This is a list of notable events relating to the environment in 1978. They relate to environmental law, conservation, environmentalism and environmental issues.

• The Kessler syndrome is proposed. It is a scenario in which the density of objects in low Earth orbit is high enough that collisions between objects could cause a cascade – each collision generating debris which increases the likelihood of further collisions. It would render space exploration unfeasible for a period of time.
• The Australian state of Victoria passes the Environment Effects Act 1978.
• The environmental issues surrounding the notorious Love Canal, a former dump site in the neighborhood in Niagara Falls, New York, in the United States, is highlighted in the media.
• The Royal Commission on Nuclear Power Generation in New Zealand reported back to the Government. The report concluded that there was no immediate need but it may be economically possible in the 21st century.
• The Green Wall of China, a major series of tree planting designed to hold back the expansion of the Gobi Desert, was started. There has been some debate about the effectiveness of the project.

• Human impact on the environment
• List of environmental issues