So what do these gases do? Greenhouse gases are transparent. They live in solar radiation invisible light. We can see right through them, like a window. But the infrared radiation, we can’t see. The infrared radiation is what the earth gives off to the rest of the universe and so it traps that heat in the atmosphere. It kind of works like this: Imagine a version of earth with no atmosphere, like the moon. It would absorb the suns radiation and warm up, the sun’s heating the ground causing the ground to warm up. The ground, just obeying the laws of physics would also give off heat or infrared radiation back to the rest of the universe. And without an atmosphere this is what it would look like, the sun’s heat come in the earth’s heat goes out and they would be in perfect balance keeping us at a temperature that we’d be in balance with that.
Now let’s add an all natural atmosphere so we’d have the natural greenhouse effect. The idea is as the earth is radiating it’s heat some of it would be absorbed by the air above it that then would be re-radiated back down to the earth’s surface. That the ability to making the earth’s surface a little bit warmer and the air above it a little bit warmer and that exactly what the earth has had and so have all of the other planets, Venus, Mars and others also have a greenhouse effect like that.
But then humans come along and we add some more of those gases into the atmosphere. It’s like adding another blanket onto your bed in the winter time, it traps more heat and keeps us warmer. So this enhanced greenhouse effect traps a little bit more heat radiates the a little bit more to warm the surface even more. So far we’ve warmed the planet by about 1 degree Celsius. I know that doesn’t sound like a lot but think about it, during the last ice age the planet as a whole was only 3 degrees colder than normal and was a totally different planet. We were under about a mile of ice. We’ve warmed the planet in the other direction by about 1 degree so far and we’re going to keep going. If we warmed the planet another 3 or 4 degrees, that could be a planet we won’t even recognize and could be very, very dangerous for our civilization.
So where do these gases come from? I’m sure that you’ve already heard that a lot of them come from burning fossil fuels, oil, natural gas, petroleum and all of these other gases that we have. And that is part of the story. Burning fossil fuels does create CO2 and that causes about 62 percent of the warming we see on the planet today. But CO2 is also produced by a few other things including chemistry. In fact a lot of industry releases CO2 into the atmosphere as well such as making cement. We also release a lot of CO2 into the atmosphere by burning down trees and deforestation, which is 11 percent. Our next green house gas is methane. Methane is produced several different things but it mostly is from agriculture and industry. Agriculture which is about 2/3 of methane emission is caused largely by cattle. Cows actually burp methane, not fart methane! The other 1/3 of this methane comes from industry, especially mining natural gas. So we need to think about energy, industry and agriculture as sources of methane. Theirs is also nitrous oxide, which most people don’t even think about but it’s a big part of our climate change equation. It comes from industry but a lot comes from agriculture from using too much fertilizer and/or manure on our farmer’s fields. And finally we have F gases or fluorinated gases, which are chemical used as refrigerants or sometimes as insulators in industrial process. And those refrigerants are rising drastically, and that’s why we have to pay attention to them. Putting all those gases together we emit about 52 billion metric tonnes of CO2 into the atmosphere each year. The next time we will talk more about that and how we can cut that down.
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