How can CO2 cause global warming when it constitutes only 0.038% of the atmoshere?

Question

How can CO2 cause global warming when it constitutes only 0.038% of the atmoshere?

Answer 1

We're lucky it does, because if our atmosphere was purged of greenhouse gasses our planet would get a whole lot colder.

But really, we're lucky plants have adapted to live on such a small amout of CO2.  The natural balance of the equation that no one thinks about is that increased CO2 in the atmosphere means increased biomass growth.

Answer 2

Better yet, co2 levels increased 100ppm over the last 100 years, or just one molecule of co2 per million a year.  This lone molecule per million is being blamed for a 7 degree rise in global temperatures.

Yet Mars atmosphere is a full 95% yet the temperatures don't go much above -100 degrees.

Answer 3

Actually a good question.  First, lets start  with the fact tha tCO2 is a greenhouse gas. Now, skipping the dentals of physical chemistry, this means it acts a blanket,trapping heat.

Now, please bear with me--I might seem to get off topic, but I'm not.

Now, think about the air we have surrounding us. It has weight--not much, compared to say, a rock--but some. Get enough of it and it can weigh a lot--and we are at the bottom of a 60 mile deep oceanof air, more or less.. If you want to know how much--that's actually easy to figure out. The amount of air above any given area on the earths surface is equal to the  force it presses down with--which is 14.7 pounds per square inch.  That means that thees 14.7 pounds of air above that square inch of ground--a column of air 60 miles high!.

Now--in one square foot, that works out to justt about 2000 pounds (metric: about 10 000 KG/square meter)

Rememberthat 0.38% CO2 you mentioned?  0.38 % of 2000 pounds is 7.6 bounds--per square foot.    Now--let's make that a bit bigger--a 6 X 5 foot square ( about the size o fa medium sized blanket)  Our CO2 "blanket" weighs just about 228 pounds!  Don't know about you, but I think that's one hellava heavy blanket!

Now--there is supposed to be some CO2 in the air.  With the normal amount, we end up with a balance at a certain temperature.  Heat is escaping as fast as its absorbed--just as it does when you get under a blanket at night. YOu warm up to a certain point, then a balance is reached and you don't get any warmer.

UNLESS  you add another blanket. If you do,  you will start getting warmer again, until a new balance is reached at a higher temperature.

Now--lets say we add another "thermal blanket" of CO2to the normal amount that's supposed to be there--not a huge amount. Say a bit over 4 pounds for our 6x5 foot square, That's a 2% increase.

Now, stop and think about this. Suppose you lie down and pull a 4-1/2 pound banket over you. Yu are going to notice that you warm up a few degrees.

That's basically it.  Add even a relaive small amount to the CO2 that's already in the atmosphere--and you get a increase in temperaure that's enough to be important.

What makes it important is the fact that the Earth IS in a complex balance.  A degree or two is enough to melt the entire Arctic ice sheet and start melting the iceaps of Greenland and Antarctica. It's enough to heat the oceans slowly but surly, shifting currents and disrupting ecologies. It s enough to alter weather patterns drastically--and I'll use that to shw WHY a small change can make such a big difference.

Think. Our weather patterns in the Northern Hemisphere are formed mostly n the Arctic.  All year long, fronts form and sweep down and across the entire Northern Hemisphere.  But--they've always formed over nice, cold ice.  If that ice is gone, sorms are going to have much warmer seawater to draw moisture and water from.  Think what that woudld mean--a climate pattern of much more severe storms, altered rainfall patterns, etc.

There's many other scenarios as well--the earth is a very large and complex system, and  global warming is just that--global. It can affect everything.  Now--so far--the effects aren't drastic.  But we are getting very close to the point where they will become drastic.  Remember, unless we are lucky, the entire Arctic ice sheet will melt-not in the distant future--THIS year.  What exactly will the effects be (other than we can figure on more violent storms generally). Right now we don't know--orhw  bad it might get as global warming continues to worsen.

And--heres another point (about ecology).  Organisms are adapted to their surroundings. Given enough time , they can adjust to changing conditions--or migrate.  ut the global warming we are now having is VERY rapid--at least 100-1000 times as fast as a natural ccle.   There is nt enough time for pants and animals to adjust.  And--take jsut one exampee. Coral reefs.  Coral is VERY sensitive to temperature change. The rise in ocean temperatures is already having an effect. Another degreeor two and the coral willstart dying--if it isn't already. That kills the plant ecology that depends on the coral. Which kills the small fish that eat the plants. then the bigger fish that eat the smaller fish.

Now--what happens if a similar ecological disaster from global warming kills off the Amazon rain forest?  That is where 20% of the oxygen on earth--the oxygen you breathe--comes from.

Sorry to go on so long--but your question is a good one and merited a complete answer (which  this is not--but at least it gives you a good outline)

Answer 4

Because if 0.01% more heat comes in than goes out, it has to be getting slowly warmer. Of course if it was 1% or 10% it would get warm faster, but you get the idea.

Answer 5

Greenhouse gasses like H2O and CO2 have large absorption cross sections on the order of 1E-19 cm^2 in the mid infrared

H2O data

http://savi.weber.edu/hi_plot/plot_hitra...

