Study debunks theory on end of 'Snowball Earth' ice age

May 25, 2011
Crystals of highly carbon-13-depleted carbonate are observed using a light microscope. Credit: Thomas Bristow

A team of scientists led by researchers from Caltech report in this week's issue of the journal Nature that the rocks on which much of a theory on how the "Snowball Earth" ice age ended 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.

There's a theory about how the Marinoan ice age—also known as the "" 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, dolostone; 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.

This image shows unusual textures exposed in the cap dolostone from the field. Hand lens for scale is about 1 inch long. Credit: Thomas Bristow

"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.

"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 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."

This is a view from one of the cap dolostone collection sites in south China, looking along the cliffs of the Yangtze Gorges. Credit: Thomas Bristow

Since this 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 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 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."

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User comments : 25

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jscroft
1.6 / 5 (14) May 25, 2011
Hmm. So... is there ANY evidence supporting the theoretical "greenhouse gas" mechanism left standing?
emsquared
5 / 5 (4) May 25, 2011
Great stuff. The "snowball earth" has always been of interest, to me at least, as an indicator of the wide range of earth's natural climatic volatility if not variability. Not to mention the uncertainty surrounding the whole thing. Granted continental arrangement and oceanic currents were vastly different then (which I would suspect has something to do with it's ultimate end just as it did it's formation). It will be very interesting to see what theories come along next.
SemiNerd
4.7 / 5 (13) May 25, 2011
Hmm. So... is there ANY evidence supporting the theoretical "greenhouse gas" mechanism left standing?

You did get that we are talking about methane oxidation and carbonate formations from 600 million years ago... right?

The 'greenhouse gas' mechanism isn't a theory. It can be demonstrated easily. The question remains however, what was the exact mechanism that caused the end of of the Marinoan Age. That it existed, and that it ended are quite well established.
kevinrtrs
1.2 / 5 (22) May 25, 2011
The question remains however, what was the exact mechanism that caused the end of of the Marinoan Age

Possibly the answer might be more visible if one gives up on long ages and begins to think in much more rapid terms of transformation. Then numerous mechanisms are suddenly available. But of course, if one is glued to long ages, one will take an interminable time to reach any concrete evidence.
that_guy
5 / 5 (5) May 25, 2011
The question remains however, what was the exact mechanism that caused the end of of the Marinoan Age

Possibly the answer might be more visible if one gives up on long ages and begins to think in much more rapid terms of transformation. Then numerous mechanisms are suddenly available. But of course, if one is glued to long ages, one will take an interminable time to reach any concrete evidence.

Well, the current view is that this ice age did end quite abruptly. As for the length of the ages - Why would they just up and drop the best conclusion they have, being smothered in evidence that supports it.
Msean1941
5 / 5 (7) May 25, 2011
Someone should write a program that scans these things and replaces "theory" with "hypothesis". Misusing the word theory just bolsters the "but it's just a theory" crowd in their attacks on evolution.
jscroft
1.6 / 5 (7) May 25, 2011
The 'greenhouse gas' mechanism isn't a theory. It can be demonstrated easily.


Only if you accept the premise that a greenhouse is a good model for Earth's atmosphere. If you do, then you have to answer this: http://arxiv.org/...61v4.pdf

Good luck with that.

P.S. Um, yah, it's a theory. Just one with a lot of ragged holes in it. Good point, @Msean1941.
Postman1
1.7 / 5 (6) May 25, 2011
jscroft- No sense talking sense to the true believers. They will still be railing against CO2 and global warming when they are huddled around campfires atop the glaciers of a new ice age. (could happen) Global warming zealots follow their dogma more faithfully than a jihadist and are harder to convert. They claim the science, but when confronted with contrary scientific evidence, they then want to claim consensus. True scientists are happy to see their theories questioned and tested. It's called the 'scientific process'.
RealScience
5 / 5 (10) May 26, 2011
kevinrtrs: That's funny coming from you.
There are so many pieces of evidence for long ages that anyone doing an open-minded assessment would find the evidence convincing. And science is open-minded enough to constantly recheck these pieces of evidence and refine age values when new evidence says to.

