A scientist takes a water sample from Monterey Bay in California to determine the environmental impact of pollution in the area's water.

The term environmental impact is a legal term introduced by the National Environmental Policy Act of 1969. This act requires federal agencies to conduct studies to determine the possible consequences for the environment of planned activity. Many states have enacted similar legislation. The results of the study are published as an environmental impact statement. These legal documents are often the basis on which an agency decides whether or not to proceed with a project.

All animals interact with their environment, so all animal activity, including human activity, has some environmental impact. However, human impact on Earth's environment far exceeds that of other species. Humans have altered the environment and landscape on a global scale.

Most species inhabit fairly limited regions within Earth's biosphere, but humans...