CO2 data

http://savi.weber.edu/hi_plot/plot_hitra...

whereas the much more abundant N2 and O2 have absorption cross sections on the order of 1E-28 in the same region.  

N2 data

http://savi.weber.edu/hi_plot/plot_hitra...

O2 data

http://savi.weber.edu/hi_plot/plot_hitra...

Note the shape of the black body radiation curve for 310 K here

http://hyperphysics.phy-astr.gsu.edu/hba...

The average earth temperature is about 288 K, so the curve for the earth is shifted shifted to slightly longer wavelengths.  Note that the H2O band near 1640 cm-1 and the CO2 band near 710 cm-1 are the main contributors to the greenhouse effect.  The stronger absorptions at about 3500 cm-1 for H2O and 2350 cm-1 for CO2 contribute less because there is not much black body radiation from the earth at those frequencies.  The N2 absorption is both very weak and at too high a frequency for the earth's thermal radiation.  

Although CO2 is 0.00038 of the earth's atmosphere, it's effect per molecule is approximately 1,000,000,000 times as large as the more abundant N2 and O2.  After factoring in abundance CO2 (and H2O) absorb thermal infrared radiation about 100,000 times more effectively than N2 and O2.  You might ask, if CO2 is so effective at absorption, is it not saturated?  Well that's where the Einstein A and B coefficients come in.  It turns out that a good absorber is also a good emitter.  When a CO2 molecule absorbs an infrared photon, it soon emits another infrared photon in a random direction, possibly back toward the ground.  Infrared photons at frequencies absorbed by CO2 or H2O can be thought of as diffusing via a torturous path to space.  An energy density gradient is established with more energy = higher temperature near the surface and less energy = lower temperature near space.

EDIT

crabby (above) picks up where I ended.  His blanket analogy corresponds to my photon diffusion.

Answer 6

It can't- there's much too little of it.

Answer 7

That's just it ! It can't ! And so called " Global Warming " has happened many times in the past ! It's all clearly laid out in the Book ' Black Gold Stranglehold ' .Do a search on that Title.Better yet, get a copy.Also, the Book accurately points out that there is no such thing as " Fossil Fuel ".It constantly regenerates within the Earth, just like Volcanic Lava.This explains why when a Volcano erupts, there is usually fire present.That ain't Lava burning ! Also, why have no Dinosaur Bones been located in the Oil Fields of the Middle East ? And, NASA has detected Petroleum beyond the Earth.Now, just how did " Fossil Fuel " get there ? The Myth of " Fossil Fuel " and " Global Warming " go hand in hand.But, when it comes to Smog, and Air Pollution, the burning of Coal and Petroleum do indeed cause problems.If every Gasoline burning Vehicle could be set up with a Fuel Vaporizer, this problem would be eliminated.But, it's illegal to even attempt to do so on any Vehicle in the U.S. from ' 96 to the present.If these Environmentalist Wackos are so concerned, then why won't they address this issue ? Because it's all about Greed, Profit, and Government Control ! And " Global Warming " makes for a perfect excuse to maintain the status quo !

Answer 8

Ahh More jello science, the observed temperature rise is 0.7 not 7 and yes Mars atmosphere is 95% C02 but its atmosphere is also 1% of Earths and has almost no atmospheric water vapor, no oceans to act as heat sinks to absorb heat, Mars is also 80 million km further from the Sun than Earth.

Answer 9

Global Warming is a myth and here is why.....

this is what they want you to believe (in quotes)...

"What causes global warming?

Carbon dioxide and other air pollution that is collecting in the atmosphere like a thickening blanket, trapping the sun's heat and causing the planet to warm up. Coal-burning power plants are the largest U.S. source of carbon dioxide pollution -- they produce 2.5 billion tons every year. Automobiles, the second largest source, create nearly 1.5 billion tons of CO2 annually."

-----guess how much co2 is in the atmosphere? ... u guessed right, 0.04% (thats right, 0.04% of the atmosphere that is co2 is causing "global warming") ... and can someone explain to me how the co2 floats up into the atmosphere but when you blow up a balloon with co2 it doesnt float? (its scientifically impossible so dont bother explaining) .......... and guess where the so called scientists/experts take their "accurate" readings of co2 from? right above the active volcano Mount Kaleau (sp?) in Hawaii ..... accurate and fair, right? ... no , not rly .......... f.y.i., mars has a atmosphere with 95.3% co2, the average temperature there is -63° C (-81° F)

"Is the earth really getting hotter?

Yes. Although local temperatures fluctuate naturally, over the past 50 years the average global temperature has increased at the fastest rate in recorded history. And experts think the trend is accelerating: the 10 hottest years on record have all occurred since 1990. Scientists say that unless we curb global warming emissions, average U.S. temperatures could be 3 to 9 degrees higher by the end of the century."

-----OMG!!!!!!!!! the 10 hottest years on record??? ... not so much, temperature has only been recorded since the late 1800s, so its not bad at all ... and since 1998 temperature has been decreasing on earth

Answer 10

It doesn't make sense to me either. Not only that, but co2 is supposed to follow increased heat by as much as 800 years. That's not in line with the theory being presented either.

