer caused by Icelandic Hekla volcano in recent times:
    Imagine what a Pinatobo or ar a Toba type eruption could do.

    • Hans, I notice the once dormant Sinabung volcano is very active now, and, it is only 25 kilometers from supervolcano Toba. Maybe a climate changing eruption there in the near future.

  15. Generally I doubt Earth was ever covered with ice.
    Also btw, doubt that Venus ever had a significant ocean or that Mars ever did.
    It seems that Earth probably had larger covering of ice as compared to all the current glacial periods have had but this is quite different Earth covered with ice.
    And also Venus and Mars may have had oceans less than 1/100th of earth’s oceans at some distant time in the past, though probably not for any significant amount of time [so say less than a billion years].
    What we do know is that for last few millions years, Earth has been about cold as Earth as ever been and that the average temperature of 15 C during the interglacial periods is about 5 to 10 C cooler than most of Earth’s history during last 1/2 billion years and most of this time we have not had polar ice caps.
    What has cause the million year ice age we are in, has number factors, but major part is having land masses within the polar regions. So Earth has 510 million square km and polar regions are about 30 million square km- or less than 1/10th the surface area. And more than 70% of earth surface is ocean [which tends to be about 4 km deep]. And if one has normal ocean depth in polar region, one does not get polar caps. Whereas we have the Antarctic continent and various large islands within the arctic circle. Random chance favors no large islands in either polar region and we have both polar region with substantial land masses within them.
    And there are other factors related to why we are in cool period [in terms recent geological time]
    which includes increased levels of mountain formation which also related to the low levels of CO2.

    • gbaikie,
      Mars definitely had significant water in its past as evidenced by its mineral composition. To me, Venus looks like a failed gas giant that lost all of its lighter gases to the solar wind, but gravity kept the heavier ones from escaping. The real questions are why does the Venusian CO2 atmosphere have the approximate mass of Earth’s oceans and why is the mass of its N2 is significantly larger than Earth, even though Venus has less gravity than Earth and is subject to stronger solar winds without the mitigation benefit of a magnetosphere.

      • –co2isnotevil
        January 18, 2016 at 2:47 pm
        Mars definitely had significant water in its past as evidenced by its mineral composition. —
        I think it’s quite possible that Mars still has a significant amount of ground water [as much as Earth {{in terms fresh water ground water}}]. And has it’s polar caps of mostly CO2 but also water, and fair amount buried glaciers of ice in it’s temperate zone. Though I also think White Mars is plausible.
        But I think the oceans of Mars would have been shallow and didn’t last last long- maybe tens of millions of years or whatever. Perhaps oceans are like lava out flow- water instead of rock, and related to larger impact events. So I think the 100 km crust of Mars has a lot of water- but it’s mostly a guess.
        –To me, Venus looks like a failed gas giant that lost all of its lighter gases to the solar wind, but gravity kept the heavier ones from escaping. —
        I think so also- but I thought might be too wild and crazy to mention it. So thing smaller than Neptune before the Sun began being on it’s main sequence.
        –The real questions are why does the Venusian CO2 atmosphere have the approximate mass of Earth’s oceans and why is the mass of its N2 is significantly larger than Earth, even though Venus has less gravity than Earth and is subject to stronger solar winds without the mitigation benefit of a magnetosphere.–
        Which answered if Venus was a small gas giant, also seems like might be a way to explain it’s lack of rotation.
        So Neptune has 17 times the mass of Earth, but it’s rocky core:”The core of Neptune is composed of iron, nickel and silicates, with an interior model giving a mass about 1.2 times that of Earth.”-
        So maybe Venus was 3 to 5 times more massive than earth with core about same as current Venus. So a lot hydrogen and helium plus a lot hotter than Venus is currently [as Neptune core surface is much hotter currently than Venus surface]
        Oh I got a wild guess- the density of Earth and Venus are vaguely similar: 5243 vs 5514 kg per cubic meter. Now I think Giant Impact hypotheses is reasonable guess which explains our Moon and Earth’s high density [it’s got an iron core from mars size dwarf differentiated planet hitting proto earth]. So wild guess is part reason Venus has it’s higher density is it was hotter and had more gravity. Likewise, Mars was not ever a mini gas giant and wasn’t as hot or have crushing atmosphere. Though also allows that proto earth was also some sort of small gas giant before being impacted.

        • gbaikie,
          I strongly suspect that all planets started as gas giants. Consider that in the time it takes for enough material to accumulate to ignite into a star is more than enough time for planets to form around the newly forming gravity well. Since the star has not ignited yet, lighter elements will still be present throughout. I’ve even considered that the ‘late bombardment ‘ was coincident with stellar ignition. As far as I can tell, this possibility is within the uncertainty of the timing of both events. Another supporting point is that most solar systems are multiple star systems which is proof of concept that multiple balls of gas can condense out of a single planetary nebula.

      • co2isnotevil
        January 18, 2016 at 6:10 pm
        I strongly suspect that all planets started as gas giants.

        I think the latest theories don’t suggest that. The inner planets supposedly formed after the gas giants and also after the solar wind had blown away most of the hydrogen/helium from the asteriod belt inward. So the terrestrial planets began as accretion of rocky “asteroids”. Water was introduced to their surfaces later from comets.

