First launched as an environmental awareness event in the United States in 1970, Earth Day (April 22) is celebrated as the birth of the environmental movement.

The first Earth Day, spearheaded by Wisconsin Governor Gaylord Nelson and Harvard University student Denis Hayes, involved 20 million participants in teach-ins that addressed decades of environmental pollution.

The event inspired the US Congress to pass clean air and water acts, and establish the Environmental Protection Agency to research and monitor environmental issues and enforce environmental laws.

In 1990, two million Canadians joined 200 million people in 141 nations in celebrating the first International Earth Day.

After all, a major message of Earth Day is that every single person has an important role in the environment.

Thirty years later, the focus has changed but the urgency remains the same. Due to increasing amounts of scientific evidence that fossil fuels are changing the global climate, the theme for Earth Day 2000 is Clean Energy. The four major goals of Earth Day 2000 are clean cars, clean power, clean air, and clean investments.