Biology professor Ron Scribner recalls the first Earth Day that took place in 1970. Previous to 1970, environmental issues attracted little attention from American society and the media.

“It was a big deal — what you would imagine,” Scribner said. “They had speakers and a lot of … hippies sitting around, playing music and talking about the environment.

The date may surprise some people, since global warming was not a well-known issue at that time. In fact, when Earth Day started, the people involved were mostly concerned with things like pollution and the loss of wilderness.

According to earthday.org, the man to thank for Earth Day is former U.S. Sen. Gaylord Nelson.

“The idea came to [Nelson] after witnessing the ravages of the 1969 massive oil spill in Santa Barbara, Calif.

“Inspired by the student anti-war movement, he realized that if he could infuse that energy with an emerging public consciousness about air and water pollution, it would force environmental protection onto the national political agenda.”

And so Earth Day was born.

The first Earth Day (which was only celebrated in the U.S. at the time) had 20 million participants.

Scribner said it changed everything.

“… What came out of that was … a new consciousness of what was going on with our environment,” he said.

Scribner recalled the year before the first Earth Day, when the Cuyahoga River in northeast Ohio that feeds into Lake Erie caught fire from the pollutants it contained.

“Things were in pretty bad shape,” he said. “But the [impact] of the first Earth Day and the subsequent Earth Days was the Clean Air Act and all the legislation to clean up our water, and regulation of auto pollution. It really did change things.”

Now, more than 1 billion people participate in Earth Day every year.