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Author Topic: New Study: Ocean Acidification Caused End-Permian Mass Extinction (Great Dying)  (Read 6042 times)

jai mitchell

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Findings showed that during the first pulse of CO2, the Earth's oceans were highly alkaline, protecting them from the release of carbon. But the second pulse triggered a widespread ocean acidification event – probably eliminating most of the heavily calcified marine life from the sea.

Clarkson said their findings are concerning because the carbon was released at a similar rate to modern emissions, helping scientists understand the possible threat posed to marine life by modern-day ocean acidification.

"Scientists have long suspected that an ocean acidification event occurred during the greatest mass extinction of all time, but direct evidence has been lacking until now," he said. "This is a worrying finding, considering that we can already see an increase in ocean acidity today that is the result of human carbon emissions."

Paper here:

Ocean acidification and the Permo-Triassic mass extinction

    M. O. Clarkson et. al.

ABSTRACT:  Ocean acidification triggered by Siberian Trap volcanism was a possible kill mechanism for the Permo-Triassic Boundary mass extinction, but direct evidence for an acidification event is lacking. We present a high-resolution seawater pH record across this interval, using boron isotope data combined with a quantitative modeling approach. In the latest Permian, increased ocean alkalinity primed the Earth system with a low level of atmospheric CO2 and a high ocean buffering capacity. The first phase of extinction was coincident with a slow injection of carbon into the atmosphere, and ocean pH remained stable. During the second extinction pulse, however, a rapid and large injection of carbon caused an abrupt acidification event that drove the preferential loss of heavily calcified marine biota.

EDITOR'S SUMMARY:  Ocean acidification and mass extinction

The largest mass extinction in Earth's history occurred at the Permian-Triassic boundary 252 million years ago. Several ideas have been proposed for what devastated marine life, but scant direct evidence exists. Clarkson et al. measured boron isotopes across this period as a highly sensitive proxy for seawater pH. It appears that, although the oceans buffered the acidifiying effects of carbon release from contemporary pulses of volcanism, buffering failed when volcanism increased during the formation of the Siberian Traps. The result was a widespread drop in ocean pH and the elimination of shell-forming organisms.
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A Science Daily link also, but not full text.

If anyone has access to the full text I would be very interested in finding out if they have quantified what the level of acidification was.  Especially in comparison to today and our current trends.
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Bruce Steele

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Knoll et al place the end Permian at a reduction of .6 pH and if we continue ff burning of the total ff inventory we should end at around a .7 in pH reduction in ocean pH.

Caldeira and Wicket 2003 place the final ocean pH at 7.3 if we burn all the worlds ff so their prediction is even more extreme than Knoll. Caldeira has us hitting 7.8 by 2100 if we emit 2500Gt carbon , BAU.


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Hi JimD,

Below is a part of figure 2 of the paper; caption "Model results of carbon cycle parameters for high- and low-CO2 end-member scenarios. ... (C) Modeled pH envelope incorporating uncertainty of seawater B isotope composition (δ11BSW) and dynamic temperatures. (D) Calculated atmospheric CO2. "

I havent' read the paper yet but I skimmed over the In-depth-comment of Erci Hand "Acid oceans cited in Earth's worst die-off" on the same Science-Issue. Here are some quotes:

"The researchers found a drop in the isotopic signal that would have corresponded to a drop of 0.6 to 0.7 pH units—a significant change in seawater chemistry. ..

The Permian-Triassic catastrophe holds mixed messages for Earth today. On the one hand, the pace of acidification was slower than it is now. The study team estimates that, in the acidification event, 24,000 gigatons of carbon were injected into the atmosphere over 10,000 yearsa rate of 2.4 gigatons per year—and most of it wound up in the oceans. Currently, scientists estimate carbon from all sources is entering the atmosphere at a rate of about 10 gigatons per year.

On the other hand, today's economically viable fossil fuel reserves contain only about 3000 gigatons of carbon—far shy of the Permian total, even if human beings burn it all. “We're injecting the carbon faster, but it's unlikely that we have as much carbon to inject,” says study co-author Tim Lenton, an Earth systems scientist at the University of Exeter in the United Kingdom. But knowing that the Permian was much worse doesn't bring Lenton much comfort. “Biology is pretty smart—it can cope with a certain amount of acidification,” he says. “But I suspect there are limits to adaptation. There will be some point at which [species] crack.” ...

