Final answer:
Chlorine, derived from chlorofluorocarbons (CFCs), is the primary molecule that destroys stratospheric ozone. It reacts with ozone to start a chain reaction that results in the breakdown of ozone molecules. The Montreal Protocol has significantly reduced CFC emissions, aiding in the recovery of ozone levels.
Step-by-step explanation:
The main molecule that destroys ozone in the stratosphere is chlorine, which comes from chlorofluorocarbons (CFCs). UV light in the stratosphere breaks down CFCs, releasing chlorine atoms that can destroy numerous ozone molecules through a series of chemical reactions. When chlorine atoms come in contact with ozone (O3), they catalyze a destructive cycle where a chlorine atom reacts with an ozone molecule to form chlorine monoxide (ClO) and molecular oxygen (O2). The chlorine monoxide can then release the chlorine atom to repeat the process with another ozone molecule. One single chlorine atom can destroy up to 100,000 ozone molecules. CFCs and other ozone-depleting substances (ODS) were mainly used in industrial applications such as refrigeration, air conditioning, and as propellants in aerosol sprays.
The production and use of CFCs have been phased out by the Montreal Protocol due to their damaging effects on the ozone layer. This international agreement is an example of how global cooperation can lead to positive environmental outcomes, leading to a decrease in CFCs in the atmosphere and a gradual reduction in the size of the 'ozone hole' over Antarctica.