WASHINGTON — Soledad O'Brien, former CNN news anchor extraordinaire, was met with a puzzling situation last Saturday. She was co-hosting a massive Earth Day extravaganza on the National Mall. She was standing in front of a crowd she estimated at 250,000 people. She had a microphone. But she was talking and nobody was listening.

"The event's hosts, newscaster Soledad O'Brien and Black Eyed Peas bandleader Will.I.Am, appeared to have a rough time of it," the Washington Post's Chris Richards wrote. "O'Brien, either frustrated by glitchy teleprompters or perhaps not clear on how a concert works, actually shushed the crowd at one point."

O'Brien's dilemma reflected what some see as a problem with Earth Days of recent vintage. Even as companies, celebrities, and the likes of My Morning Jacket and No Doubt stand by to do what they can for the planet, what they're doing doesn't seem to amount to much.

"Launched in 1970 as a protest against corporate environmental misconduct, Earth Day has become a planet-hugging marketing frenzy for companies themselves," the Wall Street Journal wrote in 2008. "Makers of everything from snack chips to sport-utility vehicles now use April 22 to boast about their efforts to help save the planet."

'Twas not always so. When Sen. Gaylord Nelson, D-Wis., saw the waters off Santa Barbara, Calif., turn black in 1969 after what was then the worst U.S. oil spill, organizing a rock concert was not on his mind. Faced with ghastly images of oil-covered birds and meager attempts to soak up oil slicks with straw, he wanted to build a coalition across political parties — across country and city.

"Gaylord's unique contribution is that he was the first person to see the political importance of conservation, that it could be used to mobilize people," Denis Hayes, one of the first Earth Day's organizers, said after Nelson's death in 2005. "He recognized the partnership between traditional conservation issues and the new emerging urban and industrial issues. Largely forgotten is that he was the first and most important to help us build bridges between environmental concerns and organized labor."

It worked. Twenty million people came out on April 22, 1970, to rally, raise hell and clean up.

"The reason Earth Day worked is that it organized itself," Nelson said. "The idea was out there and everybody grabbed it. I wanted a demonstration by so many people that politicians would say, 'Holy cow, people care about this.'"

Perhaps not coincidentally, the Environmental Protection Agency was created in 1970, the Clean Water Act was passed in 1972 and the Endangered Species Act was passed in 1973. In a country where Ohio's Cuyahoga River had caught fire less than a decade before, a Republican president, Richard M. Nixon, signed executive orders and legislation that would begin the process of cleaning up the nation.

Then, even as the Earth kept warming up, a long, cold winter set in.

"Ten years later, it has become popular in some circles to write the obituary of the environmental movement, to refer to the passing of the 'golden era' for environmentalism," Nelson wrote in 1980. "It is asserted that public interest has waned, that new worries have captured attention, that inflation, the energy crisis, and international conflict have superseded if not wiped out public concern over environmentalism."

But the "golden era" really was a golden era. Nelson was awarded the Presidential Medal of Freedom in 1995, but momentum had stalled.

"One could argue that there has been no major environmental legislation since 1990, when President George H. W. Bush signed a bill aimed at reducing acid rain," the New Yorker wrote in 2013 after the Senate tabled what would have been a landmark bill on carbon emissions. "Today's environmental movement is vastly bigger, richer, and better connected than it was in 1970. It's also vastly less successful."

Nelson had envisioned Earth Day as a "teach-in." When Earth Day returned in 1990, it "sought to 'enlist' people in a well-defined movement, not to enable them to work out their own vision of how they might make a difference," as Adam Rome, who wrote a book about the celebration, told the New Yorker.

So, the United States still hasn't ratified the Kyoto Protocol. The messaging of the day may be lost amid promotional products and greenwashing. But we do have Earth Day T-shirts and hoodies.

As Hal Harvey, environment-program director for a funder of prominent environmental groups, told the Wall Street Journal: "The danger is we let ourselves be happy with gestures rather than substance."

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