POSSIBLE EFFECTS AND INTER-RELATIONSHIP BETWEEN CHANGES OF ATMOSPHERIC OZONE CONCENTRATION AND GLOBAL WARMING

Abstract

Halogenated organic compounds such as Chlorofluorocarbons (CFCs), Hydro fluorocarbons(HCFCs) and Halons are basically used as refrigerants, aerosol propellants, solvents, for firefighting and as form blowing agents. These gases are considered as the primary cause fordepletion of stratospheric ozone layer. Carbondioxide, Methane, Nitrousoxide, CFCs, HCFCs,Halons and Hydrofluorocarbons (HFCs) are categor.zed as greenhouse gases and are leading toa global warming due to their heat trapping ability. According to recent researches, scientistshave proven that there are both positive and negative impacts on global warming arising due tothe ozone layer depletion.

Carbondioxide is the major contributor for achieving the global radiative equilibrium, whichkeeps the earth temperature above its black body temperature. In the stratosphere, ozone absorbsenergy from solar radiation and cools via the infrared emission. Thin ozone layer will let moreultraviolet to troposphere where ozone concentraion will increase. Hence the increase inconcentration of ozone will lead to a cooling of the troposphere by emitting infrared radiation.This cooling will lead to two opposing effects. Lower temperature will slow down the reactionrates of the ozone destroying catalytic cycles in gas phase chemistry. On the other hand, lowertemperature causes the increase of probability to have more stratospheric clouds and increase theconcentration of CFCs trapped in the clouds. During the springtime CFCs are release from theseclouds and they will in turn enhance rapid depletion cf ozone layer.

Oxidation of methane in lower stratosphere leads to formation of water vapour and increase thepossibility of polar stratospheric clouds in middle laitudes. This will help to provide activatechlorine and bromine radicals and enhanced ozone depletion. CFCs and halons are both ozonedepleting substances and greenhouse gases. Inadvertently, alternatives for ozone depletingsubstances such as HFCs ale green house gases and as such enhance the global warming effect.