Today's Climate Change and the Permian-Triassic Boundary

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Summary:

How does Climate Change today compare to the Greenhouse event 250 million years ago that nearly ended life on Earth?
This video shows how geologists figured out that a huge greenhouse effect nearly wiped out life on Earth 250 million years ago. The explanation is premised on an analysis of rock samples found at the Permian-Triassic Boundary in Utah. It involves a lot of Chemistry and Earth science so I wondered to what extent these complex processes are at work today during climate change.

 
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Here is a recent article about the causes of the Permian–Triassic mass extinction (unfortunately behind a paywall):
https://www.nature.com/articles/s41561-020-00646-4
The Permian/Triassic boundary approximately 251.9 million years ago marked the most severe environmental crisis identified in the geological record, which dictated the onwards course for the evolution of life. Magmatism from Siberian Traps is thought to have played an important role, but the causational trigger and its feedbacks are yet to be fully understood. Here we present a new boron-isotope-derived seawater pH record from fossil brachiopod shells deposited on the Tethys shelf that demonstrates a substantial decline in seawater pH coeval with the onset of the mass extinction in the latest Permian. Combined with carbon isotope data, our results are integrated in a geochemical model that resolves the carbon cycle dynamics as well as the ocean redox conditions and nitrogen isotope turnover. We find that the initial ocean acidification was intimately linked to a large pulse of carbon degassing from the Siberian sill intrusions. We unravel the consequences of the greenhouse effect on the marine environment, and show how elevated sea surface temperatures, export production and nutrient input driven by increased rates of chemical weathering gave rise to widespread deoxygenation and sporadic sulfide poisoning of the oceans in the earliest Triassic. Our findings enable us to assemble a consistent biogeochemical reconstruction of the mechanisms that resulted in the largest Phanerozoic mass extinction.
 
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  • #5
BillTre
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My review of the video:
A bit long, but a nice video.

I like his explanation at about 11:55 concerning what and why is is looking at particular chemical changes at different layers.
I think it could have benefited by having more of a up-to-date theoretical intro about what the current thinking on this transition is: something like:
  1. big (actually truly massive) eruptions (but spread out over a long period of time)
  2. changes in atmospheric chemistry which leads to changes in oceanic chemistry (over long periods of time)
  3. changes in water chemistry can have drastic effects on certain biological functions
  4. loss of parts of an ecosystem can lead to its collapse
  5. leading to a decrease in the amount of environmental energy/resources biology can collect
  6. smaller overall, less diverse species-ome, with many groups being lost completely (extinct), from which subsequent species evolve.
However, I think he gets to this later in the video.
I liked his technical details throughout.

I also liked his use of TOC (total organic carbon; the amount of carbon in the local biochemistry).
This is an important water condition, for water systems used to successfully rear particular organisms.
Within the geological record, TOC reflects what is going on in the ecosystem at time of deposition (how much oxygen is passing through the ecosystem). Greatly reduced at the time of the extinction.

The relationship of carbonates with pH is well known, to knowledgeable aquarists (both fresh and salt). CO2 dissolves well in water where it can combine with water (H2O), form an acid.
By changing the water pH, the ratio of dissolved and undissolved carbonate is shifted (more acidic favors greater dissolution).
Bubbling CO2 in to aquarium water (done to produce luxuriant plant growth), can change the pH.
Strong aeration can change the pH (by more rapidly blowing off CO2).

Response to Question:
Your question amounts to a compare and contrast question between the current climate change situation and the period of the end Permian extinction.

One big obvious distinction is the length of time over which the changes are occurring.

An example of a quick (and very dramatic) change would be the giant meteor impact at Chicxulub in Mexico, which (combined with subsequent environmental changes) probably killed all the dinosaurs with-in a year or two (many within a day).

Our current bout of human induced climate change (assuming for argument, that this is the current reality (this means, argue this somewhere else)), might appear slow to the individual's human awareness of a single life (much as evolution does), but it is really rapid on the evolutionary time scale, over which large evolutionary changes can be seen.

