Major tectonic collisions near the equator have caused three ice ages in the last 540 million years
Image: Christine Daniloff/MIT
Over the last 540 million years, the Earth has weathered three major ice ages — periods during which global temperatures plummeted, producing extensive ice sheets and glaciers that have stretched beyond the polar caps.
Now scientists at MIT, the University of California at Santa Barbara, and the University of California at Berkeley have identified the likely trigger for these ice ages.
In a study published in Science, the team reports that each of the last three major ice ages were preceded by tropical “arc-continent collisions” — tectonic pileups that occurred near the Earth’s equator, in which oceanic plates rode up over continental plates, exposing tens of thousands of kilometers of oceanic rock to a tropical environment.
The scientists say that the heat and humidity of the tropics likely triggered a chemical reaction between the rocks and the atmosphere. Specifically, the rocks’ calcium and magnesium reacted with atmospheric carbon dioxide, pulling the gas out of the atmosphere and permanently sequestering it in the form of carbonates such as limestone.
Over time, the researchers say, this weathering process, occurring over millions of square kilometers, could pull enough carbon dioxide out of the atmosphere to cool temperatures globally and ultimately set off an ice age.
“We think that arc-continent collisions at low latitudes are the trigger for global cooling,” says Oliver Jagoutz, an associate professor in MIT’s Department of Earth, Atmospheric, and Planetary Sciences. “This could occur over 1-5 million square kilometers, which sounds like a lot. But in reality, it’s a very thin strip of Earth, sitting in the right location, that can change the global climate.”
Jagoutz’ co-authors are Francis Macdonald and Lorraine Lisiecki of UC Santa Barbara, and Nicholas Swanson-Hysell and Yuem Park of UC Berkeley.
A tropical trigger
When an oceanic plate pushes up against a continental plate, the collision typically creates a mountain range of newly exposed rock. The fault zone along which the oceanic and continental plates collide is called a “suture.” Today, certain mountain ranges such as the Himalayas contain sutures that have migrated from their original collision points, as continents have shifted over millenia.
In 2016, Jagoutz and his colleagues retraced the movements of two sutures that today make up the Himalayas. They found that both sutures stemmed from the same tectonic migration. Eighty million years ago, as the supercontinent known as Gondwana moved north, part of the landmass was crushed against Eurasia, exposing a long line of oceanic rock and creating the first suture; 50 million years ago, another collision between the supercontinents created a second suture.
The team found that both collisions occurred in tropical zones near the equator, and both preceded global atmospheric cooling events by several million years — which is nearly instantaneous on a geologic timescale. After looking into the rates at which exposed oceanic rock, also known as ophiolites, could react with carbon dioxide in the tropics, the researchers concluded that, given their location and magnitude, both sutures could have indeed sequestered enough carbon dioxide to cool the atmosphere and trigger both ice ages.
Interestingly, they found that this process was likely responsible for ending both ice ages as well. Over millions of years, the oceanic rock that was available to react with the atmosphere eventually eroded away, replaced with new rock that took up far less carbon dioxide.
“We showed that this process can start and end glaciation,” Jagoutz says. “Then we wondered, how often does that work? If our hypothesis is correct, we should find that for every time there’s a cooling event, there are a lot of sutures in the tropics.”
Exposing Earth’s sutures
The researchers looked to see whether ice ages even further back in Earth’s history were associated with similar arc-continent collisions in the tropics. They performed an extensive literature search to compile the locations of all the major suture zones on Earth today, and then used a computer simulation of plate tectonics to reconstruct the movement of these suture zones, and the Earth’s continental and oceanic plates, back through time. In this way, they were able to pinpoint approximately where and when each suture originally formed, and how long each suture stretched.
They identified three periods over the last 540 million years in which major sutures, of about 10,000 kilometers in length, were formed in the tropics. Each of these periods coincided with each of three major, well-known ice ages, in the Late Ordovician (455 to 440 million years ago), the Permo-Carboniferous (335 to 280 million years ago), and the Cenozoic (35 million years ago to present day). Importantly, they found there were no ice ages or glaciation events during periods when major suture zones formed outside of the tropics.
“We found that every time there was a peak in the suture zone in the tropics, there was a glaciation event,” Jagoutz says. “So every time you get, say, 10,000 kilometers of sutures in the tropics, you get an ice age.”
He notes that a major suture zone, spanning about 10,000 kilometers, is still active today in Indonesia, and is possibly responsible for the Earth’s current glacial period and the appearance of extensive ice sheets at the poles.
