From Eurekalert: Caltech-led team debunks theory on end of ‘Snowball Earth’ ice age
Finds that rocks used as key geologic evidence were formed deep within Earth millions of years after the ice age ended
PASADENA, Calif.—There’s a theory about how the Marinoan ice age—also known as the “Snowball Earth” ice age because of its extreme low temperatures—came to an abrupt end some 600 million years ago. It has to do with large amounts of methane, a strong greenhouse gas, bubbling up through ocean sediments and from beneath the permafrost and heating the atmosphere.
The main physical evidence behind this theory has been samples of cap dolostone from south China, which were known to have a lot less of the carbon-13 isotope than is normally found in these types of carbonate rocks. (Dolostone is a type of sedimentary rock composed of the carbonate mineral, dolomite; it’s called cap dolostone when it overlies a glacial deposit.) The idea was that these rocks formed when Earth-warming methane bubbled up from below and was oxidized—”eaten”—by microbes, with its carbon wastes being incorporated into the dolostone, thereby leaving a signal of what had happened to end the ice age. The idea made sense, because methane also tends to be low in carbon-13; if carbon-13-depeleted methane had been made into rock, that rock would indeed also be low in carbon-13. But the idea was controversial, too, since there had been no previous isotopic evidence in carbonate rock of methane-munching microbes that early in Earth’s history.
And, as a team of scientists led by researchers from the California Institute of Technology (Caltech) report in this week’s issue of the journal Nature, it was also wrong—at least as far as the geologic evidence they looked at goes. Their testing shows that the rocks on which much of that ice-age-ending theory was based were formed millions of years after the ice age ended, and were formed at temperatures so high there could have been no living creatures associated with them.
“Our findings show that what happened in these rocks happened at very high temperatures, and abiologically,” says John Eiler, the Robert P. Sharp Professor of Geology and professor of geochemistry at Caltech, and one of the paper’s authors. “There is no evidence here that microbes ate methane as food. The story you see in this rock is not a story about ice ages.”
To tell the rocks’ story, the team used a technique Eiler developed at Caltech that looks at the way in which rare isotopes (like the carbon-13 in the dolostone) group, or “clump,” together in crystalline structures like bone or rock. This clumping, it turns out, is highly dependent upon the temperature of the immediate environment in which the crystals form. Hot temperatures mean less clumping; low temperatures mean more.
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  IMAGE: This is a view from one of the cap dolostone collection sites in south China, looking along the cliffs of the Yangtze Gorges.
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“The rocks that we analyzed for this study have been worked on before,” says Thomas Bristow, the paper’s first author and a former postdoc at Caltech who is now at NASA Ames Research Center, “but the unique advance available and developed at Caltech is the technique of using carbonate clumped-isotopic thermometry to study the temperature of crystallization of the samples. It was primarily this technique that brought new insights regarding the geological history of the rocks.”
What the team’s thermometer made very clear, says Eiler, is that “the carbon source was not oxidized and turned into carbonate at Earth’s surface. This was happening in a very hot hydrothermal environment, underground.”
In addition, he says, “We know it happened at least millions of years after the ice age ended, and probably tens of millions. Which means that whatever the source of carbon was, it wasn’t related to the end of the ice age.”
Since this rock had been the only carbon-isotopic evidence of a Precambrian methane seep, these findings bring up a number of questions—questions not just about how the Marinoan ice age ended, but about Earth’s budget of methane and the biogeochemistry of the ocean.
“The next stage of the research is to delve deeper into the question of why carbon-13-depleted carbonate rocks that formed at methane seeps seem to only be found during the later 400 million years of Earth history,” says John Grotzinger, the Fletcher Jones Professor of Geology at Caltech and the principal investigator on the work described. “It is an interesting fact of the geologic record that, despite a well-preserved record of carbonates beginning 3.5 billion years ago, the first 3 billion years of Earth history does not record evidence of methane oxidation. This is a curious absence. We think it might be linked to changes in ocean chemistry through time, but more work needs to be done to explore that.”
In addition to Bristow, Eiler, and Grotzinger, the other authors on the Nature paper, “A hydrothermal origin for isotopically anomalous cap dolostone cements from south China,” are Magali Bonifacie, a former Caltech postdoc now at the Institut de Physique du Globe de Paris, and Arkadiusz Derkowski from the Polish Academy of Sciences in Krakow.
The work was supported by an O. K. Earl Postdoctoral Fellowship, by the National Science Foundation’s Division of Earth Sciences and its Geobiology and Environmental Geochemistry program, and by CNRS-INSU (French research agency).
