Scientists link ocean acidification to prehistoric mass extinction

Apr 27, 2010 By Gwyneth Dickey

(PhysOrg.com) -- New evidence gleaned by analyzing calcium embedded in Chinese limestone suggests that volcanoes, which spewed massive amounts of carbon dioxide into the atmosphere for a million years, caused the biggest mass extinction on Earth.

In a paper published April 26 in the , a team of researchers led by a Stanford geologist said that as gas dissolved in the oceans, it raised the acidity of seawater.

The research team said it was a deadly combination - carbon dioxide in the atmosphere and higher acidity in the oceans - that eventually wiped out 90 percent of marine species and about three-quarters of land species, in a 250 million years ago known as the "end-Permian extinction."

Back then, the ocean teemed with corals, algae, clams and snails. Soon after, however, there was an abrupt change to a thick layer of bacteria and limestone, a "slime-world," dominated by bacteria.

Lead author Jonathan Payne, an assistant professor of geological and environmental sciences at Stanford, said the found in limestone from Guizhou Province in southeast China helps answer a question scientists have been debating for decades: What caused the ?

Scientists have proposed many possible reasons for the extinction, including asteroids, volcanoes, and low levels of oxygen in seawater. Payne and his colleagues earlier thought that evidence pointed to volcanoes, but they couldn't definitively distinguish between that and the other possibilities.

Two years ago, they realized that the calcium in limestone could hold the answer, because the types of calcium present in the would be different for each extinction scenario.

By looking at changes in the ratio of heavy to light calcium isotopes in fossils from different time periods and determining their "calcium signature," the team could infer the chemical changes - and their origin - that occurred in the environment.

The scientists ground up the limestone deposits, which spanned the pre- and post-extinction periods, and analyzed them to determine the relative presence of calcium isotopes. They found that the changes in the ratio matched the calcium signature predicted for , and the matching carbon dioxide signature pointed to carbon release from volcanic eruptions.

"Our best geologically supported idea is that the carbon dioxide release is related to the Siberian Traps volcanoes," Payne said.

Payne calculated that the eruptions, which lasted upwards of a million years, released 13,000 to 43,000 gigatons (1 gigaton equals 1 billion tons) of carbon in the atmosphere. By comparison, scientists estimate we would release an estimated 5,000 gigatons of carbon if we used up all the fossil fuels in the Earth.

During the eruptions, huge amounts of carbon dioxide and molten rock burst through the earth's crust, burning through coal and limestone, and releasing carbon dioxide into the atmosphere. That made oceans and rainwater more acidic, and dissolved more calcium from rocks into the ocean.

Payne said humans may not ultimately release as much carbon dioxide as the Siberian traps, but we may be doing it at a faster rate. The end-Permian extinction could be viewed as a "worst case scenario" for what we could be facing as we burn more fossil fuels and increase ocean acidity, he said.

"We won't necessarily end up with a world that looks as bad as it did after the end-Permian extinction, but that event highlights the fact that things can go very, very wrong," Payne said.

The National Resource Council recently reported that the ocean's chemistry is changing faster than it has in hundreds of thousands of years, because carbon dioxide is being released into the atmosphere and absorbed into the oceans, making them more acidic. Studies have shown increased ocean acidity decreases photosynthesis, nutrient absorption, growth and reproduction of marine organisms.

He said the next step as his research continues is to look at rock deposits in other locations from the same time period to make sure the samples they used represent a global event, as opposed to a local event. The team has already started analyzing rock deposits in south central Turkey, southern Japan, and eastern China.

Explore further: NASA sees Tropical Storm Fung-Wong move through East China Sea

More information: 'Calcium isotope constraints on the end-Permian mass extinction,' April 26, 2010, Proceedings of the National Academy Sciences www.pnas.org/content/early/201… /0914065107.abstract

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User comments : 10

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mosahlah
1.7 / 5 (6) Apr 28, 2010
It is easier to contribute to global warming hysteria than it is to contribute to global warming itself.
LuckyBrandon
1 / 5 (4) Apr 28, 2010
Payne calculated that the eruptions, which lasted upwards of a million years, released 13,000 to 43,000 gigatons (1 gigaton equals 1 billion tons) of carbon in the atmosphere. By comparison, scientists estimate we would release an estimated 5,000 gigatons of carbon if we used up all the fossil fuels in the Earth.


