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/.
Discover more from Watts Up With That?
Subscribe to get the latest posts sent to your email.
Jeff in Calgary – “I would also like to know if there was a hypothisised driver of this new CO2.”
From a long-term imbalance between natural CO2 sources and CO2 sinks.
Volcanic activity would have continued unabated during a “Snowball Earth” state, emitting as now ~300 MT CO2 per year. Over geologic timescales that’s balanced by the “biologic pump” of ocean life fixing carbon, which sinks to the ocean floors (and over time gets pulled into subduction zones), and by silicate weathering.
Current theory: With the Earth mostly covered with ice sheets, less rock is available to weather, and ocean biology decreases in activity – over time the CO2 would build up. Until the increased forcing melted the ice, increasing natural sinks, and resulting in a lowering of CO2 levels over a few hundred thousand years (http://tinyurl.com/d994sza). Estimates of the amount of CO2 required for the shift from Icehouse range from 10-30% of the atmosphere – given the very high ice albedo and low absolute humidity due to temperature, it would indeed take a lot of CO2.
The “Snowball Earth”, “Ice Age Earth” (our current state, oscillating between ice ages and interglacials), and “Greenhouse Earth” (no continental ice, alligators in the Arctic, seen over ~80% of Earth history) are currently considered fairly stable states, with a fairly large bump in forcings required (hysteresis) to shift between these stable states. But I will note that this is an open area of investigation.
Svensmark has a lot to say about three snowball episodes 750 – 580 million years ago in “The Chilling Stars.” Possibly his scenario is more likely than this one.
635 Mya, the moon was much closer — about 13,000 km, at a recession rate of 2 cm/yr.
Hence, tidal heating due to friction was much higher. I don’t see where the authors took this into consideration.
Given a 1/r^2 factor, this should be easy to estimate.
Erg!?
I thought they had a professor of Geology involved with this late night gab fest of fantasies that they might throw out as obfuscation that CAGW is a sham.
Barite (Baryte, BaSO4) from Mindat
Is a fairly soft brittle mineral that decomposes at/above 1400C (2552F).
Rough morphology or paragenesis (formation conditions) are:
“Commonly found as a gangue (no vaue) mineral in metallic ore deposits of epithermal or mesothermal origin; but it may also be found as lenses or replacement deposits in sedimentary rocks, both of hypogene and supergene origin”; Courtesy Mindat.org.
Metallic ore deposits are thermal deposits and specifically identifying exact age of formation is, well, bordering on bizarre as subsequent thermal activity modifies the deposit minerals.
Sedimentary deposits, for example shale, are permeable strata and deposited either as minerals filling available spaces in the deposits or as replacement minerals as the original minerals are dissolved out.
Which brings up these main issues:
— Absolute dating of the mineral. Absolute dating is needed in order to determine before during and after timeframes. Especially for speculation that snowball earth in fact did occur, absolutely.
— Determining that the mineral, barite is in fact absolutely unchanged from time of formation. For such a soft brittle mineral sensitive to heat, pressure, tectonics and hot sulphuric acid solutions (not unusual near magmatic or thermal vents).
— Doing far more than just assuming that CO2 was/is the reasons for Oxygen ratios in barite.
— Assumptions are always very bad things to start with and then look for without identifying all possibilities. Always an interesting challenge when the subject matter in question is greater than 550MYA.
— Sedimentary rocks, really really old sedimentary rocks that have not been affected by metamorphic events (tectonics, magma intrusions, thermal vents, mountain building, active faults) or submerged beneath oceans/lakes multiple times only to re-emerge and be eroded again are kinda sparse.
— — Yeah, we can show places exist, such as Utah’s oldest fossils. Dates for this kind of old strata are rough, very rough.
** If by some odd chance anyone wants to visit this region of Utah; I highly recommend U-Dig Fossils. Trilobites are well formed, flat, often complete and sometimes rather large. I know some places where I can find trilobites in the shales and slates of the Appalachian mountains, but every one I’ve found has suffered some serious folding from the orogenic mountain building events… Nice flat displays they are not. I am not involved, other than a very infrequent paying visitor. While the quarry is open in the summer, I do not recommend going then. It is rough enough flipping over the black shale so you can sit on the cooler under side; but very difficult when the under side is darn hot too.
