FROM THE FIELD
Climate Week NYC

You Asked: How Does Carbon Dioxide Get So High Up Into the Atmosphere?

by |September 23, 2020

September 21-27 is Climate Week in New York City. Join us for a series of online events and blog posts covering the climate crisis and pointing us toward action. This week we are dedicating our You Asked series to tackling reader questions related to climate change.

The following question was submitted by a reader, and the response comes from climate scientist Ángel Muñoz.

Q:

How does CO2 get high up into the atmosphere? With a specific gravity of about 1.5, it should fall to the earth as it cools when rising. The airlines tell us that it is -40 degrees at 30,000 ft. So why or how is it that some CO2 works its way up into the upper atmosphere?

A:

angel munoz in a vineyard

Ángel Muñoz is an associate research scientist at the International Research Institute for Climate and Society and leads the Latin American component of the Columbia World Project “Adapting Agriculture to Climate Today, for Tomorrow” (ACToday). He is also a devoted wine connoisseur and is pictured here with Carménère grapevines in Chile.

Carbon dioxide is a gas. The density of a gas increases as temperatures get colder. So, because temperatures decrease as we reach higher altitudes, gases become denser at higher altitudes. Denser objects tend to sink, pulled down by gravity. (In fact, the force of gravity pulling gas molecules towards the Earth’s surface is what maintains our atmosphere.) Different gases also have different molecular weights. CO2 is heavier than oxygen, so we might expect every CO2 molecule to sink below a layer of oxygen molecules. Generalizing this idea to the other gases in the air, we might deduce that this would result in a perfectly stratified atmosphere with separate layers of each type of gas.

We can see an example of a stratified atmosphere inside a bottle of wine. When the bottle is sealed, air between the surface of the wine and bottom of the cork includes both oxygen and CO2. Because CO2 is heavier than oxygen, gravity forces CO2 molecules to form a “layer” beneath the oxygen molecules, helping to separate the wine from the oxygen. Desirable properties of wine, such taste and smell, begin to change once the liquid is fully exposed to oxygen. Without the stratification inside the sealed bottle, we wouldn’t have that cushion of CO2 to protect the wine from oxygen, giving unopened wine a much shorter shelf life or even turning it into vinegar over time.

Earth’s atmosphere is not like the air inside a sealed wine bottle. Atmospheric gases are well-mixed, not stratified. This due to the force of diffusion. Gas molecules want to move, and they will expand to fill the volume within which they are contained. Confined to a tightly sealed container such as a corked wine bottle at constant temperature of about 52-57 degrees F, gasses have no room or enough “excitement” to expand and move around. They settle into layers based mostly on their molecular weights. However, the Earth’s atmosphere is much more expansive than a wine bottle. CO2 does not break down until about 80 kilometers from the Earth’s surface, giving atmospheric gases a huge expanse to occupy. Excited by the heat radiating from the Sun into the atmosphere, molecules move rapidly. As they bang into each other (for example, at 63 degrees F, CO2 molecules crash together about 7 billion times per second), the gas molecules intermingle, rather than settling in stratified layers. It is mainly diffusion that allows CO2 to integrate at altitudes higher than what its molecular weight alone would suggest, although other processes, like strong updraft and downdraft air currents, are also involved.

drawing of co2 behavior

A handmade drawing explaining the different forces at work in a wine bottle versus the Earth’s atmosphere. Image: Ángel Muñoz

Similarly, upon uncorking that wine bottle for the first time and bringing it from the cellar to a warmer room temperature, the trapped gasses become a part of the larger atmosphere. Gas molecules mix, and after the bottle’s vacuum seal has been broken, replacing the cork means well-mixed molecules remain in the bottle once you replace the cork yourself. Oxygen is now able to reach the wine, eventually causing the wine to taste “off.” Anyone who has opened a bottle of wine to “let it breathe” before drinking it knows that some amount of oxygenation can improve the wine’s taste, but eventually oxygenation will ruin those desirable qualities. So, remember to responsibly consume a bottle of wine within a few days for best flavor. And remember that even in an airplane at 30,000 feet, gas molecules in an open bottle of wine will mix just as they do in the rest of atmosphere!