Some are concerned that these changes (like with the dinosaurs) will be too fast for a rapid and smooth biological response to the changing environmental conditions.
This might then lead to lots of extinctions which could then be amplified through ecosystem collapse.

Some now claim that we are at the beginning of a new geological period of time, the Anthropocene, marked by things like atomic bomb radiation and plastics in sediments.
If changes in sea water chemistry were to get large enough and be maintained long enough, one should expect powerful impacts on the ocean ecosystems of the world.
This would also show up in the geological record, probably somewhat like in the Permian, a distinct transition (as seen from the distant future).

The Permian occurred about when the Siberian traps were being produced. These eruptions seem to have come in very large bursts of extruded volcanic mass (with a bunch of associated gasses coming out).
These eruptions were spread out over a much longer time period (and can be more easily distinguished geologically).
The eruptions continued for roughly two million years and spanned the Permian–Triassic boundary, or P–T boundary, which occurred between 251 to 250 million years ago.[1][2]

Large volumes of basaltic lava covered a large expanse of Siberia in a flood basalt event. Today, the area is covered by about 7 million km2 (3 million sq mi) of basaltic rock, with a volume of around 4 million km3 (1 million cu mi).[3]
I would have liked to see direct geological evidence of burned coal fields (I have not heard of these before).
Seems like that should be findable in very specific areas (in and neighboring to the traps).

I'm not clear on the detailed relationships between the timing of the eruptions and the extinctions.
I am pretty sure there have been publications on this.

Also, what are the differences between land and sea extinctions?
 
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burn up all of Canada's coal tar sands
They don't seem all that flammable - they have many outcrops, so would have been ignited by lightning or forest fires over millions of years, but I have not heard of such. Needs massive volcanism.
 
  • #9
BillTre
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Sorry, it was an illusion to industrial development.
 
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Here is a recent article about the causes of the Permian–Triassic mass extinction (unfortunately behind a paywall):
https://www.nature.com/articles/s41561-020-00646-4
I contacted the geologist who did the video and he also referred me to this article.

Not being a geologist myself I wonder if someone here can explain why the methane hydrate theory is ruled out.

@BillTre I would like to understand more quantitatively how it is known that the current build up of carbon dioxide is more rapid that during the Permian-Triassic extinction. Can the rate of CO2 build up be measured from the brachiopod fossils?
 
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BillTre
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The current change in CO2 levels has occurred in maybe 100-200 years. A very short time geologically.

Its not clear to me how fast the increases in CO2 occurred in the Permian, however, the several incidents of Siberian traps production were spread over a much longer time period. (Thus slower if you consider them all together.)

It's possible there was a rapid CO2 spike with each event.
I don't know that there is a known geological record of this with sufficient resolution to answer that.
In theory, with a finely graded geological record, this might be measurable.
 
  • #12
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The current change in CO2 levels has occurred in maybe 100-200 years. A very short time geologically.

Its not clear to me how fast the increases in CO2 occurred in the Permian, however, the several incidents of Siberian traps production were spread over a much longer time period. (Thus slower if you consider them all together.)

It's possible there was a rapid CO2 spike with each event.
I don't know that there is a known geological record of this with sufficient resolution to answer that.
In theory, with a finely graded geological record, this might be measurable.
Also the coal burning as post #6 documents could have amplified the CO2 build up. I wonder if coal burns are episodic or whether they smolder continuously.
 
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BillTre
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The coal burning thing was new and interesting to me.
I found your post informative.
 
  • #15
jim mcnamara
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Hmm. I would take that as 'methane clathrate input not required'. That does not mean we are forced to exclude/ignore all or any clathrate 'input'. In other words the driver was not clathrate.

Correct? Or am I missing something?
 
