From the AGU today, I find they are moving the cause of ancient planetary disaster from comets impacts and volcanoes or other big events to CO2 causing acidification of the oceans, literally they have a blast from the gas, to make CO2 the villain here. Of course, it’s just another modeling exercise in uncertainty.
From Wikipedia, a clear cut case of “we don’t know“:
There are several proposed mechanisms for the extinctions; the earlier phase was likely due to gradual environmental change, while the latter phase has been argued to be due to a catastrophic event. Suggested mechanisms for the latter include large or multiple bolide impact events, increased volcanism, and sudden release of methane clathrate from the sea floor; gradual changes include sea-level change, anoxia, increasing aridity, and a shift in ocean circulation driven by climate change.
From the AGU Highlights:
1. Was ocean acidification responsible for history’s greatest extinction?
Two hundred and fifty million years ago, the world suffered the greatest recorded extinction of all time. More than 90 percent of marine animals and a majority of terrestrial species disappeared, yet the cause of the Permian-Triassic boundary (PTB) die-off remains unknown. Various theories abound, with most focusing on rampant Siberian volcanism and its potential consequences: global warming, carbon dioxide poisoning, ocean acidification, or the severe drawdown of oceanic dissolved oxygen levels, also known as anoxia.
To narrow down the range of possible causes, Montenegro et al. ran climate simulations for the PTB using the University of Victoria Earth System Climate Model, a carbon cycle-climate coupled general circulation model. The model’s highlights include dynamic representations of terrestrial vegetation, ocean carbon fluxes, and net primary production. The researchers ran nine simulations, using three different concentrations of atmospheric carbon dioxide, three modes of ocean floor topography, and two competing theories for the geography of the time.
The authors find that varying the ocean floor topography by adding deep ocean ridges increases the strength of the Meridional Overturning Circulation (MOC) – a convective cycle that mixes ocean waters. Also, the presence of the MOC was not abated by elevated atmospheric carbon dioxide as was found in previous research, suggesting that the ocean would have been well mixed and well oxygenated, restricting the chances of widespread deep ocean anoxia.
Further, the researchers find that if atmospheric carbon dioxide concentrations were 3000 parts per million by volume or higher, fitting within estimates for the Permian-Triassic boundary, the ocean pH would have been 7.34 or lower. At those levels, the authors say the ocean’s acidity would have had significant negative impacts on mollusks, corals, and other species that rely on oceanic calcium carbonate, suggesting ocean acidification may have been the main culprit in the Permian-Triassic boundary extinction.
Source: Paleoceanography, doi:10.1029/2010PA002058, 2011 http://dx.doi.org/10.1029/2010PA002058
Title: Climate simulations of the Permian-Triassic boundary: Ocean acidification and the extinction event
Authors: A. Montenegro: Department of Earth Sciences, St. Francis Xavier University, Antigonish, Nova Scotia, Canada, and Environmental Sciences Research Centre, St. Francis Xavier University, Antigonish, Nova Scotia, Canada;
P. Spence and K. J. Meissner: Climate Change Research Centre, University of New South Wales, Sydney, New South Wales, Australia;
M. J. Melchin: Department of Earth Sciences, St. Francis Xavier University, Antigonish, Nova Scotia, Canada;
M. Eby and S. T. Johnston: School of Earth and Ocean Sciences, University of Victoria, Victoria, British Columbia, Canada.
Now you understand why I dropped my AGU membership.
And the outpouring of HCl or SO2 from the volcanoes we know about, for sure, had no impact on ocean pH?
If the CO2 is in the atmosphere, then it is not in the oceans to cause acidification. Unless they believe another 3000ppm went into the oceans, in which case they’d have to explain where that total of 6000ppm came from.
If I’m on the wrong track, I’m sure someone will correct me. thnx in advance.
How can they model an enviornment about which we know practically nothing about?
What exactly do we learn from simulations such as this? The models are full of assumption, best guesses and out-and-out fudge factors. You can’t duplicate the results except through another model, which hardly counts as validation.