For details on how carbon dioxide contributes to climate change, check out these posts: How Exactly Does Carbon Dioxide Cause Global Warming? and If CO2 Is Only 0.04% of the Atmosphere, How Does it Drive Global Warming?


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Orin Grovum
Orin Grovum
2 years ago

Hi,
I just read Angel Munez explanation about CO2 rising in the atmosphere. Sorry but I rate this as a non-answer. He made a comparison of CO2 and oxygen, but seemed to forget that nitrogen makes up 78% of air while oxygen makes up 21%. The specific density of nitrogen is 97, while that of oxygen is 1.1 – they will mix quite well, and make up 99% of the air or atmosphere.
CO2 has a specific density of 1.51, and is less likely to mix with the other two – in fact the majority of CO2 falls to the ground level where is is either synthesized (photosynthesis) or absorbed by the great sinks of water, forests or prairie. While Angel’s comparison to wine is charming, it just isn’t credible!
If scientists could determine the mechanism that causes some CO2 to rise, perhaps something could be done to prevent the amount of CO2 in the atmosphere from increasing. If is doesn’t rise, it won’t be up there to absorb heat. The following scientific table should be reviewed – water vapour for example has a specific density of 0.62, and it does rise up into the atmosphere. CO2 will fall, unless something happens – what is the something?

Specific Weight is defined as weight per unit volume. Weight is a force. The Specific Gravity – SG – is a dimensionless unit defined as the ratio of density of the material to the density of water at a specified temperature. The specific gravity of some common gases can be found in the table below:
As a reference, normal air has a specific gravity of 1.
If the specific gravity is greater than 1 the gas is heavier than air and the vapor will be found low; the larger the number the heavier the gas is and the lower vapors will be found.
If the specific gravity is less than 1 the gas is lighter than air and the vapor will be found high; the smaller the number the lighter the gas is and the higher vapors will be found.
Various vapors can be “layered” when multiple gasses are present.
Gas Specific Gravity
– SG –
Acetylene (ethyne) – C2H2 0.907
Air 1.000
Ammonia – NH3 0.596
Argon – Ar 1.379
Arsine 2.69
Benzene – C6H6 2.6961
Blast Furnace gas 1.02
Butadiene 1.869
Butane – C4H10 2.0061
Carbon dioxide – CO2 1.5189
Carbon monoxide – CO 0.9667
Carbureted Water Gas 0.63
Chlorine – Cl2 2.486
Coke Oven Gas 0.44
Cyclobutane 1.938
Cyclopentane 2.422
Cyclopropane 1.451
Decane 4.915
Digestive Gas (Sewage or Biogas) 0.8
Ethane – C2H6 1.0378
Ethylene (Ethene) – C2H4 0.9683
Fluorine 1.31
Helium – He 0.138
Heptanes 3.459
Hexane 2.973
Hydrogen 0.0696
Hydrogen chloride – HCl 1.268
Hydrogen sulfide – H2S 1.1763
Isobutane 2.01
Isopentane 2.48
Krypton 2.89
Methane – CH4 0.5537
Methyl Chloride 1.74
Natural Gas (typical) 0.60 – 0.70
Neon 0.696
Nitric oxide – NO 1.037
Nitrogen – N2 (pure) 0.9669
Nitrogen – N2 (atmospheric) 0.9723
Nitrous oxide – N2O 1.530
Nonane 4.428
Octane 3.944
Oxygen – O2 1.1044
Ozone 1.660
Pentane 2.487
Phosgene 1.39
Propane – C3H8 1.5219
Propene (Propylene) – C3H6 1.4523
Sasol 0.42
Silane 1.11
Sulfur Dioxide – SO2 2.264
Toluene-Methylbenzene 3.1082
Water Gas (bituminous) 0.71
Water Vapor 0.6218
Xenon 4.53

Ralph Gardner
Ralph Gardner
Reply to  Orin Grovum
2 years ago

You first say that CO2 sinks to the ground and is absorbed by plants or sinks into water then you say the CO2 is up in the atmosphere absorbing heat. Is it some of each and if so how much of each?