        • beng135,
          Everything you said about planet formation is presumption based on expectations. There is no terrestrial data that will tell us one way or another when Earth formed, relative to when the Sun ignited. As best as we can tell, the two events were at about the same time. We will only know once we can look inside a developing solar system before its star (or stars) ignites and then see what happens at ignition. I can guarantee that once we get this data our understanding of solar system formation will change dramatically, whether my hypothesis is correct or not.
          The Sun is thought to have ignited about 4.57 B years ago and the Moon is thought to have formed about 4.5 B years ago, so clearly the formation of Earth started long before. If we add 5% error bars, the Moon could have formed as much as 300 M years before the Sun ignited. The Earth had to have formed first and any planet that formed before the Sun ignited would have been on the way to being a gas giant while solar ignition would have blown away the lighter gases associated with the inner planets.
          You need to ask yourself the question, what would prevent a planet from forming before solar ignition? How can you explain binary star systems if you can’t even accommodate a small gas giant forming along with the Sun?

      • — beng135
        January 19, 2016 at 6:46 am
        I think the latest theories don’t suggest that. The inner planets supposedly formed after the gas giants and also after the solar wind had blown away most of the hydrogen/helium from the asteriod belt inward. So the terrestrial planets began as accretion of rocky “asteroids”. Water was introduced to their surfaces later from comets.–
        I think the latest theory is that gas giants form in very brief time periods- such as 100,000 years.
        Or a previous assumption was the gas giants took a long time to form.
        Or it’ was thought and is currently thought that earth took about 1/2 billion years to form and it was assume all other planets also took a similar or longer period to form. And prior to this is was thought that planetary formation didn’t take so long.
        Or generally it was thought that life had billion of years to evolve, and now it’s “known” that it seems that life had to evolve from non living to living in period of millions of years- maybe as much as 100 million years. Or in terms of geological time [very long and rather vague periods of time] it’s now seems that life began almost immediately. Or blue green algae has been dated at 3.8 billion years and oldest Earth rocks are about 4 billion and one of oldest rock on Earth, is a Moon rock from Apollo program- 4.5 billion.
        So as Earth was cooling from a ball of lava and still being hit with fairly big rocks- in roughly that environment life appears to have started and evolve to blue green algae. Of course it’s possible
        that life began earlier than last time Earth was molten ball of rock [with gaseous iron as part of atmosphere].
        The latest is also the discovery of hot Jupiter around other stars- prior to this it was though gas giants only formed beyond the solar system’s frost line.

        • gbaikie,
          Having actually detected amino acids in the interior of a carbonaceous chondrite meteorite I found, I’m leaning towards panspermia, where life and its building blocks are ubiquitous in the galaxy and rapidly colonizes any suitable host planet. We will know for sure if we ever detect CATG based DNA beyond our solar system.
          Hot Jupiters are more likely a second star in the system that didn’t collect enough H2 to ignite, but enough that ignition of the primary star didn’t blow away its atmosphere. Keep in mind that prior to solar ignition, the frost line was inside the orbit of Mercury.
          Contemporary planetary science more or less assumes a starting point after solar ignition which seems absurd since in the time it would take the Sun to form, planets and companion stars would have had more than enough time to form, as evidenced by binary star systems. You really need to consider planetary formation as 2 distinct phases. One before solar ignition and a second phase after.
          I also don’t buy the idea that water came later. If the Earth surface was over 100C, water would turn to steam, but would cool and condense as it rises into the atmosphere and liquid water is too heavy to be blown away by the solar wind. It’s conceivable that there could have been a primordial ocean of water in the atmosphere circulating in a vertical manner above a cushion of steam where its heated by the molten surface and cooled consequential to the lapse rate and then falls as virga rain. Proof of concept is that the Venusian atmosphere has about the same mass as Earth’s oceans and has a continuous virga rain of sulphuric acid. Current theory also suggests that the CO2 in the Venusian atmosphere came after its rocky core was formed. If this was the case, why is the ratio between CO2 and H2O completely reversed between Venus and Earth?
          There are just too many things that are unexplainable within the constraints of current theories, therefore, my position is that current theories are incomplete at best and better theories that can explain more are there to be discovered.

      • The most recent theory that I have read is that gas giants gradually spiral in towards the sun because of impacts with dust. This process was stopped in our solar system because Jupiter and Saturn got into pattern where Jupiter was orbiting twice for every three orbits of Saturn. The gravitational disruption caused by this even also reversed the orbits of Uranus and Neptune.

        • MarkW,
          But at the same time, tidal forces cause a planet’s orbit to spiral away from its star. It’s easy to consider one effect in isolation as a pertinent factor, but as in all of science, all factors must be accounted for, including those that are unexplained. We see this a lot in climate science. One example is where CAGW assumes massive positive feedback from water vapor, but fails to account for the end to end effect of evaporation which includes clouds, rain and weather whose combined effect is to cool (i.e. net negative feedback).

      • Harland says that the evidence for Snowball Earth is overwhelming. That’s different from Iceball Earth. It appears that Harland doesn’t say what you imagine him to. Few advocate for Iceball Earth, in which the entire planet was encased in thick ice. Snowball Earth means that the planet was icy from the poles to the equator, but that sea ice still moved around. Slushball Earth means that, as is essentially incontrovertible, ice extended on land and sea close to the equator, but might not have covered the land and sea surfaces totally nor joined north and south everywhere at sea level.

      • Glotaeus – yes, I should have been clearer. Harland rejects only the most extreme interpretation, which he refers to as ‘iceball Earth.’ He does assume glaciation reaching into very southerly latitudes.

      • I haven’t encountered many geologists in the lit or in person who support an Iceball Earth at any point in the past, even before the Cryogenic. My understanding of the term is with Planet Earth locked in rigid ice from pole to pole, like a giant Moon Europa.
        I suppose the hypothesis is physically possible, but IMO the evidence for its ever actually having happened is slim. I do feel however that there is compelling evidence for at least one Snowball Earth interval and maybe three or more, but some of those might have been more Slushball-like.

