O3 is produced when nitrous oxides from exhaust fumes from e.g. cars, come under the influence of sunlight. CFCs, Chlorofluorocarbons, are non- toxic chemicals used in coolants and some plastics. CFCc were previously used in spray boxes as a propellant. CFCs are harmful to the stratospheric ozone layer and are powerful greenhouse gases. Norwegian emissions of these gases have been substantially reduced since 1985.
Time lag Some greenhouse gases remain in the atmosphere for decades and even centuries at a time.
Consequently, the planet may continue to warm, even if we stopped producing all man-made emissions at once. The effect of this global warming on sea level rise and other ecosystem changes could be dramatic. As the economies of Central and Eastern Europe revive and as the Third World continues to boom, we can expect further increases in the production of fossil fuels. Meanwhile, the warming trend resumes with a rise in the Earth's temperature in 1994, the fifth warmest year recorded since official record keeping began around 1860. The respite of Mt. Pinatubo's eruption and the cooling effect of millions of tons of sulfate aerosols served only to delay the inevitable to provide a short-term test of the computer climate models.