AND: (CAPITALS INTENDED) ACIDIC=pH LESS THAN 7, and substantially so. The mistreatment of pH by climate science is ridiculous. Ocean acidification is a long way off, if ever. So QUIT this foolish pH-mangling and misnomering of everything from carbon to acid. Bunk.
Because 7.34, which is a slightly basic pH, is now “acidic”? And it would hurt those ancient, 100’s of million years ago animals because they were obviously adapted to the exact same conditions as current ones, and lacked any ability to adapt to gradual decreasing alkalinity in the oceans as proposed here? Oh, and of course this event in the oceans happened to be able to wipe out almost all terrestrial life as well?
I can tell you there is a mass extinction going on right now: a mass extinction of scientific fact and rationality.
I’m not sure what to make of this.
From a heretical point of view, it just shows that the science (Wild Ass Guess) is not settled on anything.
From the religious Church of Global Warming it will prove that they were right all along.
So many choices, so many decisions, so many contradictions, what to do? I will once again meet with a representitive of BEER.
the whole ‘acidification’ scare is making me insane! we should stop encouraging use of that word. i guess ‘ocean neutralization’ isnt dramatic enough….
Is there any reason why that extinction couldn’t have been caused by a widespread viral or bacterial disease?
Is it possible to be both stupid and ignorant at the same time?
Oceans currently contain something like 39,000 gigatons of carbon, and roughly 100,000,000 gigatons of carbon are contained in marine sediments and sedimentary rocks … carbon that was once in the oceans.
So oceans have had adequate means to dispose of excess carbon, and have done so.
Makes the 750 gigatons in the atmosphere and the 6 gigatons produced annually by humans seem a bit puny, doesn’t it?
An interesting hypothesis I read, regarding the P-T extinction, was that an asteroid impact antipodal to then-Siberia caused the fracturing of the Siberian crust, allowing the large volumes of lava flows that we now call the Siberian Traps. Antipodal crust fracturing has been observed on some of the moons of Jupiter and Saturn, and has been observed in computer models of asteroid impacts: the impact waves travel around the world, and all reinforce themselves on the opposite side.
Thus, ocean pH changes could have been caused by the Siberian lava flows, but the initiator was an impactor.
There’s still much investigatory science to do before the mystery is settled.
Here we go again, yet more ill thought out drivel to scare the s*** out of the gullible and get more money from governments.
I agree with the previous comments that ph 7.34 is alkaline, but where did they get the figure of 7.34 from? I can measure the ph in my fish tank tonight to either ph7.0 or ph 7.5, nothing in between! These “scientists” claim to be able to measure the ph of of the sea 250,000,000 years ago, 50 times as accurately (if my maths is correct). If Co2 was once at this level, how did it come down to the present level? Wasn’t this process supposed to be one of +ve feedback, which if my science is correct, means it should never stablise at lower levels?
And they “know” that the high CO2 levels weren’t CAUSED by whatever event caused the extinction… how?
>house burns down
>fire causes high levels of CO2 in area
>CAGW theory says high CO2 caused the house to collapse
I wonder how or if they took into consideration how different the ocean topography was at the time in their general circulation model. Or if the model only applied to “the Carbon Cycle”.
Last time I looked, the solubility of CO2 goes down with increased temperature. Putting 2 and 2 together and getting something between 3 and 5 as the answer (which these guys do not seem to be able to do) you either have to have global warming or increased carbonic acid in the oceans. Short of some really high pressures, you can’t have both.
So if 3000 PPM is supposed to kill off corals, then how did corals evolve with CO2 levels more than twice as high in the Cambrian period? http://stevengoddard.wordpress.com/2011/04/04/corals-evolved-with-co2-20x-higher-and-temperatures-10c-warmer/
What really annoys me about this is how ignorant these people are.
Carbonic acid is a very weak acid which anyway is heavily buffered in the oceans. The evidence is all around us.
