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/.
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So where’s the computation of the change in our spectrum the purported change in CO2 concentration is claimed to have caused ?
I recently watched this whole series:
http://store.discovery.com/prehistoric-disasters-dvd/detail.php?p=107097
and according to the program, when the asteroid smacked into Mexico and killed all of the dinosaurs, it also “released” all of the co2 that was being held in the rocks there.
Yes I know this is a different time period from “snowball earth”
I don’t recall how the explained the heating of the snowball.
Total, dillusional fiction
So CO2 really is the mother of all climate drivers after all. That’s me sold.
[/sarc]
Well written. This is how its done.
“An ultra-high carbon dioxide atmosphere, Killingsworth explains, where CO2 levels match levels of atmospheric oxygen, would grab more O-17 from oxygen.”
Do they really suggest that CO2 levels back then spiked up to 200,000 ppm?
If so, this provides another line of evidence that runaway greenhouse warming is impossible on Earth.
A scientist.
One who changes his theory to fit the available facts.
Seems like we found one here.
Interesting, although rather a mountain of inference that perhaps lacks an adequate consideration of alternative hypotheses. In particular, when he speaks of an atmosphere that is “half CO_2”, does he mean compared to oxygen? Both oxygen and nitrogen? Would an atmosphere that is half CO_2 (where by hypothesis the CO_2 has eaten O_17 differentially) not have directly observable effects in the chemical formation of carbonates from that era? Are there other ways either oxygen might have been differentially depleted or might isotope ratios have been altered by other exotic events, such as a gamma ray burst or million year alteration in the geosolar magnetic environment, e.g. causing it to be bound up as Ozone or some other oxide? And where the hell did the carbon come from? If one released 100% of the carbon dioxide bound up in the ocean one would multiply the atmospheric CO_2 only by a factor of roughly 60, that is to say, to an absolute maximum of perhaps 10 or 20% of the total atmosphere. But it isn’t terribly plausible that this would happen especially in a snowball Earth situation, because CO_2 is extremely stable in very cold water (which is why the ocean is such an enormous sink — the bulk if it is at the same 4K that it undoubtedly would have been during this cold episode).
So the best I can say after reading the article is “perhaps”, but I’m not certain the numbers add up convincingly or alternatives have been eliminated.
rgb
I might add that it is well known that rates of continental movement and break up were very high around this period, and I’ve read before that some have atttributed this high rate of plate tectonics to the high rates of evolutionary change-the ‘Cambrian explosion’. The high rate of plate tectonic movement and activity would have caused a high rate of volcanism and greenhouse gases, however one couldn’t really decribe this as ‘rapid’, in terms of time frames if would have been over millions/tens of millions of years.
Also, there were extensive phosphate deposits on the contintental shelves and oceans at the time which are speculated to have been crucial in the development of the Cambrian explosion-as phosphate is important in higher organisms, these deposits might also have formed under the unusual tectonic context at the time.
CO2 hypothesis is most likely nonsense. There were huge geological changes in the area of what is now parts of Africa (possibly caused by huge meteorite impact splitting Africa from South America. Carbonado diamonds of identical composition are found in the Central African Republic and Bahia region of Brazil)
Dating of zircons found in metamorphic rocks from the two ruby
deposits demonstrates the existence of Archean and Paleo –
proterozoic igneous rocks with emplacement ages between
2636 and 2448 Ma. These ancient rocks were reworked
much later (~640–600 million years ago) during the Pan-
African orogeny.
http://www.gia.edu/research-resources/gems-gemology/issues/fall2010-contents/FA10AB.pdf
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.
No, the great oxygen “catastrophe” began 2.4 billion years ago, 1.8 billion years earlier than the Marinoan.
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.
