Ethene is a colorless flammable gas with a faint "sweet and musky" odor when pure. Ethylene is widely used in chemical industry. Ethylene is also an important natural plant hormone, used in agriculture to force the ripening of fruits. it is a non refrigerant.
$CO _2$ goes in the atmosphere and make a thick layer, this layer allowes the light to enter into the atmosphere but do not allow it to exit, the heat get trapped into the atmosphere and leads to the warming up of the surface.