Why are some greenhouse gases more powerful than others?
In: Chemistry
Greenhouse gases operate by absorbing infrared radiation. This is light coming from the sun – on the way to the earth, it has a lot of energy so can pass through most of the atmosphere without too much issue, but once it bounces off the earth it loses a lot of its energy. This makes it much easier for greenhouse gases to absorb the radiation. When a gas absorbs this infrared, it basically traps the heat inside the atmosphere, instead of allowing it to dissipate into space.
Different molecules have different abilities to absorb infrared radiation. This is a very complicated sciency thing that essentially boils down to the types of atoms it’s made from and the way in which those atoms are arranged.
We use a measurement called GWP to describe how impactful a gas is on climate change. It’s a measure of how much energy 1 ton of the gas will trap over a 100 year time period, relative to carbon dioxide. Since its relative to carbon dioxide, CO2 has a GWP of 1.
Methane is much better at absorbing energy than CO2 is, so it has a GWP of 28-36 (estimated), however, methane is also a lot less stable – methane only remains in the atmosphere for about a decade, whereas carbon dioxide can stay in the atmosphere unchanged for thousands of years.
N2O is another big offender, which has a whopping GWP of 265-298. This means that one ton of N2O absorbs 298 times more energy per 100 years than CO2 does.
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