How could CO2 cause global warming?

Question

If all of the IR energy emitted by the sun (in the CO2 absorbtion spectrum) is aborbed by the atmosphere before it reaches the Earth, and all of the IR energy emitted by the Earth (in the CO2 absorbtion spectrum) is absorbed by the atmosphere before it reaches space, then how could an increase in CO2 cause increased warming?

Answer 1

Good question. If what you say is true, and no IR in CO2's absorption spectrum can get through the entire depth of the atmosphere in either direction without being absorbed, then I would assume that it's IR reflection or scattering that is causing the problem and trapping heat. Also, if you doubled the amount of CO2 in the atmosphere, wouldn't that reduce by half the mean path that IR travels from earth's surface before getting absorbed? The absorbed IR heats the molecules, and they re-radiate in all directions. I would imagine that if the mean altitude at which this IR absorption and re-radiation occurs is reduced, then this would have an effect. It sounds like a complicated problem that needs numerical modeling to really understand. But I've got a hunch that the key to resolving your paradox has to do with the fact that thermal re-radiation of the energy absorbed by those CO2 molecules is broad-spectrum (not just in the CO2 absorption band) and that lowering the altitude of the absorption and re-radiation will lower the net rate of IR re-dadiation into space. Again, this is an excellent question.

Answer 2

Because CO2 is a greenhouse gas - along with, water vapor, nitrous oxide, and methane.

The greenhouse effect is the rise in temperature that the Earth experiences because certain gases in the atmosphere trap energy from the sun. Without these gases, heat would escape back into space and Earth’s average temperature would be about 60ºF colder. These gases are important and have always been there, it has never been debated that CO2 is a greenhouse gas. The problem is when humans increase the concentration of greenhouse gases we also increase the greenhouse effect.

Answer 3

The planet is warmed due to it's proximity to the sun and it's temperature is moderated by the heat retaining properties of the atmosphere. Were it not for this heat retaining ability our planet would be bitterly cold and uninhabited.

The heat we receive from the sun reaches us in the form of solar radiation, this has a very short wavelength and passes easily through the atoms and molecules that make up our atmosphere. This heat is absorbed by anything it strikes - mostly land and water but also buildings, vehicles, roads etc.

When the ambient temperature falls heat is radiated back out from these surfaces as thermal radiation (just like a giant radiator). This thermal radiation has a longer wavelength than solar radiation and the comparatively large molecles in the atmosphere impede progress thus preventing some of the thermal radiation from exiting the atmosphere.

It's this principle of letting heat in and retaining some of it that we refer to as the greenhouse effect and it's the molecular gases such as carbon dioxide, water vapour and methane that we refer to as the greenhouse gases.

The more greenhouse gases there are in the atmosphere the better the insulative effect becomes and the current concern is largely centered around the extremely rapid rise in levels of greenhouse gases.

Answer 4

(Almost) everything that absorbs will re-radiate that energy. Of course, not all of that energy will be directed back at the Earth, but a good portion will be. Especially with relatively heavy CO2, which is primarily below the cloud layer in our atmosphere. Clouds can amplify CO2s effect by reflecting energy that would otherwise be radiated back out to space

Answer 5

Excessive CO2 in the atmosphere doesn't cause global warming. It's just a symptom of it. The direct cause of today's global warming is a natural balance being tipped. When forests are subtracted and *'radiant heat sources' and excessive combustion of earthly energy sources are added to this finite planet, global warming increases. As long as the global population of human life increases, more and more raw forest land will most likely continue to be cleared away to meet the needs of human population growth. Photosynthesis does not warm the planet.

*Radiant Heat Sources include, but are not limited to asphalt roadways, concrete earth coverings and the average buildings and rooftops.

The uncomfortable truth is that humans need to follow after the model of Cavemen, Native American Indians and Ewoks in order to keep humanity from wiping the earth's slate clean of life as we know it. Either that, or exterminate the source of the problem - Humans. I think most of them are already doing a fine job of indirectly exterminating themselves and others even though they will never admit it.

Answer 6

U need to study the CO2 thing a little better. First CO2 is very heavy and will fall right to the ground. If the CO2 has increased as much as u think u would die if u laid down on the ground. Most CO2 in our atmosphere is near the ground. We take a CO2 extinguisher to put out a fire because it smothers it. There is another part that Mother nature recycles our air with plants and photosynthesis.

Answer 7

The sun radiation (short wave) comes in. Some is re-emitted as long wave radiation which is radiated back by GHG's.
Check this link.

Answer 8

In simple terms...
Ozone is the blocker, CO2 is the ozone killer