  16. I’ve never been a big fan of the “Snowball Earth” hypothesis.
    My main sticking point is that if the earth were covered with ice, the albedo would be through the roof, and the water vapor, which is the main greenhouse gas, would be minimal.
    In these conditions I truly don’t see what could cause the snowball to melt. Someone upthread suggested volcanic dust on the ice, which sounds at least plausible … hang on …
    OK, CERES data shows that during wintertime conditions with snow and ice the surface albedo is about 70% – 80%. And the same is true for year-round ice in Greenland and Antarctica, 70%-80%. Open ocean, on the other hand, has a surface albedo of less than 10%. And globally, the surface albedo is 16%. All of that would be increased to about 70-80%
    Let’s say volcanic dust cuts that albedo by a third. Unlikely, but let’s be generous. That would mean a global albedo of about 50%, compared to the current albedo of 30%. That’s a difference of 20%, meaning we’d get 20% * 340 W/m2 insolation = 68 W/m2. Add that to the extra losses due to minimal water vapor in the air, hang on while I estimate that … OK, MODTRAN says that if there’s a tenth of the water vapor you’d get 20 W/m2 additional radiation loss to space.
    Now, between those we have a shift in the top-of-atmosphere energy balance of about 90 W/m2 even after volcanic darkening of the ice … and I’m just not seeing what could reverse that. Yeah, an explosive volcano might go off underwater … and? Or CO2 might go through the roof … hang on … OK, MODTRAN says that to make up for the water vapor dropping to 10% of its current value, CO2 would have to hit the stratospheric value of 30,000 ppmv. And that’s just to make up for the missing water vapor, that doesn’t melt any ice.
    So I remain in a state of non-belief regarding the whole “Snowball Earth” business. Not disbelief, but non-belief. The sun has cooled about 5% since the Snowball theoretically occurred, and there have been long periods affected by volcanoes and asteroid impacts, and we’ve seen ice ages … so why no recurrence of the Snowball even at the depths of the ice ages?
    Anyhow, that’s my $0.02 worth …

    • That ice sheets existed at the equator during the Cryogenian and Ediacaran Periods is not a matter of belief or disbelief. It is an inescapable inference based upon numerous observations. Glacial tillites and striations observed in and on rocks of that age then in the tropics are convincing evidence that at least Slushball Earth, if not Snowball Earth, occurred repeatedly. The arrangements of continents in low latitudes helped to spur global glaciation.
      The sun was about 6.5% weaker 720 Ma rather than 5% (one percent per 110 million years). There are, as noted above, better explanations than hyperCO2 levels to account the ends of Snowball Earth epochs, despite albedo issues.

      • GM, tend to side with Willis here. Cryogenic era Glaciation, sure? There’s geological evidence. Whole earth? Probably not, for the reasons Willis gave, plus one other. We can trace Evidence for life back billions of years (stromatolites, oxygenation evidenced by iron ore deposit formation timing). Wouldn’t be here if there had truly been a snoball. And tracing plate tectonics back that far is worse than sketchy with respect to polar/equatorial orientations.

      • Life persisted during the Cryogenic and earlier Snowball Earth intervals for the same reasons that it does under permanent sea ice today and even under thousands of meters of tens of millions of years old land ice, as in Antarctica.
        Sea ice shifts and is thin in places, letting in light. Microbes live not only in subglacial lakes and within thick ice, but on its surface, especially in caverns and crevices. Even in pitch black darkness, organisms can and do survive on nutrients in seawater, to say nothing of the ecosystems based upon hydrothermal vents.
        Among my microbiological experimentation has been the genetics of antifreeze compounds in living things.
        The fact is that there were ice sheets at the equator before, during and after the Cryogenian. There is no other satisfactory explanation for the geological observations.

      • Lektric,
        Naturally that was the first question asked when the equatorial evidence was discovered. Science knows that the rocks with the tillites and striations were tropical in the Cryogenic because of paleomagnetism, backed up by reconstructions of the arrangement of continents at that time.
        Some paleomagnetic data could be off a little for one reason or another, but this one is unassailable:
        And even those more subject to doubt leave us with the Slushball Earth hypothesis, ie ice at sea level to within at least 30 degrees of the equator.
        IMO there is no question that life could survive even the maximal Snowball Earth. It survives in the tiny pockets of water within ice, and may well have originated there. Sea ice is riven by leads and polynyas, as noted above, driven by winds, currents and various circulations. Presently, grid cells with 15% sea ice coverage are considered icy by NASA and NOAA.
        Life is remarkably tenacious.

      • GM, good points. And slushball is not equal to iceball. More ‘settled science’.
        The ‘antifreeze’ in Antarctic fish is a fairly new discovery?

      • > dbstealy: Prof. Lindzen wrote that temperatures at the equator have not changed by 1ºC over the past billion years, so there’s no way that a true ‘snowball earth’ has happened in that time.
        There are at least two key assumptions made by different groups of people that are really important here.
        1. The Earth’s magnetic field is always roughly aligned with its rotational axis. If that’s not true, then the “Snowball Earth” beds may not be equatorial, and the glaciations they record may not have extended anywhere near the equator.
        2. The sun’s intensity is well-behaved and well-understood. If that’s not true and the sun has had pronounced dim and bright periods over the history of the solar system, then a whole lot of problems such as snowball earth stages and the faint young sun paradox might not be problems any more.
        Don’t have an opinion on either or those.