Vincent
Vincent
Reply to  Ralph Gardner
1 year ago

what I ‘ve always heard is it reflects heat rays back to earth..hence the ‘glass – or green house’ effect..that’s the theory

Vincent
Vincent
Reply to  Orin Grovum
1 year ago

seems by your chart Co2 is one of the heaviest gases out there…

Peter
Peter
Reply to  Orin Grovum
1 year ago

For anyone in the west to go on about the need for ALL humanity to stop using fossil fuels demonstrates sheer ignorance or a brutal callousness. On any real issue affecting your life, it would be idiotic to have not looked into the detail. You would not do this with nearly anything else affecting your life. Yet, i find that a vast potion of my compatriots are perfectly contentr to have nefver thoghtr threu what- accoring to their very words- is the #1 issue of our times, likely the largest threat to all humanity.
But, for most westerners, US, UK and EU – i doubt they really spent any time critically thinking about the real challenges that some with the glib “stop fossil fuels” idea being pushed by activists and politicians. Arguably, if we would even be able to accomplish it, it would be the cruelest, most inhumane atrocity we would ever be able to commit onto the world population.
Refined petrol is an amazingly CLEAN fuel if only you take a second to remember that COAL, it’s far more vilified brother is STILL a VERY refined byproduct of natural synthesis- when compared to the what these things were BEFORE they were fossilized – biomass
Humans and nature have REFINED what other wise is a dirty agglomeration of energy containing biomass and made it denser.
As such, when we burn it, a LOT LESS harmful particulates are emanated.
As “dirty” as we like to think petrol products or coal are, let’s take a minute and realize that fully 75% of the world is NOT as wealthy as the west.
What does that mean from a practical point?
They cook and heat their homes with FAR dirtier alternatives like wood,straw,dung or other versions of energy dense biomass.
Poorer countries lack the strict regulation of developed industrial standards.
That quaint artisanal product you Amazon-ed from a mom and pop in rural Thailand or some small factory Mogadishu? Likely they did not produce it in a facility what had it’s effluents checked by the EPA on a monthly basis. But you don’t want to know anything about that.
It would harsh your mellow, planet saving outlook. You cut the plastic loops on a six pack and you recycle. You march for climate awareness and vote only for people that “get it”.
We could stop ALL fossil use in the US, and it would not contribute a sub-fraction of what getting the rest of the world AWAY from burning biomass and using at least centrally refined petrol or burned coal. In fact, fossil use is their sole ticket in advancing from poverty- something the ENTIRE world never could until fossil energy on a industrial scale became possible.
What does anyone propose we do about the poorer, larger part of the population – the majority?
Are we to condemn them to poverty or worse yet, interdict whatever meager means of survival they currently have access to? It seems to me we figured out how to be the world’s mosty evil a-holes while being able to keep up a convincing story that we are in fact doing good.
The entire climate movement lost me decades ago when, in the same year singers recorded “We are world” as a benefit for hunger in Africa, they did so in the same country that turned 15 million tons of corn into fuel. Despite that, we still made strides against poverty and hunger, so much so, that the world now contains more obese people than malnourished. Why? Fossil fuels!

Grant Molyneux
Grant Molyneux
Reply to  Orin Grovum
3 months ago

Your basic premise that the specific weights of molecules determining how a gaseous mixture might stratify in a closed environment subject to gravity is correct, all things being equal. (I should say, that I personally don’t believe CO2 is the driver of climate change, that is variability in solar irradiance and interstellar gamma radiation reaching us). All gases would stratify if there was no turbulence, caused by changes in gas temperature, water temperature and reflected heat from light coloured surfaces (albedo), and the fact that the earth rotates at 16,000 kph at the equator, but slower at the poles. The Gulf stream which a very turbulent pattern of wind movements in the upper atmosphere have a lot to do with the mixing of gases and water vapor that get that high (creating the blanketing affect that is the green house affect [a green house traps heat which allows people to grow vegetables in winter]). But below the jet stream, are other wind turbulence mechanisms that are constantly moving gases from one place (on the northern side of the equator they circulate in one direction on the southern side they circulate in the opposite direction). to another place around the globe. (remember what a low and high pressure air system is? That’s wind doing its thing together with changes in Temperature over land and sea). Often coming off the ocean surfaces and coming in to contact with updrafts once over a warmer land masses (not sure where you live but those big birds called condors and vultures need these updrafts and thermal (warm) winds to get air borne). You could think of gases being like a condor needing the updrafts to gain elevation. This is the exact principle that allows Glider planes and Para-gliders and delta wing gliders to even fly, with people attached to them. All of these things are heavier than CO2. Without wind turbulence or updrafts, none of these air craft or birds could take to the wing easily or at all. Final note: If there were no wind turbulence (moving air), at all on Earth, gravity would create a stratification of the gases due to there specific weight differences. But because the force of wind movement is greater than the weak force of gravity, they tend to mix.
As an aside, during the last ice age or glacial maximum (when it was at its coldest) places on Earth regularly experience winds of hurricane strength at more than two hundred kph. Due to there being a great deal of ice, there was an increased amount of Albedo also.
Hope that helped.

