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PostPosted: Tue Apr 30, 2013 4:23 pm 
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This is not something that I have given much thought to but is the amount of oxygen in the air something we need to be concerned about? This article says yes. I don't know what credence to give it but it does make sense that cutting down all these photosynthesis factories we call trees would lower the oxygen production level. Any knowledge you wish to share on the subject would be appreciated.

http://survivalacres.com/blog/oxygen-le ... -dropping/

Quote:
Trees produce oxygen and absorb carbon dioxide. This balance is now threatened:

Ahead of us we have the possible destruction of forests, vital in maintaining oxygen levels necessary for life, in the control of carbon dioxide, and in water cycle balances. Notably, the concentration of oxygen in the atmosphere has dropped from 35 to 21 percent from prehistoric times to now, and the carbon dioxide has increased in part by the human growth pollution in cities with high oxygen levels, which often comprises only 15 percent of total air. So at this rate it is obvious that in these cities we will render the “air” unbreathable. Diana Beresford-Kroeger, a botanist, says, “the abuse of forests and pollution of the oceans has caused them to produce only half the oxygen (they produced) 10,000 years ago.”** We must also consider that in the last 30 years this process has accelerated the deterioration or the collapse of almost all living systems.

This paragraph really stuck out, so I began to research the facts. Are cities really losing their oxygen?

Yes.

Dangerously low levels of oxygen are now being reported in cities around the world. Increased carbon dioxide levels are displacing oxygen in the atmosphere.

We are losing three oxygen molecules in our atmosphere for each carbon dioxide molecule that is produced when we burn fossil fuels. Studies of ice cores and recent data from direct atmospheric sampling have shown that there has been a 30% increase in carbon dioxide since the beginning of the industrial age. Atmospheric Oxygen Levels Fall As Carbon Dioxide Rises


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PostPosted: Tue Apr 30, 2013 4:45 pm 
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The math is against the concept. The CO2 increase of even 500 ppm would not have a significant displacement of O2 levels, which are between (20%) 200,000 ppm and (21%) 210,000 ppm.

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PostPosted: Wed May 01, 2013 7:37 am 
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Yeah, you're right about the math but I would add one qualifier, according to the article one unit of CO2 added to the atmosphere removes 3 units of O2. Taking another tack I'm wondering what happens if we lose a serious amount of photosynthetic capability due to forest clear cutting and increasing ocean dead zones etc.


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PostPosted: Wed May 01, 2013 8:53 am 
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Dingo wrote:
Yeah, you're right about the math but I would add one qualifier, according to the article one unit of CO2 added to the atmosphere removes 3 units of O2. Taking another tack I'm wondering what happens if we lose a serious amount of photosynthetic capability due to forest clear cutting and increasing ocean dead zones etc.


That is an oversimplification of the act of combustion where the product is CO2 and H2O, thus the oxygen atoms are counted as 3:1 for each carbon atom in the combustion equation.

The water is the other third, but still the increase of 500 ppm CO2 has no significant impact if the water is included to "remove" 750 ppm O2 from the 200,000 ppm to 210,000 ppm in the atmosphere.

This does not mean there is no impact from the loss of biomass, but that impact is not significant at this time nor would it be for some time into the future given the current trend.

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PostPosted: Wed May 01, 2013 11:15 am 
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Key word--significant.

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PostPosted: Wed May 01, 2013 7:27 pm 
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One thing great about these discussions is it forces you to do some research and you can stumble across some terrific links. Here is a comprehensive discussion of the biosphere, more than I have ever seen. http://www.answers.com/topic/biosphere

Oxygen in the atmosphere is a function of the evolution and spread of plant life. What the implications are of the reversal of this process, ie the loss of biomass, is something I need more clarity on.

Quote:
The present atmosphere would not exist without the biosphere. In order to put oxygen into the air, there had to be plants, which take in carbon dioxide and release oxygen in the process of photosynthesis. This resulted from an exceedingly complex series of evolutionary developments from anaerobic, or non-oxygen-breathing, single-cell life-forms to the appearance of algae. As plant life evolved, eventually it put more and more oxygen into the atmosphere, until the air became breathable for animal life. Thus, the atmosphere and biosphere have sustained one another.


Here's another good link. http://en.wikipedia.org/wiki/Atmosphere_of_Earth It has a good discussion on the early origin of atmospheric oxygen and mentions that oxygen was about 30% of the atmosphere about 280 million years ago.

Quote:
The constant re-arrangement of continents by plate tectonics influences the long-term evolution of the atmosphere by transferring carbon dioxide to and from large continental carbonate stores.[24] Free oxygen did not exist in the atmosphere until about 1.8 billion years ago during the Great Oxygenation Event and its appearance is indicated by the end of the banded iron formations. Before this time, any oxygen produced by photosynthesis was consumed by oxidation of reduced materials, notably iron. Molecules of free oxygen did not start to accumulate in the atmosphere until the rate of production of oxygen began to exceed the availability of reducing materials. This point signifies a shift from a reducing atmosphere to an oxidizing atmosphere. O2 showed major ups and downs until reaching a steady state of more than 15% by the end of the Precambrian.[25] The following time span was the Phanerozoic eon, during which oxygen-breathing metazoan life forms began to appear.

The amount of oxygen in the atmosphere has varied over the last 600 million years. Around 280 million years ago the amount of oxygen peaked around 30%, significantly higher than today's 21%. Two main processes govern changes in the atmosphere: Plants use carbon dioxide from the atmosphere, releasing oxygen. Breakdown of pyrite and volcanic eruptions release sulfur into the atmosphere, which oxidizes and hence reduces the amount of oxygen in the atmosphere. However, volcanic eruptions also release carbon dioxide, which plants can convert to oxygen. The exact cause of the variation of the amount of oxygen in the atmosphere is not known. Periods with much oxygen in the atmosphere are associated with rapid development of animals. Today's atmosphere contains 21% oxygen, which is high enough for this rapid development of animals.


Here's a graph of the atmospheric percentage of oxygen over the last billion years. http://en.wikipedia.org/wiki/File:Sauer ... 000mj2.png Presumably the drop in oxygen to our time meant a cooler planet could not produce enough photosynthesis to capture all the CO2 so we had a lot of sequestering so to speak. Warmer weather and more CO2 presumably should be increasing biomass and therefore oxygen but we are killing the species directly or due to too fast climate change so things can only go sort of screwy. Hard to get my head around it.


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PostPosted: Thu May 02, 2013 1:16 am 
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People live permanently on this planet from below sea level to above 18K'. I live at 8,880' with substantially less O2 than right and left coasters and flat landers. In the first half of the resequestration of CO2 time after thermageddon with most life dead and rotting at high temperatures I think the O2 level could drop to 19% or less. Still not enough to affect animal life resurgence in the several million years after total resequestration. Burgeoning new plant species could bring it up to 23% before back to 20-21%.
That is with the likelihood people will not stop fossil fuel use soon enough and will also not burn enough of it for a Venus effect. Seeing the population crash, AGW, other pollution and depletion effects will keep population levels low until thermal max in 500 years or so. :-({|= :mrgreen:

l
Note: Utterly WORTHLESS post below V. I never would have thought it of Wayne. #-o :crazy: [-X :razz: :mrgreen:

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Last edited by Johhny Electriglide on Mon May 06, 2013 1:20 pm, edited 1 time in total.

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PostPosted: Thu May 02, 2013 7:48 am 
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Unless you subscribe to the theory the lizard aliens set up oxygen generators in what is now Antarctica when they began the terra forming in preparation to colonization of Earth. :mrgreen: #-o

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