Math! How much CO2 is emitted by human on earth annually?
March 27, 2007 at 3:56 am (Environment, Math!)
Another math time! 
And again, it is closely related to GW area.
Currently (as of year 2007), human population on earth is 6.6 billion (via wikipedia). I went around to look for how much CO2 is exhaled out per person, and 2 claims were found (both via wikipedia):
claim#1: an average person’s respiration generates approximately 450 liters (roughly 900 grams) of carbon dioxide per day (CO2#Human_physiology)
I use the standard chemistry textbook theory (standard molar volume) to check this claim, 450L for 900 grams of CO2, and it is tallied.
Thus, the amount of CO2 released by human per day is 0.9 kg/day
claim#2: In an average resting adult, the lungs take up about 250ml of oxygen every minute while excreting about 200ml of carbon dioxide. (Respiratory_system)
So, 200 ml per minute and thus 200 ml x 60 X 24 = 288L
Or equivalent to 565.36g/per day = 0.565 kg/day (after divide with standard molar volume constant and times with CO2 molar weight).
Apparently claim#2 has lower CO2 emission compared to claim#1, but I will use both anyway to show the comparison.
So, if there is 6.6 billion people out there and excreting CO2 at the rate of 0.9 or 0.565 kg/day, the total CO2 emission by human alone annually is:
claim#1: CO2 emission = 0.90 X 365 x 6 600 000 000
= 2.168 x 10^9 tonnes/year
claim#2: CO2 emission = 0.565 x 365 x 6 600 000 000
= 1.362 x 10^9 tonnes/year
But human activities, through the fossil fuel burning activities, releases 24.136 x 10^9 tonnes per year (via wikipedia).
So, human breathing process contribute to about 8.99% (claim#1) or 5.65% (claim#2) compared to the fuel burning related CO2.
Conclusion? May be stop breathing does not really help in reducing CO2 emission! 
micpohling
Math! How much CO2 is released by Dairy Cow? « small-m said,
April 12, 2007 at 4:53 am
[...] compared this value to human being on earth (as of year 2007), human population is breathing about 1362 million tonnes (case#1) or 2618 million tonnes (case#2) CO2 per year. By comparing the [...]
Brian Muller said,
May 15, 2007 at 2:30 am
Your math is off in example number 1 the answer should be 2.168 x 10^12 tonnes/year.
Thats off by 1000 times do your math again.
mich said,
May 15, 2007 at 6:27 am
Hi Brian:
0.90 kg/day x 365 days x 6 600 000 000 = 2.168×10^12 kg or 2.168×10^9 tonnes/year (1 tonne=1000 kg). I skipped the kg conversion to tonnes part. Checked if the number is tallied with yours.
Neil Chapman said,
June 16, 2007 at 12:46 am
By my coarse calculation a typical car generates about as much CO2 as 12 people. That means 6.5 billion people are equivalent to 500 million cars.
micpohling said,
June 16, 2007 at 1:29 am
Hi Neil:
Well, let’s say a typical car emit 200g CO2 per 1 km travelled, and for a car to generate 12 persons CO2:12×0.9 kg = 10.8 kg CO2, that would be equivalent to 54km travelling distance per day. Do you drive your car that much?
Ed C said,
July 16, 2007 at 5:55 pm
Very interesting stuff! Also useful for someone like myself whom is convinced global warming isn’t our fault (well, cars and CO2 anyway). My maths teacher told me that 50% (could’ve misheard it, might be 15%) of CO2 emissions are emitted by the production of concrete. Can anyone back this up? Thanks!
Ed C said,
July 16, 2007 at 6:11 pm
PS: I heard the average human emitted 400kg (0.4 tonnes) of CO2 a year so 0.4[tonnes] x 6600000000 = 2640000000 (tonnes 2.64 x 10^9 tonnes/year I think) > 2.168 x 10^9 tonnes/year. Not sure what total CO2 emissions are and haven’t the time to work it out!
mich said,
July 16, 2007 at 10:59 pm
Well Ed, your average 400kg per year is definitely slightly higher than my daily 0.9kg (less than 1 kg per day x 365 days will definitely less than 400kg/year), so your calculation would yield higher number than mine. As for the concrete production, sorry for not hearing about that before. A quick check at Wikipedia, I guess the CO2 was released by Portland cement component in concrete ” Portland cement, which is made primarily from limestone, certain clay minerals, and gypsum, in a high temperature process that drives off carbon dioxide and chemically combines the primary ingredients into new compounds.”
http://en.wikipedia.org/wiki/Cement
Ed C said,
July 18, 2007 at 4:02 pm
Thanks for the info mich.
