List the four stages of the policy life cycle, and show how the discovery of ozone layer destruction and the subsequent responses to it illustrate the cycle.

The stages of the policy life cycle typically include: 1. Problem identification, where an issue is recognized and articulated. 2. Policy formulation, where possible approaches to addressing the issue are developed. 3. Policy implementation, where the selected policy is put into action, and 4. Policy evaluation, where the effectiveness of the policy is assessed.

Now, let's apply these stages to the ozone layer destruction case. 1. Problem Identification: Scientists discover a hole in the ozone layer in the 1980s, identifying it as a major environmental concern. 2. Policy Formulation: The international community comes together to develop potential solutions, culminating in the Montreal Protocol, a policy aimed at phasing out substances that deplete the ozone layer. 3. Policy Implementation: Countries around the world ratified the Montreal Protocol and began implementing policies to reduce and eventually eliminate their use of ozone-depleting substances. 4. Policy Evaluation: The protocol has been amended several times based on scientific understanding and technological advances. Ozone depletion rates have significantly decreased, showing the effectiveness of the policy.