It makes you wonder what created all that CO2 millions of years ago.
From Louisiana State University
LSU researchers find new information about ‘Snowball Earth’ period
It is rather difficult to imagine, but approximately 635 million years ago, ice may have covered a vast portion of our planet in an event called “Snowball Earth.” According to the Snowball Earth hypothesis, the massive ice age that occurred before animal life appeared, when Earth’s landmasses were most likely clustered near the equator, precipitated relatively rapid changes in atmospheric conditions and a subsequent greenhouse heat wave. This particular period of extensive glaciation and subsequent climate changes might have supplied the cataclysmic event that gave rise to modern levels of atmospheric oxygen, paving the way for the rise of animals and the diversification of life during the later Cambrian explosion.
But if ice covered the earth all the way to the tropics during what is known as the Marinoan glaciation, how did the planet spring back from the brink of an ice apocalypse? Huiming Bao, Charles L. Jones Professor in Geology & Geophysics at LSU, might have some of the answers.
Bao and LSU graduate students Bryan Killingsworth and Justin Hayles, together with Chuanming Zhou, a colleague at Chinese Academy of Sciences, had an article published on Feb. 5 in the Proceedings of the National Academy of Sciences, or PNAS, that provides new clues on the duration of what was a significant change in atmospheric conditions following the Marinoan glaciation.
“The story is to put a time limit on how fast our Earth system can recover from a total frozen state,” Bao said. “It is about a unique and rapidly changing post-glacial world, but is also about the incredible resilience of life and life’s remarkable ability to restore a new balance between atmosphere, hydrosphere and biosphere after a global glaciation.”
Bao’s group went about investigating the post-glaciation period of Snowball Earth by looking at unique occurrences of “crystal fans” of a common mineral known as barite (BaSO4), deposited in rocks following the Marinoan glaciation. Out of the three stable isotopes of oxygen, O-16, O-17 and O-18, Bao’s group pays close attention to the relatively scarce isotope O-17. According to Killingsworth, there aren’t many phenomena on earth that can change the normally expected ratio of the scare isotope O-17 to more abundant isotope O-18. However, in sulfate minerals such as barite in rock samples from around 635 million years ago, Bao’s group finds large deviations in the normal ratio of O-17 to O-18 with respect to O-16 isotopes.
“If something unusual happens with the composition of the atmosphere, the oxygen isotope ratios can change,” Killingsworth said. “We see a large deviation in this ratio in minerals deposited around 635 million years ago. This occurred during an extremely odd time in atmospheric history.”
According to Bao’s group, the odd oxygen isotope ratios they find in barite samples from 635 million years ago could have occurred if, following the extensive Snowball Earth glaciation, Earth’s atmosphere had very high levels of carbon dioxide, or CO2. An ultra-high carbon dioxide atmosphere, Killingsworth explains, where CO2 levels match levels of atmospheric oxygen, would grab more O-17 from oxygen. This would cause a depletion of the O-17 isotope in air and subsequently in barite minerals, which incorporate oxygen as they grow. Bao’s group has found worldwide deposits of this O-17 depleted sulfate mineral in rocks dating from the global glaciation event 635 million years ago, indicating an episode of an ultra-high carbon dioxide atmosphere following the Marinoan glaciation.
“Something significant happened in the atmosphere,” Killingsworth said. “This kind of an atmospheric shift in carbon dioxide is not observed during any other period of Earth’s history. And now we have sedimentary rock evidence for how long this ultra-high carbon dioxide period lasted.”
By using available radiometric dates from areas near layers of barite deposits, Bao’s group has been able to come up with an estimate for the duration of what is now called the Marinoan Oxygen-17 Depletion, or MOSD, event. Bao’s group estimates the MOSD duration at 0 – 1 million years.
“This is, so far, really the best estimate we could get from geological records, in line with previous models of how long an ultra-high carbon dioxide event could last before the carbon dioxide in the air would get drawn back into the oceans and sediments,” Killingsworth said.
