| > And why is it that modifying such a small part of the atmosphere (0.04%) can cause such a huge problem? The modification is invisible to you, but not invisible to the photons which are supposed to leave the atmosphere and cool off the earth a bit. It it were visible to you, it would look like this: https://www.youtube.com/watch?v=81FHVrXgzuA Regarding the photons of thermal frequencies leaving the Earth atmosphere, or remaining there, the simplest you can imagine is a blanket: if it's cold outside the blanket keeps the heat not leaving the area under the blanket, keeping you warm. Here, the CO2 is actually a "one-way" blanket, it doesn't block the incoming radiation: The heat coming from Sun has other frequencies as it comes than the photons blocked that would cool off the Earth. The key is: CO2 is an ink-black "blanket" for exactly a part of the radiation that cools off the Earth. It's not too big, but big enough to make in sum that 0.8 C degree change since 1880. Or to produce even more warming in the coming years as we burn always more and we haven't managed to change that. A little more precise: "Energy arrives from the sun in the form of visible light and ultraviolet radiation. The Earth then emits some of this energy as infrared radiation. Greenhouse gases in the atmosphere 'capture' some of this heat, then re-emit it in all directions - including back to the Earth's surface." (There's of course infrared radiation coming from the Sun, but the one making problem is the radiation from the Earth) Scientific details, like absorption spectra and the measurements, are here: https://skepticalscience.com/print.php?r=35 A little simpler explanation by American Chemical Society: https://www.acs.org/content/acs/en/climatescience/climatesci... Or even, for kids, "meet Mr. Sunbeam" part from Futurama: https://www.youtube.com/watch?v=0SYpUSjSgFg |