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I wonder if coal burns are episodic or whether they smolder continuously.
The process begins with a massive mafic sill preferentially intruding, heating, and mixing with thick coal seams in Siberia (Fig. 1). This mechanism is far more efficient than dikes in quickly delivering heat to coal. The hot coal–basalt mixture extrudes at numerous surface locations. The physical mechanism behind this process of pipe initiation and fracturing would be similar to that described by Jamtveit et al. (18). The coal in the mixture ignites on contact with the air, causing pyroclastic fly ash, soot, sulfate, and basaltic dust to ascend into the stratosphere.
F1.medium.gif
:wideeyed:
Explosive eruption of coal and basalt and the end-Permian mass extinction
 
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Hmm. I would take that as 'methane clathrate input not required'. That does not mean we are forced to exclude/ignore all or any clathrate 'input'. In other words the driver was not clathrate.

Correct? Or am I missing something?
It I understand this right, the video argues for the release of methane from clathrate on the ocean floor as the oceans warmed. This is supported by the barite found in early Triassic shallow sea water sediments. So even if this process did not cause the extinction it does seem to have occurred.

Another video says that the burning of coal produces methane which then makes carbon dioxide in the atmosphere. So this could be another way that methane contributed to the extinction.
 
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  • #18
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I reviewed the reasoning in the video that rejected a volcanic ash holocaust explanation in favor of a massive coal burn. Volcanic ash would be detected in sediments by elevated levels of deep earth elements that are rare on the surface such as nickel. Nickel was not significantly elevated in the samples i.e. it was not high enough to indicate massive amounts of volcanic ash nor was copper which is also brought up in volcanic eruptions. Instead, significant amounts of elements that are "sequestered" in living organisms such as mercury and zinc were found and these are released into the atmosphere when coal is burned. Additionally there were elevated levels of lead which is also found in coal but I am not sure from the video if this is also biological in origin.
 
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  • #19
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It's possible there was a rapid CO2 spike with each event.
I don't know that there is a known geological record of this with sufficient resolution to answer that.
In theory, with a finely graded geological record, this might be measurable.
@BillTre At the end of the article referenced in post #2 the authors say that the long time scale as you mentioned and difference in "carbon budgets" make this extinction event a poor "analogy" for modern human activity. They remark though that the human caused rate of emission is 14 times greater than peak emission rates during the Permian-Triassic extinction. So it seems that they are able to measure these rates.

The article is technical and would take some study for me to understand. For instance, they use an explanatory model which would need unpacking.
 
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  • #20
jim mcnamara
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Methane is a very powerful greenhouse gas.
Example - https://onlinelibrary.wiley.com/doi/full/10.1002/ese3.35
R. Howarth
"A bridge to nowhere: methane emissions and the greenhouse gas footprint of natural gas"

abstract:
While it is true that less carbon dioxide is emitted per unit energy released when burning natural gas compared to coal or oil, natural gas is composed largely of methane, which itself is an extremely potent greenhouse gas. Methane is far more effective at trapping heat in the atmosphere than is carbon dioxide, and so even small rates of methane emission can have a large influence on the greenhouse gas footprints (GHGs) of natural gas use.
 
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Methane is a very powerful greenhouse gas.
Example - https://onlinelibrary.wiley.com/doi/full/10.1002/ese3.35
R. Howarth
"A bridge to nowhere: methane emissions and the greenhouse gas footprint of natural gas"

abstract:
I found this in the Wikipedia article on Gas Venting. "The U.S. Environmental Protection Agency projects that by year 2020, global methane releases from coal mines throughout the world will exceed 35 million tons or 800 million tons of CO2-equivalent emissions..."

This seems to use a conversion factor for methane into carbon dioxide equivalents of greenhouse gas. By weight this says that methane is a much more potent greenhouse gas than carbon dioxide.

The article also says "Substantial amounts of methane-rich gas are trapped and adsorbed within coal formations, and are unavoidably desorbed in association with coal mining. In some cases of sub-surface mining, a formation is permeated with boreholes prior to and/or during extraction work, and the so-called firedamp gases allowed to vent as a safety measure. Also during work, methane enters the ventilation air system at concentrations as high as 1%, and is usually freely exhausted from the mine opening. Such ventilation air methane (VAM) is the largest source of methane from all operating and decommissioned coal mines worldwide. Substantial methane also continues to desorb from coal placed into storage and from abandoned mines..."

