Global public goods are characterized by non-excludability and non-rivalry. Which statement is correct?

• A. They are non-excludable and rival; example: eradication of smallpox
• B. They are excludable and rival; example: biodiversity protection
• C. They are non-excludable and non-rival; example: climate stability
• D. They are exclusive private goods; example: bottled water

Answer: (C)

Global public goods are defined by non-excludability and non-rivalry: you can’t practically prevent people from benefiting, and one person’s use doesn’t reduce another’s ability to benefit. Climate stability fits this perfectly because its benefits accrue to everyone around the world, and one country’s experience of a stable climate doesn’t diminish others’ ability to enjoy that same stability. In other words, no one can be easily shut out from the advantages of a stable climate, and many people can enjoy those benefits simultaneously without them getting used up.

The other options misrepresent how these goods work. Eradicating a disease is a global benefit, but the example that pairs it with rivalry contradicts the idea of a non-rival public good, since widespread health improvements from eradication are shared broadly. Biodiversity protection involves valuable public benefits as well, but it often includes elements that are excludable or rival in use, depending on how resources are managed. Bottled water is a classic private good—excludable and rival—so it doesn’t describe a global public good.