Volcanic Warming and Oxygen Deprivation: The Great Dying of Earth's History

[Orion1]

Great Dying...

An ancient version of global warming may have been to blame for the greatest mass extinction in Earth's history.

In an event known as the "Great Dying," some 250 million years ago, 90 percent of all marine life and nearly three-quarters of land-based plants and animals went extinct.

They studied the Karoo Basin of South Africa, using chemical, biological and other evidence to relate layers of sediment there to similar layers in China that previous research has tied to the marine extinction at the same period.

Studying a 1,000-foot thick section of exposed sediment, Ward's team found evidence of a gradual extinction over about 10 million years followed by a sharp increase in extinction rate that lasted another 5 million years.

Ward's team believes the extinctions were caused by global warming and oxygen deprivation over long periods of time.

Currently the atmosphere consists of about 21 percent oxygen, but the addition of gases at that time could have lowered levels to 16 percent or less, Ward said.

The more recent mass extinction that killed the dinosaurs -- 65 million years ago -- has been linked to an impact by a large asteroid or comet that struck in an area off the coast of what is now Mexico and left a distinctive layer of dust worldwide.

Reference:
http://www.boston.com/news/science/articles/2005/01/20/volcanic_warming_eyed_in_great_dying/

 

[Jikx]

of course, this begs the (off-topc) question: should we even care about global warming?

 

[Moonbear]

of course, this begs the (off-topc) question: should we even care about global warming?

I think that question is precisely the topic at hand. Though, this may be better suited for, and spark a better discussion in, the Earth forum since it really addresses climate change more than biology.

 

[kalladin]

Who are we, to determine the fate of the course set by Nature? I believe that global warming is inevitable; anything we do to try to prevent it, slow it down, is futile. If anything, what we do will be minimal in helping our problem of global warming. Besides, don't you think it's time for another mass extinction?

K.

This may yet be another ignorant post by Kalladin.

 

[Orion1]

Earth Extinction...

Currently the atmosphere consists of about 21 percent oxygen, but the addition of gases at that time could have lowered levels to 16 percent or less

21% - 16% = 5%

Could a reduction of only 5% atmospheric oxygen due to global warming actually result in the extinction of 90% of all Terran lifeforms?

How much fossil fuel is burned every year?, is this rate not increasing?

Based upon the current increasing exponential rate of fossil fuel consumption and the rate at which Terra is warming and the loss of oxygen-producing rainforest regions and other gas production from global desertification, is it not just a matter of time before the oxygen levels diminish to 16%?, will humans become extinct at this level?

The researchers seemed to imply that Humans cannot process oxygen that is only 16% very well...

 

[Ivan Seeking]

Permian extinction caused by warming?

New evidence indicates biggest extinction wasn't caused by asteroid or comet
...They contend that if there was a comet or asteroid impact, it was a minor element of the Permian extinction. Evidence from the Karoo, they said, is consistent with a mass extinction resulting from catastrophic ecosystem changes over a long time scale, not sudden changes associated with an impact. [continued]

http://www.eurekalert.org/pub_releases/2005-01/uow-nei011705.php

 

[Bystander]

Could a moderator please append this to Orion's "Great dying."

 

[Andre]

Well a lot of fuzzy things here.

Once (methane) hits the atmosphere it's the most efficient greenhouse gas on the planet," he said

A common misconception, not very correct I'm afraid:

the number one greenhouse gas is water vapor, the number two greenhouse gas is water vapor, the number three greenhouse gas is water vapor, the number four greenhouse gas is water vapor and CO2 is a distant fifth.

Jan Veizer, University of Ottawa

The point here is that the sort of logaritmic relationship between concentration of the gas and it's greenhouse forcing effectiviness. The first 10ppm is causing equally as much greenhouse gas forcing as the jump of 10,000 to 20,000 ppm where saturation of the effect prevents more heating. This is the basic error in global warming hype thinking.

Now, because methane concentration is much lower than CO2 (measured in parts per billion say 800ppb) a slight change is still having a distinct effect in Greenhouse Gas forcing. But if equal concentrations and changes would account for CO2 then it would have been double as strong as methane. Moreover methane is rather unstable and dissapears in about a decade. So overal, the effectiviness of greenhouse gas forcing of methane is rather dubious.

Furthermore I have no idea what the fuzz is about. The Siberian Traps were the singlemost strongest volcanic event on record, turning about half of Siberia into a Dante's inferno. That would be quite enough to mess up Earth's climate for millenia.

 

[Bystander]

Ward: "...21 percent oxygen, but the addition of gases at that time could have lowered levels to 16 percent or less, Ward said."

