Common Resource
IntermediateA common resource is a good that is rivalrous, meaning one person's use reduces what is available to others, but non-excludable, meaning it is hard to stop people from using it. Examples include ocean fish, groundwater and clean air.
Because no one can easily be prevented from using a common resource, and each person's use leaves less for others, these resources are at risk of being overused. This problem is known as the tragedy of the commons.
Consider a lake where anyone can fish. Each fisher gains by catching as many fish as possible. But if everyone does this, the fish population collapses and everyone loses. Each person bears only a small part of the cost of overfishing, while gaining the full benefit of their own catch.
Other examples include overgrazing on shared land, overuse of groundwater and pollution of the atmosphere.
Solutions usually involve some form of rules or ownership. Governments may set quotas, such as limits on fishing catches, charge fees or taxes for use, issue tradable permits or assign property rights. Communities can also manage shared resources successfully through local rules and cooperation. The goal is to make users take account of the cost their use imposes on others.
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