Oxygen fuels the fires of time

Aug 02, 2010

Variations in the Earth's atmospheric oxygen levels are thought to be closely linked to the evolution of life, with strong feedbacks between uni- and multicellular life and oxygen. Over the past 400 million years the level of oxygen has varied considerably from the 21% value we have today. Scientists from The Field Museum in Chicago and Royal Holloway University of London publishing their results this week in the journal Nature Geoscience have shown that the amount of charcoal preserved in ancient peat bogs, now coal, gives a measure of how much oxygen there was in the past.

Until now scientists have relied on geochemical models to estimate concentrations. However, a number of competing models exist, each with significant discrepancies and no clear way to resolve an answer. All models agree that around 300 million years ago in the Late Paleozoic atmospheric oxygen levels were much higher than today. These elevated concentrations have been linked to gigantism in some animal groups, in particular insects, the dragonfly Meganeura monyi with a wingspan of over two feet epitomizing this. Some scientists think these higher concentrations of atmospheric oxygen may also have allowed vertebrates to colonize the land.

These higher levels of oxygen were a direct consequence of the colonization of land by plants. When plants photosynthesize they evolve oxygen. However, when the carbon stored in plant tissues decays atmospheric oxygen is used up. To produce a net increase in atmospheric oxygen over time organic matter must be buried. The colonization of land by plants not only led to new but also a dramatic increase in the burial of carbon. This burial was particularly high during the Late Paleozoic when huge accumulated.

Dr. Ian J. Glasspool from the Department of Geology at the Field Museum explained that: "Atmospheric is strongly related to flammability. At levels below 15% wildfires could not have spread. However, at levels significantly above 25% even wet plants could have burned, while at levels around 30 to 35%, as have been proposed for the Late Paleozoic, wildfires would have been frequent and catastrophic".

The researchers, including Professor Andrew C. Scott from the Royal Holloway University of London, have shown that charcoal found in coal has remained at concentrations of around 4-8% over the past 50 million years indicating near to present levels of atmospheric oxygen. However, there were periods in Earth History when the charcoal percentage in the coals was as high as 70%. This indicates very high levels of atmospheric oxygen that would have promoted many frequent, large, and extremely hot fires. These intervals include the Carboniferous and Permian Periods from 320-250 million years ago and the Middle Cretaceous Period approximately 100 million years ago.

"It is interesting", Professor Scott points out, "that these were times of major change in the evolution of vegetation on land with the evolution and spread of new plant groups, the conifers in the late Carboniferous and flowering plants in the Cretaceous". These periods of high fire resulting from elevated atmospheric oxygen concentration might have been self-perpetuating with more fire meaning greater plant mortality, and in turn more erosion and therefore greater burial of organic carbon which would have then promoted elevated atmospheric oxygen concentrations. "The mystery to us", Scott states, "is why oxygen levels appear to have more or less stabilized about 50 million years ago".

Explore further: NASA balloons begin flying in Antarctica for 2014 campaign

More information: Glasspool, I.J. and Scott A.C. 2010. Phanerozoic atmospheric oxygen concentrations reconstructed from sedimentary charcoal. Nature Geoscience DOI:10.1038/NGEO923

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User comments : 29

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gopher65
5 / 5 (1) Aug 02, 2010
Great article. It's nice to finally have some significant evidence of the high oxygen concentrations in the distant past.
fixer
2 / 5 (4) Aug 02, 2010
It's also interesting to bear in mind that in some cities the oxygen content can be as low as 10% due to overcrowding and pollution.
frajo
3.3 / 5 (3) Aug 03, 2010
It's also interesting to bear in mind that in some cities the oxygen content can be as low as 10% due to overcrowding and pollution.
Where and when in the last 500 million years? Sources?
kevinrtrs
1 / 5 (8) Aug 03, 2010
Some scientists think these higher concentrations of atmospheric oxygen may also have allowed vertebrates to colonize the land.

Note the use of the word MAY.
When plants photosynthesize they evolve oxygen.