      • Don,
        The faint young sun paradox isn’t so paradoxical any more, thanks to better understanding of the early atmosphere.
        It’s possible that earth’s magnetic field behaved differently as recently as 635 Ma, but IMO that is unlikely. An independent check on paleomagnetism is, as noted, reconstruction of plate tectonics. Rodinia, its formation and break up are of course less well constrained than for Pangaea, but some continental positions are pretty fairly fixed. It appears that the tropical locations where signs of global ice sheets were found have always been at low latitudes since the Cryogenic, as other plates have rotated more widely around them.
        As for life surviving such icy intervals, consider also that microbes inhabit earth’s rocks as well as the surface of its crust. And its atmosphere, although most air might have been inhospitably cold and dry during much of the Cryogenic.

      • My opinion of the “faint sun paradox” is that atmospheric pressure was considerably higher in the past. More atmosphere, more greenhouse effect. And there’s the example of Venus, which has a much more efficient, single hadley-cell circulation setup from equator to poles, prb’ly due to the much denser atmosphere. Earth could have had that kind of circulation setup long ago, transporting equatorial heat quickly and directly to the poles.

    • Willis,
      ‘I’m not a fan of the current explanation for snowball Earth, but I can’t rule it out based on atmospheric particulates as both the initiator and terminator. We know that significant volcanism can push the average temperature way down and if it was persistent, the main albedo component would become atmospheric dust, not surface ice. Once the dust is allowed to settle out of the atmosphere without being replenished, it would fall on the ice, darkening it and causing it to quickly melt, even at latitudes towards the poles. I’ve observed this on alpine glaciers that are in close proximity to a wildfires where the ash settles on them and they melt far more rapidly. This being said, I don’t necessarily agree that the entire Earth was covered in ice, but much of it could have been. The equator gets so much direct Sunlight, that the albedo would need to be in excess of about .80 before the Sun would stop melting surface ice at the equator and only fresh snow has an albedo this high, bearing in mind that with limited water vapor, there would be limited clouds and little precipitation.
      In any event, the physics of line by line HITRAN calculations tells me that CO2 concentrations can have little to do with either the start or the end of a snowball Earth.

      • Agree, I think CO2 has little to do with it. In defense of Snowball hypothesis, It was intimated that most if not all of the volcanism was submarine origin, and dust is going to be filtered out by the water, however shallow, the only thing left will be lots of steam rising from any open ocean areas immediately above the submarine rifting, certainly enough to make nice white snow to cover any dirty ice. Since the volcanism goes in cycles, there may have indeed been times when the entire planet was frozen over.

        • lectricdog,
          Yes, there was certainly underwater volcanism, especially after the rift had spread apart, but initially, the rift would be at the surface and the initial volcanism would all be above water. As the rift spread. allowing the ocean to fill in, more activity falls into the ocean until enough of it was under water that the rate of adding atmospheric dust became less than the rate it was falling out of the atmosphere and the planet started to warm as the atmosphere returned to a state of optical transparency.
          It seems to me that a rifted continent would produce nearly continuous volcanism forever. In fact, all of the current oceanic ridges are still continuously volcanically active and all are thought to have started as larger continents broke apart.

      • > GM: Naturally that was the first question asked when the equatorial evidence was discovered. Science knows that the rocks with the tillites and striations were tropical in the Cryogenic because of paleomagnetism, backed up by reconstructions of the arrangement of continents at that time.
        Yes … But … I vaguely recall that there was a period sometime around the late PreCambrian when, based on paleomagnetism, continents appeared to move exceptionally rapidly. Maybe that’s been resolved, but my thought at the time that was set forth (1980s? 1990s?) was that an interval where the Earth’s magnetic field was not well aligned with the rotational axis and was wandering would account for the discrepancy in continental drift rates equally well. It’s not like we actually understand the dynamics of the Earth’s magnetic field all that well

      • Don K
        January 18, 2016 at 8:30 pm
        During supercontinent break ups, some plates do move rapidly. The record for post-Pangaea, IIRC, was set by India moving from Antarctica to Asia at high speed across its eponymous Ocean.

    • Willis Eschenbach January 18, 2016 at 2:11 pm
      I have a difficult time with the ice ball concept also. It would be weird.
      Without the water vapor would atmospheric pressure drop?
      What of the locations of the continents? A couple of miles of ice on top of land masses near the equator would have some interesting gravitational effects. What of tidal effects of massive bodies of water under ice caps? What would be the effects of large earth quakes in the oceans that today would produce tsunamis?
      And last how cold would it be? Today we have jets streams that transfer heat. Ocean currents that do the same. Do they simply disappear?
      Strange world I’m not sure that it is even possible.

      • Mike, agree with you on what was the land masses like. That get to not how Rodinia broke apart, but how it formed and where the subduction zones were. Several maps, based on current locations of the rock of the paleomagnetism is recorded –
        A couple of maps, but not entirely all the same.
        Good questions on currents and gravitations effects. Case in point
        The Republic of Panama has a land area: 74,340 sq km and the World 148,940,000 sq km.
        That’s 0.05 percent.
        Total surface area of earth: 510,072,000 sq km
        That’s 0.015 percent
        Yet the theory is when only one half the country raised up from 200 meters below sea level to at sea level, the glacial cycles went from every +40,000 years to +100,000 years. How accurate can the 700 million year map be?
        Polar wandering and the forced responses of a rotating, multilayered, viscoelastic planet
        Roberto SabadiniDavid A. YuenEnzo Boschi
        Sabadini and Peltier [1981] have constructed a physical model in which they found that a net polar wander could occur as a result of the periodic forcing by active glaciation and deglaciation. This phenomenon is illustrated in Figure 1. Previous work by McElhinny [1973] and Jurdy and van der Voo [1974] have concluded that the amount of true polar wander (TPW) during the last 55 m.y. has been quite small, about 2 ø. However, recent reanalysis of paleomagnetic data by Jurdy [1981] and Morgan [1981], using a reference frame based on hot spots, have revealed that TPW of between 10 ø to 15 ø had occurred since the Cretaceous. Furthermore, Morgan has proposed boldly that, in fact, 5ø-10 ø of this polar wander must have taken place in the last 10 m.y.