Yet the outgassing of the earth releases huge amounts, not even quantified or guesstimated at, of very strong acids into the oceans by volcanic action.
Moreover if there was in the recent past, by which I mean a few hundred million years evidence of acid oceans we would see it in the geologic record. But we do not.
It is just another speculative fantasy unsupported by any observation whatsoever, and if the evidence were there we would be able to detect it. That we cannot speaks volumes.
One for the circular filing cabinet I think.
Kindest Regards
Perhaps they meant “assification”?
This is simply absurd. They used ”the University of Victoria Earth System Climate Model, a carbon cycle-climate coupled general circulation model. The model’s highlights include dynamic representations of terrestrial vegetation, ocean carbon fluxes, and net primary production.”
Remember we are talking about the Permo/Triassic boundary here, that’s about 250 million years ago.
The terrestrial vegetation was vastly different from now, no flowering plants just for a starter, and we know it only by the barest outline. How do you model the vegetation dynamics of plants who are long gone? In some cases even the entire orders the plants belonged too (e. g. seed-ferns) have gone extinct.
The geography was also vastly different from now, and is only vaguely known. For example North and South China, then two separate Australia-sized continents were somewhere out in the Panthallassic Ocean. We know their latitude and orientation fairly well but the longitude is guesswork, and could easily be out by a couple of thousand kilometres. Wouldn’t the climate and ocean currents be a bit affected by moving two Australias around?
And they use the “net primary production” in their model. There has been a lot of discussion about whether the oceanic primary production went up or down at the P/T boundary, and as far as I know the jury is still out on that one.
“The authors find that varying the ocean floor topography by adding deep ocean ridges increases the strength of the Meridional Overturning Circulation (MOC) “
Again pure guesswork – there is no way we can determine where and how many deep ocean ridges there were at that time, every scrap of ocean bottom that old has long ago been subducted, except for a few bits and pieces accreted to continents (Japan for example). These show that there were ocean ridges and deep oceans basins out there somewhere, but not nhow many and where.
“the presence of the MOC was not abated by elevated atmospheric carbon dioxide as was found in previous research, suggesting that the ocean would have been well mixed and well oxygenated, restricting the chances of widespread deep ocean anoxia.”
That is very interesting since there is vast amounts of empirical evidence that there was indeed very widespread oceanic anoxia at the P/T boundary. If elevated CO2 does not have that effect, then it would suggest either that CO2 had nothing to do with the extinction or, more likely, that the model is way off.
So what did cause the P/T extinction? Almost certainly the eruption of the Siberian Traps. That is the largest magmatic province in the world, containing at least 3,000,000, and perhaps as much av 5,000,000 cubic kilometres of basalt (that is enough to cover the entire Earth (including oceans) 20 to 30 feet deep), and it all seems to have erupted in less than 2 million years, with single eruptions being as large as 20,000 cubic kilometres.
The only historical flood basalt eruption was Laki on Iceland in 1783. That was 14 cubic kilometres in eight months. It killed almost half the population of Iceland and caused crop failures and famine over much of the northern hemisphere.
“the ocean pH would have been 7.34 or lower. At those levels, the authors say the ocean’s acidity would have had significant negative impacts on mollusks, corals, and other species”
7.34 pH is not acidic. “Acidification” is the correct technical term for lowering pH whether from 7.5 to 7.3, or from 12 to 10, or from 5 to 2; but, to say [something’s] “acidity” when that [something] has a pH of 7.34 is wrong. Hopefully that’s a misquote of the scientists.
Neutralization would be the more accurate term to use in this case.
And the Deccan Traps are almost antipodal the Chicxulub impact. Interesting, no?
When it rains, it pours.
If this study is true, then shouldn’t we see evidence in the fossil record in the Eocene, Miocene and Cretaceous ages of diatoms?? Did they suffer the extinction as well? Obviously not, so we should see a clear trend of the impact of increased “acidification”.