Methane Role In The Atmosphere

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I read that methane is an even worse greenhouse gas than carbon dioxide, and cattle are a big source of methane emissions. How are they going to regulate that? Not just cattle, but dairy cows as well! That doubles the worry.

Fortunately, there is really nothing to worry about, scientifically. The main thing to worry about is over-reacting politicians and another layer of unnecessary government regulations.

To understand methane’s role in the atmosphere, first it’s necessary to understand what absorption means. When light passes through a gas (sunlight through air, for example), some molecules in the gas might absorb a photon of light and jump up to an excited state. Every molecule is capable of absorbing some particular wavelengths of light, and no molecule absorbs all the light that comes along. This holds true across the entire electromagnetic spectrum – microwave, infrared, visible,
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CH4 is 20 times more effective an absorber than CO2 – in those bands. However, CH4 is only 0.00017% (1.7 parts per million) of the atmosphere. Moreover, both of its bands occur at wavelengths where H2O is already absorbing substantially. Hence, any radiation that CH4 might absorb has already been absorbed by H2O. The ratio of the percentages of water to methane is such that the effects of CH4 are completely masked by H2O. The amount of CH4 must increase 100-fold to make it comparable to H2O.

Because of that, methane is irrelevant as a greenhouse gas. The high per-molecule absorption cross section of CH4 makes no difference at all in our real atmosphere.

Unfortunately, this numerical reality is overlooked by most people. There is a lot of misinformation floating around, causing needless worry. The tiny increases in methane associated with cows may elicit a few giggles, but it absolutely cannot be the basis for sane regulations or national

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