Normally, carbon dioxide levels in the atmosphere are in balance with levels of carbon dioxide in the ocean. However, if water and air were cut off by a thick layer of ice during Snowball Earth, atmospheric carbon dioxide levels could have increased drastically. In a phenomenon similar to the climate change Earth is witnessing in modern times, high levels of atmospheric carbon dioxide would have created a greenhouse gas warming effect, trapping heat inside the planet’s atmosphere and melting the Marinoan ice. Essentially, the Marinoan glaciation created the potential for extreme changes in atmospheric chemistry that in turn lead to the end of Snowball Earth and the beginning of a new explosion of animal life on Earth.
While previous work by Bao’s group had advanced the interpretation of the strange occurrence of O-17 depleted barite just after the Marinoan glaciation, there was still much uncertainty on the duration of ultra-high CO2 levels after meltdown of Snowball Earth. Bao’s discovery of a field site with many barite layers gave the opportunity to track how oxygen isotope ratios changed through a thickness of sedimentary rock. As the pages in a novel can be thought of as representing time, so layers of sedimentary rock represent geological history. However, these rock “pages” represented an unknown duration of time for the MOSD event. By using characteristic features of the Marinoan rock sequence occurring regionally in South China, Bao’s group linked the barite layer site to other sites in the region that did have precise dates from volcanic ash beds. Bao’s group has succeeded in estimating the duration of the MOSD event, and thus the time it took for Earth to restore “normal” CO2 levels in the atmosphere.
“To some extent, our findings demonstrate that whatever happens to Earth, she will recover, and recover at a rapid pace,” Bao said. “Mother Earth lived and life carried on even in the most devastating situation. The only difference is the life composition afterwards. In other words, whatever humans do to the Earth, life will go on. The only uncertainty is whether humans will still remain part of the life composition.”
Bao says that he had been interested in this most intriguing episode of Earth’s history since Paul Hoffman, Dan Schrag and colleagues revived the Snowball Earth hypothesis in 1998.
“I was a casual ‘non-believer’ of this hypothesis because of the mere improbability of such an Earth state,” Bao said. “There was nothing rational or logic in that belief for me, of course. I remember I even told my job interviewers back in 2000 that one of my future research plans was to prove that the Snowball Earth hypothesis was wrong.”
However, during a winter break in 2006, Bao obtained some unusual data from barite, a sulfate mineral dating from the Snowball Earth period that he received from a colleague in China.
“I started to develop my own method to explore this utterly strange world,” Bao said. “Now, it seems that our LSU group is the one offering the strongest supporting evidence for a ‘Snowball Earth’ back 635 million years ago. I certainly did not see this coming. The finding we published in 2008 demonstrates, again, that new scientific breakthroughs are often brought in by outsiders.”
Bao credits his research ideas, analytical work and pleasure of working on this project to his two graduate students, Killingsworth and Hayles, as well as his long-time Chinese collaborators. Bao brought Killingsworth and Hayles to an interior mountainous region in South China in December 2011, where the group succeeded in finding multiple barite layers in a section of rocks dating to 635 million years ago. This discovery formed a large part of their analysis and subsequent publication in PNAS.
“Nothing can beat the intellectual excitement and satisfaction you get from research in the field and in the laboratory,” Bao said.
Bao’s research is funded by the National Science Foundation and by the Chinese Academy of Sciences.
To read the original article, visit http://www.pnas.org/content/early/2013/02/05/1213154110.1.abstract.
To read more about Huiming Bao’s research, visit http://www.geol.lsu.edu/hbao/.
Stephen, I am referring to of course other proxies. Does it make any sense for this study to suddenly say they were all wrong without explaining why? I mean, perhaps if there was no other possible explanation for their samples (which I remind you are from one particular spot in China). Here is a few graphed at this site: (proxies that is) http://earthguide.ucsd.edu/virtualmuseum/climatechange2/07_1.shtml
If you notice, the CO2 concentration in the atmosphere was never proposed to rise above (even with error) 10k PPM. So how did these proxies get it so wrong assuming this study is worth anything? This is the kind of lazy science and lazy thinking that really kind of gets to me.