While I don’t question for a moment that the Chinese cap dolomites have been subjected to a high temperature and pressure regime, the article doesn’t ring exactly right to my ears. It sounds like whoever wrote/edited it thinks the dolomites are intrusive rocks like the Sierra Nevada granites — rocks injected in between existing sedimentary rock layers.
I’m not a geologist, but that seems somewhere between unlikely and highly improbable. As I understand it, dolomites are normally sediments deposited — like all sediments(?) — at the Earth-air or Earth-water boundary. They can, I believe, be either primary dolomite deposited with the Magnesium in place, or secondary dolomite — limestone where some of the Calcium has subsequently been replaced by Magnesium in some way that I, at least, don’t really understand. (And I really do have a long disused degree in Chemistry from an otherwise reputable university).
Anyway, I’d like to know a whole lot more about where the C13 depleted Carbon originally came from, why recrystalization is ruled out, etc and the hypothecated geothermal history of the rocks before I wrote off the Methane theory. In any case I think the headline is misleading. It should say something like “THEORY THAT METHANE ENDED SNOWBALL EARTH CALLED INTO QUESTION” Even if every word of the article is correct, it merely says that the evidence is dubious, not that the theory is impossible.
To John Gorter. Yes there are other hypothecated cap dolomites — The Noonday Dolomite in the Death Valley area for example. I thought that the conventional explanation is that the seas of the snowball earth were enriched in CO2 from volcanic activity and were saturated in Calcium. As the Earth started to warm — whatever the cause — the Calcium Carbonate — being less soluble in warm water than cold — precipitated out as a massive layer of carbonate rock.
Geoff Sherrington. Thanks for that. I’m glad that I’m not the only one somewhat baffled by dolomite chemistry.
The question is not why did snowball earth melt, but why did it form in the first place.
No CO2?
It looks like Piers Corbyn got it right again (three weeks in advance):
May 2011 issued 2/3:
WeatherAction long range USA Extreme weather Events & scenario forecast for May 2011 issued 2/3 May 2011 explicitly and in detail warned of the tornado swarm in the South/ mid West 22-23-(and continuing to 24th).
EXTRA TOP RED Warning 23-24
High strengthens in West and double low / complex Low deepens South/West of Great Lakes.
Hot air from South & cold air from North meet with very large temperature contrasts.
Deluges, massive hail thunder and many tornadoes – DANGEROUS tornado swarm in South / SouthEast parts – AL, TN, KY. IL. MO etc
Here is a continental reconstruction map by Christopher Scotese at 650 Mya, about 15 My before the peak of the last Marinoan Snowball period. Note that most of the continents near the equator are drifting south in this period, and meet the other continents near the South Pole at 635 Mya and form the super-continent Pannotia. Result, 5 km high glaciers.
http://scotese.com/images/650.jpg
Also note that some people who are obscessed with CO2 controlling the climate for example, will attempt to put all the continents near the equator in this period. If you try to follow all the earlier and later positions of the continents, this positioning makes no sense at all.
Now let’s go back to the previous Snowball, the Sturtian, which peaked at 715 Mya. Here are the continent positions at that point. The super-continent Rodinia.
http://nectarbug.com/clickpath/wp-content/uploads/2010/03/rodinia.gif
A really good paper which explains how these two similar continental positions would result in a Snowball.
http://www.meteo.mcgill.ca/~tremblay/Courses/ATOC530/Hyde.et.al.Nature.2000.pdf
Let’s go back to the other two Snowballs at 2.4 Bya and 2.2 Bya. Super-continent Columbia (well, we don’t know where that was exactly but you can probably guess, one of the poles).
http://en.wikipedia.org/wiki/Columbia_(supercontinent)
This paper has the only CO2 proxy estimates covering the last Marinoan Snowball event which is 12,000 ppm and then 5,000 ppm during the Sturtian Snowball. CO2 would need to be much, much higher than these levels to put even a dent in Snowball conditions.
http://www.geol.lsu.edu/images/Features/nature%20article.pdf
“As I understand it, dolomites are normally sediments deposited — like all sediments(?) — at the Earth-air or Earth-water boundary. ”
The thing about dolomite is, geologists think it can form in many ways, not just at the earths surface. Dolomite is an amigma.
Heres a quote “Dolomite in addition to the sedimentary beds is also found in metamorphic marbles, hydrothermal veins and replacement deposits. ” In other words it can form anywhere anyhow.
Read here; http://www.galleries.com/minerals/carbonat/dolomite/dolomite.htm
Of course this study has nothing to do with what is happening today, but have it clones.
