Environmental problems can be difficult to deal with for several reasons:
1. Environmental processes may be complex and not fully understood. For example, both the physical and chemical pathways a pollutant takes through the environment may not be fully understood, nor may be its exact effects as it is dispersed and transformed.
2. Environmental problems are not respecters of political boundaries. Agricultural chemicals sprayed on fields in Kansas may find their way into tributaries of the Mississippi River and end up in the drinking water of a Louisiana community a few months later. Sulfur dioxide from smokestacks in Ohio may come down as acid rain in Vermont. In 1985 the United States and Canada held talks on acid rain because acid rains in eastern Canada result in part from oxides of sulfur and nitrogen released in the American Midwest. The ultimate environmental problem is probably the greenhouse effect largely resulting from increased levels of carbon dioxide in the atmosphere. Fossil fuel burned anywhere on the planet contributes to the problem, so that it can be fully addressed only at an international level.
3. The solution of one environmental problem may become the cause of another. For example, air-quality regulations require "scrubbers," which remove a certain percentage of sulfur from the smokestacks of coal-fired electric generating facilities. However, the resulting accumulation of sulfur- containing sludge can prove to be a source of groundwater pollution.
4. Environmental issues can arouse strong emotions and produce formidable political conflict because environmental decisions may deliver both large gains and large losses to particular individuals and groups.
In general the approach to environmental problems has been piecemeal, one pollutant or one source of emissions or one land-use question at a time. This approach is not because of shortsightedness or lack of vision. The problem of achieving higher levels of environmental quality is simply so complicated that a unified approach in which all side effects are considered has yet to be devised.
5. Environmental problems can be complicated by the tragedy of the commons, a term introduced many years ago by Garrett Hardin. The image he used was the village commons on which anyone can graze his animals for free. Ultimately, the commons are destroyed by overuse. In this analogy the atmosphere and the oceans could be said to be the world's commons. One can also find smaller examples where the party that does the environmental damage either faces no costs or only a fraction of the costs of their actions and therefore, acting out of self-interest, overuses the resource.1