Today is the 40th anniversary of Earth Day.

Millions of people around the globe are holding events today that reflect on the planet and increase awareness of the environment. Back in 1970, when Earth Day was launched, the event was limited to Baby Boomer activists keen on seeing green. Now, of course, green is cool. Green is in. Green in hip. Green is, well, mainstream.

Even America’s giant corporations are involved with Earth Day activities. Good or bad, Earth Day is big business now, as a story in today’s New York Times points out. Companies like AT&T, Pepsi and F.A.O. Schwartz sponsor green events. And environmental agencies concede they must partner with corporate America in order to spread the word about the evils of fossil fuels.

But those who were involved with the movement back then lament that the environment is not a priority as it was then with participants of Earth Day. For most Americans, the environment sits low on the agenda. It’s certainly not a make-or-break issue in political campaigns. The fervor of the first Earth Day participants, say some, has been replaced with the convenience of going green with the utmost ease. It’s not hard to buy green these days.

Documentary filmmaker Robert Stone made an important point in a story that appeared in the New York Times today: that the environmental movement is a victim of its own success in clearing up tangible problems with air and water.

“Every Earth Day is a reflection of where we are as a culture,” he said. “If it has become commoditized, about green consumerism instead of systemic change, then it is a reflection of our society.”