From the MASSACHUSETTS INSTITUTE OF TECHNOLOGY and the “thank goodness we have plenty of free CO2 in the atmosphere today” department comes this claim:
Continental shifting may have acted as a natural mechanism for extreme carbon sequestration
For hundreds of millions of years, Earth’s climate has remained on a fairly even keel, with some dramatic exceptions: Around 80 million years ago, the planet’s temperature plummeted, along with carbon dioxide levels in the atmosphere. The Earth eventually recovered, only to swing back into the present-day ice age 50 million years ago.
Now geologists at MIT have identified the likely cause of both ice ages, as well as a natural mechanism for carbon sequestration. Just prior to both periods, massive tectonic collisions took place near the Earth’s equator — a tropical zone where rocks undergo heavy weathering due to frequent rain and other environmental conditions. This weathering involves chemical reactions that absorb a large amount of carbon dioxide from the atmosphere. The dramatic drawdown of carbon dioxide cooled the atmosphere, the new study suggests, and set the planet up for two ice ages, 80 million and 50 million years ago.
“Everybody agrees that on geological timescales over hundreds of millions of years, tectonics control the climate, but we didn’t know how to connect this,” says Oliver Jagoutz, associate professor of Earth, Atmospheric and Planetary Sciences (EAPS) at MIT. “I think we’re the first ones to really link large-scale tectonic events to climate change.”
Jagoutz and his colleagues, EAPS Professor Leigh Royden, and Francis McDonald of Harvard University, have published their findings in the Proceedings of the National Academy of Sciences.
Putting the squeeze on
The two tectonic collisions that the team studied stemmed from the same event: the slow northward migration of Gondwana, a supercontinent that spanned the Southern Hemisphere from 300 million to 180 million years ago and eventually broke up to form Antarctica, South America, Africa, India, and Australia.
Around 180 million years ago, tectonic activity began to push fragments of Gondwana up toward the northern supercontinent of Eurasia, which slowly squeezed and eventually closed the Neo-Tethys Ocean, an ancient body of water lying between the supercontinents.
In previous work, Jagoutz and his colleagues developed a model to simulate the tectonic shifting that occurred in and around that ocean as Gondwana fragments were crushed against Eurasia. Through analysis of ancient rocks in today’s Himalayas, the team determined a sequence of events as the continents merged.
They found that 90 million years ago, the northeastern edge of the African plate collided and slid under an oceanic plate in the Neo-Tethys Ocean, creating a chain of volcanoes. At 80 million years ago, as Africa continued advancing north, the oceanic plate was pushed further up and over the continent, exposing ocean rock to the atmosphere, while simultaneously terminating the volcanoes. Then, 50 million years ago, India merged with Eurasia in a second collision in which a different region of the oceanic plate was pushed up onto that continent.
Both collisions took place in the Intertropical Convergence Zone (ITCZ), an atmospheric region hovering over the Earth’s equator, in which trade winds come together to generate a region of intense temperatures and rainfall.
A weathering trigger
For this new paper, the researchers wondered whether the tectonic collisions in this extremely tropical region may have played a part in pulling huge amounts of carbon dioxide out of the atmosphere and triggering the ice ages.
Certain types of rock, if exposed to high heat and heavy rain, undergo chemical reactions and effectively absorb carbon dioxide, a process known as silicate weathering. These rocks include basalts and “ultramafic” rocks, which are often found within oceanic plates. If these rocks are exposed to the atmosphere in a tropical region, they can act as very efficient carbon sinks.
The team hypothesized that the two collisions, involving Africa and then India, brought basaltic and ultramafic rocks up from the oceans and onto land, creating carbon sinks 80 and 50 million years ago. Both collisions also effectively turned off carbon sources by burying volcanoes that had been emitting carbon dioxide and other gases into the atmosphere.
To know whether such a sequence of events directly reduced carbon dioxide in the atmosphere, the researchers looked to weathering rates of different rock types, including granites, basalts, and ultramafics. These rates, which have been calculated by other researchers, describe the way rocks erode and take up carbon dioxide, given exposure to a certain amount of rainfall.
They then applied these weathering rates to their model’s estimates of the amount of oceanic plate that was pushed up onto Africa and India, at 80 and 50 million years ago, respectively. After determining the amount of carbon dioxide sequestered by these rocks, they calculated the total amount of atmospheric carbon dioxide through time, from 100 million years ago to around 40 million years ago.
The team found that carbon dioxide dipped dramatically at precisely the time the two collisions occurred. The levels of carbon dioxide also mirrored the temperature of the oceans during this interval.
Jagoutz says one reason these two collisions had such an extreme effect on atmospheric carbon dioxide may have been the fact that each continent continued moving north, exposing new basaltic and ultramafic material, “like a bulldozer that brings fresh rock to the surface.”