    • Willis, I too, am somewhat skeptical of snowball earth, but it is plausible that were there to be such, volcanic darkening could do the job pretty well. The reason is, with a low humidity and no open ocean to provide more water vapor, there would be little precipitation on a snowball earth. This would make for a very patient snowball such that volcanic darkening wouldn’t get buried but would only increase with any amount of volcanic activity were present over, say a couple of million years. The snow would get progressively dirty and melt would accumulate it from deeper layers of ice melting.
      We also accumulate cosmic dust at 150-300t/day – say the lower figure. In a million years we get at least 50 billion tonnes of cosmic dust which would be landing on a surface that is accumulating no snow. That is 100t/km^2 and maybe twice that. This is ¬100 grams or a quarter of a pound per square metre – no small potatoes. It could make the snow pretty dirty. It wouldn’t be quick. Also, the frequency of bolide impacts needn’t be high – one big one like that that offed the dinosaurs, may be enough to make a huge mess and break up and melt a lot of ice and get the thing going.

    • Question way above my pay grade.
      In a “Snowball Earth” wouldn’t sublimation also go through the roof?

    • I’m pretty sure that the sun has been warming, not cooling over the last few billion years.
      Another thing is that with most of the oceans covered by ice, evaporation would be pretty close to non-existent, which means that precipitation would also be pretty close to non-existent. As a result dust/ash that fell on the ice would not be covered up by new snow. The ice would gradually get darker as time went on.

      • Even now the gray ball mean temperature in our orbit ranges from a little over 3 to 7 degrees above 273.15 from aphelion to perihelion , just a couple of percent over freezing . The gravitational increase to the surface appears to be about 3% ( got to infect other heads with 4th.CoSy before I turn to that analysis . Ask HockeySchtick ) . In any case we have a pretty thin margin to slushball Earth as can be seen in the geological record .

    • A completely ice/snow-covered Earth is very unlikely, for the simple reason that it would be sompletely covered by volcanic ash in as little as several thousand years, and the ice would melt. It would have to have at least enough of a hydrologic cycle for new frost or snow to cover up the ash. Also there are glaciomarine deposits in Oman which shows that there were calving glaciers and icebergs in the equatorial zone during the supposed “snowball” interval, so a “slushball” seems much more likely.

  17. Did some more digging, as minerology is a long standing hobby for this veteran rockhound. The post snoball carbonate caps the paper modeled are real, for example Death Valley’s Noonday dolomite. They are biologically synthesized Ca/MgCO3. Had to be emplaced after snoball earth melted for whatever reasons for the biology part to be real. The primary source of both sodium and calcium in seawater is land based, water mediated weathering of plagioclase feldspar, one of the most common substituted silicates in andesites (the other basic igneous rock type than basalts). Continental crusts are andesitic, which is why they have ‘floated’ on basaltic mantel magma ever since Earth final formed billions of years ago. Since silicon (14) is lighter than iron (26) according to the periodic table. In seafloor spreading basalts, plagioclase is usually a minor component, the major component being iron rich olivines. (Hence seafloor speading basalt ability to ‘lock in’ its geomagnetic orientation and show pole reversals, which is how plate tectonics was finally proven).
    Original seawater source of phosphorous (11th most common element) was basalt, which entrains minor igneous amounts of the various apatites (calcium hydroxy/fluoro/chloride phosphates). So that part of the paper is quite plausible. Main source today is metamorphic/sedimentary biogenic origin apatites (mineralized from bones, teeth, trilobite exoskeletons, fish scales…). Commercial phosphate deposits are >10-20% apatite in sandstone or mudstone.
    Odd paper, but led to some easy ‘google’ geology refreshers.

  18. It would seem to me that the original assumption of “Snow Ball Earth” conditions is incorrect. There must be another explanation for the deposits sited…pg

    • Please suggest an alternative explanation of the evidence for Snowball Earth episodes. No geologist has been able to do so despite decades of trying. Too bad there isn’t an Earth Science Nobel for you to win.

  19. Oh yeah.
    If plausible there was a recent volcanic event, such as described, at the North Pole back in 1998 or so.
    Under water camera brought back evidence of pyroclastic flows in the recent past.
    So did unusual amounts of CO2 or Phosphate show up there?
    kind of strange how “the volcanoes done it ” back then, yet we are assured that today underwater volcanoes have minuscule effect.
    This kind of handwaving gets dangerous, the hysterics had better calm down before someone loses an eye.

  20. So where was the location of super-continent Rodinia?
    How about it was centred right over the South Pole. As in Antarctica times 20. Which is where it was.
    Glaciers build up 5 kms high over the centre load-points, spread across all of the land that it is within reach – Albedo rises to 45% – even more glaciers build up everywhere except the 20S-20N tropics – ie Snowball Earth. 635 million years ago, the average Earth temperature is -25C from today.
    Snowball Earth ends when super-continent Rodinia starts breaking apart – as all super-continents do eventually – super-continents eventually heat up the underlying mantle and do not allow energy from the mantle to escape. Super-continents depress the mantle in central loading areas. ie. the heat builds up until rift valley volcanism breaks out and breaks the super-continent apart and starts the next cycle of continental drift.
    Rodinia splits apart into several pieces which gradually move away from the South Pole and the glaciers start melting and Albedo goes down to 40% – more glaciers melt – Albedo goes down to 30% and the landmasses have left the South Pole. The South Pole is now ocean covered where glaciers cannot build up.
    Snowball Earth ends – volcanoes have been erupting for 50 million years as the super-continent is slowly split apart and replaced by ocean.
    Now take Rodinia and place it centred over the Equator as in Pangea instead of the South Pole. Now the Earth is as hot as it can get – as in 265 million years ago with Pangea when the average Earth temperature was +10C from today.
    No CO2 needs to be involved in this explanation at all.