Valentino Pozzoli
Valentino Pozzoli
1 year ago

The explanation provided by Mr. Munez is completely wrong. Gases do not stratify, not even when confined in closed spaces. The very definition of a gas as is taught in any beginner’s physics class is that is has no shape and will fill a container uniformly of its own will. The “excitement” that Mr. Munez claims molecules need to move around the container is provided by the kinetic energy of molecules which at temperatures above 0°K (absolute zero) is always greater than zero. As a matter of fact at room temperature the molecules making up a gas travel at speeds that reach or exceed the speed of sound but as they keep bouncing off each other actual diffusion rates at the macroscopic level are much lower. This happens without an external energy source unlike what Mr. Munez claims as even without energy being provided for example by the sun’s radiation molecules will retain their kinetic energy indefinitely unless they can transfer some of it to other molecules (heat exchange) or convert it into some other form of energy such as electromagnetic radiation. In summary, gases would behave as Mr. Munez claims only at absolute zero, where the kinetic energy of its molecules would be zero, a condition that will never be found in nature. I respectfully request that this page be removed ASAP as it only serves to spread misinformation.

Dave
Dave
Reply to  Valentino Pozzoli
1 year ago

What are the “radiation molecules ” of which you speak?

Valentino Pozzoli
Valentino Pozzoli
Reply to  Dave
1 year ago

Sorry for the bad punctuation. It should have read “sun’s radiation, molecules will retain…”
Oh well, at least I did get my facts right instead of making it all up as I go, which I think is more important than punctuation especially in science…

Per wallen
1 year ago

When a volcano erupts we get along with some other gases and carbon oxide some times it erupted more that 5000 meter in to the sky. All scientists says that carbon dioxide will lay down on the ground. What’s the difference between co2 from a vulcanised co2 than from a car? Have anyone ever made any calculations on the difference. Best regards per wallen

Vincent
Vincent
1 year ago

The ambition is zero carbon mmissions..big question mark as to how this can be acheived.How would plants, trees, crops react to a drastic cut to Co2 ? could it be they would not grow as well ? Co2 is being painted as ‘the enemy’ .. but i’m not so sure …I think the world needs a re think on ‘zero emmissions’ before we waste huge amounts on something futile and not all beneficial…

Sarah Fecht
Admin
Reply to  Vincent
1 year ago

The atmosphere will still have plenty of CO2 in it if we stopped burning fossil fuels, because they will get it from natural sources.

Plants survived for hundreds of millions of years before we started burning fossil fuels, and they will definitely be fine afterwards, too.

Vincent
Vincent
Reply to  Sarah Fecht
1 year ago

you say natural…where would most of it come from ?

Sarah Fecht
Admin
Reply to  Vincent
1 year ago

It’s pretty cool actually — CO2 gets constantly recycled by nature:comment image For example, plants take it in during photosynthesis and turn it into sugar. We eat the plants and break the sugar back down into CO2, which the plants can use again. CO2 can also come from the oceans, soils, and volcanoes.

The problems happen when we bring up fossil fuels from deep underground, where they would have stored lots of carbon for millions of years. By burning them, we’re adding a lot more CO2 into the equation, and the rest of the cycle can’t keep up.

Dan
Dan
Reply to  Sarah Fecht
1 year ago

How can it heat up the earth if the co2 is up in the cold? Please explain that for me….