I checked again with my maths teacher, and she is convinced it is 51% (CO2 emitted by concrete/cement [?] production). But then again, she is just a bit mad…
I only got the 400kg pa figure from a letter written to the motoring magazine, Top Gear, so I don’t know how valid that is. Thanks again for the very useful article.
Adam said,
August 4, 2007 at 6:04 am
The catch with cement factory emissions, is that in the hardening of the lime (calcium oxide) back into limestone (calcium carbonate), the primary ingredient in concrete to make it harden, the CO2 is put back in, so the net effect is entirely from the burned fossil fuels required to heat the limestone and cook it into lime, and not of the product itself. And that’s with a rediculously efficient process. You want to talk terrible emissions, gas lawnmowers spit out all sorts of terrible crap and are horribly inefficient. Even candles are horribly inefficient as a light source.
Tell your teacher to do HER homework next time she tries to tell you to do yours
Ed C said,
August 4, 2007 at 7:44 am
Thanks Adam, I sure will! I see your point with the concrete hardening process as I recently studied this at school. The quest continues to find that global warming isn’t entirely our fault… (probably a lost cause by now)
kevin said,
August 14, 2007 at 1:09 pm
This s not really a math question, but a thought of why with technology advancing at such a rate, hasnt anybody invented/discovered a method of changing CO2 into base elements carbon and oxygen. Please forgive my ignorance if there is a simple answer to this.
mich said,
August 14, 2007 at 5:25 pm
Well, the problem is breaking a stable molecule like CO2 into base C and O requires energy (be it natural process like photosynthesis or artificial), so it will eventually comes back to original question: where do you get the energy from?
snowy said,
August 19, 2007 at 12:10 am
erh does n’t
6H2O + 6CO2 ———-> C6H12O6+ 6O2
six molecules of water plus six molecules of carbon dioxide produce one molecule of sugar plus six molecules of oxygen
so basically if we breath toward a big enough sunlit plant while we water it - that should sort our our own individual carbon offset !!!! and we get to have some sugar for our latte too
Rahul P said,
October 19, 2007 at 10:15 am
If I were to offset the CO2 by planting trees for my own quota of CO2 , how many and what type of trees are required to plant and keep em alive as long as I am breathing …
Bob Bennett said,
November 2, 2007 at 5:39 pm
How much carbon dioxide is contained in one cubic metre of limestone.
An average quantity would be most helpful to me as I need to kinow how much is given off when burning limestone at 900 degrees C ?
Max said,
November 16, 2007 at 12:26 am
Human breathing process is not contributing to net gain of CO2 because:
“human exhalation of carbon dioxide is part of a closed system. There can be no net addition of carbon dioxide to the atmosphere because the amount of carbon dioxide we exhale can’t be greater than the carbon we put into our bodies by eating plants, or eating animals that eat plants. The plants got the carbon from the atmosphere via photosynthesis.”
http://www.gcrio.org/doctorgc/index.php/drweblog/C53/
And, yes, the solution is planting trees. In my childhood days, the mantra was “5 trees per person and we’re fine”. Have no idea if this was scientifically proven/supported.
mark teeter said,
December 21, 2007 at 4:44 pm
Hello econerds! Does it not occur to anyone that humans are not the only carbon dioxide emitting organisms on earth? Please try calculating CO2 emissions for all life. Eat your pets first, but only make jerky out of them by sun drying.
Adam L said,
April 2, 2008 at 10:38 pm
I think that teacher means 51% of CO2 from manufacturing (metal refining is another big contributor in this category). Cement accounts for more like 5 to 10% of TOTAL CO2 emissions. Even livestock contribute more CO2 emissions than the cement industry. Beef livestock account for 9% of CO2 (but 37% of methane and 65% of NOx, which have greater potential warming effect than CO2).
By the way, the total amount of atmospheric CO2 only rises by about half of the total global emissions each year. The other half gets absorbed by the oceans. Basically, shellfish need it to make the CaCO3 for their shells.