This tropical zone includes some of the largest ophiolite bodies in the world and is currently one of the most efficient regions on Earth for absorbing and sequestering carbon dioxide. As global temperatures are climbing as a result of human-derived carbon dioxide, some scientists have proposed grinding up vast quantities of ophiolites and spreading the minerals throughout the equatorial belt, in an effort to speed up this natural cooling process.
But Jagoutz says the act of grinding up and transporting these materials could produce additional, unintended carbon emissions. And it’s unclear whether such measures could make any significant impact within our lifetimes.
“It’s a challenge to make this process work on human timescales,” Jagoutz says. “The Earth does this in a slow, geological process that has nothing to do with what we do to the Earth today. And it will neither harm us, nor save us.”
###
Source: Eurekalert h/t to Dennis Wingo.
The Ca and Mg were already oxidized to their 2+ state. So if they sequestered CO2, that reaction would have to have a favorable equilibrium constant, and would also release some other material as part of a metathesis reaction.
So if it were MgCl2 and CaCl2 to start, it would generate HCl and we’d see the ocean pH drop like crazy (did it?). If it were Mg(OH)2 and Ca(OH)2, then the CaCO3 could form, but MgCO3 would not.
Establishing equilibria among all of these species is a complex task, but can be done.
There is a lot of chemical data that could be used to corroborate or invalidate this hypothesis, but doesn’t seem like they looked into that. Shouldn’t have been published without doing so.
I thought that when an oceanic plate collides with a ‘land’ plate/mass the oceanic one goes underneath the land one. It is called a suduction process/zone. It is because the specific mass of the oceanic plate is larger(?). So the oceanic crust never comes to the surface to absorb the CO2.
Slivers of oceanic crust are often broken off during the collision and emplaced in among the bottom sediment “scraped off” to form mountains. These slivers are called “ophiolites” or “ophiolite suites” because serpentine (metamorphosed ultramafic rocks) are often an important part. Serpentine rocks are greenish, mottled and shiny, somewhat similar to snake skin, hence the names. Serpens = latin for snake, Ophiolithos = greek for snake-rock.
And the ophiolites are typically small in area and inconsequential when it comes to global atmospheric and oceanic chemistry. This is a crackpot hypothesis.
If it was CO2 being drawn from the atmosphere that brought on ice ages, the levels of CO2 would have to have been much lower than now. Since we are really in a CO2 impoverished state at present, would not all photosynthetic plants have become extinct? Is there evidence that green plants had to re-evolve after each ice age? Same with all animals since they depend upon green plants. Sounds like BS to me.
As usual, in their zeal to attribute to CO2, they fail to apply the same logic that they muster to caution the benefits of grinding ophiolite. The forces that drive plate collisions and maintain their sutures at high elevation produce vast amounts of CO2.
Which begs the question, what forces are driving the plates.
What drives the plates ?
Convection in the mantle
https://study.com/academy/lesson/causes-of-tectonic-plate-movement.html
ok, now lets work backwards, what is causing the convection ?
Basically the middle is very hot and the outside is cool so you have a temperature gradient.
Why is the middle hot?…
The heat driving mantle convection has three sources. “Primordial” heat (left over from the accretion and differentiation that led to the formation of Earth’s core) contributes 20 to 50% of the heat. Heating due to the decay of radioactive isotopes (mainly potassium, thorium, and uranium) contributes 50 to 80%. Thirdly, tidal friction from the Moon’s pull on the Earth contributes perhaps 10%. Mantle convection is the main mechanism by which this heat escapes from the interior of Earth.
from…https://www.khanacademy.org/partner-content/amnh/earthquakes-and-volcanoes/plate-tectonics/a/mantle-convection-and-plate-tectonics
Javier
The causality problem. It cooled and there was less CO2.
Henry
after spending so much time here on WUWT , I hope you honestly do not believe that CO2 is any factor in climate change?
The correlation between greater [CO2] in rthe atmosphere and heat is simply because there giga tons of bi-carbonates in the oceans
Both the cooling and there being less CO2 appear to be well established features of the Karoo and Late Cenozoic Ice Ages.
I don’t think the carbon cycle is sufficiently known as to draw the type of conclusions you do about causes and correlations.
@Javier
From the perspective of an experienced chemist like myself, you do reealize that I can easily prove to you that are also cooling effects of more CO2 in the atmosphere?
So what is more: the cooling effects or the warming effects
Do you have some papers on that?
“experienced chemist”?
“easily prove to you that are also cooling effects of more CO2 in the atmosphere”?
Do tell mr. experienced chemist. You are troll Javier without actually discussing Javier’s statements.