Sarah Fecht
Admin
Reply to  Dan
1 year ago

Earth’s temperature is determined by how much energy comes in from the Sun minus how much goes out to space. CO2 makes it hard for heat to get out into space. If you sit in your car on a cold day, even if the car itself is cold, it will still keep you warmer than if you were not inside the car, because it traps some of your heat.

Dan
Dan
Reply to  Sarah Fecht
1 year ago

ok thanks. Do you know the details how co2 can make that ”car effect”. I mean there is small amount of it compared to the other ”gases” up there.

Sarah Fecht
Admin
Reply to  Dan
1 year ago

Good questions. A lot of people are wondering about that, so the Earth Institute is preparing another article about this now. I’ll share the link when it’s published! In the meantime, this post might help, too: https://blogs.ei.columbia.edu/2019/07/30/co2-drives-global-warming/

But yeah, I agree that it seems kinda crazy that even though CO2 only makes up 0.04% of our atmosphere, it can have such a big effect! What I’m learning is that thinking about it as a percentage can be kind of misleading… Even .04% still adds up to a LOT of CO2 in our atmosphere — like billions and billions of tons up there.

Another thing: It’s not like the CO2 has to trap ALL of the heat to have an effect. Since Earth’s temperature = incoming energy – outgoing energy, all CO2 has to do is prevent some of the energy from leaving in order to cause heating. Sort of like how a blanket doesn’t have to be airtight to keep you warm.

I hope some of this is helpful. More details in a blog post coming soon!

Vincent
Vincent
Reply to  Sarah Fecht
1 year ago

it would be intersting to know how this is measured (the Co2) Bill Gates recently spoke of the world aiming for zero carbon emmissions…I think thats a long shot.. Planes wont run on batteries, neither will big cargo ships, even big trucks.. there is always a trade off. Ultimately it will also mean lowering our standard of living =less consumerism..

Sarah Fecht
Admin
Reply to  Vincent
1 year ago

You’re right, reaching net-zero emissions is probably not going to be easy. Thankfully we do already have a lot of tools to work toward that goal, including renewable energy, biofuels, electric vehicles, and carbon sequestration. And research suggests that taking these steps now will save a lot of trouble, money, and human lives later.

How to build a healthier and more sustainable economy is another interesting question! Earth Institute experts think it’s possible to maintain a good standard of living while trying to preserve the planet for future generations. Here are a few of their ideas on how it could work: https://blogs.ei.columbia.edu/2017/10/26/the-sharing-economy-is-transforming-sustainability/ and https://blogs.ei.columbia.edu/2018/12/04/create-circular-economy/

Janet B Chepulis
Reply to  Vincent
1 month ago

Since this is not working globally, and the less we use we buy it from other countries, then it will not make a difference, will it. We will be spending more to get it from them, but it will still be drilled in other parts of the world to meet the needs of everyone. Its a trade off, something only whereby our nation will suffer the most, economically.
.

Sceptic
Sceptic
Reply to  Sarah Fecht
1 year ago

IF CO2 blocks heat escaping, it should also block heat from entering. Your car analogy is flawed because the source of heat (you) are within the system.

Sarah Fecht
Admin
Reply to  Sceptic
1 year ago

False. The energy enters the Earth system as sunlight. When the sunlight hits Earth’s surface, that’s when it gets transformed into infrared (“heat”) energy. They’re two different forms of energy, and the molecules interact differently with each. https://blogs.ei.columbia.edu/2021/02/25/carbon-dioxide-cause-global-warming/

Vincent
Vincent
Reply to  Sarah Fecht
1 year ago

overall.. moisture, cloud cover , plays the biggest part in trapping heat and when ou think about it, we need that heat trap for life to be sustainable. Without it,it would be too damn cold ! It’s a question of balance though. I do wonder if we ended up with zero emmissions or net zero..what effect that would have on plant life, food, world temperatures ? maybe not all positive..industry & governments need to tread carefully…

Sarah Fecht
Admin
Reply to  Dan
1 year ago

Hi Dan, just wanted to tell you that we’ve published a blog post that may help to answer your questions: https://blogs.ei.columbia.edu/2021/02/25/carbon-dioxide-cause-global-warming/ Hope this helps! Take care.