Strange way to use the word evolve. Just what exactly does it mean here? CHANGE oxygen into carbon ? or into platinum? What?
These higher levels of oxygen were a direct consequence of the colonization of land by plants.
I suppose the author has documented proof that there was such an event or process? AS far as I can discern, no-one can be sure that this ever happened since no-one was there to document it. Inferring this from current conditions is a bit far-fetched at most. The assumptions that have to be made are just too tenuous and open to dispute.
might have been self-perpetuating with more fire meaning greater plant mortality,
Simply another one of thousands of mights and maybees that are required to prop up Darwinism.Believe it or not.

frajo
4.2 / 5 (5) Aug 03, 2010
Some scientists think these higher concentrations of atmospheric oxygen may also have allowed vertebrates to colonize the land.
Note the use of the word MAY.
The word "may" characterizes falsifiability-centered reasoning.
When plants photosynthesize they evolve oxygen.
Strange way to use the word evolve. Just what exactly does it mean here?
Generate, produce.
These higher levels of oxygen were a direct consequence of the colonization of land by plants.
I suppose the author has documented proof that there was such an event or process?
You don't suppose so.
no-one can be sure that this ever happened
Right.
Inferring this from current conditions is a bit far-fetched at most.
It's the least far-fetched assumption known.
and open to dispute.
As always in science.
Believe it or not.
It's very reasonable. In fact more reasonable than every alternative idea. But nobody forces you to think reasonably.
trekgeek1
5 / 5 (3) Aug 03, 2010
I agree Kev, I'm sick of not having 100% proof and believing things based on reason and evidence. I'm going with your explanation, God did it! Everyone, God did it! It feels great to say, I never have to doubt anything again! Accelerating universe? God! Higgs Boson? It's God! Finally, all the answers sitting in my lap. And the best thing, the God theory is 100% tested and proven, unlike science theories.

Geez, if I were to bait a trap for Kev, I'd use an article that contained the word "evolution" in it. That is guaranteed to lure him in for the catch. Seriously, if I want a good laugh, I scan the site for a new article that discusses evolution, age of the earth, etc. I can be confident that I will find him.
fixer
1 / 5 (2) Aug 03, 2010
@frajo
Where and when in the last 500 million years?
Mexico city, Tokyo, L.A. etc...
Sources?
News media.
There is more to life than just Physorg, not everyone reports on line.
DamienS
5 / 5 (1) Aug 03, 2010
@fixer
I still don't see any sources (links), just assertions.
frajo
5 / 5 (1) Aug 04, 2010
@frajo
Where and when in the last 500 million years?
Mexico city, Tokyo, L.A. etc...
Sources?
News media.
Unfortunately, you have a history of telling fairytales (wrt. cancer e.g.). Thus, without credible sources, I assume your "report" on 10% atmospheric oxygen content is just another urban legend.
fixer
1 / 5 (3) Aug 04, 2010
Go ahead and assume anything you like!
Obviously you never bother to check the sources I do post or you wouldn't be arguing.
How about you stop bickering and do a little research yourself?
DamienS
5 / 5 (2) Aug 04, 2010
@fixer
If it's such a slam dunk, why don't you post the links now for your claim?
fixer
1 / 5 (1) Aug 04, 2010
@DamienS
It's not my claim, the report was public news.
Of course, since I can't provide a link it must be urban legend and so not true.
Then again, there is life beyond the keyboard, some people on this site really need to get out more!
Ethelred
5 / 5 (3) Aug 04, 2010
Note the use of the word MAY.
Note the use of the word THE. When speculating about why things happened under KNOWN ancient conditions it is normal to use the word MAY. Note my use of the the phrase "known ANCIENT conditions" as we KNOW the world is much older than you think.
Strange way to use the word evolve.
That word really makes you flinch doesn't it? The rest of what you said was bizarre to say the least. The word evolve IS sometimes used that way. I wouldn't have done it. I would have said 'produce'.
I suppose the author has documented proof that there was such an event or process?
Yes. Many fossilized plants that had begun to colonize the land. Which would HAVE to increase oxygen production.

More sedimentary layers to come
Ethelred
5 / 5 (4) Aug 04, 2010
AS far as I can discern, no-one can be sure that this ever happened since no-one was there to document it
No one was there inside the Trinity bomb to document that the high explosive shell went off as planned. The unprecedented explosion was adequate evidence that it had happened.

Fossils exist. They formed a very long time ago. We CAN measure how long ago in many instances. Just claiming we weren't there, which we already know since we had ye, isn't going to make the evidence disappear.
Inferring this from current conditions is a bit far-fetched at most
Since they didn't do that why did you bring it up?
The assumptions that have to be made are just too tenuous and open to dispute.
The assumptions are based on literally rock solid evidence in many cases. Disputing it by saying NO NO NO I CAN'T BELIEVE REALITY isn't a reasoned dispute. It is a demand to remain ignorant. If you really want to remain pig ignorant so badly why are you on a science site?

layer after layer
Ethelred
5 / 5 (3) Aug 04, 2010
Simply another one of thousands of mights and maybees that are required to prop up Darwinism.Believe it or not.
As others have already pointed out YOU are the one going on fantasy. That the word is old is not speculation. That animals at one time did NOT move about the land is certain. That they moved on the land is also certain since animals once weren't on the land and now are. It would take severe brain damage or religion to claim that as speculation.

