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It's pretty easy to model to a first approximation. Gases like Carbon Dioxide reflect certain wavelengths of infrared. When they are present in the atmosphere,
by throwway120385 1mo ago
It's pretty easy to model to a first approximation. Gases like Carbon Dioxide reflect certain wavelengths of infrared. When they are present in the atmosphere, they are present at a certain percentage concentration, and as that increases they reflect more infrared.
This matters because there are three ways for a body to eliminate thermal energy: radiation, convection, and conduction. Earth is not in contact with anything else, so it cannot conduct. It does not share an atmosphere with anything else, so it cannot convect. So that leaves radiation, which is largely in the form of infrared. Then it stands to reason that if you change how much IR is reflected back to the surface by the atmosphere, say by changing the amount of CO2 in the atmosphere, then you will increase the amount of heat the Earth contains as long as there is a source of heat nearby or within. Earth has both in the form of a molten core and the Sun.
This is why they call them "greenhouse gases." Because they cause the Earth to retain more heat than it radiates in the infrared spectrum, like the glass on a greenhouse.
- OroPla 1mo agoI'm not having trouble understanding the physics. CO2 levels are now around 400ppm. During the Cambrian age it was ten times of that at around 4000ppm. If CO2 levels were so much higher before humans existed, then how did it go down? (My understanding is that plants store it by growing.) And how can we be sure that it is emissions that makes it go up, rather than killing forests that used to store it? Wouldn't it be effective to just plant a bunch of forests in our deserts that store the CO2? California used to be mostly desert, too, but then some guy from Germany came and redirected some water to make it not as much of a desert anymore and that was over 200 years ago.