Your challenge to Javier indicates that you, henryp, should be providing the proof.
Otherwise, it simply your ego boasting.
Demonstrate to everyone here your proof that CO₂ cools the atmosphere. Provide examples and details on exactly how much CO₂ cooled specific areas of Earth’s atmosphere.
“Provide examples and details on exactly how much CO₂ cooled specific areas of Earth’s atmosphere.”
Read and learn:
https://www.researchgate.net/publication/279399598_Antarctic_Specific_Features_of_the_Greenhouse_Effect_a_Radiative_Analysis_Using_Measurements_and_Models
This has actually been well-known ever since the first Nimbus satellites, but it is seldom mentioned.
http://1.bp.blogspot.com/-PwdZCD2eZ6Y/UOVpiq1CrKI/AAAAAAAAPng/Lp-Ue4Xiuuo/s640/atmospherespectra.gif
Compare the bottom spectrum with the two upper ones and you will see that in the Antarctic CO2 actually cools the atmosphere.
It is an exception and due to the same mechanism that warms the atmosphere elsewhere. Antarctica surface is actually cooler than the atmosphere temperature at the height where effective emission takes place, which is much lower at the poles. If correct it supports that CO2 must have some warming effect on the planet.
tty,
Thanks. Nice find.
Conrath, B. J. Hanel, R. A. 1970 Earth and atmosphere thermal emission spectra via Nimbus 4 Michelson interferometer, obtaining atmospheric temperature, humidity and ozone profiles
Here is the public source document.
https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19700023849.pdf
The first link goes to someone’s claim.
The second link goes to a low resolution graphic.
The note at the bottom of the graphic states:
“… Shown also are the radiances of blackbodies at several temperatures. a) Sahara Region; b) Mediterranean; c) Antarctic”
By that wording, the excerpt you post has another graphic of thermal emissions and these are comparison “blackbody” calculated temperature graphics for comparison, not actual measurements.
Nor is evident from the graphics exactly where CO₂ thermal emissions are identified.
There is a slight increase of thermal emissions near where CO₂ is active, but H₂O is also active over that frequencies.
Even at Antarctic levels of dry air,there is still more atmospheric water vapor than CO₂.
Henry, I am skeptical of your evidence. There are probably tens of thousands of experienced chemists and thousands of them with ample atmospheric expertise. Any particular reason I should trust you?
And when we are discussing about events that took place hundreds of millions of years ago, I become hyperskeptical, because the evidence to support people’s beliefs is rarely there.
There is good geological evidence about past Ice Ages, and fair proxy evidence that two of them might have had quite low CO2 levels. And that is about it. All the rest is insufficiently supported hypotheses.
Javier
and fair proxy evidence that two of them might have had quite low CO2 levels.
Henry says
Nobody denies the correlation between CO2 in the atmosphere and heat/cold.
If it gets cold, CO2 goes down in the atmosphere as it dissolves in the oceans:
[I am assuming pH does not change]
CO2 (g) + 2H2O (l) + coldness = > H3O+ + HCO3-
{this is the net result reaction}
If it gets warmer, the reaction goes the other way:
HCO3- + heat = > CO2 (g) + OH- {remember there are giga tons of carbonates and bi-carbonates dissolved in the oceans]
Hence, as I think Ian Wilson correctly reported, there is a lag time of about 800 (?) years on average before increased warmth on earth shows up as increased CO2 in the atmosphere.
To give you some clues as on how you can see that CO2 is also cooling the atmosphere:
1) we can identify and quantify CO2 presence on other planets by measuring the deflections by CO2 of sunlight in the UV range.
2) we can see the deflections caused by CO2 in the 1-2 um range. Follow the green line fig. 6 bottom and see how it returns to us, picked up via the moon, in fig 7.
3) I know that CO2 has big absoprtion between 4 and 5 um because we used to measure CO2 in nitrogen at 4.6 um.
So, to sum it up, we know that CO2 has absorption in the 14-15 um range causing some warming (by re-radiating earthshine) but as shown and proved above it also has a number of absorptions in the 0-5 um range causing cooling (by re-radiating sunshine). This cooling happens at all levels where the sunshine hits on the carbon dioxide same as the earthshine. The way from the bottom to the top is the same as from top to the bottom. So, my question is: how much cooling and how much warming is caused by the CO2? How was the experiment done to determine this and where are the test results?
{Arrhenius and Tyndall only saw half of what was happening as they performed closed box experiments. I hope you see now why their science was not complete?
