The global commons are global natural resources not particular to any one state, such as the atmosphere, the oceans and the fish in them. Valuable as they are to individual users and to the collective as a whole, free commons deter ameliorative or preventive action by individual users since that is perceived as conferring advantages and benefits on those users who fail to participate in such ameliorative action. Since nature is assumed to be a public good, destruction of forests, for example, goes unchecked although these negatively affect micro-regional, national and global environmental levels where this impact is ignored in the interest of immediate industrial gains.
The scale of human activities is the primary source of pressures on ecosystems today. These pressures are altering natural landscapes, degrading ecosystems and reducing biological diversity. The "tragedy of the commons" is the absence of a rational reason to restrain harvests that are freely available to others, (often applied to potentially renewable resources such as fisheries) and is one root cause of these pressures.
Our global commons are frequently taken for granted since they do not have any perceived owners. They are being heavily impacted since there are few incentives to manage and use them sustainably. Major threats to the global commons are posed by increasing levels of atmospheric carbon dioxide, massive use of fertilizers, and overexploitation of marine fisheries.
Energy production, for example, yields valuable services whose allocation in the economic system is, like goods and services in general, effectively handled through the market place and property rights (in a market-oriented society). But the residual mass of these energy resources, after use, flows back into the common-property resources, within or across countries, namely into the atmosphere or into water systems. When access to such waste refuses is unimpeded and free, overuse and degradation is the inevitable result.