Same old anti climate change text book move, just try to prove that the scientific community is wrong, about anything (which doesn’t occur above) then ask yourself, what else could they be wrong about? What we often discover is anti climate change theories (especially in regards to climate forcings) on sites like this are the theories that are constantly being proven false. Keep up the good work!
the earth has 500 million KM^2 surface ( some 125 million of them land ) and some folks decide, a small cliff in china represents the whole shabang accurately???
WOW!!! why are we wasting all the time studying NH/SH/all the continents? we could save a lot of loot by migrating to that cliff and doing all the studies
Little we know, almost infinite knowledge to be gained, science never settled, at the best not yet falsified. This is the wisdom we learn time and time again.
Willis Dillard says:
“What we often discover is anti climate change theories (especially in regards to climate forcings) on sites like this are the theories that are constantly being proven false. Keep up the good work!”
That is impossible because no one on this site has offered an anti-climate change theory. Unlike Warmista, we are aware that there are no physical hypotheses that explain forcings. Unlike Warmista, we have not claimed that our existing understanding of forcings can explain them. You do seem to be making the nuckle-dragging Warmista logical mistake of believing that to criticize a theory or hypothesis one must first have another to replace what is criticized. That is childish. Science is the critical enterprise par excellence.
Someday, Svensmark’s hypotheses might prove to be well confirmed. When they do I hope that he will publish on this site.
Subduction leads to orogeny. 😉
The idea that how light or dark a gray ( flat spectrum ) a radiantly heated ball is makes a difference in its equilibrium temperature continues to be a ubiquitous misconception .
The equilibrium temperature for a gray ball in our orbit is about 4c , significantly above 0c . I have yet to see a study calculating the equilibrium temperature for the spectrum of H2O snow , much less whatever material spectra can approach the 255k temperature asserted for a naked planet .
Willis Dillard,
The only crowd that refuses to believe that the climate naturally changes are Michael Mann’s acolytes.
Mann tried to convince the world that the climate never changed until the start of the industrial revolution [the long shaft of his debunked Hokey Stick chart, which attempted to erase the MWP and the LIA].
Scientific skeptics [the only honest kind of scientists] have always known that the climate naturally varies. And there is no evidence that CO2 is the cause, or that CO2 causes damage. Conclusion: CO2 is a harmless [and beneficial] trace gas, and Michael Mann is a climate charlatan.
“a small cliff in china represents the whole shabang accurately???”
Well, nobody is mentioning that at the time that rock was formed, that particular land was practically at the North Pole. That might have some influence on how things react, too.
“What we often discover is anti climate change theories (especially in regards to climate forcings) on sites like this are the theories that are constantly being proven false.”
Science has a long history of ultimately proving all theories either wrong or incomplete. The test for correctness of all scientific theories is prediction. What does the theory say about events that have not yet come to light?
If the theory is correct, then when new observations are made, it will be consistent with the theory. However, when the theory is not consistent with observation, this is reasonable evidence that either the theory is wrong or the observation is wrong.
To make sure the observation is correct, we need to look at the experimental design. Was the data collected in such a way that the experimenters own subconscious bias did not affect the results. If not, then we cannot trust the observations. Even wikipedia admits that it is impossible for an experimenter to keep their own bias out of an experiement without proper design – and the experimenter will not even be aware of what is happening.
This is a concern with global temperature records. The raw data was itself was collected by many different people. As such it is unlikely subject to bias. However, the adjustments were not made in such a fashion. They were made by the same people that control the temperature records without appropriate controls to exclude bias. As such, it is physically impossible that bias has not affected the temperature records.
Thus, since we cannot trust the adjusted temperature records to be free of bias, we cannot trust any theories or computer models that rely on the temperature records to be correct.
“In experimental science, experimenter’s bias is subjective bias towards a result expected by the human experimenter… The inability of a human being to be objective is the ultimate source of this bias. It occurs more often in sociological and medical sciences, where double blind techniques are often employed to combat the bias. But experimenter’s bias can also be found in some physical sciences, for instance, where the experimenter rounds off measurements”
http://en.wikipedia.org/wiki/Experimenter%27s_bias
“Reply: My apologies for losing it. Moderating thousands of comments a week can get tedious, but that is no excuse. The poster in question is a banned site pest who hides his URL. Info here. ~dbs, mod.”
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So, am I to understand the folks at CP are being all anti-science, again?
In the case of climate science there is a second problem beyond experimenter bias. The problem of consistency of theory with new observations. Climate science made a number of predictions for the GHG CO2 theory. The major predictions were increasing temperatures with increasing CO2 and the existence of a tropical hotspot.
