environmental impact

A change in the make-up, working, or appearance of the environment. These changes may be planned, like afforestation, or accidental, like the introduction of Dutch elm disease into Britain. Most accidental impacts bring about undesirable change, and deliberate actions may have an unexpected impact, as when the construction of a sea wall leads to the destruction of a beach. Sometimes the damage is irreversible, like the introduction of DDT into food webs.

Environmental Impact Assessment, EIA seeks to consider the probable consequences of human intervention in the environment so as to restrict environmental damage. The USA and European Union, for example, require, for any proposed development, an environmental impact statement (EIS), which gives: a brief description of the proposal; its likely impact on the environment; the range of predicted adverse and beneficial impacts, both direct and indirect; a consideration of whether these impacts are likely to be long- or short-term, reversible or irreversible, and whether the impacts are of local and/or national strategic significance.

The EIS should use empirical information, and distinguish and develop methods and procedures, to make sure that unquantified environmental factors are properly considered in decision-making. An EIS may include rankings or hierarchies to distinguish the degree of importance or magnitude of impacts, although this can be difficult to do, objectively. see environmental accounting.