Cahal said,
May 1, 2008 at 10:13 am
The carbon molecule you breathe out has come from a plant, or an animal that ate a plant. While the plant was growing, it took in this carbon molecule from the atmosphere, in the form of CO2. So the whole process is carbon neutral obviously. The same applies for all life on earth, and there is no net effect on global warming.
Apart from when the carbon molecules are formed with hydrogen to make methane (think cows). Since methane is 12? times as effective a greenhouse gas than CO2, a CO2 molecule taken up by the plant ends up as a CH4 molecule in the atmosphere.
Pigeonwolf said,
May 7, 2008 at 9:01 am
By the theory that the carbon we breathe came from a plant (or animal that ate a plant), we could use the same theory that fossil fuels come from fossilised plants or fossilised animals that ate plants and are thus carbon neutral. The theory (whilst being technically true) is obviously flawed, not least in that around the world, forests are being burned to make room for farmland to feed the ever expanding population. We are thereby losing a constant in the equation (trees).
Tyler said,
May 8, 2008 at 11:42 pm
What wikipedia page did you find that on?
SY said,
May 17, 2008 at 1:35 pm
It is true that the whole world is a closed system, with fixed amounts of carbon, oxygen and other elements. The problem is the balance between the forms of these elements. Currently we appear to be producing CO2 (gaseous form) faster that it is being re-absorbed as pants and trees (solid form).
Actually the Human Race is the problem, not only through breathing out CO2, but by consumption too. The world would be in balance with a smaller population. Population growth is the real problem to everything!
Daniel said,
June 15, 2008 at 12:30 pm
Has anyone considered that plant life on earth may be limited by the fact that CO2 is less than 0.04% of the content of air. By contributing extra CO2 we could actually be encouraging plant life to develop as there would be higher concentrations of CO2 for the plant to breathe and thus allow to grow. Even if we clear forests etc, the plants will still find a way to thrive as life always has. Maybe we will see plants grow further inland thus creating more rains (as the oxygen meets hydrogen in the air and creates clouds/rain) on mainlands. To me this is common sense. Can anyone point out otherwise?
William Tell said,
July 3, 2008 at 7:42 pm
Wikipedia, the stated source for much info generating claimed factual science should be held in the highest level of skepticism. Individuals attempting to correct their personal bio’s have reported their attempts repeatedly corrupted to reflect falsehoods. This is an example of the inside agenda of select Wikipedia editors molding topics and content. Although this is not pervasive throughout Wikipedia as yet, it is worth noting for the most polarizing topics of debate. Be sure to use multi-facet cross checking of data to support all of your facts.
Tiburon said,
July 4, 2008 at 11:11 pm
Yes, the positive effects of CO2, especially in light of our growing population’s need for food and shelter (expected to stabilize around 13 Billion or so demographically, as I recall), has been well considered! See: - CO2Science.org.
This will be an especial boon while we go through what’s beginning to look like a repeat of the Dalton Minimum (Little Ice Age/LIA).
shmoopie said,
July 6, 2008 at 5:52 pm
The problem is that you have all fallen for the construct that CO2 is bad and causes global warming.
ALL GASES are greenhouse gases.
Our atmosphere is 79% Nitrogen, 20% Oxygen, 1% everything else. The everything else makes only a small component of how radiant energy is trapped by the atmosphere. And CO2 is only 0.2% of the atmosphere. Now, on the other hand, Methane is MUCH more dense than O2, CO2, or N2. If you accept the great Global Warming Religion, we should all be burning as much natural gas as possible (currently seeping out of the ocean floor at an alarming rate) and converting it to CO2 and H2O.
BTW, the “Science” behind Global Warming is being proven fraudulent.
The 1990s and 2000s were NOT the hottest period in modern history, the 1930s were. The methodology of putting an ever increasing number of weather stations in urban an suburban settings (heat sinks- steel, concrete, and asphalt), in some cases next to air conditioning exhaust on rooftops, and comparing them against different measuring devices with less accuracy and, trying to statistically compare to within a fraction of a gradient (not possible on the older instruments) is the very definition of UnScientific.
The last 2 years have been frigid, just as the last 3 Atlantic Hurricane Seasons after Algore’s movie have been unusually quiet.
Oh, and the Earth is NOT a closed System. Heat from the Earth comes from The Sun. The Sun is not a constant. Global warming Religion makes no room for varying output from The Sun in it’s models. Strange, huh.