DailyTech - New Study Links CO2 to Paleozoic Extinctions

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Blog: Science New Study Links CO2 to Paleozoic Extinctions
Jason Mick (Blog) - September 1, 2007 11:23 AM

51 comment(s) - last by Puddleglum.. on Sep 2 at 7:27 PM

A new study by paleoecologist Margaret Fraiser at the University of Wisconsin, Milwaukee, offers an interesting new theory behind the cause of the Earth's largest extinction: copious carbon-dioxide

When most people hear the phrase "the earth's largest extinction", they think dinosaurs.

Margaret Frasier knows better. As a paleoecologist, she knows that the Earth's largest mass extinction of life occurred at the end of the Permian Period at the end of the Paleozoic Era; 252 million years before the first T-Rex ever walked the earth. The extinction destroyed the large land amphibians' dominance of the land, and paved the way for dinosaurs to emerge as the dominant land species.

University of Wisconsin-Milwaukee professor Margaret Frasier is studying this extinction avidly, looking for possible details to further our understandings of what might have caused this landmark event.

Her recent conclusions, published in an Elsevier journal [1] [2] (PDF) and detailed in a recent press release titled "When Bivalves Ruled the World," describe an Earth with run-away carbon dioxide levels. She concludes that the Permian-Triassic mass-extinction was caused by toxic, oxygen-less oceans created by too much atmospheric carbon dioxide (CO2).

The Permian-Triassic extinction event wiped out nearly 70 percent of species on land and 95 percent of sea species.

“Estimates of the CO2 in the atmosphere then were between six and 10 times greater than they are today,” Frasier states. The largest continuous volcanic eruption on Earth – known as the “Siberian Traps” – had been pumping out CO2 for about a million years prior to the Permian-Triassic mass extinction.

Her hypothesis is that high CO2 levels at the close of the Permian Period caused global warming, greatly increasing global temperatures. With no cold water at the poles, ocean circulation slowed, and the oceans were unable to mix with the little oxygen left in the air.

She cites a variety of evidence of high CO2 and low ocean oxygen levels in this fossil record. One piece of evidence is darkened rock from underwater fossil strata of the time. Darkening in ocean rock of this nature indicates a low amount of oxygen at the time of formation.

Frasier also collected evidence to support her theory in the form of bivalve fossils. The only survivors of the extinction were bivalve mollusks and gastropods -- snails. Only shallow water, tiny, small-shelled varieties with high metabolisms and a flat shape, which allowed them to spread out while feeding to extract more oxygen, survived. Deeper water varieties, where there was less oxygen, and larger shelled varieties, which needed more oxygen, became extinct, disappearing from the fossil record.

A final piece of evidence cited is the disappearance of the coral reefs. Coral reefs die if their environment lacks sufficient oxygen.

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RE: GO MASHER!

By porkpie on 9/2/2007 12:05:41 PM , Rating: 1

I did get a few giggles when Mick claimed high CO2 would suck the oxygen right out of the air.

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RE: GO MASHER!

By JasonMick

(blog) on 9/2/2007 12:28:16 PM , Rating: 3

The current CO2 level is 0.038%.

Source: http://en.wikipedia.org/wiki/Earth's_atmosphere

If CO2 actually reached these prehistoric levels x6-x10, this percent would be: 0.228%-.38%.

In rooms that were not well ventilated with large numbers of occupants, the concentrations could easily reach 1% or more leading to carbon dioxide poisoning.

Read about CO2 poisoning:
http://www.inspect-ny.com/hazmat/CO2gashaz.htm

The side effects at 1% would be relatively mild, mostly drowsiness. But it would still cause problems.

Sorry to interrupt your giggle-fest with data.

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RE: GO MASHER!

By TomZ on 9/2/2007 12:36:00 PM , Rating: 2

What does that have to do with "sucking the oxygen right out of the air," which is what the OP was saying?

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RE: GO MASHER!

By masher2

(blog) on 9/2/2007 2:04:15 PM , Rating: 2

> "In rooms that were not well ventilated with large numbers of occupants, the concentrations could easily reach 1% or more leading to carbon dioxide poisoning."

Jason, you should stop while you can. This is even sillier than your last claim. First of all, a 1% CO2 level doesn't "lead to carbon dioxide poisoning". Our own BREATH has a CO2 level of 4.5%, and even that isn't toxic unless breathed over a lengthy period....which explains why you can breath in and out of a bag for short periods without harm.

A 3% level (the minimum level which can cause any sort of respiratory problems) is a level of 30,000 ppm. That's 100 times higher than current atmospheric levels. In a crowded, very poorly ventilated room, CO2 levels can reach that high. So? That can already happen today.

So what you're really saying is, "if we wait 1000 years and CO2 levels rise 10X higher, then if we lock a large group of people in a sealed room, they'll start to suffer ill effects in 27 minutes time, rather than the 30 minutes it now takes".

This is a looming catastrophe? Come sir, this is beneath you.

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RE: GO MASHER!

By Puddleglum on 9/2/2007 7:27:15 PM , Rating: 2

quote:
First of all, a 1% CO2 level doesn't "lead to carbon dioxide poisoning". Our own BREATH has a CO2 level of 4.5%, and even that isn't toxic unless breathed over a lengthy period....which explains why you can breath in and out of a bag for short periods without harm.