Anyway, I therefore did some emprrical experiements to find there is no warming caused by more CO2. Click on my name to read my report on that.
at my point 2)
http://astro.berkeley.edu/~kalas/disksite/library/turnbull06a.pdf
Sorry, you need this paper to show the deflections of CO2 in the 1-2 um. Try and understand the paper, as it provces conclsusively that CO2 is also cooling the atmosphere by deflecting certain sunlight away to space.
Henry,
Re-radiation of incoming solar radiation is non-controversial. An atmosphere with GHGs is less transparent to incoming solar radiation, but what matters is the balance between Absorbed Shortwave Radiation (ASR) at surface and Outgoing Longwave Radiation (OLR) at top of the atmosphere. How increases in CO2 alter that balance determine the temperature effect, regardless of its effect reflecting incoming solar radiation.
Everything you say is known as far as I know. The question is that we are not capable of quantifying the CO2 effect, neither at warming nor at cooling. However theory and evidence indicate that warming dominates and the increase in CO2 has some unquantified net warming effect. If you disagree with that you should be able to prove it and publish it, because otherwise it just constitutes opinion.
Javier
it was you who said that you believe that there is an effect of warming by CO2 and that the net effect of more CO2 in the atmosphere is that of warming rather than cooling. Then you must submit to me the evidence for this and not put the onus on me to produce it? Anyway, I cannot think of a test to quantify whether the net effect of the re-radiations by CO2 is that of warming or cooling. But I did my own testing to find that there is no man made warming or that it is so small so as to be immeasurable compared to the natural factors at work. Click on my name to read my finla report on that. You are now admitting that nobody has a balance sheet showing exactly how much cooling and warming is caused by the CO2. That is a step forward.
We could have figured out easily that the effect by CO2 is nothing since it only increased from 0.03% to 0.04% over the last 50 years which is a change of only 0.01% in the atmosphere. By contrast water vapor can be about 0.5% but I think it may vary upward or downward by as much as 0.1% depending on
1) irradiation of the oceans by the sun
2) the weather
3) where to measure?
4) The amount of aeroplanes in the air making contrails
5) increased irrigations
6) cooling nuclear/gas fired/ coal fired power stations & other big factories etc
7) increased landuse – changing deserts (e.g. Las Vegas, Johannesburg)
to name but a few things that I can think influencing the amount of water vapor in the air….
Yeah…. Riiiight.
Back to CO2 is the control knob of all climate variations.
I cannot imagine that major continental collisions might disrupt oceanic circulation… Not possible.
End of reading. Full stop. Deep breath… CO₂ IS NOT THE CONTROL KNOB!!!!!!
I didn’t have to read another word after that. This is what passes of study today?!?! Where and how do these people get a degree? Who are their advisors to allow them to even pursue such easily refuted garbage? A new idea that runs counter to accepted teachings is one thing, but it needs to have at least a little actual science behind it, something that can be proven/disproven, and a valid, solid experimental design! What is this bulls***??? SMH
Shocking, it’s from EuekAlert!
In other significant news, there were no ice ages or glaciation events during unicorn migrations in all of recorded history.
Doesn’t this research show that when CO₂ is high, that continents collide? Oh Noes, it’s worse than we thought. The continents are going to start playing dodgems.
@Javier
From the perspective of an experienced chemist like myself, you do reealize that I can easily prove to you that are also cooling effects of more CO2 in the atmosphere?
So what is more: the cooling effects or the warming effects
Do you have some papers on that?
Maybe I missed it, but how can they always explain the cause of a process 50 million years ago, but they can’t explain the cause for ENSO?
Calcium and magnesium in rocks?
Magnesium in rocks, e.g. magnesium carbonate, i.e. chalk is from the accumulated deposited shells of coccolithophores.
Calcium in rocks, e.g. calcium carbonate, calcite is from accumulated deposits of shells from marine creatures, e.g. molluscs.
Yet, this calcium/magnesium sheds their carbon dioxide to rip CO₂ from the atmosphere?
Several million years gets conflated with “nearly instantaneous” geology bafflegab.
“the researchers concluded” is synonymous with confirmation biased presumptions.
“We showed that this process can start and end glaciation”; er, no; “they” assumed but did not demonstrate.
A confirmation biased “literature search” coupled with someone’s “computer simulation” to allegedly prove their predetermined decision…
Grade school science procedures at work.
Amateur here. Does the much heavier oceanic plate ride up over the lighter contintental crust? Seems odd to me.
No, it goes underneath, but part of the softer and lighter sediments on top of the oceanic plate usually gets “scraped off” and builds up against the continental plate. The “Franciscan melange” in CA is a beautiful example. It is one big scrunched up mess:
http://static.gigapan.com/gigapans0/182359/images/182359-640×360.jpg
Causation or coincidence it is interesting the results happened after three events in the tropics. The only wrinkle is the human caused global warming pitch that does not fit with the research.