So much for man made global warming...according to those figures, we couldn't even dent the environment the way those volcanoes did...which means all in all, the way volcanoes still do...it makes me wonder how much the hawaiin volcanoes spew out in a year....
Even if we do push the stuff out at a faster rate, if the estimate of 5000 gigatons is correct, then we could use all the fossil fuels in the world and still not cause the damage the planet will do to itself...
spacester
5 / 5 (2) Apr 28, 2010
Everyone is entitled to their own opinion.

I would even say that everyone is entitled to their own cherry-picking of the facts.

But fer crying out loud, you are not entitled to your own special answers to questions of arithmetic!

Taking each number at the end of the range most favorable to your point of view:

1 million years of eruptions and 43,000 gt total carbon release is an average RATE of 0.043 gt per year.

5000 gt released over the next 100 years would be a rate of 50 gt per year.

Taking the ratio of these rates shows that we are releasing carbon at 1162 times the rate of the Permian-ending volcanoes!!!

More than three orders of magnitude, and you want to convince us there is nothing to worry about!

Also, you seem to be either saying that converting our planet to a slime-world is just fine with you, or that any adverse consequences short of that extreme are nothing to worry about.

Get a grip!
thermodynamics
3 / 5 (2) Apr 28, 2010
Let me refine Spacester's comment a bit. USGS has done the arithmetic to give us an idea of how volcanoes stack up against human emissions:

http://hvo.wr.usg..._15.html

Remember, the particular event they are talking about in this article on PhysOrg was a very rare event and it would be disastrous to the entire world. mosahlah apparently has no idea of how emissions compare and Lucky seems to be OK with the idea of bacterial slime being the predominant life form. I don't subscribe to that view. However, for those too busy spouting off to look the answer up it appears that with normal volcano activity the volcanoes only put out about 1% as much as we do burning fossil fuels. This is not to say that nature cannot blast a hole in the crust that could wake up one of the super-volcanoes again and the numbers would change. But there has not been such an eruption since the Toba eruption 75,000 years ago.
TegiriNenashi
1 / 5 (3) Apr 28, 2010
To an outsider it looks like those "scientists" recycle these past extinction events in the light of what is the most fashionable scaremongering story of the day. It was meteorite strike, then volcano ash dropping the surface temperature, and finally, volcano emitting evil CO2.
LuckyBrandon
1 / 5 (1) Apr 29, 2010
we arent spreading it over a million years...our footprint will be short, and recoverable by the planet...the numbers I found were significantly lower than what you stated though, so admittedly my math could have been off.
Although, think how much more peaceful the world would be if only slime lived here...lol
Skepticus_Rex
1 / 5 (2) May 06, 2010
I love the way people average out the CO2 from volcanoes over long lengths of time to justify continuing the initial AGW claims. That might work for one or two or even a few volcanoes over the time but does not cover the amounts dumped into the atmosphere by fully active volcanoes on initial eruption--especially by the larger ones.

Even so, no way man can release that amount of CO2 over a million years so I am not too worried about the oceans being done in by anthropogenic CO2. I am more worried about our real chemical pollution which does far more damage.

I am even less concerned now that I have had the chance to see data from studies in the South China Sea and so forth, however. Over there, the acidification began and dropped Ocean pH from 8.1 to 7.9 or so four hundred years before man ever began burning fossil fuels! :)

Note: I linked one of the studies on Instability of pH in the South China Sea, and a chart, in another article's thread somewhere around here.
JayK
1 / 5 (2) May 06, 2010
What if you put a volcano in a jar with NaCl glass? Huh, huh? What then, huh?
Skepticus_Rex
1 / 5 (2) May 06, 2010
What if you put a volcano in a jar with NaCl glass? Huh, huh? What then, huh?


There is no such thing as an NaCl glass jar, ignoramus. There is IR transparent glass that can be pressure molded into jars but not NaCl glass jars. That comment speaks volumes about something you appear to know little to nothing about.

Additionally, there is no way to place a volcano in a jar other than of the science fair variety. Go away, troll. Find a bridge to hide under with the rest of your sockpuppets.
Skepticus_Rex
1 / 5 (2) May 06, 2010
One other note, for those interested there is a such thing as a company called NACL, which makes coatings for glass. And, small amounts of NaCl are used in making glass and pottery but there is not a glass made solely from the stuff.

But, I know you mistakenly thought that is what I meant when I mentioned IR transparent glass so the clarification is not for you. Likely, further factual clarification would not help you anyway.