This wholepaper is nothing but religiously driven wishful thinking. Did anyone explain to Bao that data actually exist already on the history of CO2 concentration in the atmosphere? CO2 was sky high – by today’s standards, THROUGHOUT the Marinoan/Varanger snowball earth ice age, as well as the Sturtian ice age that preceded it by a couple of hundred milion years. The peak of CO2 concentration actually followed these glaciations into the Cambrian reaching 10-15000 ppm but oxygen was still at levels similar to today, about 20%, far higher than CO2.
I cant believe the language of this paper. It seems sufficient for Bao to fantasise a scenario for it suddenly to become a serious scientific proposal. “What if oxygen only appeared inthe atmosphere in the Cambrian? What if CO2 magically ended the Marinoan ice age?” Yes science really is fun when you play by those rules, its just like writing novels or making films. A pure work of fiction.
From just some isotope ratios in barite crystals the whole history of earth’s atmosphere is re-written for compliance with the CO2 religion. This is utterly depressing rubbish.
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.
Did anyone explain to Bao the existence of a scientific discipline called biology. So life somehow “lived through” the Marinoan and the subsequent CO2 fantasy? What a malign effect all that CO2 obviously had on the bioshpere. What lived before the Marinoan/Varanger? Some bacteria, some “small shelly fauna”, some single celled and a few simple multicelled eukaryotes. And what emerged after the Marinoan after the CO2 devastation? Only the CAMBRIAN EXPLOSION YOU TOTAL MORON!!! Every single phylum of multicellular life (bar one or two) that now lives, emerged in the most remarkable explosion of life-forms in the earth’s history.
How can Bao call the Cambrian explosion “devastating” and be taken seriously and accepted for publication?
These high priests of CO2 satanism do not have history on their side when they argue that CO2 is a bad thing. But when you have political power on your side, and environmentalism is the new state religion, the beast and the antichrist (metaphorically) then history is yours to be written. That’s why its such fun like people like Bao with creative imaginations.
“To some extent, our findings demonstrate that whatever happens to Earth, she will recover, and recover at a rapid pace…”
*
This is why I never believed in anthropogenic catastophe. As a child my scientific parents taught me that the Earth self-regulated. If nature got out of balance, the automatic reactions that kick in will return that balance. You only have to look at the way a plague (of anything) disappears with or without human intervention to realize that.
They also taught me that plants breathe in CO2 and breathe out oxygen – and how that flips at night. Marvellous stuff.
The activists don’t need to be scared. They don’t need to cull our activities. They certainly don’t need to cull humans. If it’s necessary to the plot (Earth’s, that is, not activists), nature will deal with it. If the alarmists want us to end up back in caves in hunter-gather mode, then all they have to do is sit back and gleefully wait for Earth to do its thing. They don’t have to force us there.
Back to my parents – we didn’t always see eye to eye – but they did teach me stuff. Best of all my lessons perhaps is they taught me to not to be afraid of the dark and to look at the stars…
I have a lot to thank them for, I might have been a green-idiot were it not for them.
The basic problem with this theory is that the temperature response to CO2 is always logarithmic. Even if CO2 levels were to rise from zero to say 10,000 ppm surface temperatures could then only increase by at most 7 degrees. I suppose that the authors then rely on positive water feedbacks and a series of various other tipping points in order to explain the rest of their narrative.
Yawn !
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.
When it comes to the Pre-Cambrian, the Present is NOT key to the Past.
Models on Snowball Earth and Cambrian explosion: A synopsis
S. Maruyamaa, , , M. Santoshb
a Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Tokyo 152-8551, Japan
b Faculty of Science, Kochi University, Akebono-cho 2-5-1, Kochi 780-8520, Japan
Abstract At:
http://www.sciencedirect.com/science/article/pii/S1342937X0800004X
Bao’s previous study using this technique had the CO2 level at only 12,000 ppm at the end of this major glaciation event.
http://www.snowballearth.org/Bao08.pdf
The new study doesn’t really put a number on CO2 levels, it just says they were very high for a time.
http://www.pnas.org/content/early/2013/02/05/1213154110.1.full.pdf
Wait.. I thought the sun was the cause of all climate change.
