NEW YORK - Spinal Tap is back, and this time the band wants to help save the world from global warming.

The mock heavy metal group immortalized in the 1984 mockumentary "This is Spinal Tap" will reunite for a performance at Wembley Stadium in London as part of the Live Earth concerts scheduled worldwide for July 7.

The original members of Spinal Tap will be there: guitarist Nigel Tufnel (played by Christopher Guest), singer David St. Hubbins (Michael McKean) and bassist Derek Smalls (Harry Shearer). Rob Reiner, who both directed "This is Spinal Tap" and played the fake documentarian Marty DeBergi in the film, will also be there.

A new 15-minute film directed by Reiner on the band's reunion was scheduled to be played last night at the opening of the Tribeca Film Festival in New York.

The festival, which continues through May 6, opened with a showing of several global warming-themed short films produced by the SOS (Save Our Selves) campaign. SOS is also putting on the Live Earth concerts, to be held across seven continents.

"They're not that environmentally conscious, but they've heard of global warming," said Reiner. *