Interestingly, a similar process is taking place today, albeit at a smaller scale, near the island of Java. The same tectonic activity that shifted Gondwana northward more than 100 million years ago is today pushing the Australian plate north, and as a result, is piling up basaltic material on Java within the ITCZ, which Jagoutz says is “a huge carbon sink.”
“What nature shows us is, if you put a lot of these rocks in the tropics, where it’s hot, muggy, wet, and rains every day, and you also have the effect of removing the soil constantly by tectonics and thus exposing fresh rocks, then you have an excellent trigger for ice ages,” Jagoutz says. “But the question is whether that is a mechanism that works on the timescale that is relevant for us.”
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Additional background
ARCHIVE: Newly discovered flux in the Earth may solve missing-mantle mystery
ARCHIVE: India joined with Asia 10 million years later than previously thought
The scenarios sound plausible. Not irrefutable, but not crazed. However, I’m having a bit of difficulty with the dates. 80 million years bp would be the Upper Cretaceous, right? Glaciation? There were tropical seas in the Dakotas and Alberta. 50 million years ago? Early Eocene. I was under the impression that time period was quite warm also although there was cooling from then until the Oligocene (34 million years ago and even more thereafter.
Apparently there is something here that I’m not following
>>Glaciation?
Yeah, likewise confused. In my post below about albedo cooling, I assumed they were correct about these ice age timings. But this simplistic Wiki temperature graph might suggest they are not. But the same mechanism would apply, whatever the era.
Ralph.
That’s an unusual – and rather indirect – interpretation of Milankovitch Cycles.
Thank you Don Easterbrook^^+100. This fallacy of “Icehouse” and “greenhouse” climate state is something the AGW jihad has worked into the language for years now. As Don states, there were no glacial episodes 80 mya (late Cretaceous Period) or 50 mya (early Eocene), but the “climate language police” place the “icehouse” label to make one believe that the earth was suffering from severe cold temperatures. Sorry, geologic evidence does not support that conclusion. The Antarctic ice sheet may have started to develop during the late Eocene to early Oligocene (38-33 mya), but that does not constitute a glacial period, The Pleistocene (2.56 mya) constitutes a glacial climate with ice sheets developing on both poles and impacting global scale climate. Don’t go along with the numbnut scientists that prefer to use the icehouse/greenhouse language to wrongly simplify a ‘climate’ state that supposedly lasts for 10’s of millions of years without any detailed data to support the assertion. P.S., there is no ‘continental drift’, the correct term is plate tectonics and is much different and significantly more complex than the original and very simplified idea of continental drift….
The implicit assumption underlaying this idea is that CO2 is the most important climate driver. It is not, except when you start at very low concentrations (10% of pre industrial, for instance). Under those conditions, however, there would have been no plant life left. That clearly hasn’t happened.
Someone forgot to update these guys with the modern confirmation that “the science is settled”.
That’s it folks. The debate is over. All the results are in and the earth’s climate has been conclusively described in fullness (on Skeptical Science, of course, and also now on Wikipedia).
So, no more new theories, or lousy guesses, or “just-so stories” or wild imaginings, or hapless hand flailing, or searching for the missing pieces. Since no pieces are missing and nothing needs to be explained.
Consensus climate science certainly has no need for these kind of attempts to re-explain the very most fundamental principles of climatic process and documented shifts in the earth’s climate over eons.
What are these people trying to achieve?
There attempts to explain basic things suggest that we humans don’t know what the hell is going on!!!
This tomfoolery will not be tolerated!!!
(some sarc.)
Apologies typo: “there attempts” should read “these attempts” or “their attempts”, obviously.
Didn’t they forget something, like establishing a link between the level of CO2 in the atmosphere and the amount of warming.
There were times in the past when it was cold and the CO2 levels were high.
This ‘study’ is beyond stupid. The simple truth is painfully obvious: all ice ages begin and end suddenly and come at a fairly even pace and the only thing able to do this is the sun. Turning on and off the level of heat has immediate impact.
If the cooling was all one way, this story might be slightly plausible but periodic cold/warm cycles: no way.
Or albedo.
The trouble with assuming that CO2 is ALWAYS responsible, is that you may ALWAYS be wrong. Sometimes it is better to have a few eggs in another basket, otherwise your theory becomes a creed, and your science becomes a religion.
.
In this case, it is equally likely that albedo was responsible for these ancient ice age eras, not CO2.
Continental collisions result in continental uplift,
And continental uplift results in surface cooling, at 6.6oc/1000m,
And surface cooling results in massive ice sheets,
And ice sheets result in higher albedo, from 0.3 to 0.9.
And high albedo results in less much insolation absorption,
And reduced insolation absorption means global cooling.
