How many metric tons are there in 1ppm of carbon dioxide?

Question

I've been reading websites about global warming (fun...), which all talk either in terms of parts per million (ppm, currently approximately 380 ppm globally) or emissions in metric tons.

What I don't understand is, how many metric tons of carbon dioxide equal one of those ppm floating around in the atmosphere? As a bonus question, how much emissions in metric tons do people say is sustainable at X number of ppm in the atmosphere? I've read that in the past (prior to the industrial revolution) it was about 300 ppm...

Hopefully that makes sense.

Answer 1

PART ONE

2,130,000,000 metric tons of CO2 = 1ppm

Concentrations of the different atmosphereic gases are measured in parts per million, billion or trillion. Currently there are 386 parts per million by volume of CO2 in the atmosphere (0.0386%) and this has a total mass of 822 billion tons (± 1%). 1 ppmv would therefore have a mass of 2.13 billion tons (822 ÷ 386).

Previous answers are excellent but there is an error in that it's not possible to divide the total mass of the atmosphere by the concentration of carbon dioxide, this would only work if all atmospheric gases had the same mass per unit - they don't, they vary from 1 for hydrogen to 220 for radon, CO2 is 44.

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PART TWO

3 billion tons of CO2 emissions per annum is sustainable.

Over long periods of time the level of sustainability varies. In the past there have been times when CO2 levels have been much higher and much lower than they are at present. These changes happen through natural processes which generally happen over long periods of time and so allow nature the time it needs to adjust.

All the time humans have been on the planet levels of CO2 have varied between approx 190 and 280ppmv, levels have been fairly constant and changes in levels have been slow. As such, nature has adapted to the changes and a level of suatainablility has been maintained.

If we look only at natural cycles there is a surplus capacity for the removal of 3 billion tons of CO2 each year (2 billion tons to the oceans and 1 billion tons to biomass). In this respect the production of 3 bn tons of CO2 would be a sustainable amount.

It's not quite as simple as that. If we now factor in global warming it means there has been a disruption to the natural cycles and some of them are now able to remove more CO2. A warmer climate slowly leads to warmer oceans which can absorb greater amounts of CO2.

Greenhouse gases are resident in the atmopshpere for quite some time (it varies from a few years to tens of thousands of years depending on the gas in question), if we ceased production of all greenhouse gases the planet will keep warming and a peak would be reached when approx 9 billion tons of CO2 were being removed from the atmosphere each year.

Answer 2

Weight of the atmosphere is about 5 X 10 to the 18th kilograms. 5 X10 to the 15th metric tons.

http://jupiterscientific.org/review/shnecal.html

So 1 ppm CO2 is about 5 X 10 to the 9th metric tons.

Or 5 "gigatonnes". (Close enough to patrick, we're both making some rough assumptions). Or about 10 thousand billion pounds.

Jim z - It's simpler than that. We're at about 400 ppm and increasing it by about 2 ppm a year or 0.5 % or 1/200. Our emissions are a bit more than that (the Earth absorbs some) so our emissions are close to 1/130.

You're off a factor of 1000 somewhere.

EDIT 2 - jim z. 6 orders of magnitude for ppm, + 3 orders of magnitude for converting kg to metric tons; is where the 9 comes from. I suspect your error of 1000 is in the kg-metric tons conversion.

EDIT 3 Trevor (of course) has nailed Patrick and myself for inappropriately mixing weight and ppm by volume. His number is correct.

But we're all three saying about the same thing, all answers are "a few" gigatonnes. 2, to be fairly precise.

Answer 3

human activity creates a surplus of about 15 billion tonnes of CO2 in the atmosphere each year, and CO2 is apparently increasing at about 2ppm/year, so the number should be around 7.5 billion metric tonnes/ ppm.

this picture shows the atmophere contain 750 Gt of carbon

http://en.wikipedia.org/wiki/Image:Carbon_cycle_diagram.jpg

which equals 750*(44 amu CO2/ 12 amu C) = 2750 Gt of CO2

2750 Gt / 380 ppm = 7.24 Gt/ppm

nature takes back about 1/2 of our current emisions, or about 15Gt/year. But this number is also dependent on other factors like temperature and concentration. In other words, depending on conditions nature will take back less or more.

higher concetration in the atmosphere makes nature want to take back more and higher temperature makes nature want to take back less -competing forces.

edit

FYI
"ppm" can refer to several different concentration units
for example...

ppm weight:
ie 1 microgram/gram
or
ppm by number of molecules:
ie 1micromol/mol
or
ppm by volume:
1 microLiter / liter

and a few others

typically when dealing with gases, ppm by volume is used

my estimation is rough, but im sure 1ppm will be in the neighborhood of 10^9 tonnes

edit 2:

trevors 822Gt is refering to elemental carbon weight, and it the same calculation i did. This becomes a point of confusion that I didn't figure out until recently when they say 822Gt carbon they really mean elemental carbon - not co2.

so adjust trevors answer as follows:

822( 44 g/mol CO2/ 12 g/mol C) = 3014Gt CO2

3014 /386 = 7.8 Gt/ ppm

edit 3

ya, i'm not mixing weight, my method is the same as trevors, I am adding two extra oxygens for every carbon, his only accounts for elemental carbon weight. Trevors answer is how much weight is added to the atmosphere by 1ppm, mine is how much 1 ppm of CO2 in the atmosphere weighs, which is what you were asking.

Answer 4

Darn it, I erased my first answer.
(this may be it)
Mass of the atmosphere is 5.1361×10^18 kg (from wiki)which is equal to about 380/1,000,000 is CO2. Therefore 1.95 X10^15 metric tons of carbon. If we produce 15X10^9 metric tones per year as someone said, then that would be adding 1/130,000 of the CO2 in the atmosphere per year assuming my calcs are correct. I am rusty in my calcs but I think it is even less than I thought it would be.

I have been having some internet problems.

Actually Bob is off by a thousand. ppm is parts per million (10^6) not parts per billion (10^9). so multiply his number by 1000. In other words, subtract 6 from 18 not the 9 which he did.

Also, it weighs nothing but does have mass

Answer 5

definite. Technically, mass and weight are 2 diverse properties as our calculus minded buddy noted. Laymen use them interchangeably nonetheless. to place it in perspective, human beings generate approximately 35 billion a lot of CO2 each year. the finished biosphere generates approximately six hundred billion a good deal, interior the cycle between flowers and animals. so the $sixty 4 question is, is this added 35 billion a good deal sufficient to make a measurable distinction interior the ambience? And the jury remains out on that question.

Answer 6

That question cannot be answered.

You ask how much does 1 part per million weigh. You don't specify the volume.

1ppm of one cubic foot weighs differently as 1ppm of one cubic meter.

Answer 7

Do you know what it is that you are asking? I don't!