Kortpeel (imported) wrote: Fri Oct 02, 2009 11:19 pm A question: Why hasn't the percentage of oxygen in the atmosphere declined? With the massive clearing of forests and the colossal amounts of fossil fuel being consumed 24/7 I would have expected a reduction in atmospheric oxygen...
Kortpeel
Now this part of the answer is not directed at Kortpeel.
The reason that the right-wing nutcakes want to obliterate and rewrite science (evolution, warming, dinosaur ages, stuff like that) is that most global warming deniers need the fuzziness of "intelligent Design" or Creationism to explain why we don't have to deal with global warming. They are ignorant fools wanting to die for God and they hate modern civilization. You have to think in the modern world. No one had to think in the medieval world.
That being said, I don't believe Kortpeel is part of this gang of loony-tunes.
I think he's asked a serious question. It's not a hard question to answer but it is involved.
First, we can all read a rather long article on Wikipedia about CO2 and the many ways it is used. It's like ubiquitous... it's everywhere. It's in everything. It's a building block of life itself.
http://en.wikipedia.org/wiki/Carbon_dioxide
Second, For those of us interested in global warming, go here:
http://en.wikipedia.org/wiki/Carbon_dio ... atmosphere
The opening sentence about CO2 in the atmosphere. From Wiki: Carbon dioxide in earth's atmosphere is considered a trace gas currently occurring at an average concentration of about 383 parts per million by volume or 582 parts per million by mass.
Now there is one part of the answer to Kortpeel's question. Atmospheric CO2 is measure in part per million. Oxygen is 21% of the atmosphere, 60 or 70 THOUSAND times greater in concentration than CO2.
If you want more involved science, you can get into the carbon cycle. That includes everything from coal formation to photosynthesis. If you really want to understand why modeling the carbon cycle and global warming is so hard, DIG IN HERE. It's an elegant cycle, a true work of art in nature, but it's not trivial. And mankind still does not understand all of it.
The second part of the question is to understand the toxicity of CO2.
Remember that 1,000,000 parts per million (PPM) is 1 percent (1%) -- by volume or mass or number of marbles hidden in a kid's ideal basement)...
Wiki says this:
http://en.wikipedia.org/wiki/Carbon_dioxide#Toxicity
Toxicity and its effects increase with the concentration of CO2, here given in volume percent of CO2 in the air:
* 1%, as can occur in a crowded auditorium with poor ventilation, can cause drowsiness with prolonged exposure.[2]
* At 2% it is mildly narcotic and causes increased blood pressure and pulse rate, and causes reduced hearing.[38]
* At about 5% it causes stimulation of the respiratory centre, dizziness, confusion and difficulty in breathing accompanied by headache and shortness of breath.[38]
* At about 8% it causes headache, sweating, dim vision, tremor and loss of consciousness after exposure for between five and ten minutes.[38]
Now global warming involves an increase of CO2 in the atmosphere of 100 PPM maybe 200 ppm. That doesn't even bring the overall level up to a tenth of a percent by volume. So we would not notice that increase because it's much lower than even the 1% that we might notice in a crowded, poorly ventilated bar, a tunnel (big time in tunnels), music events, train stations, etc...
And that should explain why we don't notice the increased CO2.
To deal with oxygen deprivation is much harder.
a) dropping the oxygen concentration in air (increasing nitrogen will do it) is one form of oxygen deprivation.
b) Carbon monoxide models won't work because of the interaction of carbon monoxide with hemoglobin.
c) Nitrous oxide also enters the blood stream and becomes biologically active. NO2 is why viagra works. Plus we get giddy on NO2 (laughing gas for dentists).
d) Wikipedia's article of hypoxia (lack of oxygen) http://en.wikipedia.org/wiki/Hypoxia_%28medical%29
doesn't do much for me other than make my head hurt with too much information of the scientific type. I don't recommend it.
But I can't find a good article explaining the effects of lowering the percentage of oxygen in the air and its effects on the human body. Sorry about that...
I do not think that a decrease of oxygen by 1% would be noticed on a routine basis. I don't have a source to confirm that. Let me say that LA Paz Bolivia is 13,000 feet in the air and we don't require supplemental oxygen. Airplanes are maintained at 8500 feet. I don't have a good way of back-calculating that to oxygen partial pressure (not concentration in this case, but partial pressure). We do carry oxygen bottles up to the peak of Mount Everest at 29,000 feet. The answer is somewhere in between those two heights above sea level man would notice the lack of oxygen.