    • Bill,
      Well said, as usual.
      The continents were arranged a little differently during the two Cryogenic megaglaciations, but your geologic explanation for termination is far more plausible than the magic gas as cause.

    • Bill
      Could you put all your thoughts on climate and geology into a book? (Or several?)
      Or have you already?

    • It is quite well established that there was extensive glaciation quite close to the equator during the Cryogenian. This is shown by the “frozen in” magnetism in glacial deposits that show that they were emplaced at low latitudes (though on an “iceball earth” no glacial deposits could form – they are formed by moving glaciers, which requires snowfall).

  21. I’ve pointed this out to the science-lite participants in the effect of volcanoes on the chemistry of the ocean. Basalts are MAGNESIUM SILICATES. Calcium is largely contributed from land erosion.

  22. Excellent discussion here, many good points presented for and against the snowball/slushball Earth. I will bookmark this topic for later review. 🙂

  23. The uncertainties are so large any conclusions are not much more than mere hand waving magic induction.

  24. Although I’ve always been skeptical of the ‘snowball Earth theory, I’ve tried to keep an open minding while waiting to see the evidence for the concept. So far, all I’ve seen is wild, mostly absurd, speculation and no conclusive evidence. Maybe I just haven’t seen the right paper with definitive data. What I do know, is that CO2 ALWAYS lags temperature in ice cores, so the notion that CO2 was responsible for a super ice age that covered the entire Earth with ice for millions of years is sheer geofantasy.

  25. I live on a glacial bench. There’s nothing passive about ice. Speculation about the unknowable isn’t science, it is guesswork. I have an awful feeling taxpayers funded this fishwrap.
    Dear Scientists – please stop tweeting your speculations and suppositions about the unknowable. And if you ever write that something “may” happen have the brass to write that same something may not happen.

  26. Just another “stunning ” example of There’s nothing CO2 can’t do. Amazing gas that CO2.
    Can we just stop calling “climate science” science?

  27. The lava erupted explosively in shallow waters producing large volumes of a glassy pyroclastic rock called hyaloclastite.

    This is nonsense. The mid oceanic ridges (spreading centers) Gernon is referring to are characterized by the nonexplosive eruptions typical of basaltic magmas with low viscosities and low gas content. Under water they form the famous pillow lavas. The explosive eruptions are common with andesitic-rhyolitic magmas with high viscosities and high gas content.

    • Indeed this is nonsense, pure and simple. Hyaloclastite is normally formed when volcanoes erupt under glaciers, not under water. it is very common on Iceland (it is called móberg in Icelandic).
      As a matter of fact the linkage to glaciation is so close that the distribution of the móberg can be used to map the extent and thickness of the ice at the time of the eruption. As soon as a volcano penetrates the top of the ice it changes eruptive style and starts producing ordinary lava instead. Herdhubreidh volcano is a beautiful example, it looks almost like a western mesa but is actually a móberg cone with a “conventional” lava plateau on top.
      For this harebrained scheme to work would require:
      1. Mid ocean-ridges subaerial or at very shallow depth
      2. A completely different style of eruptions than is normal at ridges (explosive rather than the normal effusive or dyke intrusion)
      3. A completely different chemistry at the ridges with ultrabasic/carbonatitic magma, normally found only in intra-continental or island-arc settings.
      The last is the killer since it requires a planet with a completely different chemistry of the mantle than the Earth has.

  28. Not having read the paper I can only comment on what is written on this thread. Gernon points out:

    We find that many geological and geochemical phenomena associated with Snowball Earth are consistent with extensive submarine volcanism along shallow mid-ocean ridges.

    He seems to forget that there are two sides to a coin: when new crust is formed along the mid-ocean ridges somewhere else crust is being consumed. That “somewhere else” are the subduction zones along which there is another type of volcanism, the explosive type. Most of todays explosive eruptions are taking place there (along “the ring of fire”) e.g. Krakatoa and Pinatubo etc.

