Greenhouse Gases
Greenhouse gases are gases in the atmosphere that trap the heat reflected from the surface of the Earth. These gases include carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), chlorofluorocarbon-12 (CFCs), and hydrofluorocarbon-23 (HFCs), among other minor ones. This blanketing effect is actually a good thing – without these greenhouse gases life on Earth would not be possible, at least not how we know it. It keeps us warm. The problem is that now the blanket is too thick, and the overall average temperature of the Earth is increasing very fast. “The combined heating influence of all major greenhouse gases has increased by 43% since 1990”, illustrated by the figure below (NOAA).
As you can clearly see, carbon dioxide and methane are the two largest contributors. However, there are two important factors to note for each greenhouse gas: atmospheric residence time and global warming potential. Atmospheric residence time is the amount of time after emission that a greenhouse gas will remain in the atmosphere. For example, if a bus traveling down a street let out a big puff of exhaust, the greenhouse gases in that exhaust will remain in the atmosphere for a set amount of time before it dissipates and is cycled back to Earth. Global warming potential is a term referring to the potency of these greenhouse gases. As you continue to read, you’ll come to realize how important these two conditions are.
I fully realize that this can be confusing and that it’s a lot of information. So I have given each greenhouse gas their own section so it’s somewhat easier to digest and a lot of visuals. And as always, if anyone has any questions feel free to comment below!
| Greenhouse gas | Residence time | Global Warming Potential | Sources |
| Carbon dioxide | 100 years | 1 | fossil fuel combustion, deforestation, cement production |
| Methane | 12 years | 28-36x CO2 | fossil fuel production, agriculture, landfills |
| Nitrous oxide | 114 years | 298x CO2 | fertilizer application, fossil fuel and biomass combustion, industrial processes |
| CFCs | 100 years | 10,900x CO2 | refrigerants, compressed air (1930s) |
| HFCs | 270 years | 14,800x CO2 | refrigerants, compressed air (1930s) |
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