It’s frozen, so where did the CO2 come from?
If it was already there, how could it freeze over in the first place?
What other literature is cited in the article?
“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.
========
OMG, they have it backwards.
She wants to kill us, like it’s Her job.
She can’t be satiated.
I read a few research papers on this and several postulate that volcanoes added the CO2
Soon after its agglomeration from debris in space the earth
must have been very largely molten. It still has a
molten iron core. The heat very probably came largely from the
radioactive decay of short lived transuranic elements which no longer
exist. Very possibly the atmospheric gases are the end products of the
decay of these transuranic elements. We will never know for certain.
It had to be largely molten for the core, mantle, oceanic crust and
continental crust to differentiate. The mantle consists of olivine rich
crystalline rock. At some point it was molten. It is not now. Much of
the oceanic crust and continental crust have been molten though not
necessarily at the same time. There is a measurable geothermal gradient
everywhere it can be measured. The geothermal gradient implies that the
earth as a whole is losing heat to space. Obviously when the earth was
hottest it was losing heat fastest. Now it is losing heat slowly. Thus
the cooling of the earth is explained. Carbon dioxide does not enter
into it.
Carbon, which must have been in largely inorganic crystalline form soon
after the agglomeration of this planet gradually combined with oxygen
and was, from little more than 500 million years ago, converted into
deposits of limestone, marble, peat, coal, oil and gas. Of course
throughout later geological time volcanoes incremented atmospheric
carbon dioxide almost as fast as it was decremented by the processes
described above.
That the earth should cool and the tenor of carbon dioxide should fall
fall together requires no other explanation. Needless to say periods of
intense volcanic activity and changes in the activity of the sun have precluded
them from falling in total lockstep.
Another explanation of the end of Snowball Earth is sufficiently large volcanic eruptions covered large areas of ice with dark low albedo material that caused melting. Once the melting starts (ignoring seasons) embedded ash from earlier eruptions accumulates on the surface progressively decreasing albedo in a positive feedback.
Accelerating surface melt from embedded material accumulating on the surface is what we see with Arctic sea ice, and with the Greenland and Antarctic ice sheets.
These dark debris bands are commonly seen in icebergs indicating several years of net surface melting before enough snow falls in a winter to cover them.
A reference to Early Cambrian and Pre-Cambrian (690 ma, 600 ma) Paleogeographic reconstructions.
Plate Tectonic and Paleogeographic Mapping: State of the Art*
By Christopher Scotese 1 Search and Discovery Article #40312 (2008)
Posted July 22, 2008
http://www.searchanddiscovery.com/documents/2008/08029scotese/index.htm
it has a 19 MB PDF, plus 10 individual linked figures and
three animations of 62, 180, 659 MB.
Also:
GCM simulations of snowball earth conditions during the Late Proterozoic
Gregory S. Jenkins, Steven R. Smith
Article first published online: 20 DEC 2012
Part of the abstract:
A Snowball Earth would have very little moisture in the atmosphere–perhaps so little that clouds would be absent. Insolation would be at a maximum so getting the Earth warmed up after being covered with ice wouldn’t be that difficult. We could credit the sun for warming and melting the snow-bound Earth, not an unusually high level of CO2. Lack of clouds trump CO2 as the reason for the recovery.
Not sure I buy this.
Assuming that there was such a thing as “snowball earth”, and assuming that the proxy actually measures the CO2 density in the atmosphere, that still leaves two major questions:
1) The logarithmic nature of IR energy absorption by CO2 makes higher levels of CO2 increasingly inefficient as a GHG.
2) The radically-changed albedo of a “snowball earth” may leave very little energy in the narrow IR windows in which CO2 can absorb radiation at all.
Is it possible that the study was predicated on a way to tie the current bug-bear, CO2, to interesting geologic observations?