So methane is trapped in coal beds in large amounts and is released naturally during mining. Would volcanic sill intrusions into coal layers in Russia have released enormous amounts of methane into the atmosphere? If so how would geologists detect this in fossils and rock strata?
 
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  • #22
jim mcnamara
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I was trying to convey what I thought I saw:
It seems like the video was ignoring or minimizing a methane effect. It did report Barium.

Methane release on the scale required to alter shallow water chemistry would have increased the "heat" signal. But that signal would be a far larger effect (circa 80 times more per mole) on temperature than merely it's ##CO_2 ## creation later on in the atmosphere.

Correct me where I am off target here.
 
  • #23
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I was trying to convey what I thought I saw:
It seems like the video was ignoring or minimizing a methane effect. It did report Barium.

Methane release on the scale required to alter shallow water chemistry would have increased the "heat" signal. But that signal would be a far larger effect (circa 80 times more per mole) on temperature than merely it's ##CO_2 ## creation later on in the atmosphere.

Correct me where I am off target here.
Can you explain the heat signal point?

The video spends a lot of time on methane. I am still trying to wrap around this stuff so I will just try to paraphrase some of it. About 40 minutes in he discusses the pyrite that he found in samples about 70 centimeters above the boundary. He found several separated layers which indicate episodes of anoxia in shallow sea waters. Under these oxygen depleted conditions sulfate reducing bacteria metabolize methane and expel hydrogen sulfide as waste. Pyrite is made of sulfur and iron and the crystals what he calls "pyrite framboid crystals" that he found in the sediments are the same as those made in laboratories using hydrogen sulfide.

He goes on to elaborates the methane ice theory based on the appearance of barite in the same shallow water sediments as the pyrite. Barite is a compound of barium and sulfate both of which are found in the deep ocean floor in oxygen rich oceans. Sulfate is made by sulfate reducing bacteria and barium ion comes from "hydrothermal vents" on the sea floor. Barite precipitates out of the water and falls to the deep ocean floor. But barite is found in his shallow water sediments. The question is how did it get from the depths into the shallows? As the oceans warmed methane clathrates were disrupted and the released methane upwelled carrying the barite along with it. The methane gave an energy source to the sulphate reducing bacteria and hydrogen sulphide was formed. Hence the pyrite in the same layers as the barite.

Interestingly these pyrite containing layers contained a low amount of organic matter so organic matter was not the source of the methane. The other possible source is the methane ice.

Using patterns of nitrogen fluctuation in the post boundary sediments he is able to measure the time from the Permian-Triassic boundary for the oceans to become anoxic i.e. to the first pyrite layer. He says it is about 20 thousand years and this is consistent with measurements made in China using other methods. So all of this happened after the great extinction had already begun 20 thousand years earlier.
 
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  • #24
jim mcnamara
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Chemical/isotope signature, or a proxy for the earlier presence of a reactant or reaction == signal. Like ##C^12/C^13## ratio for photosynthetic carbon.

I saw the whole video. Good selection. Here's why I'm asking about methane.

Clathrate gun hypothesis: https://en.wikipedia.org/wiki/Clathrate_gun_hypothesis Some of this may be overstated but it does have some merit, instead of a "gun" maybe more of a slower fizz.

Look at the second graph on the right with the extreme spike.
 
  • #25
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Chemical/isotope signature, or a proxy for the earlier presence of a reactant or reaction == signal. Like ##C^12/C^13## ratio for photosynthetic carbon.

I saw the whole video. Good selection. Here's why I'm asking about methane.

Clathrate gun hypothesis: https://en.wikipedia.org/wiki/Clathrate_gun_hypothesis Some of this may be overstated but it does have some merit, instead of a "gun" maybe more of a slower fizz.

Look at the second graph on the right with the extreme spike.
So you are saying that the methane that rose from clathrates heated the ocean further and this created a feedback loop? Also it may have further acidified the ocean?

From the geological samples it would seems that oceans had already warmed a lot before the reactions that made the pyrite and barite happened, before the oceans became anoxic. Are you saying that at a lower level, a fizz, methane could have still upwelled earlier on as the oceans warmed and could have contributed to the warming?
 
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