Summation:
I am somewhat shocked that anyone knowledgeable in the geological processes would speculate rather freely based on such a fragile mineral. Unchanged over eons it is not.
sarc on
I doubt that Star Trek’s finest could make such a sure determination from barite oxygen ratios… Perhaps the researchers above should take a trip to the past to verify? I’ll bet they can calculate just how close to the sun and what speeds they need to achieve in order to jump 650MY into the past…
/sarc
DB Stealy:
When are you talking about? At the time of this “snowball earth” there was no North AMerica or Europe. If you mean the recent manfiestations of the continental crust which are called N.America and Europe, I must differ with you – MOST of N.A. was not covered – during the most recent glacial maximum the western areas were mostly ice free all the way to Alaska and the east was ice covered all the way as far south as northern New Jersey. Granted that Canada is larger than America, one could conclude the MOST of NA consists of canada as it comprises more than 50% of the land area, but much of Western Canada was ice free in the most recent glacial max. Or are you talking about the previous three of the recent glacial maxima – Illinoisan, Nebraskan and Kansan? In which case there were variations in the above distribution.
Before anyone reads that paper one should answer the question. Where is that carbon now? Given all known estimates of oil, oil reserves, shale, coal and even guesses at Methane clathrate can not even come close to sequestering that amount of carbon. So why even consider this paper?
A solar explanation is the most logical explanation then as it is now. Forcing CO2 to be “the bad guy” simply isn’t working. Then or now…
“An ultra-high carbon dioxide atmosphere, Killingsworth explains, where CO2 levels match levels of atmospheric oxygen, would grab more O-17 from oxygen.”
Imagine all the dissolved CO2 in the ocean waters under that ice due to undersea vents with the water around 28-29 degrees, heavy with salts as well as dissolved gasses. Then the earth warms up, the ice melts, the water temps spike up to 40 then 50 then 60 degrees. Ocean circulation begins with deep sea currents rising to the surface. The dissolved CO2 is liberated.
Looking up the solubility of CO2 in water and then assuming all the oceans were saturated then, I get a total C02 mass of 4.1×10-18 kg – which almost approaches the current mass of the entire atmosphere which is 5.4×10-18 kg.
http://www.engineeringtoolbox.com/gases-solubility-water-d_1148.html
Taking this further, the average temp of the ocean is listed at 3.9 C. The difference between 3.9 C and 0 C (snowball earth) in terms of solubility of CO2 is about 0.4 g/kg of water. Plugging that into the total mass of the oceans yields 5.48×10-17 which is about 10 percent of the total mass of the atmosphere.
Taking this even further, looking at the slope of the solubility vs temp graph, I get a slope of .08 g/kg/C for the saturation of CO2 in water. Plugging in a .01 change in ocean temp, I get a release of 1×10-15 kg of C02 for each rise of .01 degrees. The total mass of C02 in the atmosphere is around 3.6×10-15 kg. It would seem that even very small changes in ocean temp drive massive releases of C02. No wonder CO2 releases lag earth temp changes.
Tom G,
I recently saw a map of the extent of ice cover during snowball earth. It showed ice down to around Texas. Can’t find it now. But I’ve had the Lindzen quote saved for a couple of years. As a geologist, you know more about this than I do.
TImothy Sorenson says: “Given all known estimates of oil, oil reserves, shale, coal and even guesses at Methane clathrate can not even come close to sequestering that amount of carbon.”
I’m surprised anyone would ask this question — it’s been roundly covered in the literature in recent years.
The total fossil fuel resource base is about 12,500 GtC (Swart and Weaver, Nature Climate Change, Jan 2012).
I’ll leave it to you to convert that into atmospheric ppmv.
so let’s see…
cold causes C02 levels to rise….and extremes of heat or cold are unstable
…got it
Following is copied from
http://www.geocraft.com/WVFossils/Carboniferous_climate.html
Note that most of today’s continental drift that separated the dinosaurs’ original single continents, the three dinosaur eras themselves, the meteor impact that killed them, and all
of today’s mammals are from the period AFTER the carboniferous era.