On these two major predictions, the CO2 GHG theory has not matched observations. Unadjusted temperatures have not continued to increase with increased CO2 and the measurements show there is no tropical hotspot. In any other branch of science this would constitute falsification of the CO2 GHG theory. Clearly some underlying assumption in the theory is at odds with the real world.
Mainstream climate science has in the past use aerosols to explain why the CO2 GHG theory did not match predictions from 60 years ago (pollution) and from 120 years ago (volcanoes). It appears that this same argument is being dragged out this time (mt pinatubo dead cat bounce) to explain why temperatures have repeated the same pattern 60 year and 120 years latter. Coinicidence or is there a simply a 60 year cycle in the climate that mainstream climate science has missed?
My understanding was that snowball earth started due to having a single land mass from pole to pole. It ended because plate techtonics allowed sea water to flow around the inbetween the new land masses coupled with the volcanic activity that came with the movement putting ash on the ice/snow. The combined effects ended snowball earth.
Willis Dillard says:
May 26, 2011 at 7:36 am
Really, why not look into this?
There is only one mechanism that can warm the surface sea/ocean from the atmosphere and that is by convection. This convection only occurs when winds blow warm air from land over onto the coasts towards to sea/ocean. This is limited to so many miles away from the coast and will have no affect once reached a certain distance away. The rest of the ocean surface (~98 percent of it) convection has no affect and the atmosphere can’t warm the surface because the temperature is less than 0.5c difference between the surface and 2m above it (with the 2m temp normally cooler – gets cooler with increasing height).
Latent heat always has much larger influence then any change this 0.5c has. Therefore this comes about to the only possibilty, can the 2% warm the entire world oceans. The simply answer is no because energy gained during the Summer months is lost during the Winter by convection, but of course with much cooler air. (this can be observed by looking at SST’s through the years) Depending on weather patterns and tropics, the 2% warming or cooling of coastal areas is never reached anyway.
Increasing ocean heat content is not confirmation that GHG atmospheric warming is occuring. This is due to other factors do cause the ocean heat content to rise and there is no evidence that GHG’s can increase the actual heat content. The only evidence so far is it can retain energy a bit longer in the skin layer. This tiny energy gain is easily lost and therefore balanced out during the night period, when there is of course much less SWR to maintain it. I’m not the first that mentioned evaporative cooling exchanges, far larger energy amounts on a daily basis (orders higher).
El Ninos and cloud albedo covering the ocean have a large influence on short wave radiation (SWR) reaching the ocean surface and therefore do change the ocean heat content. Global cloud albedo has declined over recent decades until this century, when it had stabilised, until a very recent increase. Too much a coincidence that global temperatures have also stabilised too? (no, because it is the only one that matches all different trends) A one percent change in global cloud levels is easily enough to have influence on ocean heat content and global atmospheric temperatures. Especially when SWR not only warms the ocean, but also controls them too, with El Nino and La Nina there common sign of energy transfer around the ocean via albedo.
The ocean heat content (OHC) is responding well to global cloud levels shown below. (satellite data originally from NASA)
http://www.climate4you.com/images/CloudCoverTotalObservationsSince1983.gif
A decrease in 5 percent of global cloud levels until 2001 then little rise with stable levels since. (shown up to 2009)
Atmospheric and ocean temperatures also respond the same way.
http://www.woodfortrees.org/plot/uah/from:1983/normalise/plot/uah/from:2002/trend/offset:-0.2/plot/rss/from:1983/normalise/plot/rss/from:2002/trend/offset:-0.2/plot/hadcrut3gl/from:1983/normalise/plot/hadcrut3gl/from:2002/trend/offset:-0.3/plot/hadsst2gl/from:1983/normalise
Not suprising really since shortwave radiation (SWR) controls the temperature of the oceans and a movement has resulted due to changing levels of clouds that cause increases in OHC, SST’s and global temperatures. Now over recent years cloud levels have become stable the OHC, SST’s and global atmospheric temperatures also follow suit. Could this be a coincidence? I really don’t think so because the energy involved in 5 percent reduced global cloud levels is higher than most of the energy change since the 1850′s according to the IPCC.