Dave
Dave
Reply to  Sarah Fecht
1 year ago

How much of the sun’s energy is blocked or reflected by our atmosphere, incl6from clouds?

Musheer
Musheer
1 year ago

Please anyone can be explain me , my question is why do we feeling CO2 is up rise on oxygen bottom phase at rooms.?

fgfgkni
fgfgkni
Reply to  Musheer
1 year ago

Surprisingly, there is no conclusive scientific explanation why gas stratifies in layers of the atmosphere and yet mixes on the earth surface. Only some theories that all contradict each other.

Vincent
Vincent
1 year ago

Online Shopping..I dont think this gets enough scrutiny-and not just for finance issues. The shift from retail stores/shops to online webstores has meant more warehouses that take up a lot of land..and more traffic .A lot of the trucks & vans clogging up & polluting the highways are in effect , internet traffic..so many people clicking a mouse which sets off a whole chain of events..often for a low number of cheap items

Last edited 1 year ago by Vincent
anthony
anthony
1 year ago

This statement is scientific Incorrect. All gases densities are altered at different elevations and temperatures… not just one particular gas as you increase in elevation.

Ashley
Ashley
1 year ago

Air is made up of Nitrogen, Oxygen, Neon, Argon & Krypton, or so I have always been led to understand. So where does Carbon dioxide fit into the mix ? Surely this must be generally low down for plant life to exist.

Ashley
Ashley
1 year ago

Anyway, we should have listened to the hippies, & what some of the rock groups were telling us some 60 or more years ago. They were prophets of their time, & no one cared or took any notice!

Mike
Mike
1 year ago

It is logical that the denser CO2 molecule can diffuse. But there have been theories claiming the upper atmosphere is an important contributor to the greenhouse effect. With 0.04% CO2 perfectly diffused the argument would be strong. But isn’t it logical to assume that density does influence diffusion versus elevation? Do measurements conclusively prove an identical concentration of CO2 independent of altitude?

Scott
Scott
3 months ago

The root mean square (R.M.S) speed V of the molecules of an ideal gas is given by the expression, v=sqrt(3RTM) and v=sqrt(3KTm) where R is universal gas constant, T is the absolute (Kelvin) temperature, m is the molar mass, K is Boltzmann’s constant and M is the molecular mass.
Speeds of gasses
Gas Molar mass/grms speed of molecules at 300 K
Helium 4 1370m/s
Nitrogen 28 517 m/s
Carbon dioxide 44 413m/s.

Basically the molecules are constantly moving and colliding with each other and the walls so they will never stratify in a container (unless they undergo a transition change)
In the atmosphere there will be a height and temperature where the gas is moving too slowly and will fall back to earth under gravity.
Hydrogen is the only gas that has sufficient speed to escape the earths gravity and that is why H2 in the atmosphere is only 0.00005%.

Similarly although CO2 in the atmosphere is mostly originating in the Northern Hemisphere (especially in spring/summer) it is pretty much evenly distributed across the planet. The readings in Mauna Loa are nearly the same as Cape Grim. The Cape Grim readings show the seasonal variation even though the Southern Hemisphere largely does not have deciduous plants.

Liz
Liz
24 days ago

A bottle of wine is, when stored long-term, stored tilted on its side to keep the cork, made of real cork, not a modern screw cap with plastic seal. moist.

Any gases in the bottle rise to the “top”, or the upper side of the bottle. They can stratify there, with CO2 in contact with the wine and lighter gases near the glass.

The bottle is tilted so sediment will gather in the lower corner of the base.

Thermal action by solar heating on rocks, buildings, roads, roofs, desert sands and oceans is far more powerful than gravity and this results in constant mixing of atmospheric gases. Tornados, hurricanes, typhoons and cyclones mix the gases in a violent way. All these are basically created by solar heating.

The heavier gases have no chance to sink to the ground while being pulled by the weak force of gravity when they are being sucked upwards by the huge force of these weather events and other violent storms

William Duncan
William Duncan
7 days ago

I needing an answer to the best position to place a CO2 alarm regs in the UK state six inches 150mm from ceiling height . One to three meters away from source of burning . I work in construction an feel bad for this error in regs which i dont agree with.

Cheers Billy