It is you who are glued to short ages.
Rather than actually looking at what the evidence says, you have your mind made up in advance and refuse to believe any evidence that contradicts the notion that you are glued to.
Bigblumpkin36
not rated yet May 26, 2011
I thought it was dino poo, go figure i guess
Ethelred
5 / 5 (7) May 26, 2011
Possibly the answer might be more visible if one gives up on long ages
Yes. Of course. Absolutely if you give up on using evidence and use strong hallucinogenics that fantasies do become more visible.

Then numerous mechanisms are suddenly available.
Especially ones that don't depend on an actual evidence or physical laws or pretty much anything testable.

But of course, if one is glued to long ages, one will take an interminable time to reach any concrete evidence.
The alternative then is to go on ancient book, written by men who were even more ignorant then Kevin and that fails to match evidence or history.

And has a Flood that Kevin is afraid to discuss.

Ethelred
Ethelred
4.6 / 5 (10) May 26, 2011
Only if you accept the premise that a greenhouse is a good model for Earth's atmosphere. If you do, then you have to answer this: http://arxiv.org/...61v4.pdf
OK. I can do that. Its a BAD model that was used in that paper. One that produces an Earth that is MUCH colder than the one we live in. Thus it is crap.

http://arxiv.org/...24v1.pdf

The Earth is warmer than a it should be if there was no greenhouse effect. MUCH warmer. Since that paper is so disconnected from the actual evidence it is pure crap. It has as much connection with reality as post by Kevin.

If you were to go that first paper you would never wear a jacket since they violate the 2nd law of thermodynamics according to the paper. Since jackets DO work the paper is crap.

Now how about you ostriches start dealing with reality instead using fantasy papers that don't match the world we live in.

Ethelred
Birger
5 / 5 (7) May 26, 2011
The article covers a period from another geological age, when conditions were very different from today (for instance, the oxygen content was too low for large multicellular organisms to exist).

Re the greenhouse effect: Check the conditions on Venus. Exactly the greenhouse effect you can expect considering the huge amount of CO2 (500 degrees C or more).

Re. current warming warming on Earth; go to northern Alaska -the warming is most evident in the coldest areas on Earth. Permafrost thawing out. Tundra vegetation retreating, being replaced with ordinary forest.
--- --- --- --- --- --- --- ---
"You are entitled to your opinions, but you are not entitled to your own facts"
Ethelred
4 / 5 (4) May 26, 2011
(for instance, the oxygen content was too low for large multicellular organisms to exist).
I keep wondering how strong the evidence is for that. There are other reasons for large organisms to not exist. Almost certainly sexual reproduction had to evolve for large orgnisms and we don't when that occured.

Check the conditions on Venus. Exactly the greenhouse effect you can expect considering the huge amount of CO2 (500 degrees C or more).
Venus also has a lot of SO4 in the atmosphere and that is pretty opaque. It is why Venus has such a high albedo. Any light that gets through that atmosphere is going to stick around for awhile.

-the warming is most evident in the coldest areas on Earth.
Which exactly fits a greenhouse effect. Heat is retained longer by both CO2 and H2O but if it cold enough there won't be much H2O in the atmosphere thus making CO2 a more important greenhouse gas in the high latitudes and over deserts.

Ethelred
jscroft
1 / 5 (3) May 26, 2011
If you were to go that first paper you would never wear a jacket since they violate the 2nd law of thermodynamics according to the paper.


Do you mean to suggest that jackets work because they are transparent to visible light, but opaque to IR?
Ethelred
4 / 5 (4) May 26, 2011
No. I mean that by the standards of the article they violate the 2nd law of thermodynamics. In other words the paper is wrong about greenhouse gasses because it makes a prediction that is WAY off of the world we live in.

Ethelred
CSharpner
5 / 5 (2) May 29, 2011
The question remains however, what was the exact mechanism that caused the end of of the Marinoan Age

Possibly the answer might be more visible if one gives up on long ages and begins to think in much more rapid terms of transformation. Then numerous mechanisms are suddenly available. But of course, if one is glued to long ages, one will take an interminable time to reach any concrete evidence.