    • “This is nonsense. The mid oceanic ridges (spreading centers) Gernon is referring to are characterized by the nonexplosive eruptions typical of basaltic magmas with low viscosities and low gas content. Under water they form the famous pillow lavas. The explosive eruptions are common with andesitic-rhyolitic magmas with high viscosities and high gas content.”
      Not so fast there 🙂
      The mid ocean ridges DO explode violently, and have even been recorded happening “live”. Known about it for 8+ years or so now.
      “Water from the volcano is very acidic, with some samples collected directly above the eruption measuring somewhere between battery acid and stomach acid. Julie Huber, a microbiologist at the Marine Biological Laboratory, found diverse microbes even in such extreme conditions.”
      “Mission scientists believe 80 percent of eruptive activity on Earth takes place in the ocean, and most volcanoes are in the deep ocean. Until this discovery, NOAA and NSF had sponsored research on submarine volcanoes for 25 years without observing a deep-ocean eruption. Scientists believe further study of active deep-ocean eruptions will provide a better understanding of oceanic cycles of carbon dioxide and sulfur gases, how heat and matter are transferred from the interior of the Earth to its surface, and how life adapts to some of the harshest conditions on Earth.”
      So, 80% of ALL of the eruptive activity on Earth takes place in the ocean…and these eruptions are spewing out stuff that is somewhere between battery acid and stomach acid….acid…..ACID….”acidifying the oceans”.
      WHEN will the climate scientists LISTEN? If oceans are acidifying and warming, isn’t the Occam’s Razor point where we go…Um….it’s coming from IN the oceans instead of magically somehow in a not explainable way coming from the atmosphere above the ocean?
      4 TIMES the amount of Co2 and heat and sulfurs and chemicals and acids that are “put into the air” by land volcanoes is being pumped into the ocean 24/7 !! And both “hot” water AND hot Co2 rises….to warm higher layers than bottom ocean layers. Right? And sea creatures are LIVING and THRIVING in the mineral rich and VERY warm water around hydro thermal vents in the ocean floor.
      I refuse to take ANY climate scientist seriously until we have mapped the entire ocean floor, quantified the amount of heat/CO2/acid being pumped into the oceans by marine volcanism, quantified how THAT underwater stuff is cycled into our atmosphere, and then entered into the models along with every other thing we haven’t put into them yet.

      • Aphan, I am not saying that submarine volcanos cannot be explosive, I am saying that mid-atlantic ridges where new crust is being formed are basaltic (Iceland for instance) and that those are not explosive, in contrast to the ones around the Pacific (submarine or not) which are lining the subduction zones where crust is being consumed.
        You don’t seem to understand the difference between the two types.

        • You did not say “mid atlantic”, you said mid-oceanic.
          And ANY kind of magma becomes explosive depending upon chemical concentrations in it and the pressure/force driving it.

          “The abundance of volatile compounds, and particularly CO2, in the upper oceanic mantle affects the style of volcanic eruptions. At mid-ocean ridges, eruptions are generally dominated by the gentle effusion of basaltic lavas with a low volatile content. However explosive volcanism has been documented at some ocean spreading centres1, 2, 3, indicative of abundant volatile compounds. Estimates of the initial CO2 concentration of primary magmas can be used to constrain the CO2 content of the upper oceanic mantle, but these estimates vary greatly4, 5. Here we present ion microprobe measurements of the CO2 content of basaltic melt trapped in plagioclase crystals. The crystals are derived from volcanic ash deposits erupted explosively at Axial Seamount, Juan de Fuca Ridge, in the northeast Pacific Ocean. We report unusually high CO2 concentrations of up to 9,160 ppm, which indicate that the upper oceanic mantle is more enriched in carbon than previously thought. We furthermore suggest that CO2 fluxes along mid-ocean ridges4, 5 vary significantly. Our results demonstrate that elevated fluxes of CO2 from the upper oceanic mantle can drive explosive eruptions at mid-ocean ridges.”
          I’m not disagreeing with the point that basaltic eruptions OFTEN create pillow lava at mid ocean ridge points. BUT it is FALSE to claim that basaltic magma entry at the mid ocean ridges is never explosive or violent.

      • Aphan, you start splitting hairs. There was no Atlantic during snow ball earth so I have to generalize and call it mid-ocean ridges (places where new crust is being formed). The point I am making is that Gernon was assuming that during crust formation most if not all volcanoes were explosive and that is false as the quoted text you posted confirms:

        At mid-ocean ridges, eruptions are generally dominated by the gentle effusion of basaltic lavas with a low volatile content.

        • Not splitting hairs at all. There is evidence of violent submarine explosions in places where scientists believed there never could be due to depth and pressure. That discovery has changed the way ocean scientists look at volcanic activity on the ocean floor.
          You claimed that basalt eruptions at the mid ocean ridges are not explosive, and I demonstrated that they can be and have been. I am not saying anything about snowball earth or whether the authors conclusions are valid or not. Simply pointing out that your conclusion about basaltic eruptions, was not.

  29. Research by the OU many years ago discounted the Snowball Earth theory due to drop stones found in sediments of the correct age. Drop stones fall from icebergs as they melt.

  30. For anyone interested in Snowball Earth some detailed discussion here with the general conclusion of don’t know how/why it started and don’t know how/why it ended..
    I suspect that things were more complicated than Gernon suggests.
    For example if the break up of Rodinia caused planet wide glaciation why did the break up of other supercontinents, for instance Pangea, not lead to similar massive glaciation ?

    • Rodinia wasn’t in the same geographical position as Pangaea. It might be more accurate to state, as per Bill Illis above, that the formation of Rodinia may have facilitated the creation of a Snowball Earth, while its breakup may have hastened exit from the global grasp of ice. However, there were apparently two snowballs or slushballs during the Cryogenian, ie the Sturtian and Marinoan.

      • Also, Pierrehumbert, et al, rely IMO far too heavily on CO2 and CH4 in explaining global glaciations.

  31. Sorry, don’t have time to read, but. Has the paper calculated 1) where Earth/our Solar System had “orbited/traveled” in the Milky Way galaxy (Svensmark) and 2) where the continents were located? Absolute musts (probably among others — including the science of CO2) — if there is to be any science.

  32. These guys invoke weathering drawdown and volcanic production of CO2 in ad hoc fashion, whichever suits their immediate need. They don’t consider the amount of ridge volcanism that would be required push all the continents into a pile at the south pole and keep them there. They consider only the weathering of the mountains resulting from the collisions to plunge the planet into snowball, but then conveniently invoke the ridges again to burn us out of it.

  33. If a drop in CO2 levels caused worldwide glaciation, why do we not have world wide glaciation today, despite the fact that CO2 levels are lower today than they were then?