Answer 11

because some environmentalist scientist said so!

Answer 12

0.038% and rising.  This rise in this type of greenhouse gas can make the Earth slightly hotter, unnoticeable by mere humans, but our ecosystem can detect this temperature difference quite nicely.

Answer 13

Because it holds in the heat from the Sun.  It's the same reason it's warmer on a cloudy night than a clear one.  

It's a small effect, only a few hundredths of a degree C per year. but one that will cause great damage, if we don't do something about it.

Answer 14

It has a relatively large effect because of a number of things.  Nitrogen, the largest constituent of the atmosphere, is almost completely transparent to infrared radiation.  Diatomic oxygen is also not much of a greenhouse gas.  That's about 99% of the dry atmosphere right there that doesn't participate in global warming.  Water vapor is a relatively large part of the atmosphere and is a greenhouse gas, but the amount of water vapor is regulated by the temperature of the planet--that is, if you put more in the atmosphere it just rains out, and if there is a "shortage" you just get more evaporation from the oceans.  So water vapor is not a driver of global warming, although it will increase the size of the effect.

That leaves CO2 as the most important gas for causing global warming, despite its small concentration. It's not that surprising, really, there lots of things that can have large effects in small concentrations.

EDIT: CrazyConservative, so you admit that CO2 is a greenhouse gas and is increasing? Nobody said that the change was huge every year, but it just keeps adding up, year after year, which forces the Earth's temperature to increase.  Of course this will warm up the oceans and evaporate more water vapor into the atmosphere, which you already said was the most important greenhouse gas.

Also, you mention how overnight temperatures plummet in the deserts, so I just wanted to mention that the temperature has dropped to a frigid 98 degrees in Palm Springs at 10pm, by early morning it may almost be down to 80 degrees.  Brrr!

EDIT2: Palm Springs temperature update--5am and it's dropped to an almost unbearably cold 91 degrees!!

Answer 15

there is no such thing as global warming...

Answer 16

"How can CO2 cause global warming when it constitutes only 0.038% of the atmoshere?"

0.038% is not an acurate figure as several above point out  the bulk of the atmosphere has no greenhouse effect

oxygen 20% and nitrogen 78% have no greenhouse effect thats 98% all the greenhouse gases fall in the last 2%, including water vapor.

Answer 17

0.038% doesn't sound like much, does it?  Of course, arsenic will kill you at a level of about 0.006%, so a small percentage doesn't mean much.  You need more information than that.  In the case of arsenic, you need to know its toxicity.  In the case of CO2, you need to know its global warming potential.

Moreover, 99% of the atmosphere isn't greenhouse gases.  Nitrogen, oxygen, and argon are transparent to infrared wavelengths.  So while CO2 is only 0.038% of the atmosphere, it's a much larger percentage of the greenhouse gases in the atmosphere.  In fact, CO2 accounts for 9-26% of the greenhouse effect on Earth.  Seeing how water vapor accounts for the most but is a feedback and not a forcing, CO2 is absolutely critical to global warming.  

See Myths #8 and #9 in the link below for further details.

Answer 18

Not only that, but it is a MINOR greenhouse gas. Look at the linked graph. What it shows are the different wavelengths absorbed by the different greenhouse gases. Compare CO2 to the water vapor. Water vapor absorbs wavelengths through out the spectrum. Co2 only absorbs wavelengths in 4 small bands (around 3, 4, 6, and 15. Of these areas, the first is rather minor, the second area is completely over shadowed by water vapor, the third does absorb most of the wavelength and the fourth overlaps again with water vapor. The actual absorption of sunlight by Co2 is only about 8%. Compare that to water vapor and you will see that CO2 does very little as far as greenhouse effect is concerned.

Last thought, in a desert temps soar into the triple digit range. But at night, the temps plummet because there is so little water vapor. The CO2 content is about the same as everywhere else, but it does little to retain the heat. Compare that to a humid day and everyone should realize how little CO2  does.

http://wattsupwiththat.files.wordpress.c...

Answer 19

This is why some people claim that co2 is the biggest scam.  All of the answers above are misleading.

According to IPCC science, a doubling of co2 alone without any feedbacks will cause about one degree Cecilius increase over one hundred years.  That part is not in dispute, even by most climatologists who are skeptics.  

The scam is when the doom sayers are saying that this small increase will be amplified many times over, by a positive feedback.  But yet none of the top contributors seemed fit to explain that to you.  Do you know why? Because that part of AGW theory is very dubious and highly questionable.

Answer 20

It's the increase in volume of CO2 in the atmosphere that contributes to global warming.  When the CO2 is constant there is no global warming as the CO2 absorbs heat at a balanced rate to help keep our Earth warm.  Until the past couple of decades our Earth's temperature rarely exceeded a 1 degree change from year to year.  In other words the world's temperature, overall, was constant year by year.

Now we have unforeseen temperature increases mostly at the poles.  Many parts of the Canadian Arctic are now 5 degrees above normal.

Answer 21

How can you drown in the top few feet of water in the ocean when there are thousands of feet of water underneath you?