Of course, if one "gives up" on "long ages", then what do we do with facts like we can see objects and events in the universe more than 6000 light years away?... BILLIONS of light years away? This is the 3rd or 4th time I've asked you this TODAY! and probably the 30th time overall. You have YET to even ATTEMPT an answer it!
jscroft
1 / 5 (3) Jun 01, 2011
If you were to go that first paper you would never wear a jacket since they violate the 2nd law of thermodynamics according to the paper.

Do you mean to suggest that jackets work because they are transparent to visible light, but opaque to IR?


No. I mean that by the standards of the article they violate the 2nd law of thermodynamics.


OK, I'll bite: HOW do jackets violate the 2nd Law, according to the article I cited?
jscroft
1 / 5 (3) Jun 01, 2011
In other words the paper is wrong about greenhouse gasses because it makes a prediction that is WAY off of the world we live in.


Really? What prediction does it make? Copy and paste, please.
jscroft
1 / 5 (5) Jun 01, 2011
What do we do with facts like we can see objects and events in the universe more than 6000 light years away?... BILLIONS of light years away? This is the 3rd or 4th time I've asked you this TODAY! and probably the 30th time overall. You have YET to even ATTEMPT an answer it!


Here, I'll try: nobody is answering your question because it's tiresome.

The premise of your argument is that the Universe abhors a paradox, that two mutually exclusive truths cannot coexist. And this appears to be the case... within the CONTEXT of the Universe we can observe.
jscroft
1.5 / 5 (6) Jun 01, 2011
What of contexts we CAN'T observe? I am perfectly comfortable with the notion of a ~14 billion-year-old Universe because that hypothesis has survived every test we can throw at it, within the mutually supportive physical context of everything ELSE we know about the Universe.

But the context occupied by G-d is unknowable BY DEFINITION. To argue that our physical models preclude a divine creation event sixty centuries ago is TRUE, but ultimately not RELEVANT to any discussion that depends fundamentally on a question of faith, any more so than an objection that G-d's timetable leaves no room for the Big Bang will make even the slightest splash at a cosmology convention.

So we can accept the story told by cosmology, because it comports with observation... AND we can accept the story told by G-d, because in a very unambiguous sense none of us has any idea what He is talking about anyway. We can chalk any APPARENT inconsistencies up to a failure of our own, minutely limited perspective.
JayK
5 / 5 (1) Jun 01, 2011
Halpern 2010 disproved Gerlich's paper.
astro_optics
1 / 5 (5) Jun 02, 2011
I hope that all these "Alarmist" scientists realise that they will not have a future when the world wakes up to the fact that it was all a huge hoax, and after they've caused huge damage to our society and the climate, it's just a matter of time...
frenchie
5 / 5 (2) Jun 14, 2011
it shouldn't take 10 pages to find out that Mr Gelrich has some severe issues with proper wording,fact checking and elementary thermodynamics. Additionally the paper was initially published as an editor's choice, ei: not peer reviewed, although I'm sure some here would claim liberation from us superior intellectual elite.

Green house effects violate the 2nd law of thermodynamics???

The atmosphere of the Earth is less able to absorb shortwave radiation from the Sun than thermal radiation coming from the surface. The effect of this disparity is that thermal radiation escaping to space comes mostly from the cold upper atmosphere, while the surface is maintained at a substantially warmer temperature. This is called the "atmospheric greenhouse effect", and without it the Earth's surface would be much colder.

Thermodynamics aren't a theory or hypothesis gentlemen. They're Laws.

Please continue posting papers but research more to avoid posting garbage (applies to pro or con anything)
Ethelred
5 / 5 (1) Jun 15, 2011
Gelrich used the Moon for a model. The Moon has rather long days and nights. He COULD have used something else that spins faster but that might have showed that there IS an atmospheric greenhouse effect.

What else could he have used?

How about something man made. That didn't have a heater but did have humans. Apollo 13. They had to shut of the heat to conserve power.

It got very cold in the LEM with three humans putting out heat. In the command module it FROZE. This shows that the Sun is not putting out enough heat to keep something at one AU from freezing up. Without the atmosphere the water on Earth would be frozen. That is a fact. Not an opinion and Gelrich was clearly not interested in real world evidence. He had an axe to grind and the only reason I can think of is political. Perhaps he just hates Greens so much he is incapable of using reason.

There that ought to get me a bunch of ones that no one can up. Go ahead IF you can give a rational reason.

Ethelred