So the dramatic obstruction to the Earth’s massive atmospheric and oceanic heat distribution systems are of no consequence? You can arrange the continents any way you like and global average temperatures will remain the same?
Just another attempt to convince everyone that CO2 drives climate.
Haven’t measurements shown that ice ages begin and end abruptly? How does chemical weathering of newly exposed rock fit this time scale?
Glaciations are rather short and start and end rather abruptly and are rather obviously controlled by orbital mechanics.
But glacial epochs are much longer. The present one has already lasted for 35 million years. That said, it did start rather abruptly at the Eocene/Oligocene border (the “Grande Coupure”), probably within a few hundred thousand years.
There is actually a much simpler explanation for the low CO2 during the Carboniferous-Permian. The Carboniferous isn’t called carboniferous for nothing. Huge amounts of coal were deposited during this interval, probably because efficient decomposers that “eat” dead vegetation had not yet evolved. This is a straightforward process with no need for hypothetical weathering processes.
The trouble with this hypothesis is that during the Cretaceous even more carbon was taken out of the atmosphere by the formation of huge volumes of chalk and world-wide emplacement of organics-rich shale in the oceans (most oil is Cretaceous). But the climate stayed extremely warm.
Did some quick research on this hypothesis. Easy to find two BIG qualitative problems with this extension of ‘CO2 as the climate control knob’ on geological time scales.
First, ophiolites ( basaltic ocean crust thrust up and exposed onto continental crusts) do exist. The form at the techtonic beginning of a subduction zone. BUT they are comparatively narrow so small in area. Extremely doubtful they could affect CO2 so much, especially since subduction zones recycle carbonate rocks into CO2 via heating and volcanism. And since the chemistry of actual ophilites does not show so much oxidation.
Second, ophiolites formed as landmasses wandered, meaning ocean circulations were very different. Ocean circulation governs planetary heat content, because that is where the bulk of heat resides, based simply on thermal mass. The present ‘ice ages’ starting about 2.5mya are thought to have been triggered by formation of the Panama isthmus at that time, drastically altering circulation exchange between the Atlantic and Pacific oceans.
At this point I wouldn’t be surprised to discover the mining of Vibranium by Wakanda has been responsible for the predicted global warming.
Wakanda can do no wrong! Nothing they do is harmful! Prepare to be reeducated.
If anything coincides with CO2 then by definition CO2 must be the causal factor. This is just another feeble attempt to terrify children. Like that arch dope George Monbiot who today claimed we were on track for a 4 C degree rise in temperature this century on an ever compliant BBC.
Yes Totally weird. Academic reputation has sunk to very low levels these days.
Their Figure 2 is here:
Accompanying Figure legend:
Phanerozoic suture length in the tropics compared to the latitudinal extent of continental glaciation.
(A) Total length of active suture length. (B) Total length of active sutures that are reconstructed to be within 10°, 15°, and 20° of the equator over the past 520 million years. (C) Blue marks the latitudinal extent of continental ice sheets, excluding Alpine glaciers (table S3).
My thoughts:
Their proposition is entirely plausible to the extent of necessary but not sufficient to explain the totality of the global temperature decrease of the Quaternary compared to past glaciations.
Their Tropical suture hypothesis ignores the likely huge contribution to cooling the global climate of the current polar-centered location of the Antarctic continental land-mass, as well as a possible smaller role for the closing of the Panama Isthmus between the Atlantic and Pacific.
But it is the near CO2 starvation of the last Pleistocene LGM (around 180 ppm by some proxies) that should give the serious scientist pause. For that should come with a realization that humanity’s recent addition of CO2 (by digging up fossil fuels and burning them) may one day be properly viewed as a saving grace for the biosphere and all higher life on this planet.
They will entertain no other theory except those that show CO2 as a driver of climate. I’m not saying that tectonics don’t play a role in ice ages, but CO2 isn’t the mechanism. It’s been shown many times that CO2 changes is the effect, not the cause, of temperature change.
I thought Ice Ages came into being when there are land masses at both poles? To get glaciation at the poles, you need land masses there.
That may not be correct. According to Frozen Earth, a book by geologist Douglass MacDougal about the ice ages, an open pole can radiate more heat to space and this was involved in at least one of the ice ages. A more likely cause is equatorial mountain building which causes tropical ice. The ice over the poles does not reflect much sunlight to space. They actually slow the rate of cooling of the earth.