  34. The breakup of Pangea caused a warming spike and the end-Triassic extinction event.
    So why would a Rodinia breakup cause cooling?
    Its all too familiar, simply more “CO2 is the answer now what’s the question”.

  35. The reduction of CO2 would be the result of glaciation why would anyone claim otherwise? Volcnoes could cause a glaciation regardless of the amount of CO2 in the atmosphere by way of Gay-Lussac’s law – which simply states that pressure is inversely proportional to temperature… I find it difficult to believe there are scientists who think that CO2 does not conform to the environmental temperature conditions that it is found in… the other thing I was thinking about is, what could cause a large up tick in volcanic activity? Some kind of core movement caused by a shifting polar field??

  36. I believe that submarine vulcanism probably does play a role in ice formation that results in the growth of continental glaciers. Somehow water is transported from the oceans to the land masses where it remains locked in a frozen state. The ocean levels drop anywhere from 350 to 500 feet during glacial epochs. Something has to put that extraordinary amount of water into the atmosphere where it can become ice crystals that are deposited on land over time.
    El Nino events are a good example of how it might occur. Look at the huge amounts of snow being deposited in the Sierra Nevada mountains presently. During El Ninos, what causes the water to warm in the Pacific? Do we have a good explanation for that?
    The other part of the theory, where CO2 warms the atmosphere sufficiently for melting to begin, seems a bit of a stretch, however.

  37. How could you design a planet at Earth distance from the Sun so entire planet is covered by ice?
    It seems the easiest way is to put dust at Sun/Earth L-1. Or stop the sunlight from reaching Earth.
    The L-1 has larger volume of space than compared to Earth.
    If you had .1 of gram per cubic meter, a column 1 by 1 meter by 1 km has 100 grams of dust, and if
    10,000 km, it’s 1 million grams of dust or 1000 kg. And 2500 kg is 1 cubic meters of solid dust and 10 cm deep is 250 kg, or 1000 is equal to 40 cm deep by meter square. So if had density of .1 of gram per cubic meter filling entire zone of L-1 that would block nearly all the sunlight and make such planet colder than Pluto. Or one could say that one needs less then .1 grams of dust per cubic meter.
    And volume of say 20,000 km sphere is 4.19×10^21 cubic meters. Which .1 gram per cubic meter
    is 4.19×10^17 kg. In comparison our Moon 7.3 ×10^22 kg. Or our Moon is more than 5 orders more massive. Or Mars moon, Phobos, is 1 x 10^16 kg, or this dust would be mass of about 40 Phobos moons. So one has so much dust that it’s a problem [in long term] is terms of have too much gravity
    to remain as dust, but probably don’t need a planet colder than Pluto.
    Let’s say instead you want it as cold as the dwarf planet Ceres [much warmer than Pluto] and say after sunlight goes thru the atmosphere it’s 100 watts per square meter with clear skies and sun at zenith.
    This has sunlight which is strong enough to evaporate ice and one would have some water vapor in an atmosphere. So this might be around .01 grams per cubic meter, 4 cm thick, or about 4 Phobos moons of mass of dust. And it seems this would give you planet completely covered in ice.
    But let’s use even less dust, so that one gets 500 watts per square meter at the surface when sun is at zenith, and we have something like Mars rather than Ceres. Now, it’s something like Mars but it also quite different as we roughly assuming it’s earth size, has earth atmosphere, has the Moon and is tilted and rotating like Earth [though rotation and tilt would like Mars].
    With a denser atmosphere one could similar amount sunlight when sun is at zenith, but with earth one has less sunlight reaching the surface when sun is not at zenith. Or summertime on Earth is more similar to summertime on Mars, but Spring, Fall, and Winter have more of a difference.
    Or one could also say that is more similar if just comparing earth and mars tropics, and much greater difference if comparing their Temperate and Polar Zones.
    So with earth at equator at noon in equinox, and clear skies one gets 500 watts per square meter, and with Mars equator with same conditions it’s +500 watts. And with Earth 3 hours before and after zenith it’s about 400 watts and with Mars it’s still +500 watts.And when at 4 hour +/- of zenith and level ground, the sunlight is being spread over about twice as much area, so instead 400 it’s about 200 watts per square reaching surface. Plus in addition sunlight is passing thru more atmosphere when at 30 degree angle plus the atmosphere is reflecting more sunlight- and the latter aspects are different than Mars.
    So similar when sun is at zenith and becomes more dissimilar as sun moves significantly away from zenith but most similar at equator or tropics.
    Now were Earth to get 500 watts per square meter at zenith at it’s surface, I have little doubt that outside
    the tropics is going to be a frozen Hell- on Earth [but btw, less so on Mars] but even under such an extreme change I am uncertain about the tropics. Or were there a huge wall at Tropic of Cancer and Capricorn, it seems average temperature could be well above freezing. Now without the large walls the factor of greatest uncertainty seems to be evaporation heat loss from the tropics [or biggest way of transporting heat from the tropics via ocean circulation would blocked by rest of the planet being a frozen Hell [ocean would be frozen in these regions]. And assuming this evaporation at any rate, and given enough time- thousands of years, all the water could migrate poleward where it remains frozen
    Or we could have started point of completely frozen earth and then turn on the Sun and evenually all water would be evaporate from the tropics.
    Or other thing to start with is the tropics completely covered with land. Tropics is 40% surface area of Earth, and total land area is 30% and currently 80% of earth’s tropics is ocean. But were we to have 40%
    land area and all of it in the tropics, one gets about the same thing- blocks heated tropical ocean [because there isn’t one] and prevents a lot of evaporation from the tropics from transporting to rest of the world.

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