In other words, the evidence that we have are “strange” rocks from one location on the Earth that are 600 million years old. Who knows what kind of processes created the deficient O17 in them? 600 million is a long period of time after all and to say that the proxies are wrong without actually proving anything is rather bone-headed and lazy type thinking. Perhaps if they at least pointed out that their theory is in disagreement with standard scientific thoughts about this period then I would be more in line to accept their conclusions without anymore disagreement. But the point is that the carbonated rocks are scant proof against numerous other studies that put CO2 concentrations of the atmosphere in our past closer to 5k PPM. Are these studies now all wrong? Personally, the entire theory that CO2 is the lone culprit to climate change is just as bad as Mosher going on about the “sun” to every sceptic. Its just as lazy to do either one, because solar, greenhouse gases and numerous other factors change the climate which as a chaotic system does not have just one input. It does not even have one driver. The truth is that the Earth’s climate over the eons is effected by numerous factors which have to all be considered before you even begin to describe the climate.
In this case, the study here only considers ONE possible attribute to what made the climate change and to top that off they could not even get that one possible attribute to agree with the current science. Pure laziness nowadays if you ask me…..
Stephen Rasey says:
February 28, 2013 at 2:10 pm
The Cambrian Explosion might be a real flowering of life. But there is no doubt that some of the “Explosion” is the development of hard body parts and exoskeletons which greatly aids the preservation of evidence for and the variety of life.
The pregnant question is what allowed for the development of hard body parts? Could it be a significant change in ocean chemistry? Even if it had been a gradual change in ocean chemistry using up the buffering capacity of iron-rich waters until the pH and chemical composition of waters changed to allow for retention of calcarious structures that life could begin to use.
Interesting point, a significant number of the new phyla at the Cambrian explosion did indeed learn the trick of calcifying their tissues. Shelled organisms and animals with mineralised armour plates proliferated – consider the monster Anomalocaris for example, as did corals and other sessile calcified organisms. They did this while atmospheric CO2 levels were in the range 10,000-15,000ppm. But this is most odd, since current climate dogma is that increases of a few tens of ppm from the current ~400 ppm are going to cause the calcified shells of marine organisms to start dissolving.
The “acidification” coral scare is utter nonsense and even the “dim sun” can get them out of it.
So much here that is crap.
First the Snowball Earth theory was debunked a few years ago by several studies but the most notable was the research of sediments of that age in Scotland. Ocean bed deposits contain drop stones. These, as the name implies, are stones large and small that have dropped from icebergs floating in OPEN water. Open water implies a lack of total ice cover that the SB theory claims. Another study at Imperial College, London calculated that the increase in albedo that total ice cover gave would negate any melting thus ensure that the ice age would never end. Though ”never” may be too strong a word melting delay would have changed the geological history that followed.
Secondly the proto atmosphere was nearly all CO2 with some ammonia, sulphur dioxide, hydrogen chloride etc. Oxygen was first found in the atmosphere over 2 billion years ago due to the photosynthesizing by cyanobacteria that grew into stromatolites still seen in Western Australia. The oceans then were far different to today’s in that they contained a lot of soluble iron which was precipitated out around 2Ba ago because of the oxidation forming the banded iron formations now a rich source of iron ore. This caused a great anoxic event stripping oxygen from the atmosphere and converting ocean waters to something like we now have, providing water far more likely to propagate life, and increasing atmospheric CO2 levels. Cyanobacteria continued to modify the atmosphere to increase oxygen levels through photosynthesis.
Most atmospheric CO2 was sequestered as limestone, the most plentiful of sedimentary rocks, a little as fossil fuel. There is still, thankfully, CO2 in the atmosphere to continue the carbon cycle of which we are but a small part. Without this life giving gas we would not exist and earth would be a wet dead planet. It has never driven climate only life.
Tom G(ologist) says:
February 28, 2013 at 6:05 pm
I like the image of the modern day Earth covered in ice. In late Proterozoic times the landforms of Earth were unrecognizable from today’s image.