“West Virginia today is mostly an erosional plateau carved up into steep ridges and narrow valleys, but 300 million years ago, during the Carboniferous Period, it was part of a vast equatorial coastal swamp extending many hundreds of miles and barely rising above sea level. This steamy, tropical quagmire served as the nursery for Earth’s first primitive forests, comprised of giant lycopods, ferns, and seed ferns.
North America was located along Earth’s equator then, courtesy of the forces of continental drift. The hot and humid climate of the Middle Carboniferous Period was accompanied by an explosion of terrestrial plant life. However by the Late Carboniferous Period Earth’s climate had become increasingly cooler and drier. By the beginning of the Permian Period average global temperatures declined by about 10° C.
Interestingly, the last half of the Carboniferous Period witnessed periods of significant ice cap formation over polar landmasses– particularly in the southern hemisphere. Alternating cool and warm periods during the ensuing Carboniferous Ice Age coincided with cycles of glacier expansion and retreat. Coastlines fluctuated, caused by a combination of both local basin subsidence and worldwide sea level changes. In West Virginia a complex system of meandering river deltas supported vast coal swamps that left repeating stratigraphic levels of peat bogs that later became coal, separated by layers of fluvial rocks like sandstone and shale when the deltas were building, and marine rocks like black shales and limestones when rising seas drowned coastlands. Accumulations of several thousand feet of these sediments over millions of years caused heat and pressure which transformed the soft sediments into rock and the peat layers into the 100 or so coal seams which today comprise the Great Bituminous Coalfields of the Eastern U.S. and Western Europe.
Earth’s climate and atmosphere have varied greatly over geologic time. Our planet has mostly been much hotter and more humid than we know it to be today, and with far more carbon dioxide (the greenhouse gas) in the atmosphere than exists today. The notable exception is 300,000,000 years ago during the late Carboniferous Period, which resembles our own climate and atmosphere like no other.
The Carboniferous Ice Age
Two special conditions of terrestrial landmass distribution, when they exist concurrently, appear as a sort of common denominator for the occurrence of very long-term simultaneous declines in both global temperature and atmospheric carbon dioxide (CO2):
1) the existence of a continuous continental landmass stretching from pole to pole, restricting free circulation of polar and tropical waters, and
2) the existence of a large (south) polar landmass capable of supporting thick glacial ice accumulations.
These special conditions existed during the Carboniferous Period, as they do today in our present Quaternary Period.
Climate change during the Carboniferous Period was dominated by the great Carboniferous Ice Age. As the Earth alternately cooled then warmed, great sheets of glacial ice thousands of feet thick accumulated, then melted, then reaccumulated in synchronous cycles.
Vast glaciers up to 8,000 feet thick existed at the south pole then, moving from higher elevations to lower, driven by gravity and their tremendous weight. These colossal slow-motion tidal waves of ice destroyed and pulverized everything in their path, scraping the landscape to bare bedrock– altering mountains, valleys, and river courses. Ancient bedrock in Africa, Australia, India and South America show scratches and gouges from this glaciation.
Image credit:
Department of Environmental and Geophysical Sciences
Manchester Metropolitan University
Manchester, UK
Earth’s continents during the Carboniferous Period were arranged differently than they are today. South America, Africa, India, Australia, Antarctica, and a few minor pieces were joined together near the south pole to comprise the supercontinent known as Gondwanaland.
Gondwanaland was a formidable polar landmass. While ice caps and glaciers can’t grow large over open oceans, they can and do attain great thickness over polar continents– like Gondwanaland.
Although cycles of glaciation are believed to occur in response to solar input variations like the Milankovich Cycle and Precession of the Equinoxes, another important factor is the rearrangement of continental landmasses over geologic time by the processes of continental drift.
Throughout the Carboniferous Period, continental drift was rearranging most (but not all) of the Earth’s landmasses into a single supercontinent stretching from the south polar region to the north polar region. Although the precise mechanisms involved are still a matter of debate this appears to cause regional humidity changes and redistribution of ocean currents which in turn promote ice accumulation and glacier formation over the earth’s polar continents. These glacial ice caps grow larger during periods of reduced solar input, and because ice caps are very good solar reflectors this tended to accelerate and perpetuate cyclical relapses to global cooling.