Edit: Ah, Bruce beat me to it  8)


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This seemed like the best existing thread to post this under.
Check out the following link to a scientific study suggesting a new understanding of acidification, ocean deposits and athmospheric C02 during the PETM and what that may say about cimate sensitivity to CO2 today.

If the high amount of acidification seen in the Atlantic Ocean had been caused by atmospheric CO2 alone, that would suggest a huge amount of CO2 had to go into the atmosphere to cause 5°C warming. If this were the case, it would mean our climate was not very sensitive to CO2.

But our findings suggest other factors made the Atlantic far more corrosive than the rest of the world’s oceans. This means that sediments in the Atlantic Ocean are not representative of worldwide CO2 concentrations during the PETM.

Comparing computer simulations with reconstructed ocean warming and sediment dissolution during the event, we could narrow our estimate of CO2 release during the event to 7,000 – 10,000 GtC. This is probably similar to the CO2 increase that will occur in the next few centuries if we burn most of the fossil fuels in the ground.


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 Daniel H. Rothman

Thresholds of catastrophe in the Earth system

I hypothesize that perturbations of Earth’s carbon cycle lead to mass extinction if they exceed either a critical rate at long time scales or a critical size at short time scales. By analyzing 31 carbon isotopic events during the past 542 million years, I identify the critical rate with a limit imposed by mass conservation. Identification of the crossover time scale separating fast from slow events then yields the critical size. The modern critical size for the marine carbon cycle is roughly similar to the mass of carbon that human activities will likely have added to the oceans by the year 2100.

Is it sensible?
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It's got a lot going for it, I think... cautiously. By not modelling theoretical variables, and simply looking at what has happened in the past, he negates a lot of the usual uncertainties. It doesn't matter that he's not covering all the variables, because there are always lots of variables, and when the data are this messy, then broadly they should cancel out. Unless the current global situation is fundamentally different to the past, of course, in a way that it never has been before.

Given that messiness, though, what you can't do is predict exactly when the threshold will be crossed... because clearly there is variability in the threshold depending on the specific parameters (tectonic, biological, geochemical) of the time, as well as what we do on route. The paper's pretty clear on that as well. I note that we're in range of some of the scenarios already (given his presumed 50% error margins).

I'm not entirely sure that this is telling us much that is new, though, beyond the details. We know that there are points beyond which acidification and temperature rise are very bad news, and 2100 is a time by which pigeons will be well and truly home to roost. What this does, though, is give us more confirmation that the models and urgency are reasonable in predicting the worst scenarios. Not only do the theoretical predictions point to all this; the past does, too.

Note, however, that I've not gone through his methodology in detail - there might be some glitches lurking there that could knock it down. I suspect not, though; take a blunt-instrument approach, and it's hard to find a way to push it over completely.

Thanks for bringing it to our attention!  :)


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Volcanic injection of nickle from siberian traps

"Earth's largest extinction event likely took plants first"

"Tracy Frank, professor and chair of Earth and atmospheric sciences, said the finding points to the eruption of lava through nickel deposits in Siberia. That volcanism could have converted the nickel into an aerosol that drifted thousands of miles southward before descending on, and poisoning, much of the plant life there. Similar spikes in nickel have been recorded in other parts of the world, she said.

"So it was a combination of circumstances," Fielding said. "And that's a recurring theme through all five of the major mass extinctions in Earth's history."

If true, the phenomenon may have triggered a series of others: herbivores dying from the lack of plants, carnivores dying from a lack of herbivores, and toxic sediment eventually flushing into seas already reeling from rising carbon dioxide, acidification and temperatures."

don't see a link to the paper, maybe


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There is an earlier Rothman paper in the bulletin of the american mathematical society v52, 1, Jan 2015
on earth's carbon cycle.

sorry, no doi

Abstract. The carbon cycle represents metabolism at a global scale. When
viewed through a mathematical lens, observational data suggest that the cycle
exhibits an underlying mathematical structure. This review focuses on two
types of emerging results: evidence of global dynamical coupling between life
and the environment, and an understanding of the ways in which smaller-scale
processes determine the strength of that coupling. Such insights are relevant
not only to predicting future climate but also to understanding the long-term
co-evolution of life and the environment.

Nice paper, points out the ubiquity of the lognormal distribution and derives several interesting turnover times. You can see how he got to the 2017 paper.