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The image doesn’t represent late Proterozoic times. It represents the near future, geologically speaking — say, sixty million years hence. It’s pretty clear that Earth is teetering on the brink of a snowball event, with glacial cycles getting progressively colder:
http://en.wikipedia.org/wiki/File:65_Myr_Climate_Change.png
Stephen Richards says: March 1, 2013 at 1:23 am
This was an hypophesis put out some 10-15 years ago and shown opn the BBC.
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Yes, I saw that Horizon program.
But their evidence for a snowball Earth included glaciation in Africa, and glacial drop-stones off the coast of Africa, which ‘proves’ that the whole Earth was glaciated. But now I see that Africa was down at the South Pole, at the time, so glaciation around Africa is hardly surprising.
Errr, so just what is the ‘evidence’ for a snowball Earth??
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Does this not put into question Warmists’ arguments about past higher co2 levels and subsequent glaciations – assuming their assertions that the far lower co2 levels of today’s levels is the main driver of climate?
Blame the Sun for the Ordovician glaciation under high c02 (10x)
http://www.skepticalscience.com/CO2-was-higher-in-late-Ordovician.htm
So many problems with that paper, as others have already brought up. The most obvious one from the viewpoint of CO2 heating the atmosphere and melting the ice is: where did the LW radiation come from that CO2 would then perform its magic on, if nearly all the SW solar was being reflected by the ice?
“if all you have is a hammer, everything looks like a nail”
http://en.wikipedia.org/wiki/Golden_hammer
So, according to these guys who’re probably being paid by someone’s taxes and using their own assumptions of GHG’s, the Snowball Earth was radiating freezing temps and when the unbelievably high concentration of CO2, which magically appeared from who knows where and acting totally on it’s own without regard to any other earth or atmospheric components, started backradiating the freezing temps downward, was able to suddenly melt the Snowball. Al Gore will love this and media advocacy lapdogs will of course lap this up. Gee, science is so simple, but it’s obvious it means we’re doomed-again.
Is this article written by Anthony Watts? I ask because it seems odd him making the statement “However, if water and air were cut off by a thick layer of ice during Snowball Earth, atmospheric carbon dioxide levels could have increased drastically. In a phenomenon similar to the climate change Earth is witnessing in modern times, high levels of atmospheric carbon dioxide would have created a greenhouse gas warming effect, trapping heat inside the planet’s atmosphere and melting the Marinoan ice.”. ??
Earth’s albedo would have been quite high when covered in ice. During that period, Earth would have continued to receive a dusting from meteorites, asteroid impacts, etc, covering that ice in layers of dust, decreasing the albedo and leading to melting of the glaciers.
I remember years ago, in “Scientific American”, when “Scientific Amrican” was scientific and Ameican, about “Goldilocks and the three planets.
http://www.physics.sdsu.edu/~johnson/writing/climate.html
According to the “Goldilocks” hypothesis,
Volcanoes release CO2 into the atmosphere, rainwater washes that additional CO2 out of th eatmosphere.
“A fully active carbon cycle acts as a thermostat, regulating a planet’s climate.,,,,,.The carbon cycle has similar negative feedback. Suppose the Earth gets too warm. Then more water will evaporate from the oceans, and the additional precipitation will remove CO2 from the atmosphere, moderating the Greenhouse effect and cooling the planet. If the planet cools too much, less water will evaporate and there will be less precipitation to remove CO2; the CO2 will build up, warming the planet.
Does anyone have a clip of Harry Morgan (Colonel Potter, MASH) shouting, “Horse apples!”? That’s what comes to mind while reading the article.
A.D. Everard says:
February 28, 2013 at 2:07 pm
Back to my parents – “…….I have a lot to thank them for, I might have been a green-idiot were it not for them.”