Since the 1850′s?
http://www.woodfortrees.org/plot/hadcrut3gl/normalise/plot/hadsst2gl/normalise/offset:-0.2
The offset is just for easier on the eye comparison of global SST”s and atmospheric temperatures. Notice since the 1850′s there has actually only been a increase in temperatures of around 0.5c which may suprise some people. Yet the temperature increase since 1983 is around 0.4c which only occured while global cloud levels were decreasing by 5 percent.
mkelly says:
May 26, 2011 at 10:54 am
“My understanding was that snowball earth started due to having a single land mass from pole to pole. It ended because plate techtonics allowed sea water to flow around the inbetween the new land masses coupled with the volcanic activity that came with the movement putting ash on the ice/snow. The combined effects ended snowball earth.”
Plate techtonics and the positioning of land masses are indeed the best explaination for snowball Earth and why there are ice ages over millions of years, whereas different periods over millions of years there are none. It is the only explaination at the moment because at those time scales nothing else changes slow enough to have a enough influence. These greatly affect how much the global albedo can range for over a very long time.
GEOCARB III Puts the bottom of the uncertainty region for CO2 levels at 600 mya at well over 2500 ppm.
Graphed here.
Lets’ see, Dr. Hansen’s catastrophic tipping point is about at 450 ppm, am I right. So it has already happened before, right?
Did the lack of oxygen come before or after the earth got snowed in? What happens to the temperature when, like, 95% of the oxygen production is killed off, what with methane and CO2 would rise after such an event, and oxygen, of course, tend to keep things exciting. :p
CO2 increased after the temperature increased yet was still cited as the cause of the temperature increase, so what’s the problem?
As a geologist – it is hard for me to comprehend this so called methane warming theory as anything other than fantasy. Apart from anything else, depositional environments (for sediments) are not ‘fixed’ and post depositional changes (to the rock formations) can and will occur for any number of reasons (think igneous intrusions, etc!). Whilst I accept that chemical analysis of rocks has helped in many parts of geology – in others, in can merely obfuscate the view.
Take slate for example – it’s a mudstone that has been heated and pressured at a later date – making it hard, etc. – chemical changes will have occurred also but they do not necessarily reflect the depositional environment of the original mud!
So, using this information, from a slate, all we know is that there was a mud forming environment – chemical analysis does not adequately confirm the pre-metamorphis state at all! Ergo, it follows that care is required in any interpretation of rocks!
Coldish says:
May 26, 2011 at 3:13 am
“The authors argue that with the world ocean 100% ice covered (itself IMO a speculative idea, not proven)”
It’s controversial but only to the degree of whether or not coverage was total or some thin equatorial belt was spared.
“the steady CO2 output of volcanoes could not be dissolved in the ocean and would accumulate in the atmosphere until the latter became so warm that it melted the ice.”
No. The most of the world’s volcanoes are on the ocean floor in deep trenches, the so-called ring of fire where new crust forms. At that depth the pressure is so great that CO2 forms droplets of pure liquid which is a very recent discovery.
If the oceans are covered by ice one wonders how volcanic CO2 would possibly escape. One might liken the ice to a cork on a champagne bottle. Then on might wonder what happens when a sufficiently large meteor breaks it. Over a long enough period of time you can bank on large meteorite impact…
“The main piece of empirical evidence to support this theory is the observation in several parts of the world of substantial carbonate deposits – in some cases primary aragonite CaCO3 rather than dolomite CaMg(CO3)2 – overlying the supposed glacial tillites and dropstone beds. These deposits are explained by the rapid incorporation of the excess atmospheric carbon into marine carbonate once the ocean was re-exposed to the atmosphere.”
The re-exposure might have been more rapid than they presumed and the increase in atmospheric CO2 when the cork popped far higher for a brief period of time.
“I don’t buy the theory, but IMO it does deserve to be taken seriously.”
I’m going with the champagne cork hypothesis until someone convincingly explains to me where they think it goes wrong.
JimF says:
May 25, 2011 at 8:55 pm
Hmm. Hot, hydrothermally formed dolomite. Sounds like an ore-forming environment to me. I hope someone is sampling this stuff and the environs and analyzing for Au, Ag, whatever. The Earth is an amazing chemist.
Instead of Ag Au, which are usually found in silicate rich environments, I would look at the rare earth elements. And China is the world’s largest producer of REE.
Matt G says:
May 26, 2011 at 12:00
Especially when SWR not only warms the ocean,
How?
You’ve mentioned this several times in your post, and its taken for granted that this is so by both warmists and skeptics, yet, I can’t get one explanation that makes sense.
Surely on a site with so many scientists someone can explain and show workable that Visible Light can heat the land and oceans? Can Blue Visible Light heat even a cup of water?
It bounces off, is scattered, by all the molecules of Nitrogen and Oxygen in the Air, hence our blue sky, it just keeps on going until it fades away in our oceans, transmission, how is it heating anything?