Many decades ago, before CO2 became the devil that controlled everything on the planet, people made other suggestions and theories. One of those suggestions was by Matthias Khule, who suggested that the change from obliquity regulated ice ages to precessionary regulated ice ages – at the Mid Pleistocene Transition (MPT) 1 million years ago – was caused by Himalayan uplift. If the Himalaya plateau rose by 500m to 1000m, the Himalaya ice sheet would grow substantially and reflect much more insolation. And because of its southerly location and high altitude, Kuhl reasoned that it would reflect up to four times as much annual insolation as the northern ice sheets do (per unit area). And this great blob of cooling near the tropics, would be enough to drag down global temperatures and cause the MPT – the sudden shift from smaller ice ages to large ones.
Well exactly the same could have happened 50 and 80 million years ago. The continental collision-uplift caused ice sheets, high albedo, and global cooling. And the cooling climate caused lower CO2 levels, through the natural increased solubility of colder oceans. And since this is a much faster process that waiting for continental erosion to take effect, and reduce CO2 and temperatures, it is a much more reasonable and likely theory.
So CO2 is merely following temperature, not regulating it. And once again, this may well suggest that everything that has been said about CO2, may be completely wrong. And so everything within modern climate science may also be wrong – every last drop (or molecule) of it.
Ralph
Thanks, Ralph. Good post.
Isn’t the term “weathering” wonderful. All one has to do is use the word “weathering” and everyone on the pro-global warming side of the debate enters some type of trance where any explanation for any phenomenon becomes believable.
Weathering is only about 0.5% of the annual Carbon Cycle flux and thus, can be completely ignored. It is tiny compared to plants or the oceans annual flux.
Just an update, weathering is only 0.2% of the annual Carbon Cycle so the math just does not work in this case or any other “weathering” case.
Climate scientists are just very, very bad at basic math (it is almost a pre-requisite to get into the profession) and I think they migrate into the profession from Environmental Science or whatever because it is just accepted in this scientific field.
A couple of things:
1 – Change in CO2 lags change in temperature. link Do they have an explanation for that? It’s hard to say CO2 changed temperature if the temperature change happened first.
2 – They say Java has the right conditions to absorb CO2 the same way they say happened 80 million years ago. As far as I can tell, Java has a high CO2 concentration. It doesn’t look like much of a sink. link I’ll bet they don’t deal with that either. If Java was a CO2 sink, you would expect it to have low CO2 levels.
The fly in the ointment for all ideas about the cause of the last ice age, is “why did the climates of North America and northern europe become the extreme cold events they did. The only reason that l can see why that would happen is if the cause was due to the weather.
They got it wrong because adding CO2 to the atmosphere does not cause warming. More CO2 in the atmosphere causes a slight decrease in the lapse rate in the troposphere which is evidence of cooling not warming. It is the colder temperatures that caused CO2 to decrease in the atmosphere. There is no real evidence that CO2 has any effect on climate. Changes of CO2 with climate are an effect of climate change and not a cause. If a greenhouse gas was responsible then climate change then H2O has got to be the primary culprit but that is not part of their theory. The real effect on climate that the moving continents had is how they affected ocean currents.
To Bryan A. 1816 was the year without a summer.
“I think we’re the first ones to really link large-scale tectonic events to climate change.”
No you are not. You are just the most recent ones to be wrong.Tectonic activity PRODUCES CO2 and water. Check out a modern Carbon cycle. Weathering is lunch money.
It’s almost embarrassing reading this stuff. They seem to be taking credit for identifying patterns of plate tectonic activity that have long been known and documented. Then they seem to be creating “ice ages” where none existed before and stretching the concept of ice ages to include a long slow cooling period with no NH glaciation. And they start from the assumption that the “ice age” must have been caused by lower CO2 rather than fairly well established patterns of oceanic circulation (and oh, yes, let’s not forget the sun). And they use a model instead of actual observations, which (if their proposed events actually took place) might have been noted by some of the geologists who still go out and look at rocks
If their concept is right (almost certainly not) and if they’re looking for basalt to suck CO2 out of the air, there have been some stupendously huge volcanic events in the Cenozoic that put millions of cubic kilometres of basalt right on surface, with no need to invoke subduction or underplating. Don’t these people even read geology textbooks? Oh I forgot, volcanism emits CO2, doesn’t it. Oh well, there must have been that much more to sequester. (/sarc)
I can’t take much more of this armchair arm-waving masquerading as “research”.
I agree with you. With so many variables and over such a long geological period how they build carbon dioxide into the equations is magical. These guys knew the answer they wanted and constructed the narrative to provide it.
The massive tectonic changes were just an aside to the carbon dioxide that controlled all the planet’s climate zones.
“and stretching the concept of ice ages to include a long slow cooling period with no NH glaciation.”
Actually there was fairly large-scale NH glaciation during this “long slow cooling period”. Greenland has had tidewater glaciers at least since the Oligocene (possiby Eocene) and by the Pliocene there were tidewater glaciers in Alaska, Iceland and Norway as well,, while in East Greenland the large fiords already existed by the Pliocene.