Is it reasonable to believe carbon dioxide from human activity warms the Earth?
Ultraviolet radiation enters the atmosphere and warms soil, rock, and so on. The warmed matter radiates infrared radiation. The idea is that the infrared escapes into space more easily if there is less carbon dioxide in the air, and stays if there's more.
* The physics is well understood, and can be demonstrated in a laboratory;
* The planet is warming;
* There has been a correlation between temperature (with a dip in the 1940s) and industrial production of carbon dioxide since about 1870, when consistent, global measurements began;
* There has been a correlation between ancient temperatures and atmospheric carbon dioxide shown in ice cores and and mud cores taken from under the oceans;
* The atmosphere has warmed, as shown by a higher tropopause (the boundary between the lower atmosphere and the stratosphere; gases expand when they are warmed).