Earth Day reverberated around the world on Sunday, with festivals from Tokyo to Barcelona to San Francisco. In the United States, the key urban festivals attracted crowds of thousands as entertainers blasted music in New York City’s Central Park, the Mall in Washington D.C. and Golden Gate Park in San Francisco.

But while the day was intended for fun and learning, Earth Day organizers stuck to business, collecting names for the “Sky petition” that asks lawmakers to pass more stringent global warming legislation. The lead up to Earth Day (officially on Tuesday) aims to raise a collective call for action by Congress. “If you do one thing, call the Capitol,” said Judit Varga of the Earth Day Network at the Dallas event. That number: 202 224-3121.

Photo © 2008 by Kim Komenich | Distributed by Noofangle Media

San Francisco: Though she wasn’t on the official concert lineup, singer and activist Joan Baez dances on stage during an appearance Sunday at the 2008 Green Apple Festival. Commemorating Earth Day, the show at San Francisco Golden Gate Park was one of eight major festivals in the U.S.

• View the full San Francisco slideshow

Photo © 2008 by Justin Kase Conder | Distributed by Noofangle Media

Washington D.C.: A globe illustrating the “cap and trade” environmental program sits against a cloudy sky late Sunday afternoon on the mall in Washington D.C., as a Green Apple Festival stage crew member makes his way across the back of the concert stage. The festivities were part of the national Green Apple Festival, “America’s Largest Earth Day Celebration.” Lightning and heavy thunderstorms forced organizers to cancel the D.C. event half-way through, for the safety of those attending.

• View the full Washington, D.C. slideshow

Photo © 2008 by Barbara Kessler | Distributed by Noofangle Media

Dallas: Children at Dallas’ Fair Park look over a one-person electric car owned by Nancy Brecher of the North Texas Electric Auto Association. The event included performances by Junior Brown and Los Lonely Boys.

• View the full Dallas slideshow