Come on Kevin show some guts and try to justify that rubbish you shovel. If you can't manage to support that fertilizer perhaps you should just accept reality.

Yes I will show that you are wrong of course. Your fear of this is evidence that, deep inside, you know that you are just shouting 'la la la I can't hear the truth'.

If you really believed you wouldn't scarper off all the time.

Ethelred
Skeptic_Heretic
5 / 5 (3) Aug 04, 2010
I suppose the author has documented proof that there was such an event or process? AS far as I can discern, no-one can be sure that this ever happened since no-one was there to document it. Inferring this from current conditions is a bit far-fetched at most. The assumptions that have to be made are just too tenuous and open to dispute.

As opposed to the assumption that Noah could fit two of each of the known 90 million plus species on a boat smaller than a highschool gymnasium.

Then that those creatures could all swim or fly their way from the Middle East to be distributed around the world.

How far ahead of time did God give notice to the Peruvian Sugar Beetle so that they could make it across the Atlantic? They can only move about 5 to 10 miles a month going full out 24/7 so I think we're looking at something akin to 5000 years notice. Especially if they had to learn to sail, since they can't fly or swim.

What's more probable kev?
Ethelred
4.7 / 5 (3) Aug 04, 2010
two of each of the known 90 million


Wherever did you get that number? Are you counting viruses and bacteria? Millions yes but that number is an order of magnitude greater than I have ever seen claimed before.

And high school gymnasiums aren't as big as Noah's Big Ass Boat. Usually they are only about 50% larger than the basketball court they contain. Basketball courts are about 92 feet long.

The Big Ass Boat, if it had built to specs, would have been 400 by 400 by 400 feet. Which is larger than ANY wooden boat ever made, in ANY dimension. The longest wooden ship ever made was less than 400 long and it cracked due to stress. And that was by experienced ship builders working with real wood, mainly oak. What the hell gopher wood is no one knows but I doubt that is used for ship building. Jehovah doesn't know how to build a ship. Not surprising since the ancient Israelites that made up Jehovah didn't know either.

Ethelred
DamienS
5 / 5 (2) Aug 04, 2010
It's not my claim, the report was public news.
Of course, since I can't provide a link it must be urban legend and so not true.

As someone who keeps daily tabs on all manner of scientific news, I'd never come across that claim before. Of course, I could have missed it, but you make it seem like it's general public knowledge, so I was interested in reading about the study you were talking about. As you still cannot provide any links, I must assume it was either very obscure or that you just made it up based on a faulty recollection of something else.

Then again, there is life beyond the keyboard, some people on this site really need to get out more!

I didn't mean to intrude on your fabulous, action packed lifestyle, just wanted a source. I guess all you have is anecdote.
frajo
1 / 5 (1) Aug 05, 2010
The Big Ass Boat, if it had built to specs, would have been 400 by 400 by 400 feet. Which is larger than ANY wooden boat ever made, in ANY dimension. The longest wooden ship ever made was less than 400 long and it cracked due to stress. And that was by experienced ship builders working with real wood, mainly oak.
Ever heard of Zheng He's fleet? The "treasure ship", used by the commander of the fleet and his deputies, nine-masted, about 126.73 metres long and 51.84 metres wide, China, 15th century.
Skeptic_Heretic
5 / 5 (1) Aug 05, 2010
Wherever did you get that number? Are you counting viruses and bacteria? Millions yes but that number is an order of magnitude greater than I have ever seen claimed before.
In reality I don't go along with the division moniker of "species", but you're correct my statement is WAY off. I think the real number is somewhere around 1.3 or 1.4 million according to the vague definition of what a species is in science.
Ethelred
not rated yet Aug 05, 2010
No I hadn't. So I looked it up.

http://en.wikiped...re_ships

Some scholars argue that it is highly unlikely that Zheng He's ship was 450 feet (140 m) in length, some estimating that it was 110-124 m (390-408 feet) long and 160-166 feet wide instead [15] while others put them as 61-76 m (200-250 feet) in length[16][17], since in later historical periods ships approaching the extreme sizes claimed for the treasure ships (such as HMS Orlando and the schooner Wyoming) were unwieldy and visibly undulated with the waves, even with steel braces.


