As a vocalist-guitarist in the band Guster, Adam Gardner knows that environmental activism and the rock 'n' roll lifestyle aren't a natural fit.

"It's not easy to go green when you're on the road," says Gardner, whose New England-based band has toured extensively with acts such as Barenaked Ladies. "Your job is to put on a show night after night, and try to stay healthy.

"It's not something that many bands can really take on all by themselves. They don't have the information or the resources."

Gardner and his wife, Lauren Sullivan, established the nonprofit organization Reverb to assist musicians in their efforts to be friendly to the globe while they travel it.

Reverb has worked with 50 tours since 2004, often helping musicians select biodiesel for fuel, biodegradable material for dining needs and organic cotton for souvenir T-shirts.

The other half of Reverb's mission, Gardner says, is to relay the conservation message to concert attendees.

"It starts with the artist, and it reverberates out to the fans, their friends, etc.," he says.

One of Reverb's high-profile associates, singer-songwriter Jack Johnson, ranked No. 1 on Billboard magazine's list of Top 10 "green" musicians published in March. Johnson will perform June 13 at Verizon Wireless Music Center to promote his current album, "Sleep Through the Static."

Johnson oversees the All at Once online community (www.jackjohnsonmusic.com/allatonce), where fans explore topics ranging from climate change and water quality to land preservation and community gardens. All at Once spotlights Keep Indianapolis Beautiful and Friends of the White River as local organizations scheduled to be on hand at Johnson's June 13 concert.

"I'm not even sure he would be touring if there wasn't an environmental campaign associated with the tour," Gardner says.

To save paper, Johnson prohibited concert promoter Live Nation from printing fliers to advertise the Verizon date.

"I like that he uses his celebrity to push people to think differently," says Live Nation spokeswoman Susan Kreiner.

Johnson and other musicians work to reduce their carbon footprint -- often defined as the amount of carbon dioxide emitted during day-to-day life -- as they travel from city to city. But 85 percent of any tour's "footprint" is from fans driving to and from shows, Reverb statistics say.

For Radiohead's Aug. 3 date at Verizon, the U.K. rock band is setting aside "preferred" parking spaces for fans who arrive in hybrid vehicles or in vehicles carrying five or more passengers.

Radiohead isn't linked to Reverb, but John 8Mayer (set to play July 5 at Verizon), the Dave Matthews Band (July 25-26 at Verizon) and Maroon 5 (Aug. 28 at Verizon) are.

Reverb co-founder Gardner says he tries to apply light-hearted context to a serious issue.

"It's not a sky-is-falling, doomsday message at all," he says. "It's about positive ways we all can be making differences."

About Reverb Founded by husband-and-wife team Adam Gardner and Lauren Sullivan, Reverb assists musicians through environmental education and outreach to fans. Visit www.reverbrock.org.

"Green" musicians headed to Indianapolis

Missy Higgins, May 1, the Vogue. Ranked No. 9 on Billboard magazine's list of Top 10 "green" musicians, Higgins is a 24-year-old Australian who performed during last summer's Live Earth concert in Sydney. Higgins uses recycling facilities backstage at venues and on the tour bus, and uses organic produce. Visit www.missyhiggins.com

Panic at the Disco, May 18, the Murat Egyptian Room. A portion of the proceeds from each ticket to this spring's Honda Civic Tour starring rock band Panic at the Disco will be donated to nonprofit tour partners Reverb and Global Inheritance. Visit civictour.honda.com/eco-partner

KT Tunstall, May 21, the Murat Egyptian Room. Ranked No. 6 on the Billboard list, Tunstall fuels her tour bus with biodiesel. Visit www.kttunstall.com/ecology

Jack Johnson, June 13, Verizon Wireless Music Center. Ranked No. 1 on Billboard's list of "green" musicians, Johnson oversees the environment-themed online community All At Once. Visit www.jackjohnsonmusic.com/allatonce

John Mayer, July 5, Verizon Wireless Music Center. Rock star Mayer endorses utility/grocery bags made from hemp, and he has donated cash to Keep Indianapolis Beautiful, according to KIB executive Linda Broadfoot. Visit www.johnmayer.com

Dave Matthews Band, July 25-26, Verizon Wireless Music Center. Ranked No. 4 on Billboard's "green" list, the group uses biodegradable and reusable catering products while on tour. Visit www.davematthewsband.com

Radiohead, Aug. 3, Verizon Wireless Music Center. Ranked No. 8 on the Billboard list, Radiohead offers parking perks to fans who carpool or drive hybrid cars to concerts. Visit www.radiohead.com

Maroon 5, Aug. 28, Verizon Wireless Music Center. The members of pop-rock band Maroon 5 promote the Global Cool initiative, which aims to motivate 1billion people to reduce personal energy use by 2017. Visit www.maroon5.com