Greenhouse effect is the name for the process by which an atmosphere warms a planet, like Earth. This effect can be induced or influenced by Humans, often having a negative connotation if the greenhouse effect is not natural.
For years, the colonists on Penthara IV tried to avoid anything that would create a greenhouse effect. When the planet was hit by a type C asteroid in 2368 however, a greenhouse effect was the only thing that could save the colony from freezing. By boring holes into subterranean caverns filled with carbon dioxide and thereby releasing the gas into the atmosphere, the cooling down could be postponed for some time, giving the planet time to mend itself. (TNG: "A Matter of Time")