07/08/2007 AT 03:00 PM EDT
John Mayer was eco-friendly onstage – wrapping up Live Earth by jamming with The Police at Giants Stadium on Saturday – but backstage he had some global warnings.
For one, don't ask him about Jessica Simpson.
"I'm going to practice some conversation conservation right now and minimize my bull---- footprint," he told a reporter who asked if Mayer still spoke to Simpson.
Also, don't ask him if he has any "eco-sins" (as many of Live Earth's electricity-using, private-jet-flying rockers readily confessed to).
"What is my eco-sin?" Mayer answered. "I don't know if that is that provocative a question for me. I don't know. I'm still trying to figure out what my motivation is – what is the positive side to the things that I could do?" He later added: "If you want to peg me as not being entirely eco-friendly, you'll win," though he said, "We have a tour, which is inherently carpooling."
Less confrontational was Kelly Clarkson, who says that while she recycles and carpools, she's still learning the best ways to conserve resources.
"We need just as much information as the audience," she said after her Giants Stadium set. "We're not brilliant. I'm not the most educated on the process, but I'm learning."
Rosario Dawson said backstage that not only is she "that person who turns off the light every time I walk out of a room," but that she'd seriously question dating anybody who isn't green.
"I'd probably have a really huge problem with that," she said.
Reporting by BETHANY LYE, KC BAKER and RENNIE DYBALL