And the treasure ships had iron reinforcement in any case. The Big Ass Boat was Bronze Age and even that isn't mentioned.

The last time I looked this stuff up this site did not yet exist.

http://en.wikiped...en_ships

I think I used Ask Jeeves the last time.

Ethelred
Ethelred
not rated yet Aug 05, 2010
In reality I don't go along with the division moniker of "species",
I don't have a problem with the term. It is the lack of a real definition that bugs, literally in some cases, me. The usual method of calling something a separate species is not based on genetics but on whether the two gene pools ORDINARILY interbreed. As far as I am concerned if they CAN, when given the opportunity, interbreed they are the same species as I go on the genetics.

Thus I do not pretend that European bees and African bees are a separate species since they clearly interbreed when the opportunity arises.

So to me even the number of species usually tossed around is a bit inflated. Which I suppose would make my definition a favored one by those looking for ways to get around the Endangered Species act.

Ethelred
Skeptic_Heretic
5 / 5 (1) Aug 05, 2010
As far as I am concerned if they CAN, when given the opportunity, interbreed they are the same species as I go on the genetics.
See this is my problem with the definition.

There;'s a snail, can't recall the name but due to the construction of it's shell it is actually two different species. There are left handed snails and right handed snails. Since the shell curves in one or the other direction it creates an inability to mate with snails of the opposite "shell dominance". The issue here, is through random genetic propagation one species can give birth to members of the other through chance and recessive genetics, yet they're considered two distinct species as they physically cannot interbreed.

This would also show some breeds of dog to not be a species at all since they cannot breed without medical intervention. It is quite a tricky term to even start to define. I've ignored the species moniker and now I've been moving more into cladistics.
frajo
1 / 5 (1) Aug 05, 2010
And the treasure ships had iron reinforcement in any case. The Big Ass Boat was Bronze Age and even that isn't mentioned.

The last time I looked this stuff up this site did not yet exist.
I'm not really interested in ship dimensions and ship history. I came across the subject when reading about Chinese history. Whether Zheng He's ships were 100 m or 60 m doesn't itch me.
My point is that we don't see enough when we exclusively look through Western glasses.
Javinator
5 / 5 (3) Aug 05, 2010
It's also interesting to bear in mind that in some cities the oxygen content can be as low as 10% due to overcrowding and pollution.


The only websites I can find support this "10% oxygen levels in cities" claim are holistic medicine websites that are trying to sell therapies for oxygen depletion to people.

The only thing that really affects the percentage of oxygen in the air in the altitude at which the city sits (and guess what, mexico's up there).

From what I know, air pollution and smog are generally particulates. The main polluting gases are usually SOx's, NOx's, CO, and CO2. I mean come on... even CO2 which is produced in every combustion reaction involving hydrocarbons makes up less than 1% of our atmosphere. I have a tough time believing that oxygen levels in cities would be reduced by 11% from normal. In that case it wouldn't just be the elderly or the sick who would have troubles breathing. It would be everyone.
Ronan
not rated yet Aug 08, 2010
For what it's worth, the largest wooden boat ever constructed (with iron supports, mind) were the HMS Orlando and Mersey (the reported lengths of Zheng He's treasure ships are probably exaggerations, as they would have difficulty remaining afloat in rough seas), at 336 feet long--and they were barely seaworthy, as they were so long that they flexed noticeably with the passage of waves, allowing water to seep into the ships in the process. http://en.wikiped...o_(1858)

...Which is all completely irrelevant to this article, really. Very interesting; I hadn't realized that there was a peak in oxygen concentrations ~100 MYA, although after a quick google search it seems that that peak shows up with other proxies, as well. Does anyone know if there were any signs of insect gigantism at that time, or anything of that nature? It'd be an interesting test of the idea that high O2 levels were responsible for the Carboniferous giant arthropods.
fixer
1 / 5 (1) Aug 09, 2010
There was a TV series a year or so back called "Prehistoric park" which is available on DVD and is very watchable.
Whilst being pure fantasy it was well researched and dealt in part with giantism in insects.
fixer
1 / 5 (2) Aug 09, 2010
And to continue an earlier argument with frajo, I found this!
http://www.intern...rapy.htm
Enjoy.
frajo
3 / 5 (2) Aug 21, 2010
And to continue an earlier argument with frajo, I found this!
http://www.intern...rapy.htm
You are out of context.
In this thread we discussed a claim brought up by you without sources that "in some cities the oxygen content can be as low as 10 percent".
In this thread we did not discuss oxygen therapy. Thus you should place your link into the correct thread.

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