As CO2 accumulates in the atmosphere, trapping and re-radiating heat, Earth continues to warm. Rising CO2 acts like a blanket, reducing the amount of energy escaping into space and causing the lower atmosphere, and surface, to warm.
A long-standing misconception is that the greenhouse effect is “saturated,” suggesting that adding more CO2 will not increase the amount of energy being trapped. This view fails to recognize that the atmosphere consists of multiple layers.
Heat energy can only escape Earth from the upper atmosphere where the air is thin. CO2 adds “thickness” to upper atmospheric layers, which are not yet saturated. This lowers the rate of heat escape, much like adding more blankets to a bed.