An ambiguous statement if ever there were --- might be Ward, or words put into his mouth. First possibility: addition of gases to reduce O₂ content to 16% means the mass of the atmosphere increased without any change in quantity of oxygen --- no effect, metabolism depends on partial pressure of oxygen which hasn't changed. Second possibility: add gases (or anything) to consume sufficient oxygen to reduce composition to 16% --- from where? And, where is the "ash" from such a burning event? Both possibilities invoke storage of large masses of combustibles or diluents, in the neighborhood of 2x10¹⁴ tons, the mass of O₂ between 16 and 20%, in a reservoir separate from the atmosphere-hydrospere-biosphere complex, through a large part of the Cambrian, ANNDDD, of either an equal mass of oxygen to be released following the extinction event, or a re-sequestration of the diluent/combustible mixture.

To calibrate intuitions, we're talking 400 kg/m² oxygen for the Earth surface (land andwater), equivalent masses of nitrogen (dilution) or cellulose (burning accumulated trash), 60-70 kg /m²of methane for combustive "gas release," and 130-140 kg /m²carbon (we'll say the schungite in the Siberian traps is residue from a hot coke eruption).

Bottom line? Not bloody likely.

 

[Mentat]

It's interesting to me that Ward is being quoted as saying that the extinction was "long". In "Rivers in Time", Ward makes a case for a much quicker extinction than had previously been held (he goes into more detail in "Gorgon", but I haven't finished that one yet). Granted, he doesn't give the possible asteroid/meteorite as much credit as some others have, but he also doesn't allow for a long, drawn-out extinction.

 

[Andre]

Based upon the current increasing exponential rate of fossil fuel consumption and the rate at which Terra is warming and the loss of oxygen-producing rainforest regions and other gas production from global desertification, is it not just a matter of time before the oxygen levels diminish to 16%?

No, as Bystander indicates there are several orders of magnitude difference. Remember that all the fossil burning increased the carbon dioxide about 90 parts per million from a pre industrial 285ppm to the present 377 ppm. So a possible decrease in free oxygen is in the same order of magnitude. That would mean a decrease of roughly 210,000 ppm to 209,900 ppm but there are many more factors governing oxygen.

Bystander, as the Siberian traps may have reduced a considerable amount of limestone/ carbonates (perhaps complete mountain chains) the amount of carbon dioxide in the atmosphere may have increased to several percent. That would increase the absolute contents of the atmosphere, reducing the relative amount of oxygen. However the numbers are very rough over the thumb of course.

 

[Bystander]

(snip)Bystander, as the Siberian traps may have reduced a considerable amount of limestone/ carbonates (perhaps complete mountain chains) the amount of carbon dioxide in the atmosphere may have increased to several percent. That would increase the absolute contents of the atmosphere, reducing the relative amount of oxygen. However the numbers are very rough over the thumb of course.

Not bad --- suffocation due to excess CO₂ rather than an oxygen depletion event --- plenty of room in Mesozoic limestones for "the smoking gun I was worried about in the earlier post.

Takes care of the "great dying" for the animal kingdom. Now, what're we going to do to kill the plants? Nasty little details ("present is key to the past") keep popping up, as well --- such as, the cats, the fish, the plants, the rest of the family, and I are all perfectly comfortable at p_O2 = 16.5 kPa, the skibums up the road are happy at 12-14, there's a fair population in the Andes at 10, adapted to over 10ka --- we're going to have to double the oxygen loss to save Ward, and that still ain't going to phase the greenery.

Looking worse and worse.

 

[FluidSpace]

Hi everyone,

I believe that the Earth, like other objects in the universe, goes through a natural cycle that purges itself of waste and threats. The human population is increasing in magnitudes that in another 1,500 years or so that, unfortunately, humanity too will also be purged.

However, the Earth will continue and someday another dominant species (whether sentient or not) will emerge. Maybe, it's the bugs turn to rule!

Just a thought.

FluidSpace

 

[Locrian]

I believe that the Earth, like other objects in the universe, goes through a natural cycle that purges itself of waste and threats.

You can believe that, but there isn't any evidence for it.

 

[Andre]

Looks like http://www.ecotao.com/holism/gem_lovelock.htm. A cute idea.

 

[FluidSpace]

You can believe that, but there isn't any evidence for it.

Everyone is entitled to their own belief which constitutes their own perceived reality. But just look around you, open your mind, and I hope you will see the universal trends.

Without some kind of colossal intervention, the human race will be "naturally" obliterated whether by itself and/or by "mother nature".

Fluidspace

 

[matthyaouw]

But just look around you, open your mind, and I hope you will see the universal trends.

Which trends are these? Describe them to me, with specific examples and evidence please.

 

[Bystander]

This is the point at which the moderator(s) split fluid space off to TD or S&D --- this is contributing nothing to the original point of the thread.

To A, L, M --- "please do not feed the trolls."