Why is Methane considered a greenhouse gas?

Question

Why is Methane considered a greenhouse gas?

Answer 1

Because it traps heat in the atmosphere as other people have said before me. Although there's much less of it than other greenhouse gases such as water vapour and CO2, it's more potent. That means it traps heat more efficiently.

Also, in case it's interest to you, methane is produced by landfills and things like that aswell as farm animals digestive tracts. Lovely :]

Answer 2

methane is actually the third most abundant greenhouse gas. a greenhouse gas basically traps atmospheric heat. thats what methane does. if too much heat is trapped, the earth becomes too warm. hence the term greehouse effect.:)

Answer 3

You asked why is methane a greenhouse gas, and the short, common answer is that it traps heat.  But how does it do that?

The primary way that Earth gets its heat is as energy from the Sun in the UV and visible parts of the spectrum.  70 percent of the solar energy is transmitted through the atmosphere to be absorbed by the ground and water.  This heats up the surface of the earth and energy is radiated from these warmed surface as infrared energy.

Without greenhouse gases this infrared energy would be radiated back into space.  Of course we don't want to lose all of the thermal energy.  Water vapor, itself a very "powerful" greenhouse gas, and naturally occurring CO2 will absorb IR light and keep it from leaving by warming the atmosphere.  This natural balance of energy coming in and energy leaving maintains a constant atmospheric temperature.

But add additional gases to the atmosphere that absorb infrared energy, and the atmosphere heats up.

How does methane or any other greenhouse gas absorb IR?  Methane, CH4, has four bonds from a central carbon atom to four hydrogen atoms.  Don't think of these bonds as rigid "sticks", but as springs.  The springs can stretch and compress and the springs can wag back and forth.

That's what chemical bonds do, they are constantly vibrating at certain very high  frequencies which have the same frequencies as different wavelengths of light (UV, vis and IR).

When light of a particular frequency strikes methane, in which the bonds are vibrating at the same frequency, then the energy of the light is absorbed by the vibrating bonds and makes them vibrate stronger. This is called resonance.  It's like pushing a child on a swing at just the right times to make the swing continue to swing and even to grow in amplitude.

Now you should see that methane is a greenhouse gas because of the frequencies at which its vibrating bonds absorb energy in the infrared part of the spectrum.  The same infrared energy that would otherwise be radiated into space.

Answer 4

Any gas which prevents heat from escaping into the atmosphere and thereby increases the earths overall temperature (Green house effect) is a greenhouse gas.

methane is, as I understand it, a MUCH worse gas than Co2. Like 50 times worse.

Answer 5

Methane is a greenhouse gas primarily because of it being alkaline and being released from petroleum whilst being processed, it burns to give off carbon dioxide and water and being an industrial source of hydrogen.

Answer 6

Methane trapped in marine sediments as a hydrate represents such an immense carbon reservoir that it must be considered a dominant factor in estimating unconventional energy resources; the role of methane as a 'greenhouse' gas also must be carefully assessed.  

Answer 7

because it traps in heat... like any other green house gass. did you know water vapor is a greenhouse gass aswell?