Very insightful.This brings me to a news flash for all. The only antidote for the corrosive socialist environment that your children are obliged to go through in schools and universities, is a thoughtful, interactive two-way education parents can provide through teaching, discussion, listening, argument (keep it on the rails as best you can!) and doing things together. I give myself a C+ on this score (there were six of them plus two nieces for a few years, so hard to hold back the chaos) and managed to make a couple of physicists (one who served as a post doc at Scripps and JPL, a mathematician-philosopher, a poet (and furniture mover), a linguist and MBA, a performing classical musician, and all of them classical musicians (remarkably, the music appears to have come from me playing homey-homely banjo songs to them at bedtime). Exhausting but it works and C+ is sufficient.
This seems plausible, but that’s all. The atmospheric pressure is important too — almost certainly higher or much higher than now, causing different atmospheric circulation patterns. 200000 ppm CO2 at a much higher pressure? Don’t think that’s relevant to today’s atmosphere, other than for scaremongering.
What happend 5-6-700 millions years with Earth’s climate is a pretty difficult task? I mean we have huge problems with the last 10.000 years dont we?
If you dont know the historic airpressure at sealevel your lost?
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Following the Marinoan glaciation by definition there was warming which increased the CO2 from soil moisture, decomposition of oceanic organic matter and the oceans. That is not a case as Bao implies for CO2 causing warning.
What caused the Marinoan glaciation must be factored into what caused the end of the glaciation. Since it appears, based on what is in WUWT’s post, that was not addressed. In which case the paper is not grounded well contextually.
It appears relatively high CO2 levels going into the Marinoan glaciation and during it plus after it would be a very important aspect in a paper on the Marinoan glaciation phenomena. However, to me that does not appear as a primary focus in the paper.
I give it a grade of C+.
The authors can improve it and I hope they do.
John
Ah, so it’s to be turtles, er, I mean CO2 all the way down, eh?
I like the collision, hot spot, volcanic winter theory better. Consider a major planetary collision which punched a hole in the crust, forming long periods of volcanic activity. After a strike, the atmosphere immediately fills with dust and gas, albedo is high, solar penetration is low, temperatures drop. Because of the new hot spot, ongoing volcanic activity from the impact refreshes atmospheric particulates and sulfates and CO2, but it is optical albedo effects which keep solar penetration low that’s responsible for cooling the lower atmosphere, rather than CO2 and other gases inhibiting the escape of infrared radiation. After many years, of course the impact site cools and new crust begins to form, or plates, moving more quickly now because of the impact, cover or impede the hot spot. Volcanic activity slows, skies clear, and you get rapid warming? This seems much simpler than blaming CO2.
Are hot spots, such as the Hawaii and Yellowstone, the result of impacts? Many seem to think so. http://www.sciencedaily.com/articles/h/hotspot_(geology).htm
A few other considerations:
1) With ice covering the Earth there would have been little dust and no clouds which would have reduced significantly the major players in the GHE today. Could CO2 have made up for that loss? Doubtful.
2) We see almost no troposphere at the poles today. With the lack of warmth we should see basically none over the entire Earth. That means little convection and light winds perfect for optimal radiation to space. The CO2 that was present could have precipitated out of the atmosphere, especially during night and at the poles.
3) What is the albedo of a an Earth covered in ice? 90%? Without something in the atmosphere to absorb sunlight (H2O and dust) almost no energy is captured there either. How does it ever warm once the CO2 rains down on the surface?
Without answering some of these question this paper is without much scientific depth.
Here is a revision / replacement of the first paragraph from my comment @John Whitman on March 1, 2013 at 6:55 am
Following the Marinoan glaciation by definition there was warming which reasonably can be viewed as a cause of increased CO2 from soil moisture, decomposition of oceanic organic matter and the oceans. That did not come out clearly in Boa’s PR statement.
