There are various different gases in the atmosphere, including 78% nitrogen, 21% oxygen, 0.93% argon, and 0.04% carbon dioxide (CO2) . Now hold on, just 0.04% CO2? Yes! That’s enough to have a big warming effect on the planet . How does this work?
Sunlight (also called solar radiation ) comes in different frequencies . Around half of the light coming from the sun comes in frequencies we can see (e.g. green) and the other half in ones we can’t see (e.g. infrared and ultraviolet) [5,6]. There are three things that can happen to it once inside the atmosphere :
1) About 30% is reflected back into space by clouds, gases, particles, and the Earth’s surface
2) About 20% is absorbed by the atmosphere
3) About 50% is absorbed by the land and ocean
Now comes the most important bit: when light from the sun hits the Earth, the Earth reflects it back with a changed frequency, most often infrared . This is where greenhouse gases, such as CO2, come in: they absorb infrared light more than other types of light (e.g. many of those coming from the sun).
Why does this cause warming? Absorbing light, makes greenhouse gases vibrate more ; they are “energized” and collide with other molecules, transferring energy to them . This is what heat is . Therefore greenhouse gases increase the temperature of the air . You can think of this as “trapping” heat close to the Earth .
 https://www.ipcc.ch/site/assets/uploads/2017/09/WG1AR5_Chapter01_FINAL.pdf Within report see: Key Concepts in Climate Science, page 126
 https://www.acs.org/content/acs/en/climatescience/greenhousegases/properties.html Within article see: paragraph 2
 https://science.nasa.gov/ems/07_infraredwaves Within article see: monitoring the Earth
 https://www.acs.org/content/acs/en/climatescience/greenhousegases/properties.html Within article see: paragraph 3
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