Basically, Earth undergoes alternating periods of ice ages and warming whenever a continuous continental landmass extends from one polar region to the other while at the same time there exists a large polar continent capable of supporting thick ice accumulations. These conditions existed 300 million years ago during the Carboniferous Period as they do for the Earth today. However for most of geologic history the distribution of the continents across the globe did not satisfy this criteria. Continental drift continually rearranges the continents, moving at rates of only a few centimeters per year.”
So, according to other scientists – who don’t make their money trying to spread a carbon-die-oxide catastrophic awespell – this whole theory matches no other facts before or after or since or during those ice ages.
RACookPE1978 says:
“So, according to other scientists – who don’t make their money trying to spread a carbon-die-oxide catastrophic awespell – this whole theory matches no other facts before or after or since or during those ice ages.”
Great response. I hope you will be submitting your thoughts to PNAS for publication in rebuttal to this misguided paper. Yes?
The sun is why we have a climate to change. The sun can change the climate. The climate can change without a changing sun. Wild fires and volcanoes can change the climate. Mostly they just change the weather. Algae can change the climate and the weather. The sun can change the weather. It happens all the time. We have evidence.
We don’t have evidence that people can change the climate.
rgbatduke says:
February 28, 2013 at 1:58 pm
Are there other ways either oxygen might have been differentially depleted?
===============
Say for example the evolution of oxygen breathing micro-organisms (early animals) that could survive under the ice without photosynthesis.
The problem with the CO2 = GHG = warming theory is that it cannot explain how the earth recovers from an ice age, because the CO2 gets bound up in the cold water under the ice, as does water vapor itself. The atmosphere dries and CO2 goes into solution. If GHG = warming there is no way for the earth go get out of the snowball.
The more rational explanation is that GHG actually cools the atmosphere which in combination with gravity creates the lapse rate. This is self-evident when you look at the atmosphere above the GHG layer. Without GHG the atmosphere would be isothermal, or increase in temperature with altitude as we see in the layers of atmosphere above the GHG layers and as we see in the oceans and as we see in the sun’s atmosphere.
Thus as the earth cools and GHG is bound up in the oceans, the cooling effect of GHG is reduced, which in combination with the small eccentricity in the earth’s orbit, warms the planet and brings us out of the ice age. It is the warming effect of reducing CO2 and H2O in the atmosphere that explains the paradox of how the earth gets out of ice ages, which should be impossible give current GHG = warming theory.
In point of fact, Climate Science has got the sign wrong in one of the most monumental scientific stuff ups in human history – which is saying something. Temperatures increased co-incidentally during the past 300 years due to reasons unrelated to CO2 and GHG, which has led a generation of scientists down the wrong path.
I second PeterMG’s 4:53 pm observation that the atmospheric pressure in the Late Pre-Cambrian is likely a lot higher than today.
PeterMG says it could be as high as Venus, near 100 bar. I won’t go that far. I go with the catastrophic creation of the Moon from an Giant impact of the a proto-Earth an another proto-planet. See “Giant Impact Hypothesis”. If that is true, I view it as one reason we don’t have a Venusian thick atmosphere and why the Moon is desiccated. So I think it prudent to work with a late Pre-Cambrian atmosphere anywhere from 50 -10-2 bar (80% conf distribution).
I cannot bring myself to include 1 bar (current pressure) in the confidence interval because I think the fossil evidence for large flying insects and animals in the Paleozoic and Mesozoic
points to a thinker atmosphere then than now.
So the lesson here is pay more attention to paleo-atmospheric pressures before getting to ppmv estimates of gas fractions. Maybe partial pressures would be a useful shortcut.
Scotese’s reconstructions for 690 Ma and 600 Ma show continents accumulating around the southern pole. Scotese holds open (held?) the possibility that the inclination of the axis was much greater than today. The Rare Earth theory hold that the Moon is a necessary influence on keeping the Earth’s axis stable. I think the moon’s inclination would have to be at a bigger angle to the ecliptic, too. So can the moon’s orbit inclination be reduced by Venus, Mars, and Jupiter gravitational influences? So if we had a highly inclined Earth’s spin axis, enabling extreme seasons and thick ice caps over a northern ocean, then a Snowball Earth is easier to sustain.