John
So “snowball earth” is a fact now? I hadn’t realized, that this hypothesis, had progressed into “consensus” science. Apparently, not only is “snowball earth” fact,, but the mechanism of it’s exit is now known, and I am once again, behind the eight ball. GK
“However, if water and air were cut off by a thick layer of ice during Snowball Earth, atmospheric carbon dioxide levels could have increased drastically. In a phenomenon similar to the climate change Earth is witnessing in modern times, high levels of atmospheric carbon dioxide would have created a greenhouse gas warming effect, trapping heat inside the planet’s atmosphere and melting the Marinoan ice”
Interesting comment to make. Given that the water is cut off, then the main positive feedback mechanism assumed in the climate models cannot possibly be acting in the same way in the case of the snowball Earth.
There will be a slight increase of vapour pressure of water over ice, but the change in vapour pressure over ice between -10C and 0C is about 0.25 mmHg per degree; over water at 15 degrees it is around 0.75 mmHg per degree as far as I can find, so the feedback should also be about a third today if this is a strong feedback mechanism. I accept that less of the Earth will be feeding in vapour today, but with the coverage of oceans, with existing ice caps feeding back in the same way and with inland water, forest and all but the driest land contributing it must be greater than double the snowball Earth feedback if water vapour is causing feedback.
I leave others to ponder the implications of this, mostly because I have very little idea what they are. Most of all it depends if the models are right that water causes positive feedback or the interpretation of empirical evidence that water causes little or negative feedback is correct.
By the way – what is that about this being revived in 1998? I finished my Earth Sciences degree in 1995 and it was certainly mentioned as a possibility. It was thought unlikely because of the lack of known mechanism to break out of the high-albedo state, but it was accepted that there was strong empirical evidence. My lecturers had respect for empirical evidence, even that contrary to their scientific model.
I read Snowball Earth http://www.amazon.com/Snowball-Earth-Maverick-Scientist-Catastrophe/dp/1400051258 almost a decade ago. Have it on my shelf. I though she presented the case fairly convincingly back then. This fits with what was known when the book was written.
Just another potential resource.
phlogiston says:
March 1, 2013 at 2:23 am
Stephen Rasey says:
February 28, 2013 at 2:10 pm
…
The “acidification” coral scare is utter nonsense and even the “dim sun” can get them out of it.
I meant can’t
Bill Illis says:
February 28, 2013 at 3:54 pm
Here are the Continental positions just as this Snowball Earth was starting. Super-Continent Pannotia which was generally moving south at this point.
http://www.scotese.com/images/650.jpg
This study shows how the Snowball happened peaking at 635 Mya.
http://www.meteo.mcgill.ca/~tremblay/Courses/ATOC530/Hyde.et.al.Nature.2000.pdf
http://upload.wikimedia.org/wikipedia/en/d/dc/SnowballSimulations.jpg
http://www.nature.com/nature/journal/v405/n6785/images/405425aa.2.gif
Pretty simple. Glaciers build up on land – Super-Continent Pannotia – which was concentrated over the South Pole. Glaciers build up at the South Pole/central spreading region to 5 kms high. They spread out by gravity across all the land and continental shelf possible. Earth Albedo rises to close to 50%. Ocean freezes up to 30S and 30N. Snowball ends when Super-Continent Pannotia splits down the middle (as they tend to do) and land moves away from the South Pole.
http://wdict.net/img/pannotia.jpg
Perfectly explainable in logical simple sensible terms (and without any magical need to invoke CO2 at all).
Bill Illis is right, as usual. 600 Mya Antarctica was the whole world (land mass). With no global distribution of continents there were no obstruction to – together with the coriolis force – make the ocean currents to distribute heat from equator to poles. Thus the “skull-cap earth” continental configuration led to the “snowball earth” glacial mode. It was continental break up and northward spreading that ended the Marinoan/Varanger ice age, just as it was the re-estabilshment of the current isolated Antarctica 50 odd million years ago and of the Antarctic circumpolar current (and cessation of the current along Africa’s west coast down to Antarctica) that brought in our current glacial period. (This I also learned from Bill Illis.)
Subducting sea floor along faults produces volcanoes that liberate CO2 from calcium carbonate. If snowball earth shuts down most photosynthesis and volcanoes continue to liberate CO2, then CO2 could rise until the greenhouse effect melted the ice.