International environmental public goods

Many of the externalities of biodiversity change stem from the fact that the ecosystem services supported by biodiversity are public goods. This encourages free-riding. Because people cannot be excluded from the benefits of environmental public goods once they are provided, they have an incentive to free-ride on the efforts of others. It also encourages undersupply. Because people cannot capture the benefits of provision, they have an incentive to supply less than is socially desirable. Both problems are especially acute for environmental public goods that span national boundaries. They do, however, vary from one environmental public good to another, depending on supply technologies and the existence of thresholds in the level of supply, or the number of contributing countries. The incentive for countries to free-ride on the efforts of others is greatest in the case of public goods with additive supply technologies such as the conservation of widespread but endangered species or climate regulation from carbon sequestration. The incentive to free-ride is least in the case of weakest-link technologies such as the management of infectious disease, pest control, or the eradication of invasive species. Conversely, the incentive for countries to act unilaterally is greatest in the case of best-shot supply technologies such as vaccine development, or the provision of information about pest and pathogen risks, and least in the case of additive technologies. Free-riding also depends on the costs and benefits of public good provision. It was noted, for example, that free-riding was likely to be less of a problem for (impure) public goods that also deliver a private benefit, such as quarantine and port inspections, than it is for (pure) public goods that do not.