Conceivably, we have a 10 bar atmosphere, with ocean dwelling life and nothing that we know of further out of the water than Stromatillites.
Here’s an idea. See the Wikipedia reference to Cambrian Substrate Revolution In this theory, there could be a huge reservoir of anoxic and sulphidic organic matter under photosynthetic algal and microbial mats. If the Cambrian Substrate Revolution is the development of mobil and borrowing life that turns over this sulphidic substrate, then I see a potential for a SO2 catastrophe Large reservoirs of SO2 liberated from the seas into the atmosphere, especially if sea levels drop from an ice age. SO2 in the atmosphere raises the albedo, cools the planet, more ice… I think I see a “Tipping Point”
Correct me if I am wrong, but how in the world did co2 levels rise to such high levels without leaving evidence ? Was it magical co2 ? In other words we see no evidence of levels as high as they claim here elsewhere. A clever fiction, but we still have co2 levels at around 5-6k ppm during this era and nothing even close to what they are claiming.
For the trolls: learn to think before you post.
Mosher and Phobos both. Here is a tip: if you can not handle the intellectual level of wuwt, try realclimate, I heard unthinking automatons who can regurgitate science papers without thinking are welcomed there. If you can think, well show it and join the conversation and prove it! Either way, its posts like those which make me think all warmists are unable to think or are just lazy and refuse to do so
I know how the CO2 got there. James T Kirk and the Enterprise went back in time (they do that all the time anyway), and beamed in a CO2 bomb, similar to the Genesis Device. And BOOM! CO2.
[snip – your name is not Al Gore – fakes like this don’t get posted – mod]
The “Snowball Earth” refers to a series of glaciations between 750MA and 570MA, not a single event. Some prefer the term Slushball as they are not convinced of the extent of the glaciations.
Individual glaciations are estimated to have had durations of between 4Ma and 30Ma [Hoffman et al, Science 281].
And individual glaciations are believed to have ended extremely abruptly [see discussion http://isites.harvard.edu/fs/docs/icb.topic568107.files/snowball_poster.pdf%5D.
During a snowball glaciation photosynthesis by algae would have dropped dramatically while CO2 would have risen as volcanism would have continued on as usual. So where was the CO2 greenhouse warming?
What caused the glaciations? Hypotheses abound.
What ended the glaciations? Hypotheses are similarly abundant.
Bao and his mates may have part of the answer but we don’t even know what the whole question is yet.
The question is always whether the temperature responsiveness to carbon dioxide levels is constant under all scenarios or whether it changes radically.
Here you are saying that, with a huge ice covering, responsiveness to high carbon dioxide is significant. I’ll let others determine whether it was in fact the carbon dioxide which triggered the temperature changes, as opposed to something else which was accompanied by it.
If we are at todays’ temperatures or warmer, where ice coverage is limited to the Poles, what actual conditions pertain in terms of responsiveness to carbon dioxide??
I don’t think you can possibly extrapolate from an ice-covered world to an ocean-exposed world.
It would be like saying that because Usian Bolt can run 100m in under 10 secs, so could I.
There is no logic in that assumption whatsoever.
This is an interesting article to have on WUWT.. It explains that when CO2 is increased the Earth warms up.. Are you trying to point out that CO2 has to be in a high concentration for it to warm up the Earth? Because this paper is looking at a period on Earth a long time ago when the Sun was weaker.. Or are you trying to show that we will all die from increased CO2 but over millions of years it will be weathered out of the atmosphere and what little life is left will survive?
This was an hypophesis put out some 10-15 years ago and shown opn the BBC. They claimed that volcanos couldn’t erupt through ice for centuries and then, all of sudden it inlarge numbers. All the CO² released then warmed the earth. Just can’t believe myself. The BS alarm was going off like a siren.
Correct me if I am wrong, but how in the world did co2 levels rise to such high levels without leaving evidence ?
The evidence is supposedly in the amount of carbonated rocks found at that stratification level.